Metals Sentence Examples
This salt may be used for the separation of cobalt and nickel, since the latter metal does not form a similar double nitrite, but it is necessary that the alkaline earth metals should be absent, for in their presence nickel forms complex nitrites containing the alkaline earth metal and the alkali metal.
In light Kundt's name is widely known for his inquiries in anomalous dispersion, not only in liquids and vapours, but even in metals, which he obtained in very thin films by means of a laborious process of electrolytic deposition upon platinized glass.
Davy showed that they were oxides of various metals.
By far the greater portion of these metals came from the southern part of the state.
Vases of all kinds, carved in marble or other stones, cast or beaten in metals or fashioned in clay, the latter in enormous number and variety, richly ornamented with coloured schemes, and sometimes bearing moulded decoration.Advertisement
The astrological belief that plants, animals and minerals are under the influence of the planets is shown in the older names of some of the metals, e.g.
The metals comprising this group are never found in the uncombined condition, but occur most often in the form of carbonates and sulphates; they form oxides of the type RO, and in the case of calcium, strontium and barium, of the type R02.
The hydrogen of the hydroxyl group in phenol can be replaced by metals, by alkyl groups and by acid radicals.
The metallic derivatives (phenolates, phenates or carbolates) of the alkali metals are obtained by dissolving phenol in a solution of a caustic alkali, in the absence of air.
It combines with many metals to form sulphides, and also decomposes many metallic salts with consequent production of sulphides, a property which renders it extremely useful in chemical analysis.Advertisement
The sulphites are prepared by the action of sulphur dioxide on the oxides, hydroxides or carbonates of the metals, or by processes of precipitation.
Notwithstanding the wealth of the country in minerals and metals of all kinds, and the endeavours made by government to encourage mining, including the imposition of protective Mining tariffs even against Finland (in 1885), this and the related and re- industries are still at a low stage of development.
The imports of foreign metals in the rough and of coal are steadily increasing, while the exports, never otherwise than insignificant, show no advance.
By 1882 they had produced $60,000,000 of precious metals.
Many salts of the acid are known and, with the exception of those of the alkali metals, they are difficultly soluble in water.Advertisement
The citrates are a numerous class of salts, the most soluble of which are those of the alkaline metals; the citrates of the alkaline earth metals are insoluble.
In the narrow sense of the word, alchemy is the pretended art of making gold and silver, or transmuting the base metals into the noble ones.
Some are in Greek and demotic, and one, of peculiar interest from the chemical point of view, gives a number of receipts, in Greek, for the manipulation of base metals to form alloys which simulate gold and are intended to be used in the manufacture of imitation jewellery.
The author of these receipts is not under any delusion that he is transmuting metals; the MS. is merely a workshop manual in which are described processes in daily use for preparing metals for false jewellery, but it argues considerable knowledge of methods of making alloys and colouring metals.
Thus, in the treatise known as Physica et Mystica and falsely ascribed to Democritus (such false attributions are a constant feature of the literature of alchemy), various receipts are given for colouring and gilding metals, but the conception of transmutation does not occur.Advertisement
Later, however, as in the Commentary on this work written by Synesius to Dioscorus, priest of Serapis at Alexandria, which probably dates from the end of the 4th century, a changed attitude becomes apparent; the more practical parts of the receipts are obscured or omitted, and the processes for preparing alloys and colouring metals, described in the older treatise, are by a mystical interpretation represented as resulting in real transmutation.
The conception of man, the microcosm, containing in himself all the parts of the universe or macrocosm, is also Babylonian, as again probably is the famous identification of the metals with the planets.
Of the first group the most interesting and possibly the oldest is the Book of Crates; it is remarkable for containing some of the signs used for the metals by the Greek alchemists, and for giving figures of four pieces of apparatus which closely resemble those depicted in Greek MSS., the former being never, and the latter rarely, found in other Arabic MSS.
The fundamental theory of the transmutation of metals is to be found in the Greek alchemists, although in details it was modified and elaborated by the Arabs and the Latin alchemists.
This is briefly the doctrine that the metals are composed of mercury and sulphur, which persisted in one form or another down to the 17th century.Advertisement
Later, as in the works attributed to Basil Valentine, sulphur, mercury and salt are held to be the constituents of the metals.
But even among the late Arabian alchemists it was doubted whether the resources of the art were adequate to the task; and in the West, Vincent of Beauvais remarks that success had not been achieved in making artificial metals identical with the natural ones.
The metals he produced are said to have proved genuine on assay; when, however, in the following year he was challenged to repeat the experiments he was unable to do so and committed suicide.
Like most of the other metals of the group, it absorbs gases.
The chief imports are cotton piece goods, cotton twist, salt, sugar, provisions, railway materials, raw cotton, metals, coal, tobacco, spices and kerosene oil.
The search for this essence subsequently resolved itself into the desire to effect the transmutation of metals, more especially the base metals, into silver and gold.
In the view of some alchemists, the ultimate principles of matter were Aristotle's four elements; the proximate constituents were a " sulphur " and a " mercury," the father and mother of the metals; gold was supposed to have attained to the perfection of its nature by passing in succession through the forms of lead, brass and silver; gold and silver were held to contain very pure red sulphur and white quicksilver, whereas in the other metals these materials were coarser and of a different colour.
From an analogy instituted between the healthy human being and gold, the most perfect of the metals, silver, mercury, copper, iron, lead and tin, were regarded in the light of lepers that required to be healed.
Notwithstanding the false idea which prompted the researches of the alchemists, many advances were made in descriptive chemistry, the metals and their salts receiving much attention, and several of our important acids being discovered.
Metals on calcination gave calces from which the metals could.
