News, 1891, 63, p. 1); just above the boiling point the vapour is orange-yellow, but on continued heating it darkens, being deep red at 50o; at higher temperatures it lightens, becoming straw-yellow at 650°.
At low temperatures SA predominates, but as the temperature is raised S, increases; the transformation, however, is retarded by some gases, e.g.
The runners might encounter any kind of weather, including freezing temperatures, fog, rain, or snow.
He wondered about the different temperatures of their bodies.
Heated at 190-300° in a current of hydrogen it gives the oxide C0304, while at higher temperatures the monoxide is formed, and ultimately cobalt is obtained.
It is a bluish-black powder which at high temperatures decomposes into the metal, dioxide and oxygen.
1 3 2, p. 374), is an exceedingly stable colourless gas at ordinary temperatures, becoming solid at about -120° C. Sulphuryl chloride, SO 2 C1 2, first obtained in 1838 by Regnault (Ann.
Ouray County was perfect for invigorating outdoor activity, with its crystal clear air and dry, windless temperatures just below freezing.
The pod was well-insulated; she didn't feel the three-thousand-degree temperatures a foot from her.
The average temperatures are: at Vyernyi (2405 ft.
Hansen showed that the microscopic appearance of film cells of the same species of Saccharomycetes varies according to the temperature of growth; the limiting temperatures of film formation, as well as the time of its appearance for the different species, also vary.
At low temperatures, on the other hand, they find, using an initial pressure of 'coo mm., that the temperatures on the helium scale are measurably higher than on the hydrogen scale, owing to the more perfectly gaseous condition of helium.
The variations of temperature are very great in Siberia, amounting near the coast to more than 100° Fahr., between the mean of the hottest and coldest months, and to still more between the extreme temperatures of those months.
Equally disastrous are those climatic or seasonal changes which involve temperatures in themselves not excessive but in wrong sequence; how many more useful plants could be grown in the open in the United Kingdom if the deceptively mild springs were not so often followed by frosts in May and June!
Schwann in 1839) was studied by Hansen, who found that each species only developed spores between certain definite temperatures.
Temperatures above ioo° and below-15° are rare.
Thus at high temperatures a helium thermometer is of no special advantage.
It does not react with the alkali metals, but combines with magnesium at a low red heat to form a boride, and with other metals at more or less elevated temperatures.
It also possesses the power of combining with most metallic oxides at high temperatures, forming borates, which in many cases show characteristic colours.
summer and mean winter temperatures may be set down as averaging not more than 20°, a range smaller than is found in most other parts of the world.
temperatures radiates out a most brilliant white light.
Beyond this parallel the gradient is directed towards the north-west, and temperatures are much higher on the European than on the American side.
Below 500 fathoms the western centres of maximum disappear, and higher temperatures occur in the eastern Atlantic off the Iberian peninsula and north-western Africa down to at least 1000 fathoms; at still greater depths temperature gradually becomes more and more uniform.
The communication between the Atlantic and Arctic basins being cut off, as already described, at a depth of about 300 fathoms, the temperatures in the Norwegian Sea below that level are essentially Arctic, usually below the freezing-point of fresh water, except where the distribution is modified by the surface circulation.
The isothermals of mean surface temperature in the South Atlantic are in the lower latitudes of an cn- shape, temperatures being higher on the American than on the African side.
The climate is hot and humid in the lowlands and along the lower Parnahyba, but in the uplands it is dry with high sun temperatures and cool nights.
Rice is cultivated in low-lying, moist lands, where spring and summer temperatures are high.
in greenhouses where plants requiring very different optimum temperatures and illumination are kept together.
The indirect geographical elements, which, as a rule, act with and intensify the direct, are mainly climatic; the prevailing winds, rainfall, mean and extreme temperatures of every locality depending on the arrangement of land and sea and of land forms. Climate thus guided affects the weathering of rocks, and so determines the kind and arrangement of soil.
high), for the year 46.4° F., for January 17°, for July 74°; at Przhevalsk (5450 ft.), for the year 36.5°; for January 23°, for July 63°; still higher in the mountains, at Naryn (6900 ft.) the average temperatures are only, for the year 43.
It is unstable at ordinary temperatures and rapidly decomposes into its generators on warming.
The aqueous solution of the acid is fairly stable at ordinary temperatures.
The lowest temperatures are experienced in January, the average being as low as 20° to 5° Fahr.
On the whole, February and March continue to be cold, and their average temperatures rise above zero nowhere except on the Black Sea coast.
The summer isotherms cross the winter isotherms nearly at right angles, so that Kiev and Ufa, Warsaw and Tobolsk, Riga and the upper Kama have the same average summer temperatures of 64°, 622° and 61° respectively.
A " perfect engine " receiving and rejecting steam at the same temperatures as the actual engine of the locomotive, would develop about twice this power, say 1400 I.H.P. This figure represents the ideal but unattainable standard of performance.
Table Xxi It is instructive to inquire into the limiting efficiency of an engine consistent with the conditions under which it is working, because in no case can the efficiency of a steam-engine exceed a certain value which depends upon the temperatures at which it receives and rejects heat.
If h is the water heat at the lower temperature, h l the water heat at the higher temperature, and L the latent heat at the higher temperature, the heat supply per pound of steam is equal to h1 - h2+L1, which, from the steam tables, with the values of the temperatures given, is equal to 1013 B.Th.U.
Compound working permits of a greater range of expansion than is possible with a simple engine, and incidentally there is less range of pressure per cylinder, so that the pressures and temperatures per cylinder have not such a wide range of variation.
Both hot and cold springs are numerous, with temperatures ranging from 50° to 204° F.
In spite of the high temperatures of summer, however, the low humidity prevents the heat from being oppressive, and cases of sunstroke are unknown.
The spleen continues to enlarge; the urine is now scanty and high-coloured; the body temperature is high, but the highest temperatures occur during the chill; there is considerable thirst; and there is the usual intellectual unfitness, and it may be confusion, of the feverish state.
since the initial and final temperatures, which alone determine the variation in the thermal effect, are in almost all cases within the ordinary laboratory range of a few degrees, this influence may in general be neglected without serious error.
But during the summer, temperatures are affected as much by altitude as by latitude, and the coast is cooled at night by breezes from the Gulf.
The climate of Minas Geraes is characterized by high sun temperatures and cool nights, the latter often dropping below the freezing point on the higher campos.
The temperatures at the head of the Persian Gulf approximate to those of northern India, and those of Aden to Madras.
The extreme temperatures in Siberia may be considered to lie between 80° and 90° Fahr.
These figures sufficiently indicate the main characteristics of the air temperatures of Asia.
The very high summer temperatures of the area north of the tropic of Cancer are sufficiently accounted for, when compared with those observed south of the tropic, by the increased length of the day in the higher latitude, which more than compensates for the loss of heat due to the smaller mid-day altitude of the sun.
Although the foregoing account of the temperatures of Asia supplies the main outline of the observed phenomena, a very important modifying cause, of which more will be said hereafter, comes into operation over the whole of the tropical region, namely, the periodical summer rains.
The arboreous forms which least require the humid and equable heat of the more truly tropical and equatorial climates, and are best able to resist the high temperatures and excessive drought of the northern Indian hot months from April to June, are certain Leguminosae, Bauhinia, Acacia, Butea and Dalbergia, Bombax, Shorea, Nauclea, Lagerstroemia, and Bignonia, a few bamboos and palms, with others which extend far beyond the tropic, and give a tropical aspect to the forest to the extreme northern border of the Indian plain.
Thus its non-liability to freeze (when not absolutely anhydrous, which it practically never is when freely exposed to the air) and its nonvolatility at ordinary temperatures, combined with its power of always keeping fluid and not drying up and hardening, render it valuable as a lubricating agent for clockwork, watches, &c., as a substitute for water in wet gas-meters, and as an ingredient in cataplasms, plasters, modelling clay, pasty colouring matters, dyeing materials, moist colours for artists, and numerous other analogous substances which are required to be kept in a permanently soft condition.
The highest mean temperatures for the whole year are those of Lenkoran (60.3°) and of Sukhum-kaleh and Poti (about 58°), and the lowest at Ardahan (5840 ft.), in the province of Kars, namely, 37.9°, and at Gudaur (7245 ft.), a few miles south of Kasbek, namely, 38.6°.
From 1879 to 1888 he was engaged on difficult experimental investigations, which began with an inquiry into the corrections required, owing to the great pressures to which the instruments had been subjected, in the readings of the thermometers employed by the "Challenger" expedition for observing deep-sea temperatures, and which were extended to include the compressibility of water, glass and mercury.
In 1879, at Kilburn, the competition was of railway waggons to convey perishable goods long distances at low temperatures.
It is often taught that gneisses are the further stages of the crystallization of schists and belong to a deeper zone where the pressures and the temperatures were greater.
The average temperatures are - year 51 0, January 26°, July 73° at Temir-khanshura (42° 49' N.; alt.
It melts at 70° C.and at higher temperatures decomposes, with evolution of carbon dioxide and formation of aceto-nitrile, CH 3 CN.
The surface-layers of this immense basin are heated in the summer up to temperatures of 55z° to 57° F., both close to the shores and at some distance from the mouth of the Selenga; but these warmer layers are not deep, and a uniform temperature of nearly 39° F.
The boiling point, being determined by the character of the constituents of the oil, necessarily varies greatly in different oils, as do the amounts of distillate obtained from them at specified temperatures.
Other theories of a like nature were brought forward by various chemists, Mendeleeff, for example, ascribing the formation of petroleum to the action of water at high temperatures on iron carbide in the interior of the earth.
Similarly there is a difference of opinion as to the conditions under which the organisms have been mineralized, some holding that the process has taken place at a high temperature and under great pressure; but the lack of practical evidence in nature in support of these views has led many to conclude that petroleum, like coal, has been formed at moderate temperatures, and under pressures varying with the depth of the containing rocks.
They found that the paraffin was thus converted, with the evolution of but little gas, into hydrocarbons which were liquid at ordinary temperatures.
Under such conditions, distillation takes place at higher temperatures than the normal boiling-points of the constituent hydrocarbons of the oil, and a partial cracking results.
The earliest form of testing instrument employed for this purpose was that of Giuseppe Tagliabue of New York, which consists of a glass cup placed in a copper water bath heated by a spirit lamp. The cup is filled with the oil to be tested, a thermometer placed in it and heat applied, the temperatures being noted at which, on passing a lighted splinter of wood over the surface of the oil, a flash occurs, and after further heating, the oil ignites.
Since the semitropical and sub-tropical zones are nearer the course of the Gulf Stream, and are swept by the trade winds, their temperatures are more uniform than those of the zones of southern climate; indeed, the extremes of heat (103° F.) and cold (13° F.) are felt in the region of southern climate.
The processes of soap manufacture may be classified (a) according to the temperatures employed into (I) cold processes and (2) boiling processes, or (b) according to the nature of the starting material - acid or oil and fat - and the relative amount of alkali, into (1) direct saturation of the fatty acid with alkali, (2) treating the fat with a definite amount of alkali with no removal of unused lye, (3) treating the fat with an indefinite amount of alkali, also with no separation of unused lye, (4) treating the fat with an indefinite amount of alkali with separation of waste lye.
All the metals are solids at ordinary temperatures with the exception of mercury, which is liquid.
The molecule of every compound must obviously contain at least two atoms, and generally the molecules of the elements are also polyatomic, the elements with monatomic molecules (at moderate temperatures) being mercury and the gases of the argon group. The laws of chemical combination are as follows: I.
When nitric peroxide, N204, is converted into gas, it decomposes, and at about 180° C. its vapour entirely consists of molecules of the composition N02; while at temperatures between this and o C. it consists of a mixture in different proportions of the two kinds of molecules, N 2 O 4 and N02.
Wollaston discovered palladium, especially interesting for its striking property of absorbing (" occluding ") as much as 376 volumes of hydrogen at ordinary temperatures, and 643 volumes at 90 0.
Intermolecular transformations-migrations of substituent groups from one carbon atom to anotherare of fairly common occurrence among oxy compounds at elevated temperatures.
Berthelot first accomplished the synthesis of benzene in 1870 by leading acetylene, HC: CH, through tubes heated to dull redness; at higher temperatures the action becomes reversible, the benzene yielding diphenyl, diphenylbenzene, and acetylene.
Obviously, therefore, liquids are comparable when the pressures, volumes and temperatures are equal fractions of the critical constants.
Other metals were tested in order to determine if their atomic heats approximated to this value at low temperatures, but with negative results.
Monoclinic sulphur, obtained by crystallizing fused sulphur, melts at I 19.5°, and admits of undercooling even to ordinary temperatures, but contact with a fragment of the rhombic modification spontaneously brings about the transformation.
25, p. 613), but both modifications may exist in metastable forms at higher and lower temperatures respectively; the rhombic form may be cooled down to ordinary temperature without changing, the transformation, however, being readily induced by a trace of the red modification, or by friction.
Lehmann it melts at 168° (or at a slightly lower temperature in its water of crystallization) and on cooling forms optically isotropic crystals; at 125.6° the mass becomes doubly refracting, and from a solution rhombohedral (optically uniaxial) crystals are deposited; by further cooling acicular rhombic crystals are produced at 82.8°, and at 32.4° other rhombic forms are obtained, identical with the product obtained by crystallizing at ordinary temperatures.
Calcium carbonate separates as hexagonal calcite from cold solutions (below 30°), and as rhombic aragonite from solutions at higher temperatures; lead and strontium carbonates, however, induce the separation of aragonite at lower temperatures.
As a general rule the modification stable at higher temperatures possesses a lower density; but this is by no means always the case, since the converse is true for antimonious and arsenious oxides, silver iodide and some other substances.
It is remarkable that a great many polymorphous substances assume more symmetrical forms at higher temperatures, and a possible explanation of the increase in density of such compounds as silver iodide, &c., may be sought for in the theory that the formation of a more symmetrical configuration would involve a drawing together of the molecules, and consequently an increase in density.
He was distinguished as the discoverer of radioactivity, having found in 1896 that uranium at ordinary temperatures emits an invisible radiation which in many respects resembles Rntgen rays, and can affect a photographic plate after passing through thin plates of metal.
On an average the coast-belt temperatures are some 10 0 higher than those of the plateau.
In consequence of the elevation of the plateau and the dryness of the air, the heat is less oppressive than is indicated by the temperatures recorded.
for different months, and with a range between the means of the coldest and warmest months of 10 (70° to 80°); temperatures below 50° or above 90° being rare.
At low temperatures it is a colourless crystalline solid which melts at -10.14° C. (W.
It is very unstable, decomposing slowly even at ordinary temperatures.
Here we may probably find the lowest temperatures of the northern hemisphere.
On Nansen's expedition temperatures of about - 49° F.
The probability also is that there is more precipitation, and that the mean temperatures are lower.
Fibrinogen is insoluble in water, but soluble in salt solutions; it has three different coagulation temperatures, 56°, 6 7°, 75°.
Nevertheless, in certain cases, the temperature coefficient of conductivity becomes negative at high temperatures, a solution of phosphoric acid, for example, reaching a maximum conductivity at 75° C.
At higher temperatures the viscous liquid suffers decomposition with the formation of various liquid hydrocarbons, principally members of the terpene series.
At the polar meteorological station of Sagastyr, in the delta of the Lena (73° 23' N.), the following average temperatures have been observed: January - 34.3° F.
The minimum temperatures recorded at these two stations are - 84° F.
The former is produced at temperatures below, the latter at temperatures above the fusing-point of the oxide.
When heated with hydriodic acid and phosphorus it forms phenylacetic acid; whilst concentrated hydrobromic acid and hydrochloric acid at moderate temperatures convert it into phenylbromand phenylchlor-acetic acids.
For soft iron, tungsten-steel and nickel little difference appeared to result from lowering the temperature down to - 186° C. (the temperature of liquid air); at sufficiently high temperatures, 600 to 1000° or more, it was remarked that the changes of length in iron, steel and cobalt tended in every case to become proportional to the magnetic force, the curves being nearly straight lines entirely above the axis.
The influence of high temperature on cobalt was very remarkable, completely altering the character of the change of length: the curves for annealed cobalt show that at 45 this metal behaves just like iron at ordinary temperatures, lengthening in fields up to about 300 and contracting in stronger ones.
.+] steel and nickel when heated up to high temperatures were those of J.
After one of the rings had been annealed at 840°, its maximum permeability at ordinary temperatures was 4000 for H =1.84; when it had been subsequently annealed at 1150°, the maximum permeability rose to 4680 for H =1.48, while the hysteresis loss for 2 B = t 4000 was under 500 ergs per c.cm.
Specimens of curves showing the relation of induction to magnetic field at various temperatures, and of permeability to temperature with fields of different intensities, are given in figs.
The critical temperatures for three different specimens of iron were 795°, 780°, and 770° respectively.
Above these temperatures the little permeability that remained was found to be independent of the magnetizing force, but it /1, appeared to vary a little with the temperature, one specimen showing a permeability of 100 at 820°, 2.3 at 950°, and 17 at 1050°.
Experiments were made at several constant temperatures with varying magnetic fields, and also at constant fields with rising and falling temperatures.
The paper contains tables and curves showing details of the magnetic changes, sometimes very complex, at different temperatures and with different fields.
The behaviour of cobalt is particularly noticeable; its permeability increased with rising temperature up to a maximum at 500°, when it was about twice as great as at ordinary temperatures, while at 1600°, corresponding to white heat, there was still some magnetization remaining.
Shimizu,' who experimented at temperatures ranging from - 186° to 1200°.
As regards the higher temperatures, the chief point of interest is the observation that the curve of magnetization for annealed cobalt shows a small depression at about 450°, the temperature at which they had found the sign of the length-change to be reversed for all fields.
As thus defined the critical temperatures for iron, nickel and cobalt were 1 Journ.
Experiments on the effect of high temperatures have also been made by M.
Soc., 1896, 60, 81) were the first to experiment on the permeability and hysteresis of iron at low temperatures down to that of liquid air (-186° C.).
After this operation had been repeated a few times the iron was found to have acquired a stable condition, and the curves corresponding to the two temperatures became perfectly definite.
The values of the permeability corresponding to the highest and lowest temperatures are given in the following table.
If, however, this non-magnetic substance is cooled to a temperature a few degrees below freezing-point, it becomes as strongly magnetic as average cast-iron (µ = 62 for H = 40), and retains its magnetic properties indefinitely at ordinary temperatures.