The objections of the antiphlogistonists, such as the fact that calces weigh more than the original metals instead of less as the theory suggests, were answered by postulating that phlogiston was a principle of levity, or even completely ignored as an accident, the change of qualities being regarded as the only matter of importance.
Gold, the most perfect metal, had the symbol of the Sun, 0; silver, the semiperfect metal, had the symbol of the Moon, 0j; copper, iron and antimony, the imperfect metals of the gold class, had the symbols of Venus Mars and the Earth tin and lead, the imperfect metals of the silver class, had the symbols of Jupiter 94, and Saturn h; while mercury, the imperfect metal of both the gold and silver class, had the symbol of the planet,.
Gerhardt found that reactions could be best followed if one assumed the molecular weight of an element or compound to be that weight which occupied the same volume as two unit weights of hydrogen, and this assumption led him to double the equivalents accepted by Gmelin, making H= 1, 0 =16, and C = 12, thereby agreeing with Berzelius, and also to halve the values given by Berzelius to many metals.
All the metals are solids at ordinary temperatures with the exception of mercury, which is liquid.
But the difference between these two classes of elements is one of degree only, and they gradually merge into each other; moreover the electric relations of elements are not absolute, but vary according to the state of combination in which they exist, so that it is just as impossible to divide the elements into two classes according to this property as it is to separate them into two distinct classes of metals and non-metals.
The metals may be arranged in a series according to their power of displacing one another in salt solutions, thus Cs, Rb, K, Na, Mg, Al, Mn, Zn, Cd, Tl, Fe, Co, Ni, Sn, Pb, (H), Sb, Bi, As, Cu, Hg, Ag, Pd, Pt, Au.
An acid (q.v.) is a compound of hydrogen, which element can be replaced by metals, the hydrogen being liberated, giving substances named salts.
The action of these acids on many metals was also studied; Glauber obtained zinc, stannic, arsenious and cuprous chlorides by dissolving the metals in hydrochloric acid, compounds hitherto obtained by heating the metals with corrosive sublimate, and consequently supposed to contain mercury.
Vauquelin in 1797, and Klaproth's investigation of tellurium in 1798, the next important series of observations was concerned with platinum and the allied metals.
The great number and striking character of the compounds of this group of metals have formed the subject of many investigations, and already there is a most voluminous literature.
Considerable uncertainty existed as to the atomic weights of these metals, the values obtained by Berzelius being doubtful.
Berzelius's investigation of the action of the electric current on salts clearly demonstrated the invaluable assistance that electrolysis could render to the isolator of elements; and the adoption of this method by Sir Humphry Davy for the analysis of the hydrates of the metals of the alkalis and alkaline earths, and the results which he thus achieved, established its potency.
Here he met with greater difficulty, and it is to be questioned whether he obtained any of these metals even in an approximately pure form (see Electrometallurgy).
Schneider and others, have proved the existence of " colloidal silver "; similar forms of the metals gold, copper, and of the platinum metals have been described.
Within two years of the invention the authors announced the discovery of two metals, rubidium and caesium, closely allied to sodium, potassium and lithium in properties, in the mineral lepidolite and in the Diirkheim mineral water.
Cleve proposed to divide the " rare earth " metals into two groups, (1) " perfectly characterized "; (2) " not yet thoroughly characterized."
Of recent years the introduction of various organic compounds as precipitants or reagents has reduced the labour of the process; and advantage has also been taken of the fairly complex double salts which these metals form with compounds.
These crude earths, yttria and ceria, have supplied most if not all of the " rare earth " metals.
Bergman laid the foundations of systematic qualitative analysis, and devised methods by which the metals may be separated into groups according to their behaviour with certain reagents.
He applied himself more particularly to the oxygen compounds, and determined with a fair degree of accuracy the ratio of carbon to oxygen in carbon dioxide, but his values for the ratio of hydrogen to oxygen in water, and of phosphorus to oxygen in phosphoric acid, are only approximate; he introduced no new methods either for the estimation or separation of the metals.
This has led to the estimation of sugar by means of the polarimeter, and of the calorific power of fuels, and the valuation of ores and metals, of coal-tar dyes, and almost all trade products.
The limits of space prevent any systematic account of the separation of the rare metals, the alkaloids, and other classes of organic compounds, but sources where these matters may be found are given in the list of references.
Oxygen, recognized by its power of igniting a glowing splinter, results from the decomposition of oxides of the noble metals, peroxides, chlorates, nitrates and other highly oxygenized salts.
Certain substances, such as the precious metals, are quite insoluble in the bead, but float about in it.
The procedure for the detection of metals in solution consists of first separating them into groups and then examining each group separately.
If, however, phosphoric acid is present in the original substance,we may here obtain a precipitate of the phosphates of the remaining metals, together with aluminium, chromium and ferric hydrates.
The phosphates of aluminium, chromium and iron are precipitated, and the solution contains the same metals as if phosphoric acid had been absent.
The remaining metals are tested for separately.
Details will be found in the articles on particular metals.
Lead and manganese are partially separated as peroxides, but the remaining metals are not deposited from acid solutions.
It is therefore necessary that the solution should be free from metals which may vitiate the results, or special precautions taken by which the impurities are rendered harmless.
Nilson and Pettersson's observations on beryllium and germanium have shown that the atomic heats of these metals increase with rise of temperature, finally becoming constant with a value 5.6.
Other metals were tested in order to determine if their atomic heats approximated to this value at low temperatures, but with negative results.
This fact finds a parallel in the atomic weights of these metals.
Gold had fallen still further from the diffusion of the Persian treasure, and Alexander struck in both metals on the Attic standard, leaving their relation to adjust itself by the state of the market.