Alloys containing different proportions of nickel were found to exhibit the phenomenon, but the two critical temperatures were less widely separated.
] Honda and Shimizu (loc. cit.) have determined the two critical temperatures for eleven nickel-steel ovoids, containing from 24.04 to 70.32% of nickel, under a magnetizing force of 400, and illustrated by an interesting series of curves, the gradual transformation of the magnetic properties as the percentage of nickel was decreased.
They found that the hysteresis-loss, which at ordinary temperatures is very small, was increased in liquid air, the increase for the alloys containing less than 30% of nickel being enormous.
Now iron, nickel and cobalt all lose their magnetic quality when heated above certain critical temperatures which vary greatly for the three metals, and it was suspected by Faraday 3 as early as 1845 that manganese might really be a ferromagnetic metal having a critical temperature much below the ordinary temperature of the air.
4 But it has been shown that the critical temperatures of iron and nickel may be changed by the addition of certain other substances.
Among the most important experiments on the influence of magnetic force at different temperatures are those of J.
They also experimented with constant temperatures of -79°, -185° and -203', and found that at these low temperatures the effect of magnetization was enormously increased.
It will be seen that for H = 2450 and H =5500 the minimum resistance occurs at temperatures of about -80° and -7° respectively.
Important experiments on the susceptibility of oxygen at different pressures and temperatures were carried out by P. Curie (C.R.
The magnetic properties of the metal at different temperatures and in fields up to 1350 units have been studied by P. Curie (loc. cit.), who found that its " specific susceptibility " (K) was independent of the strength of the field, but decreased with rise of temperature up to the melting-point, 273° C. His results appear to show the relation - K X10 6 = I'381 - O'o0155t°.
de Phys., 18 95, 4, 204) of the specific susceptibility K of other diamagnetic substances at different temperatures.
The lower members of the series are neutral liquids possessing a characteristic smell; they are soluble in water and are readily volatile (formaldehyde, however, is a gas at ordinary temperatures).
It is readily polymerized, small quantities of hydrochloric acid, zinc chloride, carbonyl chloride, &c. converting it, at ordinary temperatures, into paraldehyde, (C 2 H 4 0) 3, a liquid boiling at 124° C. and of specific gravity oï¿½998 (15° C.).
1825) he devised a method for determining vapour densities at temperatures up to 1400° C., and, partly with F.
The forest-covered, lowland valley of the Amazon is a region of high temperatures which vary little throughout the year, and of heavy rainfall.
The coastal plain as far south as Santos is a region of high temperatures and great humidity.
The higher valleys of the Parana and its tributaries, and of the rivers which flow northward, are sub-tropical in character, having high sun temperatures and cool nights.
Above these, the chapadas lie open to the sun and wind and have a cool, bracing atmosphere even where high sun temperatures prevail.
The flora falls naturally into three great divisions: that of the Amazon basin where exceptional conditions of heat and moisture prevail; that of the coast where heat, varying rainfall, oceanic influences and changing seasons have greatly modified the general character of the vegetation; and that of the elevated interior, or sertao, where dryer conditions, rocky surfaces, higher sun temperatures and large open spaces produce a vegetation widely different from those of the other two regions.
The yearly amount of rain at Urga (altitude 4350 ft., at the northern foot of the Kentei Mountains) is only 92 in., and the average temperatures are: year 27° F., January-18°, July 64°; a minimum of - 35° F.
The climate of Ulyasutai (J400 ft.) may be taken as typical, its average temperatures being: year 31.6°, January-12°, July 66°.
It is a region of lakes and morasses, of arid plains and high temperatures, but experiments with irrigation toward the end of the 19th century were highly successful and considerable tracts have since been brought under cultivation.
The powdery metal when heated in air to 150° or 170° C. catches fire and burns brilliantly into U 3 0 8; it decomposes water slowly at ordinary temperatures, but rapidly when boiling.
Recent investigations point to the conclusion that the immediate cause of the arrest of vitality, in the first place, and of its destruction, in the second, is the coagulation of certain substances in the protoplasm, and that the latter contains various coagulable matters, which solidify at different temperatures.
The metal is dimorphous: by cooling molten tin at ordinary air temperature tetragonal crystals are obtained, while by cooling at a temperature just below the melting point rhombic forms are produced, When exposed for a sufficient time to very low temperatures (to - 39° C. for 14 hours), tin becomes so brittle that it falls into a grey powder, termed the grey modification, under a pestle; it indeed sometimes crumbles into powder spontaneously.
At ordinary temperatures tin proves fairly ductile under the hammer, and its ductility seems to increase as the temperature rises up to about 100° C. At some temperature near its fusing point it becomes brittle, and still more brittle from - 14° C. downwards.
(2) A similar oxide (flores jovis) is produced by burning tin in air at high temperatures or exposing any of the hydrates to a strong red heat.
The more nearly the composition of guncotton approaches that represented by C6H702(N03)3, the more stable is it as regards storing at ordinary temperatures, and the higher the igniting temperature.
The low temperatures of the night in these regions lower the mean annual temperatures.
The lowest temperatures recorded in official reports are those of Mucuchies, in the state of Merida, where the maximum is 68°, the minimum 43° and the mean 56°.
It behaves as a strong acid and on treatment with phosphorus pentachloride at high temperatures gives triazole.
A little vapour is given off at ordinary temperatures and pressures, and when under a few millimetres pressure only it rapidly vaporizes below Ioo° C. The freezing-point is uncertain, owing perhaps to the existence of two modifications, as suggested by Kast (Zeits.
Ammonium hydroxide has no appreciable action at ordinary temperatures, but strong solutions of sodium or potassium hydroxides start a decomposition, with rise of temperature, in which some nitrate and always some nitrite is produced.
In the Comstock mines at Virginia City, Nevada, it is possible to continue mining operations at rock temperatures of 130° F.
In some places work was conducted with rock temperatures as high as 158° F., with air 135° F.
In the Alpine tunnels, where the air was moist and probably not as pure as in the Comstock mines, great difficulty was experienced in prosecuting the work at temperatures of 90° F.
Long experience has fixed the mixtures, so far as ordinary furnace temperatures are concerned, which produce the varieties of glass in common use.
In all mercurial thermometers there is a slight depression of the ice-point after exposure to high temperatures; it is also not uncommon to find that the readings of two thermometers between the iceand boiling-points fail to agree at any intermediate temperature, although the iceand boiling-points of both have been determined together with perfect accuracy, and the intervening spaces have been equally divided.
Ruff and Curt Albert (Ber., 1905, 38, p. 53) by decomposing titanium fluoride with silicon chloroform in sealed vessels at 100 -120° C. It is a colourless gas which may be condensed to a liquid boiling at -80 2° C. On solidification it melts at about -110° C. The gas is very unstable, decomposing slowly, even at ordinary temperatures, into hydrogen,, silicon fluoride and silicon: 4SiHF 3 =2H 2 +3SiF 4 +Si.
It is a very stable colourless liquid which boils at 58° C. Oxygen only attacks it at very high temperatures.
It is a colourless fuming liquid which boils at 146-148° C. It is decomposed by water, and also when heated between 350° and 1000° C., but it is stable both below and above these temperatures.
These liquids, when exposed to higher temperatures, some sooner than others, pass into vapours.
What these vapours are like is not known in many cases, since, as a rule, they can be produced only at very high temperatures, precluding the use of transparent vessels.
The liquid metals, when cooled down sufficiently, some at lower, others at higher, temperatures freeze into compact solids, endowed with the (relative) non-transparency and the lustre of their liquids.
As liquidity might be looked upon as the ne plus ultra of softness, this is the right place for stating that, while most metals, when heated up to their melting points, pass pretty abruptly from the solid to the liquid state, platinum and iron first assume, and throughout a long range of temperatures retain, a condition of viscous semi-solidity which enables two pieces of them to be "welded" together by pressure into one continuous mass.
Water, at ordinary or slightly elevated temperatures, is decomposed more or less readily, with evolution of hydrogen gas and formation of a basic hydrate, by (I) potassium (formation of KHO), sodium (NaHO), lithium (LiOH), barium, strontium, calcium (BaH 2 O 2, &c.); (2) magnesium, zinc, manganese (MgO 2 H 2, &c.).
Mercury, within XVIII.7 a a certain range of temperatures situated close to its boiling point, combines slowly with oxygen into the red oxide, which, however, breaks up again at higher temperatures.
Tin, at high temperatures, passes slowly into oxide, Sn02.
Chlorine.-All metals, when treated with chlorine gas at the proper temperatures, pass into chlorides.
All the rest, when heated by themselves, volatilize, some at lower, others at higher temperatures.
The following, though volatile at higher temperatures, are not volatilized at dull redness: KC1, NaCI, LiC1, NiC1 2, CoC1 2, MnC1 2, ZnCl 2, MgCl 2, PbCl 2, AgCI, the chlorides of potassium, sodium, lithium, nickel, cobalt, manganese, zinc, magnesium, lead, silver.
All chlorides, except those of silver and mercury (and, of course, those of gold and platinum), are oxidized by steam at high temperatures, with elimination of hydrochloric acid.
scale as the heat most proper to be used and applied in order to secure and preserve the colour and crystallizability of the sugars, and most easily to be obtained with precision and uniformity by means of the water bath and steam bath, yet when circumstances or choice may render the same desirable I do make use of higher temperatures, although less beneficial."
Howard at any rate saw clearly what was one of the indispensable requisites for the economical manufacture of fine crystal sugar of good colour - the treatment of saccharine solutions at temperatures very considerably lower than 212° F., which is the temperature of water boiling at normal atmospheric pressure.
Nor was he long in providing means for securing these lower temperatures.
Soil whose temperature remains low, whether from its northerly aspect or from its high water content or other cause, is unsatisfactory, because the germination of seeds and the general life processes of plants cannot go on satisfactorily except at certain temperatures well above freezing-point.
The salt fuses at 316°; at higher temperatures it loses oxygen (more readily than the corresponding potassium salt) with the formation of nitrite which, at very high temperatures, is reduced ultimately to a mixture of peroxide, Na202, and oxide, Na 2 0.
Owing to the fact that at temperatures between its melting and boiling point zinc has a strong affinity for iron, it is often contaminated by the scraper while being drawn from the condenser, as is shown by the fact that the scraper wears away rapidly.
At higher temperatures, or with stronger acid, nitric oxide, NO, is produced besides or instead of nitrous.
At a boiling heat, zinc chloride dissolves in any proportion of water, and highly concentrated solutions, of course, boil at high temperatures; hence they afford a convenient medium for the maintenance of high temperatures.
The midday temperatures recorded by Huber at Hail during January and the first half of February average about 65° F., and water froze on several nights; at Medina the winters are cold and night frosts of frequent occurrence, and these conditions prevail over all the western part of the Nejd plateau.
The present article, as explained under Electrochemistry, treats only of those processes in which electricity is applied to the production of chemical reactions or molecular changes at furnace temperatures.
The furnace used by Henri Moissan in his experiments on reactions at high temperatures, on the fusion and volatilization of refractory materials, and on the formation of carbides, suicides and borides of various metals, consisted, in its simplest form, of two superposed blocks of lime or of limestone with a central cavity cut in the lower block, and with a corresponding but much shallower inverted cavity in the upper block, which thus formed the lid of the furnace.
The fact that energy is being used at so high a rate as Too H.P. on so small a charge of material sufficiently indicates that the furnace is only used for experimental work, or for the fusion of metals which, like tungsten or chromium, can only be melted at temperatures attainable by electrical means.
But in some cases in which the current is used for electrolysis and for the production of extremely high temperatures, for which the calorific intensity of ordinary fuel is insufficient, the electric furnace is employed with advantage.
It is not necessary that all electric furnaces shall be run at these high temperatures; obviously, those of the incandescence or resistance type may be worked at any convenient temperature below the maximum.
This advantage is especially observed in some cases in which the charge of the furnace is liable to attack the containing vessel at high temperatures, as it is often possible to maintain the outer walls of the electric furnace relatively cool, and even to keep them lined with a protecting crust of unfused charge.
Ordinarily carbon is used as the electrode material, but when carbon comes in contact at high temperatures with any metal that is capable of forming a carbide a certain amount of combination between them is inevitable, and the carbon thus introduced impairs the mechanical properties of the ultimate metallic product.
Borchers predicted that, at the high temperatures available with the electric furnace, every oxide would prove to be reducible by the action of carbon, and this prediction has in most instances been justified.
Alumina and lime, for example, which cannot be reduced at ordinary furnace temperatures, readily give up their oxygen to carbon in the electric furnace, and then combine with an excess of carbon to form metallic carbides.
When prolonged heating is required at very high temperatures it is found necessary to line the furnace-cavity with alternate layers of magnesia and carbon, taking care that the lamina next to the lime is of magnesia; if this were not done the lime in contact with the carbon crucible would form calcium carbide and would slag down, but magnesia does not yield a carbide in this way.
At ordinary temperatures it is a gas, but may be condensed to a liquid which boils at - 6° C. It has a strong ammoniacal smell, burns readily and is exceedingly soluble in water.
Cadaverine is a syrup at ordinary temperatures, and boils at 178-179° C. It is readily soluble in water and alcohol, but only slightly soluble in ether.
By fractional distillation is meant the separation of a mixture having components which boil at neighbouring temperatures.
The mean annual temperature at Providence is 50°; the mean for the summer, 72°; and for the winter, 30°; while the highest and lowest temperatures ever recorded are respectively 102° and - 9°.
The chlorine reacts with the caustic soda, forming sodium hypochlorite, and this in turn, with an excess of chlorine and at higher temperatures, becomes for the most part converted into chlorate, whilst any simultaneous electrolysis of a hydroxide or water and a chloride (so that hydroxyl and chlorine are simultaneously liberated at the anode) also produces oxygen-chlorine compounds direct.
Hypochlorites were made, at ordinary temperatures, and chlorates at higher temperatures, in a cell without a partition in which the cathode was placed horizontally immediately above the anode, to favour the mixing of the ascending chlorine with the descending caustic solution.
The substances which we at present term anhydrous acids (acid oxides) only become, for the most part, capable of forming salts with metallic oxides after the addition of water, or they are compounds which decompose these oxides at somewhat high temperatures."
Situated at an altitude of 1375 ft., it has a severe climate, the average temperatures being - year, 56°; January, 22°; July, 65°.
In such a diagram, a point P defines a particular mixture, both as to percentage, composition and temperature; a vertical line through P corresponds to the mixture at all possible temperatures, the point Q being its freezing-point.
The cooling soon recommences and these crystals continue to form, but at lower and o°c lower temperatures because the still liquid part is becoming richer in B.
All mixtures whose temperature lies above the line ACB are wholly liquid, hence this line is often called the "liquidus "; all mixtures at temperatures below that of the horizontal line through C are wholly solid, hence this line is sometimes called the " solidus," but in more complex cases the solidus is often curved.
At temperatures between the solidus and the liquidus a mixture is partly solid and partly liquid.
This alloy, if allowed to solidify completely before chilling, turns into a uniform solid solution, and at still lower temperatures the solid solution breaks up into a pearlite complex.
We then extract one ingot after another at successively lower temperatures and chill each ingot by dropping it into water or by some other method of very rapid cooling.
We learn also that solid solutions which exist at high temperatures often break up into two materials as they cool; for example, the bronze of fig.
Its high coefficient of thermal expansion, coupled with its low freezing point, renders it a valuable thermometric fluid, especially when the temperatures to be measured are below - 39° C., for which the mercury thermometer cannot be used.
Fleming and James Dewar on dielectric constants at low temperatures: " On the Dielectric Constant of Liquid Oxygen and Liquid Air," Proc. Roy.
Soc., 1897, 60, p. 360; " Note on the Dielectric Constant of Ice and Alcohol at very low Temperatures," ib., 1897, 61, p. 2; " On the Dielectric Constants of Pure Ice, Glycerine, Nitrobenzol and Ethylene Dibromide at and above the Temperature of Liquid Air," id.
The object of the present article is to illustrate the practical application of the two general principles - (I) Joule's law of the equivalence of heat and work, and (2) Carnot's principle, that the efficiency of a reversible engine depends only on the temperatures between which it works; these principles are commonly known as the first and second laws of thermodynamics.
The area ABCD, representing the work, W, per cycle, is the difference (H' - H") of the quantities of heat absorbed and rejected at the temperatures 0 and 0".
He remarks that ” the law according to which the motive power of heat varies at different points of the thermometric scale is intimately connected with that of the variations of the specific heats of gases at different temperatures - a law which experiment has not yet made known to us with sufficient exactness."
An ideal gas is a substance possessing very simple thermodynamic properties to which actual gases and vapours appear to approximate indefinitely at low pressures and high temperatures.
It has the characteristic equation pv=Re, and obeys Boyle's law at all temperatures.
The most natural method of procedure is to observe the deviations from Boyle's law by measuring the changes of pv at various constant temperatures.
But this procedure in itself is not sufficient, because, although it would be highly probable that a gas obeying Boyle's law at all temperatures was practically an ideal gas, it is evident that Boyle's law would be satisfied by any substance having the characteristic equation pv = f (0), where f (0) is any arbitrary function of 0, and that the scale of temperatures given by such a substance would not necessarily coincide with the absolute scale.
By experiments at different temperatures between o° and 00° C., they found that the cooling effect per atmosphere of pressure varied inversely as the square of the absolute temperature for air and CO 2.
Putting d0/dp=A/0 2 in equation (15), and integrating on the assumption that the small variations of S could be neglected over the range of the experiment, they found a solution of the type, v/0 =f(p) - SA /30 3, in which f(p) is an arbitrary function of p. Assuming that the gas should approximate indefinitely to the ideal state pv = R0 at high temperatures, they put f(p)=Rip, which gives a characteristic equation of the form v= Re/p - SA /30 2 .
For CO 2 at ordinary temperatures n =2, as in the JouleThomson equation.
The introduction of the covolume, b, into the equation is required in order to enable it to represent the behaviour of hydrogen and other gases at high temperatures and pressures according to the experiments of Amagat.
(18) Experiments at two temperatures suffice to determine both c and n if we assume that b is equal to the volume of the liquid.
Neville determined it to be 1061 7° C.; Daniel Berthelot gives 1064° C., while Jaquerod and Perrot give 1066.1-1067.4° C. At still higher temperatures it volatilizes, forming a reddish vapour.
Gold is permanent in both dry and moist air at ordinary or high temperatures.