Mining is carried on only to a small extent for arsenic, although there are traces of former more extensive workings for other metals.
Traditions of gold and silver, dating from the time of the Spanish conquest, still endure, but these metals are in fact extremely rare.
Mining for the precious metals ceased at a very early date, after rich discoveries were made on the continent.
The proportion of imports taken from the United States is greatest in foodstuffs, metals and metal manufactures, timber and furniture, mineral oils and lard.
It combines directly with lithium, calcium and magnesium when heated, whilst nitrides of the rare earth metals are also produced when their oxides are mixed with magnesium and heated in a current of nitrogen (C. Matignon, Comptes rendus, 1900, 131, p. 837).
It converts many metallic oxides into mixtures of nitrates and nitrites, and attacks many metals, forming nitrates and being itself reduced to nitric oxide.
The imports are woollen and cotton piece-goods, metals and petroleum.
The rare earth metals are found in the minerals gadolinite, samarskite, fergusonite, euxenite and cerite.
Volta's cell consists essentially of two plates of different metals, such as zinc and copper, connected by an electrolyte such as a solution of salt or acid.
This observation showed that nascent hydrogen was not, as had been supposed, the primary cause of the separation of metals from their solutions, but that the action consisted in a direct decomposition into metal and acid.
In 1807 he decomposed potash and soda, previously considered to be elements, by passing the current from a powerful battery through the moistened solids, and thus isolated the metals potassium and sodium.
The salt must therefore be derived from an acid, chloroplatinic acid, H 2 PtC1 6, and have the formula Na 2 PtC1 6, the ions being Na and PtCls", for if it were a double salt it would decompose as a mixture of sodium chloride and platinum chloride and both metals would go to the cathode.
When two metallic conductors are placed in an electrolyte, a current will flow through a wire connecting them provided that a difference of any kind exists between the two conductors in the nature either of the metals or of the portions of the electrolyte which surround them.
A current can be obtained by the combination of two metals in the same electrolyte, of two metals in different electrolytes, of the same metal in different electrolytes, or of the same metal in solutions of the same electrolyte at different concentrations.
In ordinary cells the difference is secured by using two dissimilar metals, but an electromotive force exists if two plates of the same metal are placed in solutions of different substances, or of the same substance at different concentrations.
It is now evident that the electromotive force of an ordinary chemical cell such as that of Daniell depends on the concentration of the solutions as well as on the nature of the metals.
If secondary effects are eliminated, the deposition of metals also is a reversible process; the decomposition voltage is equal to the electromotive force which the metal itself gives when going into solution.
Many experiments have been made with a view of separating the two potential-differences which must exist in any cell made of two metals and a liquid, and of determining each one individually.
On the other hand, it is commonly thought that the single potentialdifferences at the surface of metals and electrolytes have been determined by methods based on the use of the capillary electrometer and on others depending on what is called a dropping electrode, that is, mercury dropping rapidly into an electrolyte and forming a cell with the mercury at rest in the bottom of the vessel.
The contact differences of potential at the interfaces of metals and electrolytes have been co-ordinated by Nernst with those at the surfaces of separation between different liquids.
In metals the electrons can slip from one atom to the next, since a current can pass without chemical action.
The vats for depositing may be of enamelled iron, slate, glazed earthenware, glass, lead-lined wood, &c. The current densities and potential differences frequently used for some of the commoner metals are given in the following table, taken from M ` Millan's Treatise on Electrometallurgy.
By varying this process, designs in metals of different colours may readily be obtained.
Other alloys may be produced, such as bronze, or German silver, by selecting solutions (usually cyanides) from which the current is able to deposit the constituent metals simultaneously.
Pliny treats of these two metals as plumbum nigrum and plumbum album respectively, which seems to show that at his time they were looked upon as being only two varieties of the same species.
Lead unites readily with almost all other metals; hence, and on account of its being used for the extraction of (for instance) silver, its alchemistic name of saturnus.
Practically the metals iron, nickel and cobalt, and some of their alloys and compounds constitute a class by themselves and are called ferromagnetic substances.
In the case of the ferromagnetic metals and some of their alloys and compounds, the permeability has generally a much higher value.
The value of the constant / 7 ranges in different metals from about o ooI to 0.04; in soft iron and steel it is said to be generally not far from 0.002.
These are to be regarded merely as typical specimens, for the details of a curve depend largely upon the physical condition and purity of the material; but they show at a glance how far the several metals differ from and resemble one another as regards their magnetic properties.
In hardened iron and steel the effect can scarcely be detected, and in weak fields these metals exhibit no magnetic hysteresis of any kind.
Honda, measured the changes of length of various metals shaped in the form of ovoids instead of cylindrical rods, and determined the magnetization curves for the same specimens; a higher degree of accuracy was thus attained, and satisfactory data were provided for testing theories.
Nagaoka and Honda, who employed a fluid dilatometer, found that the volume of several specimens of iron, steel and nickel was always slightly increased, no diminution being indicated in low fields; cobalt, on the other hand, was diminished in volume, and the amount of the change, though still very small, was greater than that shown by the other metals.
Knott, who made an exhaustive series of experiments upon various metals in the form of tubes, concluded that in iron there was always a slight increase of volume, and in nickel and cobalt a slight decrease.
It is uncertain how far these various results are dependent upon the physical condition of the metals.
So, too, the Villari reversals in iron and cobalt might have been predicted - as indeed that in cobalt actually was - from a knowledge of the changes of length which those metals exhibit when magnetized.
It would hardly be safe to generalize from these observations; the effects may possibly be dependent upon the physical condition of the metals.
For each of the metals tabulated in the first column all the effects hitherto observed have the same sign; there is no single instance in which some are positive and others negative.