The metal oxidizes very slowly in dry air at ordinary temperatures, but somewhat more rapidly in moist air or when heated.
matter which at ordinary temperatures exists as a solid or liquid.
Troost made it available for specially high temperatures by employing porcelain vessels, sealing them with the oxyhydrogen blow-pipe, and maintaining a constant temperature by a vapour bath of mercury (3500), sulphur (4400), cadmium (860°) and zinc (1040°).
(3) For substances boiling at higher temperatures, or for any substance which reacts on mercury, Meyer's "air expulsion method" must be used.
By varying the material of the bulb, this apparatus is rendered available for exceptionally high temperatures.
For higher temperatures the bulb of the vapour density tube is made of porcelain or platinum, and is heated in a gas furnace.
9) on the latter is carefully counted, and the experiments repeated at different temperatures.
It forms colourless, very hygroscopic prisms, which attack glass, slowly at ordinary temperatures, more rapidly when heated (Ber., 1909, 4 2, p. 49 2).
Thus at o C. the viscosity of sea-water of 35 per mille salinity is 5.2% greater and at 25° C. 4% greater than that of pure water at the same temperatures; in absolute units the viscosity of sea-water at 25° C. is only half as great as it is at o C.
How closely two bodies of water at different temperatures may come together is shown by the fact that in the Baltic in August between 10 and 11 fathoms there is sometimes a fall of temperature from 57° to 46.5° F.
The warmest parts of the Indian Ocean and Western Pacific have a mean annual temperature of 82° to 84° F., but such high temperatures are not found in the tropical Atlantic. In the Indian Ocean between 15° N.
The figures quoted above are differences between the average surface temperatures of the warmest and of the coldest month.
Curve B shows the typical distribution of temperature in an enclosed sea, in this case the Sulu Basin of the Malay Sea, where from the level of the barrier to the bottom the temperature remains uniform or homothermic. Curve C shows a typical summer condition in the polar seas, where layers of sea-water at different temperatures are superimposed, the arrangement from the surface to 200 fathoms is termed FIG.
Temperatures so low as 31.5° to 31.3° F.
in approximately 3000 fathoms the bottom temperature is 31.1° F.; in the Cape Trough it is 32.7° in 45° S., and 33.8° to 34.3° in 35° S., while north of the Walfisch Ridge and east of the South Atlantic Rise bottom temperatures of 36° to 36.7° F.
On the floor of the Indian Ocean temperatures of 33.3° to 33.6° occur south of 35° S.
the prevailing bottom temperatures are from 34 o to 34.3°.
In similar depths in the Pacific south of the equator temperatures of 33.8° to 34.5° are found, and north of the equator bottom temperatures at the same depth increase to 35.1° in the neighbourhood of the Aleutian Islands, again completely justifying the conclusion as to the Antarctic control of deep water temperature throughout the ocean.
At temperatures about 17° F.
Prestwich, " Tables of Temperatures of the Sea at Different Depths ...
It is infusible at temperatures up to 2000° C., but can be fused in the electric arc. When heated to temperature of 2 4 5° C. in a stream of chlorine gas it becomes incandescent, forming calcium chloride and liberating carbon, and it can also be made to burn in oxygen at a dull red heat, leaving behind a residue of calcium carbonate.
Pure crystalline calcium carbide yields 5.8 cubic feet of acetylene per pound at ordinary temperatures, but the carbide as sold commercially, being a mixture of the pure crystalline material with the crust which in the electric furnace surrounds the ingot, yields at the best 5 cubic feet of gas per pound under proper conditions of generation.
The climate is continental and dry, the average temperatures being - year 43° Fahr., January 13°, July 72° at Uryupina (in 50° 48' N.; alt.
While the majority of his researches bear on one or other of the subjects just mentioned, others deal with such widely different topics as the birds of Greenland, ocean temperatures, the Gulf Stream, barometric measurement of heights, arcs of meridian, glacier transport of rocks, the volcanoes of the Hawaiian Islands, and various points of meteorology.
The mean temperatures are 43° F.
At ordinary temperatures it crystallizes from aqueous solutions in large colourless monoclinic prisms, which effloresce in dry air, and at 35° C. melt in their water of crystallization.
The monthly average of the mean temperatures for 23 years (1881-1903 inclusive) varied from S3° in January to 67° in August.
During April and October the temperatures in eastern Washington are nearly the same as those in western Washington, but during July the temperatures in eastern Washington are subject to a range from 40° to 110°, and during January from 65° to - 30°.
The winters are long and marked by exceedingly low temperatures, but as they are the driest season of the year, the extremes are not so disagreeable as they would be in a more humid region.
The absolute minima at these two places are respectively-46° and -29°; the absolute maxima, III ° and 1066°, and the mean annual temperatures, 42° and 46°.
At Ashcroft, in the extreme north-west, the mean annual temperature is 44 0; the mean for the summer 68°; and for the winter 20°; while the highest and lowest temperatures ever recorded are respectively 114° and 44°.
The mean monthly temperatures vary between 20 in January and 70° in July, with extremes of loo° and - 25° The mean annual precipitation is 31.4 in.
As a general rule, temperatures are highest in the W.
The season, however, on account of the dryness of the climate, is not so harsh as the low temperatures would seem to indicate.
3NH 3 at temperatures below 15° C.; the other, 2AgC1.3NH 3 at temperatures above 20° C. On heating these substances, ammonia is liberated and the metallic chloride remains.
By the addition of sodium amalgam to a concentrated solution of ammonium chloride, the so-called ammonium amalgam is obtained as a spongy mass which floats on the surface of the liquid; it decomposes readily at ordinary temperatures into ammonia and hydrogen; it does not reduce silver and gold salts, a behaviour which distinguishes it from the amalgams of the alkali metals, and for this reason it is regarded by some chemists as being merely mercury inflated by gaseous ammonia and hydrogen.
Moissan); it has been liquefied, the liquid also being of a yellow colour and boiling at - 187° C. It is the most active of all the chemical elements; in contact with hydrogen combination takes place between the two gases with explosive violence, even in the dark, and at as low a temperature as - 210 C.; finely divided carbon burns in the gas, forming carbon tetrafluoride; water is decomposed even at ordinary temperatures, with the formation of hydrofluoric acid and "ozonised" oxygen; iodine, sulphur and phosphorus melt and then inflame in the gas; it liberates chlorine from chlorides, and combines with most metals instantaneously to form fluorides; it does not, however, combine with oxygen.
Soc., 1889, 55, p. 163) determined the vapour density of hydrofluoric acid at different temperatures, and showed that there is no approach to a definite value below about 88° C. where it reaches the value 10.29 corresponding to the molecular formula HF; at temperatures below 88° C. the value increases rapidly, showing that the molecule is more complex in its structure.
At ordinary temperatures the metal has the consistency of wax and can be readily cut; on cooling it hardens.
The bromide and iodide crystallize from hot solutions in anhydrous cubes; from solutions at ordinary temperatures in monoclinic prisms with 2H 2 O; and at low temperatures with 5H 2 O.
Iooi), who obtained cubic crystals from a supersaturated solution of sodium and aluminium sulphates below 20°, higher temperatures giving monoclinic crystals.
We may here notice the "percarbonates" obtained by Wolffenstein and Peltner (Ber., 1908, 41, pp. 2 75, 280) on acting with gaseous or solid carbon dioxide on Na202, Na203 and NaHO 2 at low temperatures; the same authors obtained a perborate by adding sodium metaborate solution to a 50% solution of sodium peroxide previously saturated with carbon dioxide.
Cholera and typhoid organisms are less resistant, and are killed more quickly than tubercle bacilli at the above temperatures.
- The alteration of carbon at high temperatures into a material resembling graphite has long been known.
When made at higher temperatures it is much more dense, and its ignition point is considerably higher.
At ordinary temperatures it is a colourless gas, possessing a penetrating and suffocating smell.
It is a powerful reducing agent, especially at high temperatures.
Carbon dioxide dissociates, when strongly heated, into carbon monoxide and oxygen, the reaction being a balanced action; the extent of dissociation for varying temperatures and pressures has been calculated by H.
Supposing that the scale under this wire is divided into 2000 parts and that we are in possession of a standard Clark cell, the electromotive force being known at various temperatures, and equal, say, to 1.434 volts at 15° C. The first process is to set the potentiometer.
At temperatures below o° C. it is pretty hard and brittle; at the ordinary temperature it is so soft that it can be kneaded between the fingers and cut with a blunt knife.
Potassium at temperatures from 200 to 400°C. occludes hydrogen gas, the highest degree of saturation corresponding approximately to the formula K 2 H.
Exposed to moist air it loses oxygen, possibly giving the dioxide, K 2 0 2; water reacts with it, evolving much heat and giving caustic potash, hydrogen peroxide and oxygen; whilst carbon monoxide gives potassium carbonate and oxygen at temperatures below loo°.
The weight of a cubic decimetre of water reaches 1000 grammes under a pressure of four atmospheres; but in vacuo, at all temperatures, the weight of water is less than a kilogram.
The maximum temperatures in this region are 98° at Hermosillo and 119° at Guaymas.
Even here the high sun temperatures give a sub-tropical character to the country.
A fertile soil, abundant rainfall and high temperatures have covered these mountain slopes and lowland plains with a wealth of vegetation.
It volatilizes slowly at ordinary temperatures, but rapidly on heating.
Thus, the density of air being taken as unity, Victor Meyer found the following values for the density of iodine vapour at different temperatures: T° C...
8.89 8.84 8.73 6-08 5.75 5.67 This shows that the iodine molecule becomes less complex in structure at higher temperatures.
The winters are often without frost at all in the lowlands, while the lowest temperatures observed are 18° F.
They boil at temperatures somewhat lower than those of the corresponding nitriles; and are stable towards alkalis, but in the presence of mineral acids they readily hydrolyse, forming primary amines and formic acid: RNC+2H 2 O = RNH2+H2C02.
The average temperatures for these months at places of different altitudes, as given by Dr Karl Sapper, are shown on the following page.
Two leading features, from which many others follow, are the intermediate value of the mean annual temperatures and the prevalence of westerly winds, with which drift the areas of high and low pressurecyclonic and anticyclonic areascontrolling the short-lived, non-periodic weather changes.
The effects of the continent are already visible in the mean annual temperatures, in which the poleward temperature gradient is about twice as strong as it is on the neighboring oceans; this being a natural effect of the immobility of the land surface, in contrast to the circulatory movement of the ocean currents, which thus lessen the temperature differences due to latitude: on the continent such differences are developed in full force.
In virtue of these physical characteristics, the air over the land becomes much warmer in summer and much colder in winter than the air over the oceans in corresponding latitudes; hence the seasonal changes of temperature in the central United States are strong; the high temperatures appropriate to the torrid zone advance northward to middle latitudes in summer, and the low temperatures appropriate to the Arctic regions descend almost to middle latitudes in winter.
Indeed the contrast between the moderate temperatures of the Pacific coast and the overheated areas of the next interior deserts is so great that the isotherms trend almost parallel to the coast, and are even overturned somewhat in southern California, where the most rapid increase of temperatures in July is found not by moving southward over the ocean toward the equator, but north-eastward over the land to the deserts of Nevada and Arizona.
So strong is the displacement of the area of highest interior temperatures westward from the middle of the continent that the Gulf of California almost rivals the Red Sea as an ocean-arm under a desert-hot atmosphere.
The strong changes of temperature with the seasons are indicated also by the distribution of summer maxima and winter minima; summer temperatures above 112 are known in the south-western deserts, and temperatures of 100 are sometimes carried far northward on the Great Plains by the hot winds nearly to the Canadian boundary; while in winter, temperatures of 40 occur along the mid-northern boundary and freezing winds sometimes sweep down to the border of the Gulf of Mexico.
The climatic effects of relief are seen directly in the ascent of the higher mountain ranges to altitudes where low temperatures prevail, thus preserving snow patches through the summer on the high summits (over 12,000 ft.) in the south, and maintaining snowfields and moderate-sized glaciers on the ranges in the north.
South of the Gulf of St Lawrence, however, the maritime provinces have much more genial temperatures, averaging 40° F.
There is a much lighter snowfall in winter than in northern Ontario and Quebec, with somewhat lower temperatures.
Northwards chinooks become less frequent and the winter's cold increases, but the coming of spring is not much later, and the summer temperatures, with sunshine for twenty hours out of twenty-four in June, are almost the same as for hundreds of miles to the south, so that most kinds of grain and vegetables ripen far to the north in the Peace river valley.
can be adjusted for different temperatures, and which also indicates the contraction in volume incident on bringing the spirit to proof strength.
The slider upon the rule serves to adjust the scale for different temperatures, and then indicates the strength of the spirit in percentages over or under proof.
A table provides the necessary corrections for other temperatures.
The metal as obtained in this process is lustrous and takes a polish, does not melt in the oxyhydrogen flame, but liquefies in the electric arc, and is not affected by air at ordinary temperatures.
Chromium as prepared by the Goldschmidt process is in a passive condition as regards dilute sulphuric acid and dilute hydrochloric acid at ordinary temperatures; but by heating the metal with the acid it passes into the active condition, the same effect being produced by heating the inactive form with a solution.
If the violet solution is allowed to evaporate slowly at ordinary temperatures the sulphate crystallizes out as Cr2(S04)3.15H20, but the green solution on evaporation leaves only an amorphous mass.
It crystallizes in yellow laminae,which melt at 96° C. and explode at slightly higher temperatures.
Although he had previously published meritorious researches on piezoelectricity, the magnetic properties of bodies at different temperatures, and other topics, he was chiefly known for his work on radium carried out jointly with his wife, Marie Sklodowska, who was born at Warsaw on the 7th of November 1867.
Adopting the definition we should have no difficulty in proving that in a vacuum tube gases may be luminous at very low temperatures, but we are doubtful whether such a conclusion is very helpful towards the elucidation of our problem.
highest temperatures at our command it is small compared with the energy of translatory motion, but as the temperature increases, it must ultimately gain the upper hand, and if there is anywhere such a temperature as that of several million degrees, the greater part of the total energy of a body will be outside the atom and molecular motion ultimately becomes negligible compared with it.
The lines of the trunk seem to appear at lower temperatures, which may account for the fact that it can be observed as absorption lines.
The experiment proves only the transparency of the gases experimented upon, and this is confirmed by the fact that bodies like bromine and iodine give on heating an emission spectrum corresponding to the absorption spectrum seen at ordinary temperatures.
The problem of magnesium reduction is in many respects similar to that of aluminium extraction, bait the lightness of the metal as compared, bulk for bulk, with its fused salts, and the readiness with which it burns when exposed to air at high temperatures, render the problem somewhat more difficult.
Grignard (Comptes rendus, 1900 et seq.) observed that magnesium and alkyl or aryl halides combined together in presence of anhydrous ether at ordinary R temperatures (with the appearance of brisk boiling) to form compounds of the type RMgX(R = an alkyl or aryl group and X = halogen).
The acid on being heated to Ioo° C. loses water and is converted into metaboric acid, HBO 3 i at 140° C., pyroboric acid, H 2 B 4 0 7, is produced; at still higher temperatures, boron trioxide is formed.
Of his earlier papers, some deal with questions of organic chemistry, others with Graham's hydrogenium and its physical constants, others with high temperatures, e.g.
Liveing, one of his colleagues at Cambridge, he began in 1878 a long series of spectroscopic observations, the later of which were devoted to the spectroscopic examination of various gaseous constituents separated from atmospheric air by the aid of low temperatures; and he was joined by Professor J.
Fleming, of University College, London, in the investigation of the electrical behaviour of substances cooled to very low temperatures.
His name is most widely known in connexion with his work on the liquefaction of the so-called permanent gases and his researches at temperatures approaching the zero of absolute temperature.
He next experimented with a highpressure hydrogen jet by which low temperatures were realized through the Thomson-Joule effect, and the successful results thus obtained led him to build at the Royal Institution the large refrigerating machine by which in 1898 hydrogen was for the first time collected in the liquid state, its solidification following in 1899.
The Royal Society in 1894 bestowed the Rumford medal upon him for his work in the production of low temperatures, and in 1899 he became the first recipient of the Hodgkins gold medal of the Smithsonian Institution, Washington, for his contributions to our knowledge of the nature and properties of atmospheric air.
Low temperatures are prevalent throughout these western regions, whose bleak desolation is unrelieved by the existence of trees or vegetation of any size, and where the wind sweeps unchecked across vast expanses of arid plain.
This relation does not hold for very soluble gases, such as ammonia, at low temperatures.
As a general rule gases are less soluble at high than at low temperatures - unlike the majority of solids.
At D the composition of the two liquids becomes identical, and at temperatures above D, 68°C the liquids are soluble in each other in all proportions, and only one liquid phase can exist.
If the two substances are soluble in each other in all proportions at all temperatures above their melting points we get a diagram reduced to the two fusion curves cutting each other at a nonvariant point.
p. 77, 1897.) The behaviour of argon at low temperatures was investigated by K.
The resistance of lichens is extraordinary; they may be cooled to very low temperatures and heated to high temperatures without being killed.
In 1800 he became a secretary of the society, and in the following year he presented the important paper or series of papers, entitled "Experimental Essays on the constitution of mixed gases; on the force of steam or vapour of water and other liquids in different temperatures, both in Torricellian vacuum and in air; on evaporation; and on the expansion of gases by heat."
The second of these essays opens with the striking remark, "There can scarcely be a doubt entertained respecting the reducibility of all elastic fluids of whatever kind, into liquids; and we ought not to despair of effecting it in low temperatures and by strong pressures exerted upon the unmixed gases"; further, after describing experiments to ascertain the tension of aqueous vapour at different points between 32° and 212° F., he concludes, from observations on the vapour of six different liquids, "that the variation of the force of vapour from all liquids is the same for the same variation of temperature, reckoning from vapour of any given force."
The bath is heated internally with the current rather than by means of external fuel, because this arrangement permits the vessel itself to be kept comparatively cool; if it were fired from without, it would be hotter than the electrolyte, and no material suitable for the construction of the cell is competent to withstand the attack of nascent aluminium at high temperatures.
At elevated temperatures the metal decomposes nearly all other metallic oxides, wherefore it is most serviceable as a metallurgical reagent.
By drying at ordinary temperatures, the hydrate Al(OH) 3 ï¿½H 2 0 is obtained; at 300° this yields A10(OH), which on ignition gives alumina, Al 2 O 3.
Its vapour density at temperatures above 750 corresponds to the formula AlCl 3 j below this point the molecules are associated.