The magnetometric method was employed, and the metals, in the form of ovoids, were heated by a specially designed burner, fed with gas and air under pressure, which directed 90 fine jets of flame upon the asbestos covering the ovoid.
Honda and Shimizu have made similar experiments at the temperature of liquid air, employing a much wider range of magnetizing forces (up to about 700 C.G.S.) and testing a greater variety of metals.
It may be remarked that, whereas Fleming and Dewar employed the ballistic method, their specimens having the form of rings, Honda and Shimizu worked magnetometrically with metals shaped as ovoids.
An alloy containing about 3 parts of iron and I of nickel - both strongly magnetic metals - is under ordinary conditions practically non-magnetizable (1 1=1'4 for any value of H).
All the metals were annealed.
The metals used in different combinations included tin, aluminium, arsenic, antimony, bismuth and boron; each of these, when united in certain proportions with manganese, together with a larger quantity of copper (which appears to serve merely as a menstruum), constituted a magnetizable alloy.
So far, the best results have been attained with aluminium, and the permeability was greatest when the percentages of manganese and aluminium were approximately proportional to the atomic weights of the two metals.
Next to aluminium, tin was found to be the most effective of the metals enumerated above.
Manganese, though belonging (with chromium) to the iron group of metals, is commonly classed as a paramagnetic, its susceptibility being very small in comparison with that of the recognized ferromagnetics; but it is remarkable that its atomic susceptibility in solutions of its salts is even greater than that of iron.
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.
If this view is correct, it may also be possible to prepare magnetic alloys of chromium, the only other paramagnetic metals of the iron group.
Thomson (Lord Kelvin), who in 1856 announced that magnetization rendered iron and steel positive to the unmagnetized metals.'
Meyer thinks that the susceptibilities of the metals praseodymium, neodymium, ytterbium, samarium, gadolinium, and erbium, when obtained in a pure form, will be found to equal or even exceed those of the well-known ferromagnetic metals.
The process of electric conduction in metals consists in the movement of detached electrons, and many other phenomena, both electrical and thermal, can be more or less completely explained by their agency.
Rowland,' whose careful experiments led to general recognition of the fact previously ignored by nearly all investigators, that magnetic susceptibility and permeability are by no means constants (at least in the case of the ferromagnetic metals) but functions of the magnetizing force.
Besides wool, leading imports are jute, cotton, flax, timber, petroleum, coal, pitch, wine, cereals, oil-seeds and oil-cake, nitrate of soda and other chemical products, and metals.
Debray (1827-1888) he worked at the platinum metals, his object being on the one hand to prepare them pure, and on the other to find a suitable metal for the standard metre for the International Metric Commission then sitting at Paris.
It is worthy of observation, that Brazil was the first colony founded in America upon an agricultural principle, for until then the precious metals were the exclusive attraction.
There is trade in agricultural produce, wine, metals, &c. The canal from the Rhone to the Rhine passes under the citadel by way of a tunnel, and the port of Besancon has considerable trade in coal, sand, &c.
There are extensive copper and goldyielding areas, and in some districts these metals are mined.
In chemistry he made a speciality of the platinum metals.
Platinum itself he discovered how to work on a practical scale, and he is said to have made a fortune from the secret, which, however, he disclosed in a posthumous paper (1829); and he was the first to detect the metals palladium (1804)(1804) and rhodium (1805) in crude platinum.
He saw that the amount of money in circulation did not constitute the wealth of the community, and that the prohibition of the export of the precious metals was rendered inoperative by the necessities of trade.
The mother liquor includes generally more or less of nickel, cobalt, zinc and other heavy metals, which, as Wailer showed, can be removed as insoluble sulphides by the addition of ammonium sulphide; uranium, under the circumstances, is not precipitated by this reagent.
Of minerals containing this element mention may be made of cassiterite or tinstone, Sn02, tin pyrites, Cu 4 SnS 4 + (Fe,Zn) 2 SnS 4; the metal also occurs in some epidotes, and in company with columbium, tantalum and other metals.
There are coal-mines at Nong-Son, near Tourane, and gold, silver, lead, iron and other metals occur in the mountains.
Special methods of mining are dealt with in the separate articles on Coal, Gold, and other minerals and metals.
Other metals, such as manganese, copper, nickel, may show their presence by characteristic colours.
On the other hand, in the case of less regular deposits, including most metalliferous veins, and especially those of the precious metals, the uncertainty is often very great, and it is sometimes necessary to work on a small scale for months before any considerable expenditure of money is justified.
In mines of copper, lead and the precious metals, in which the cars are moved by hand, the usual load is from 1200 to 3000 lb.
It did excellent service in the hands of Graham for the extraction of gases occluded in metals.
The theory most widely accepted at present is that glass is a quickly solidified solution, in which silica, silicates, borates, phosphates and aluminates may be either solvents or solutes, and metallic oxides and metals may be held either in solution or in suspension.
C. Maxwell Garnett, who has studied the optical properties of these glasses, has suggested that the changes in colour correspond with changes effected in the structure of the metals as they pass gradually from solution in the glass to a state of crystallization.
It is found in the form of oxide (silica), either anhydrous or hydrated as quartz, flint, sand, chalcedony, tridymite, opal, &c., but occurs chiefly in the form of silicates of aluminium, magnesium, iron, and the alkali and alkaline earth metals, forming the chief constituent of various clays, soils and rocks.
It combines directly with many metals on heating, whilst others merely dissolve it.
When heated with the alkali and alkaline earth metals it yields silicon and the corresponding metallic chlorides.