In connexion with these experiments he developed the electric furnace as a convenient means of obtaining very high temperatures in the laboratory; and by its aid he prepared many new compounds, especially carbides, silicides and borides, and melted and volatilized substances which had previously been regarded as infusible.
The art of retarding the period of flowering in certain plants consists, in principle, in the artificial application of cold temperatures whereby the resting condition induced by low winter temperature is prolonged.
When required for use they are removed to cool sheds to thaw, and are then gradually inured to higher temperatures.
Night temperatures also should always be allowed to drop somewhat, the heat being increased again in the morning.
- For the successful culture of stove plants two houses at least, wherein different temperatures can be maintained, should be devoted to their growth.
- For the successful cultivation of a mixed collection of tropical orchids, it is necessary that two or three houses, in which different temperatures can be maintained, should be provided.
Continue the usual operations of disbudding and thinning of fruit, and take care to keep up the proper temperatures.
Keep up the necessary temperatures for the ripening of the various fruits.
Keep up moderate temperatures in the stove, and merely repel frosts in the greenhouse, guarding against damp, by ventilation and by the cautious use of water.
Two monosulphonic acids (a and 0) result by acting with sulphuric acid on the hydrocarbon, the a-acid predominating at low temperatures (80° C. and under) and the 0-acid at higher temperatures (170°-200° C.).
1), in which vertical distances represent temperatures and horizontal ones the percentage of carbon in the iron, aids our study of these constituents of iron.
for all temperatures below Mhsp'.
1 shows the constitution of these iron-carbon alloys for all temperatures and all percentages of carbon when the undissolved carbon exists as cementite, so there should be a diagram showing this constitution when all the undissolved carbon exists as graphite.
For steel containing less than about 0.13% of carbon, the embrittling temperature is in a different range, near 700° C., and such steel refines at temperatures above 900° C.
r, each with its own set of constitutents, and remember that by different rates of cooling from different temperatures we can retain in the cold metal these different sets of constituents in widely varying proportions; and when we further reflect that not only the proportion of each constituent present but also its state of aggregation can be controlled by thermal treatment, we see how vast a field is here opened, how great a variety of different properties can be induced in any individual piece of steel, how enormous the variety of properties thus attainable in the different varieties collectively, especially since for each percentage of carbon an incalculable number of varieties of steel may be made by alloying it with different proportions of such elements as nickel, chromium, &c. As yet there has been only the roughest survey of certain limited areas in this great field, the further exploration of which will enormously increase the usefulness of this wonderful metal.
Similar results have been obtained by using diazotized para-anisidine, a synand an anticompound being formed, as well as a third isomeric cyanide, obtained by evaporating para-methoxybenzenediazonium hydroxide in the presence of an excess of hydrocyanic acid at ordinary temperatures.
The alkali metals and alkaline earth metals decompose water at ordinary temperatures; magnesium begins to react above 70° C., and zinc at a dull red heat.
It is probable that the whole phenomenon of isomerism is due to the possibility that compounds or systems which in reality are unstable yet persist, or so slowly change that practically one can speak of their stability; for instance, such systems as explosives and a mixture of hydrogen and oxygen, where the stable form is water, and in which, according to some, a slow but until now undetected change takes place even at ordinary temperatures.
Consequently, of each pair of isomers we may establish beforehand which is the more stable; either in particular circumstances, a direct change taking place, as, for instance, with maleic acid, which when exposed to sunlight in presence of a trace of bromine, yields the isomeric fumaric acid almost at once, or, indirectly, one may conclude that the isomer which forms under greater heat-development is the more stable, at least at lower temperatures.
Now these modifications show hardly any tendency to persist, the one stable at high temperatures being formed at elevated temperatures, but changing in the reverse sense on cooling.
In the case of the quadrivalent carbon, diamond seems to be the stable form at ordinary temperatures, but one may wait long before it is formed from graphite.
Both formula and experiment proved that an increase of pressure of one atmosphere elevated the transition point for about o 04° The same laws apply to cases of more complicated nature, and one of them, which deserves to be pursued further, is the mutual transformation of cyanuric acid, C 3 H 3 N 3 O 3, cyanic acid, Chno, and cyamelide (Chno).; the first corresponding to prismatic sulphur, stable at higher temperatures, the last to rhombic, the equilibrium-symbol being: cyamelide 1 .?
The coefficient of expansion increases very rapidly above 750°, and diminishes very rapidly at low temperatures; the maximum density is attained about - 42° C.
For the twenty years1883-1902the annual average of mean monthly temperatures was 26.8° C., the maximum being 27.4° in 1889 and 1897, and the minimum 26.2° in 1884.
To take the simple case of the " wall " or flat plate considered by Fourier for the definition of thermal conductivity, suppose that a quantity of heat Q passes in the time T through an area A of a plate of conductivity k and thickness x, the sides of which are constantly maintained at temperatures B' and 8".
If the plate is thin, it is necessary to measure the thickness with great care, and it is necessary to assume that the temperatures of the surfaces are the same as those of the media with which they are in contact, since there is no room to insert thermometers in the plate itself.
The temperatures indicated by the different pairs of wires differed by as much as 10 %, but the mean of the whole would probably give a fair average.
(2) If k is constant the solution is evidently B =a log r+b, where a= and b and k are determined from the known values of the temperatures observed at any two distances from the axis.
This gives an average value of the conductivity over the range, but it is better to observe the temperatures at three distances, and to assume k to be a linear function of the temperature, in which case the solution of the equation is still very simple, namely, 0+Ze6 2 =a log r+b, (3) where e is the temperature-coefficient of the conductivity.
- If the inside of a glass tube is exposed to steam, and the outside to a rapid current of water, or vice versa, the temperatures of the surfaces of the glass may be taken to be very approximately equal to those of the water and steam, which may be easily observed.
Observations were taken at mean temperatures of 102° C. and 54°C., with the following results: Cast iron at 102°C., k/c = 1296, c= 858, k = 1113.
Some of these results have been widely quoted, but they are far from consistent, and it may be doubted whether the difficulties of observing rapidly varying temperatures have been duly appreciated in many cases.
The external heat-loss was eliminated by comparing observations taken at the same mean temperatures during heating and during cooling, assuming that the rate of loss of heat f(S) would be the same in the two cases.
It was also tacitly assumed that the thermo-electric power of the couples for the gradient was the same as that of the couples for the mean temperature, although the temperatures were different.
The thermal capacity and electrical conductivity were measured at various temperatures on the same specimens of metal.
Similarly if A is hotter than B, or if there is a gradient of temperature between adjacent layers, the diffusion of molecules from A to B tends to equalize the temperatures, or to conduct heat through the gas at a rate proportional to the temperature gradient, and depending also on the rate of interchange of molecules in the same way as the viscosity effect.
Experiments by the capillary tube method have shown that the viscosity varies more nearly as 0 1, but indicate that the rate of increase diminishes at high temperatures.
In a fine state of division it takes fire on heating in air, but is permanent at ordinary temperatures in oxygen or air; it is readily attacked by hydrochloric and sulphuric acids, but scarcely acted on by nitric acid.
In Alsace-Lorraine the Vosges and the plateau of Lorraine are also remarkable for low temperatures.
The northern parts as far south as the north shore of Lake Superior have long and cold but bright winters, sometimes with temperatures reaching 50° F.
The city has a monument (1900) to John Gorrie (1803-1855), a physician who discovered the cold-air process of refrigeration in 1849 (and patented an ice-machine in 1850), as the result of experiments to lower the temperatures of fever patients.
The mean maximum temperatures are 99 F.
The mean temperatures of the four coldest months, December to March, are 33.26°, 31.
irup, fire, Arpov, a measure), an instrument for measuring high temperatures.
The mode of preparation is to calcine the gypsum at temperatures which depend on the class of cement to be produced.
769) by acting with hydrogen peroxide on an alkaline solution of thallous sulphate at low temperatures, an initial red precipitate rapidly changing into a bluish-black compound.
There is hardly any seasonal change to be observed, and the dampness of the climate causes the heat to be more oppressive than are higher temperatures in drier climates.
Oxygen may be prepared by heating mercuric oxide; by strongly heating manganese dioxide and many other peroxides; by heating the oxides of precious metals; and by heating many oxy-acids and oxy-salts to high temperatures, for example, nitric acid, sulphuric acid, nitre, lead nitrate, zinc sulphate, potassium chlorate, &c. Potassium chlorate is generally used and the reaction is accelerated and carried out at a lower temperature by previously mixing the salt with about one-third of its weight of manganese dioxide, which acts as a catalytic agent.
These serve to modify the temperatures of the plateau, which is swept by cold winds at all seasons of the year.
Bleaching-powder is a compound obtained by the action of free chlorine on hydrated lime, containing a slight excess of water at ordinary temperatures or slightly above these.
(Sectional Elevation.) heat for some hours in order to settle out 'the ferric oxide which it always contains, and which becomes insoluble (through the destruction of the sodium ferrite) only at high temperatures.
He became professor at Leiden in 1882, and devoted himself especially to the study of properties of matter at low temperatures.
FUSIBLE METAL, a term applied to certain alloys, generally composed of bismuth, lead and tin, which possess the property of melting at comparatively low temperatures.
By suitable modification in the proportions of the components, a series of alloys can be made which melt at various temperatures above the boiling point of water; for example, with 8 parts of bismuth, 8 of lead and 3 of tin the melting point is 123°, and with 8 of bismuth, 30 of lead and 24 of tin it is 172°.
The greater part of the Deccan and the Central Provinces are included within the hottest area, though in May the highest temperatures are found in Upper Sind, north-west Rajputana, and south-west Punjab.
He also studied the alkaloids and organic acids, introduced a classification of the metals according to the facility with which they or their sulphides are oxidized by steam at high temperatures, and effected a comparison of the chemical composition of atmospheric air from all parts of the world.
Throughout the archipelago the mean annual temperature varies much more with the altitude than with the latitude, but the range in mean monthly temperatures increases from 3.96° F.
In the latter case two steady currents of water at different temperatures, say o° and too° are passed through an equalizer, and the resulting temperature measured without mixing the currents, which are then separately determined by weighing.
Person and Hess avoided the error of water sticking to the ice by using dry ice at various temperatures below o° C., and determining the specific heat of ice as well as the latent heat of fusion.
This Formula Has Since Been Very Generally Applied Over The Whole Range O° To 200° C., But The Experiments Could Not In Reality Give Any Information With Regard To The Specific Heat At Temperatures Below 100° C. The Linear Formula Proposed By J.
It Appears Probable That His Values For Higher Temperatures May Be Adopted With This Reduction, Which Is Further Confirmed By The Results Of Reynolds And Moorby, And By Those Of Liidin.
Many Authors, Adopting Regnault'S Formula, Have Selected O° C. As The Standard Temperature, But This Cannot Be Practically Realized In The Case Of Water, And His Formula Is Certainly Erroneous At Low Temperatures.
The Specific Heat At 4° Could Be Accurately Determined At The Mean Over The Range O° To 8° Keeping The Jacket At O° C. But The Change Appears To Be Rather Rapid Near O°, The Temperature Is Inconveniently Low For Ordinary Calorimetric Work, And The Unit At 4° Would Be So Much Larger Than The Specific Heat At Ordinary Temperatures That Nearly All Experiments Would Require Reduction.
The Energy Of Vibration May Be Appreciable At Ordinary Temperatures, And Would Probably Increase More Rapidly Than That Of Translation With Rise Of Temperature, Especially Near A Point Of Dissociation.
The Atomic Heat Of A Metal In The Solid State Is In Most Cases Larger Than Six Calories At Ordinary Temperatures.
Considering The Wide Variations In The Physical Condition And Melting Points, The Comparatively Close Agreement Of The Atomic Heats Of The Metals At Ordinary Temperatures, Known As Dulong And Petit'S Law, Is Very Remarkable.
Trans., 1900), The Atomic Heats Of Pure Nickel And Cobalt, As Determined From Experiments At The Boiling Points Of 02, And C02, Diminish So Rapidly At Temperatures Below O° C. As To Suggest That They Would Reach The Value 2.42 At The Absolute Zero.
This Is The Value Of The Minimum Of Atomic Heat Calculated By Perry From Diatomic Hydrogen, But The Observations Themselves Might Be Equally Well Represented By Taking The Imaginary Limit 3, Since The Quantity Actually Observed Is The Mean Specific Heat Between O° And 182 5° C. Subsequent Experiments On Other Metals At Low Temperatures Did Not Indicate A Similar Diminution Of Specific Heat, So That It May Be Doubted Whether The Atomic Heats Really Approach The Ideal Value At The Absolute Zero.
Evaporation of a solution at ordinary temperatures gives colourless monoclinic prisms of Th(SO 4) 2.9H 2 O, which is isomorphous with uranium sulphate, U(S04)2.9H20.
Another method, which is suitable for volatile liquids or low temperatures, is to allow the liquid to evaporate in a calorimeter, and to measure the quantity of heat required for the evaporation of the liquid at the temperature of the calorimeter and at saturation-pressure.
p. 173) that the increase of the total heat of a saturated vapour between any two temperatures should be equal to the specific heat S of the vapour at constant pressure multiplied by the difference of temperature, provided that the saturated vapour behaved as an ideal gas, and that its specific heat was independent of the pressure and temperature.
Taking the difference between the values of H for any two temperatures 1 " Latent Heat of Steam," Phil.
The specific heat of steam was determined shortly afterwards by Regnault (Comptes Rendus, 36, p. 676) by condensing superheated steam at two different temperatures (about 125° and 225° C.) successively in the same calorimeter at atmospheric pressure, and taking the difference of the total heats observed.
He suggested that the high value for S found by Regnault might be due to the presence of damp in his superheated steam, or, on the other hand, that the assumption that steam at low temperatures followed the law pv = R0 might be erroneous.
Assuming this result to hold generally, we should have S=0.306 at o° C., which agrees with Rankine's view; but increasing very rapidly at higher temperatures to S =1.043 at 200° C., and 1.315 at 220° C. The characteristic equation, if SQ = constant, would be of the form (v+SQ) = Roil ', which does not agree with the well-known behaviour of other gases and vapours.
Regnault's experiments at lower temperatures were extremely discordant, and have been shown by the work of E.
37, p. 504, 1889) to give values of the total heat to to 6 calories too large between o° and 40° C. At low pressures and temperatures it is probable that saturated steam behaves very nearly as an ideal gas, and that the variation of the total heat is closely represented by Rankine's equation with the ideal value of S.
In order to correct this equation for the deviations of the vapour from the ideal state at higher temperatures and pressures, the simplest method is to assume a modified equation of the Joule-Thomson type (Thermodynamics, equation (17)), which has been shown to represent satisfactorily the behaviour of other gases and vapours at moderate pressures.
(17) and diminishes from 0.478 at o° C. to about o 40 at loo° and 0.20 at 200° C., decreasing more rapidly at higher temperatures.
Since the specific heat of the liquid increases rapidly at high temperatures, while dH/d0 diminishes, it is clear that the latent heat must diminish more and more rapidly as the critical point is approached.
If we assume formulae of the simple type A+B/0 for two different substances which have the same vapour-pressure p at the absolute temperatures 0' and 0" respectively, we may write log p=A'+B'/0'= A"+B"/0", .
(20) from which we deduce that the ratio 0'/0" of the temperatures at which the vapour-pressures are the same is a linear function of the temperature 0' of one of the substances.
17, p. 1 77, 1882) in a slightly different form, and appropriately applied to the calculation of the vapour-pressures of mercury at ordinary temperatures, where they are much too small to be accurately measured.
The errcrs from both causes increase more rapidly at higher temperatures.
1902) for the specific heat of water between ioo° and 200° C., we find the values of the difference (d4-dh/9) to be less than one-tenth of do at 200° C. The whole correction is therefore probably of the same order as the uncertainty of the variation of the specific heat itself at these temperatures.
The mean temperatures for the different seasons are normally about 41.6°, 61.1°, 78.8° and 61.9° F.
That is, the variation of mean annual temperatures for different parts of the state is only 6° F.
It is extremely volatile, boiling at 12.5° C. (54.5° F.), and is therefore a gas at ordinary room temperatures; it is stored in glass tubes fitted with screwcapped nozzles.
At the other extreme, temperatures of - 20° to - 36° are recorded yearly on the Central (Southern) Pacific line near Lake Tahoe.
At any rate it may be said that generally speaking the maximum, minimum and mean temperatures of points of approximately equal altitude are respectively but slightly different in northern or southern California.2 Death Valley surpasses for combined heat and aridity any meteorological stations on earth where regular observations are taken, although for extremes of heat it is exceeded by places in the Colorado desert.
It combines with fluorine with incandescence at ordinary temperatures, and with chlorine at 250-300°; carbon, silicon, and boron, when heated with it in the electric furnace, give crystals harder than the ruby.
This salt is obtained by roasting wolfram with sodium carbonate, lixiviating, neutralizing the boiling filtrate with hydrochloric acid and crystallizing at ordinary temperatures.
The salt forms large monoclinic prisms; molecules containing 25 and 21 H 2 O separate from solutions crystallized at higher temperatures.
In the lower Bighorn Valley, summer temperatures rise to 95° or toe, but at heights of 6000 to 7000 ft.
on neighbouring ranges, summer temperatures seldom rise above 90°, and frosts may occur at any time.
have a mean annual temperature of from 40° to 47°, but high mountain areas and cold valleys may have mean temperatures as low as 34°.
The air is clear and dry, and although temperatures of 100° are recorded, sunstrokes are practically unknown.
Winter temperatures as low as - 51° have been recorded, but these very low temperatures occur in the valleys rather than on the higher elevations.
All four of the halogens unite with hydrogen, but the affinity for hydrogen decreases as the atomic weight increases, hydrogen and fluorine uniting explosively at very low temperatures and in the dark, whilst hydrogen and iodine unite only at high temperatures, and even then the resulting compound is very readily decomposed by heat.
On the other hand the stability of the known oxygen compounds increases with the atomic weight, thus iodine pentoxide is, at ordinary temperatures, a well-defined crystalline solid, which is only decomposed on heating strongly, whilst chlorine monoxide, chlorine peroxide, and chlorine heptoxide are very unstable, even at ordinary temperatures, decomposing at the slightest shock.
At ordinary temperatures it unites directly with many other elements; thus with hydrogen, combination takes place in direct sunlight with explosive violence; arsenic, antimony, thin copper foil and phosphorus take fire in an atmosphere of chlorine, forming the corresponding chlorides.