Most metals form carbonates (aluminium and chromium are exceptions), the alkali metals yielding both acid and normal carbonates of the types Mhco 3 and M 2 CO 3 (M = one atom of a monovalent metal); whilst bismuth, copper and magnesium appear only to form basic carbonates.
The acid carbonates of the alkali metals can be prepared by saturating an aqueous solution of the alkaline hydroxide with carbon dioxide, M OH+ C02= Mhco 3, and from these acid salts the normal salts may be obtained by gentle heating, carbon dioxide and water being produced at the same time, 2Mhco 3 = M2C03+H02+C02.
Most other carbonates are formed by precipitation of salts of the metals by means of alkaline carbonates.
All carbonates, except those of the alkali metals and of thallium, are insoluble in water; and the majority decompose when heated strongly, carbon dioxide being liberated and a residue of an oxide of the metal left.
The individual carbonates are described under the various metals.
In modern chemistry, however, the metals are a division of the elements, the members of which may or may not possess all these characters.
This definition, however, is highly artificial and objectionable on principle, because when we speak of metals we think, not of their chemical relations, but of a certain sum of mechanical and physical properties which unites them all into one natural family.
All metals, when exposed in an inert atmosphere to a sufficient temperature, assume the form of liquids, which all present the following characteristic properties.
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.
These frozen metals in general form compact masses consisting of aggregates of crystals belonging to the regular or rhombic or (more rarely) the quadratic system.
To this remarkable combination of properties more than to anything else the ordinary metals owe their wide application in the mechanical arts.
In former times a high specific gravity used to be quoted as one of the characters of the genus; but this no longer holds, since we now know a series of metals lighter than water.
This, in the case of even the solid metals, is perhaps only a very low degree of transparency.
Most (perhaps all) metals are capable of crystallization.
Perhaps all metals are crystalline, only the degree of visibility of the crystalline arrangement is very different in different metals, and even in the same metal varies according to the slowness of solidification and other circumstances.
The crystalline structure which exists on both sides becomes visible only in the metals of the first class, and only there manifests itself as brittleness.
Closely related to the structure of metals is their degree of "plasticity" (susceptibility of being constrained into new forms without breach of continuity).
The quality of plasticity is developed to very different degrees in different metals, and even in the same species it depends on temperature, and may be modified by mechanical or physical operations.
Pure iron, copper, silver and other metals are easily drawn into wire, or rolled into sheet, or flattened under the hammer.
But all these operations render the metals harder, and detract from their plasticity.
Tresca show that the plasticity of certain metals at least goes considerably farther than had before been supposed.
He operated with lead, copper, silver, iron and some other metals.
Of the better known metals potassium and sodium are the softest; they can be kneaded between the fingers like wax.
After these follow first thallium and then lead, the latter being the softest of the metals used in the arts.
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.
All metals are elastic to this extent that a change of form, brought about by stresses not exceeding certain limit values, will disappear on the stress being removed.
This varies in metals from 594 (lithium) to 22.48 (osmium), and in one and the same species is a function of temperature and of previous physical and mechanical treatment.
The following table gives the specific gravities of many metals.
Thermal Properties.-The specific heats of most metals have been determined.
The coefficient of expansion is constant for such metals only as crystallize in the regular system; the others expand differently in the directions of the different axes.
To eliminate this source of uncertainty these metals were employed as compressed powders.
The following table gives the electric conductivities of a number of metals as determined by Matthiesen, and the relative internal thermal conductivities of (nominally) the same metals as determined by Wiedemann and Franz, with rods about 5 mm.
Metals may unite chemically both with metals and with non-metals.
Metallic Substances Produced by the Union of Metals with Small Proportions of Non-Metallic Elements.
Hydrogen, as was shown by Graham, is capable of uniting with or being occluded by certain metals, notably with palladium (q.v.), into metal-like compounds.
Mercury and copper and some other metals are capable of dissolving their own oxides.
But the presence of moderate proportions of cuprous oxide has been found to correct the evil influence of small contaminations by arsenic, antimony, lead and other foreign metals.
Arsenic combines readily with all metals into true arsenides, which latter, in general, are soluble in the metal itself.
Most metals when molten are capable of dissolving at least small proportions of carbon, which, in general, leads to a deterioration in metallicity, except in the case of iron, which by the addition of small percentages of carbon gains in elasticity and tensile strength with little loss of plasticity.
Silicon, so far as we know, behaves to metals pretty much like carbon, but our knowledge of facts is limited.
The metals to be referred to are always understood to be given in the compact (frozen) condition, and that, wherever metals are enumerated as being similarly attacked, the degree of readiness in the action is indicated by the order in which the several members are named - the more readily changed metal always standing first.
In the case of group I the action is more or less violent, and the hydroxides formed are soluble in water and very strongly basic; metals of group 2 are only slowly attacked, with formation of relatively feebly basic and less soluble hydroxides.
Disregarding the rarer elements, the metals not named so far may be said to be proof against the action of pure water in the absence of free oxygen (air).
Copper, in the present connexion, is intermediate between iron and the following group of metals.
Mercury, if pure, and all the "noble" metals (silver, gold, platinum and platinum-metals), are absolutely proof against water even in the presence of oxygen and carbonic acid.
The metals grouped together above, under 1 and 2, act on steam pretty much as they do on liquid water.
Hot (concentrated) sulphuric acid does not attack gold, platinum and platinum-metals generally; all other metals (including silver) are converted into sulphates, with evolution of sulphur dioxide.
All other metals, including palladium, are dissolved as nitrates, the oxidizing part of the reagent being generally reduced to oxides of nitrogen.
Aqua Regia, a mixture of nitric and hydrochloric acids, converts all metals (even gold, the "king of metals," whence the name) into chlorides, except only rhodium, iridium and ruthenium, which, when pure, are not attacked.
Of metals not decomposing liquid pure water, only a few dissolve in aqueous caustic potash or soda, with evolution of hydrogen.
But of the rest the majority, when treated with boiling sufficiently strong alkali, are attacked at least superficially; of ordinary metals only gold, platinum, and silver are perfectly proof against the reagents under consideration, and these accordingly are used preferably for the construction of vessels intended for analytical operations involving the use of aqueous caustic alkalis.
In chemical laboratories fusions with caustic alkalis are always effected in vessels made of gold or silver, these metals holding out fairly well even in the presence of air.
All other metals, when heated in oxygen or air, are converted, more or less readily, into stable oxides.
Potassium, for example, yields peroxide, K202 or K204; sodium gives Na202; the barium-group metals, as well as magnesium, cadmium, zinc, lead, copper, are converted into their monoxides MeO.
Sulphur.-Amongst the better known metals, gold and aluminium are the only ones which, when heated with sulphur or in sulphur vapour remain unchanged.
The metals of the alkalis and alkaline earths, also magnesium, burn in sulphur vapour as they do in oxygen.
Of the heavy metals, copper is the one which exhibits by far the greatest avidity for sulphur, its subsulphide Cu 2 S being the stablest of all heavy metallic sulphides in opposition to dry reactions.
Chlorine.-All metals, when treated with chlorine gas at the proper temperatures, pass into chlorides.
For the characters of metals as chemical elements see the special articles on the different metals.
The sulphur exists in the soil chiefly in the form of sulphates of magnesium, calcium and other metals; the phosphorus mainly as phosphates of calcium, magnesium and iron; the potash, soda and other bases as silicates and nitrates; calcium and magnesium carbonates are also common constituents of many soils.
Heated with many metals it converts them into oxides, and with combustible substances, such as charcoal, sulphur, &c., a most intense conflagration occurs.
Moreover, zinc and bismuth were confused, and the word spiauter (the modern spelter) was indiscriminately given to both these metals.
A bath, even of very impure zinc, is allowed to stand at about the temperature of the melting-point of the metal for forty-eight or more hours, whereupon the more easily oxidizable impurities can be largely removed in the dross at the top, the heavier metals such as lead and iron settling towards the bottom.
Zinc being more electro-positive even than nickel, all the heavy metals must be removed before its deposition is attempted.
Borchers, trace it to the presence of oxide, produced, for example, either by the use of a solution containing a trace of basic salt of zinc (to prevent which the bath should be kept just - almost imperceptibly - acid), or by the presence of a more electro-negative metal, which, being co-deposited, sets up local action at the expense of the zinc. Many processes have been patented, the ore being acted upon by acid, and the resulting solution treated, by either chemical or electrolytic means, for the successive removal of the other heavy metals.
It is chemically related to cadmium and mercury, the resemblance to cadmium being especially well marked; one distinction is that zinc is less basigenic. Zinc is capable of isomorphously replacing many of the bivalent metals - magnesium, manganese, iron, nickel, cobalt and cadmium.
If care be taken to keep the zinc in excess, the solution will be free from all foreign metals except iron and perhaps manganese.
Zinc sulphate, like magnesium sulphate, unites with the sulphates of the potassium metals and of ammonium into crystalline double salts, ZnS04 R2S04-+-6H20, isomorphous with one another and the magnesium salts.
When the furnace with this well-known regulating device was to be used, say, for the melting of metals or other conductors of electricity, the fragments of metal were placed in the crucible and the positive electrode was brought near them.
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.
Moissan succeeded in fusing about 4 lb of either of these metals in 5 or 6 minutes in a furnace similar to that last described.
There is, however, one (not insuperable) drawback in the use of the electric furnace for the smelting of pure metals.
Aluminium, iron, platinum and many other metals may thus take up so much carbon as to become brittle and unforgeable.
Lead, zinc and other metals have also been reduced in this manner.
In the number and variety of its leather and other fancy goods Vienna rivals Paris, and is also renowned for its manufacture of jewelry and articles of precious metals, objets d'art, musical instruments, physical chemicals and optical instruments, and artistic products generally.
In common with Gay Lussac and Davy, he held subterraneous thermic disturbances to be probably due to the contact of water with metals of the alkalis and alkaline earths.
They used these precious metals in decorations and as ornaments, but apparently attached no great value to them.
Of other metals, lead is widely distributed, its chief source being a high grade galena accompanied by silver.
The manufacturing industries of Peru are confined chiefly to the treatment of agricultural and mineral products - the manufacture of sugar and rum from sugar cane, textiles from cotton and wool, wine and spirits from grapes, cigars and cigarettes from tobacco, chocolate from cacao, kerosene and benzine from crude petroleum, cocaine from coca, and refined metals from their ores.
Although the double standard was in force, gold was practically demonetized by the monetary reform of 1872 because of the failure to fix a legal ratio between the two metals.
As workers in metals and as potters they displayed infinite variety of design, while as cultivators and engineers they excelled their European conquerors.
He is a firespirit, who is pressed into man's service, and typifies the advance from the stone age to a higher stage of civilization (working in metals).
Its principal imports are cotton and woollen goods, yarn, metals, sugar, coffee, tea, spices, cashmere shawls, &c., and its principal exports opium, wool, carpets, horses, grain, dyes and gums, tobacco, rosewater, &c. The importance of Bushire has much increased since about 1862.
Both these compounds afford delicate, unobtrusive and effective grounds for inlaying with gold, silver and other metals, as well as for sculpture, whether incised or in relief.
Shibuichi inlaid with shakudo used to be the commonest combination of metals in this class of decoration, and the objects usually depicted were bamboos, crows, wild-fowl under the moon, peony sprays and so forth.
Iron was the metal used exclusively for work of this kind down to the 16th century, but various metals began thenceforth to be combined.
The preparation, properties, &c., of cyanides are treated in the article Prussic Acid; reference should also be made to the articles on the particular metals.
The principle usually followed in the electrolytic refining of metals is to cast the impure metal into plates, which are exposed as anodes in a suitable solvent, commonly a salt of the metal under treatment.
Soluble impurities which are more electro-negative than the metal under treatment must, if present, be removed by a preliminary process, and the voltage and other conditions must be so selected that none of the more electro-positive metals are co-deposited with the metal to be refined.
For details of the practical methods see Gold; Silver; Copper and headings for other metals.
Of the general characters of acids we may here notice that they dissolve alkaline substances, certain metals, &c., neutralize alkalies and redden many blue and violet vegetable colouring matters.
At about the same time Boyle investigated several acids; he established their general reddening of litmus, their solvent power of metals and basic substances, and the production of neutral bodies, or salts, with alkalies.
This and other reasons led to his rejection of the dualistic hypothesis and the adoption, on the ground of probability, and much more from convenience, of the tenet that " acids are particular compounds of hydrogen, in which the latter can be replaced by metals "; while, on the constitution of salts, he held that " neutral salts are those compounds of the same class in which the hydrogen is replaced by its equivalent in metal.
Only the salts of the alkali metals are soluble in water.
These substances are for all practical purposes new metals.
The two ingredients revealed by this process are not pure copper and pure tin, but each material contains both metals.
It would seem, indeed, that any process by which the particles of two metals are intimately mingled and brought into close contact, so that diffusion of one metal into the other can take place, is likely to result in the formation of an alloy.
For example, if vapours of the volatile metals cadmium, zinc and magnesium are allowed to act on platinum or palladium, alloys are produced.
Spring has shown that by compressing a finely divided mixture of i 5 parts of bismuth, 8 parts of lead, 4 parts of tin and 3 parts of cadmium, an alloy is pro duced which melts at ioo C., that is, much below the meltingpoint of any of the four metals.
The phenomena which succeed each other are then very similar, whether A and B are two metals, such as lead and tin or silver and copper, or are a pair of fused salts, or are water and common salt.
A great many mixtures of metals have been examined in the above-mentioned way.
In the case of this pair of metals, or indeed of any metallic alloy, we cannot see the crystals forming, nor can we easily filter them off and examine them apart from the liquid, although this has been done in a few cases.
The substance AuAl 2 is the most remarkable compound of two metals that has so far been discovered; although it contains so much aluminium its melting-point is as high as that of gold.
Various compounds of the alkali metals with bismuth, antimony, tin and lead have been prepared in a pure state.
So far we have been considering alloys containing two metals; the phenomena they present are by no means simple.
But when three or more metals are present, as is often the case in useful alloys, the phenomena are much more complicated.
We have here a comparatively simple case, as the metals do not form compounds.
The alloy of the point e is the ternary eutectic; it deposits the three metals simultaneously during the whole period of its solidfication and solidifies at a constant temperature.
It is evident that any other property can be represented by similar diagrams. For example, we can construct the curve of conductivity of alloys of two metals or the surface of conductivity of ternary alloys, and so on for any measurable property.
When a current is passed through a solid alloy, a series of Peltier effects, proportional to the current, are set up between the particles of the different metals, and these create an opposing electromotive force which is indistinguishable experimentally from a resistance.
The metals have therefore passed into an insoluble form by a comparatively slight elevation of temperature.
Roberts-Austen pointed out that surfusion might be easily measured in metals and in alloys by the sensitive method of recording pyrometry perfected by him.
The addition of a third metal will sometimes render the mixture of two other metals homogeneous.
Since 1875 increased attention has been devoted to the applications of the rarer metals.
One of the most interesting amongst recent alloys is Conrad Heusler's alloy of copper, aluminium and manganese, which possesses magnetic properties far in excess of those of the constituent metals.
The importance is now widely recognized of considering the mechanical properties of alloys in connexion with the freezing-point curves to which reference has already been made, but the subject is a very complicated one, and all that need be said here, is that when considered in relation to their meltingpoints the pure metals are consistently weaker than alloys.
It has also been stated that alloys of metals with similar meltingpoints have higher tenacity when the atomic volumes of the constituent metals differ than when they are nearly the same.
With regard to the history of the metallurgy of gold, it may be mentioned that, according to Pliny, mercury was employed in his time both as a means of separating the precious metals and for the purposes of gilding.
Gold has a characteristic yellow colour, which is, however, notably affected by small quantities of other metals; thus the tint is sensibly lowered by small quantities of silver, and heightened by copper.
The presence of minute quantities of cadmium, lead, bismuth, antimony, arsenic, tin, tellurium and zinc renders gold brittle, 2 ' 0 15th part of one of the three metals first named being sufficient to produce that quality.
In the alluvial deposits the associated minerals are chiefly those of great density and hardness, such as platinum, osmiridium and other metals of the platinum group, tinstone, chromic, magnetic and brown iron ores, diamond, ruby and sapphire, zircon, topaz, garnet, &c. which represent the more durable original constituents of the rocks whose distintegration has furnished the detritus.
Of this increase, a considerable part was derived from gold-quartz mining, though much was also obtained as a by-product in the working of the ores of other metals.
Alloys.-Gold forms alloys with most metals, and of these many are of great importance in the arts.
Other metals which find application in the metallurgy of gold by virtue of their property of extracting the gold as an alloy are lead, which combines very readily when molten, and which can afterwards be separated by cupellation, and copper, which is separated from the gold by solution in acids or by electrolysis; molten lead also extracts gold from the copper-gold alloys.
Matthiessen observed that the density of alloys, the composition of which varies from AuAg 6 to Au 6 Ag, is greater than that calculated from the densities of the constituent metals.
The alloys of tin and gold are hard and brittle, and the combination of the metals is attended with contraction; thus the alloy SnAu has a density 14.243, instead of 14.828 indicated by calculation.
In these proportions the density of the alloy is less than the mean of its constituent metals.
These metals are stated to alloy in all proportions.
According to Chenevix, the alloy composed of equal parts of the two metals is grey, is less ductile than its constituent metals and has the specific gravity i i.
Similar plates are often used to catch any particles of gold that may be thrown back, while the main operation is so conducted that the bulk of the gold may be reduced to the state of amalgam by bringing the two metals into intimate contact under the stamp head, and remain in the battery.
One of the greatest difficulties in the treatment of gold by amalgamation, and more particularly in the treatment of pyrites, arises from the so-called " sickening " or " flouring " of the mercury; that is, the particles, losing their bright metallic surfaces, are no longer capable of coalescing with or taking up other metals.
The extraction of gold from auriferous minerals by fusion, except as an incident in their treatment for other metals, is very rarely practised.
By continuing the treatment of these in the ordinary way of refining, poling and granulating, all the foreign matters other than gold, copper and silver are removed, and, by exposing the granulated metal to a high oxidizing heat for a considerable time the copper may be completely oxidized while the precious metals are unaltered.
The high volatility of gold in the presence of certain metals must also be considered.
At the same time any lead, calcium, barium and strontium present are precipitated as sulphates; it is therefore advantageous to remove these metals by the preliminary addition of sulphuric acid, which also serves to keep any basic iron salts in solution.
The gold and other metals are precipitated on the under surfaces of the turnings and fall to the bottom of the compartment as a black slime.
Consequently the separation of these two metals is one of the most important metallurgical processes.
The second process depends upon the fact that, if chlorine be led into the molten alloy, the base metals and the silver are converted into chlorides.
It is especially suitable to gold containing little silver and base metals - a character of Australian gold - but it yields to the sulphuric acid and electrolytic methods in point of economy.
Other undesirable impurities are the platinum metals, special treatment being necessary when these substances are present.
A cyanide bath, as used in electroplating, would dissolve the gold, but is not suitable for refining, because other metals (silver, copper, &c.) passing with gold into the solution would deposit with it.
In this process all the anode metals pass into solution except iridium and other refractory metals of that group, which remain as metals, and silver, which is converted into insoluble chloride; lead and bismuth form chloride and oxychloride respectively, and these dissolve until the bath is saturated with them, and then precipitate with the silver in the tank.
The slimes are treated chemically for the separation of the metals contained in them.
The main imports were coal, timber, metals, jute.
It was probably unknown to the Greeks and Romans, but during the middle ages it became quite familiar, notwithstanding its frequent confusion with other metals.
It is precipitated as the metal from solutions of its salts by the metals of the alkalis and alkaline earths, zinc, iron, copper, &c. In its chemical affinities it resembles arsenic and antimony; an important distinction is that it forms no hydrogen compound analogous to arsine and stibine.
Bismuth readily forms alloys with other metals.
When present in other metals, even in very small quantity, bismuth renders them brittle and impairs their electrical conductivity.
His work also included observations on putrefaction and fermentation, which he spoke of as sisters, on the nature of salts, and on the preparation of pure metals.
Though he lived in an atmosphere of alchemy, he derided the notion of the alkahest or universal solvent, and denounced the deceptions of the adepts who pretended to effect the transmutation of metals; but he believed mercury to be a constituent of all metals and heavy minerals, though he held there was no proof of the presence of "sulphur comburens."
In general these compounds are decomposable by heat, but some of them, such as those of gold, silver, copper and the alkali metals, even when heated above the boiling point of mercury retain mercury and leave residues of definite composition.
It burns, and also, like sulphuretted hydrogen, precipitates many metals from solutions of their salts.
The normal salts are all insoluble in water; the complex acid, hexatantalic acid, H $ Ta 6 0, 9 (which does not exist in the free state), forms soluble salts with the alkaline metals.
In modern chemistry alkali is a general term used for compounds which have the property of neutralizing acids, and is applied more particularly to the highly soluble hydrates of sodium and potassium and of the three rarer "alkali metals," caesium, rubidium and lithium, also to aqueous ammonia.
In a smaller degree these alkaline properties are shared by the less soluble hydrates of the "metals of the alkaline earths," calcium, barium and strontium, and by thallium hydrate.
This hypothesis, however, does not accord with the theory of the development of the earth from the state of a sphere of molt s en rock surrounded by an atmosphere of gaseous metals by which the first-formed clouds of aqueous vapour must have been absorbed.
Acetylene is readily soluble in water, which at normal temperature and pressure takes up a little more than its own volume of the gas, and yields a solution giving a purple-red precipitate with ammoniacal cuprous chloride and a white precipitate with silver nitrate, these precipitates consisting of acetylides of the metals.
When acetylene was first introduced on a commercial scale grave fears were entertained as to its safety, it being represented that it had the power of combining with certain metals, more especially copper and silver, to form acetylides of a highly explosive character, and that even with coal gas, which contains less than i %, such copper compounds had been known to be formed in cases where the gas-distributing mains were composed of copper, and that accidents had happened from this cause.
The term is more customarily given to productions of flame such as we have in the burning of oils, gas, fuel, &c., but it is conveniently extended to other cases of oxidation, such as are met with when metals are heated for a long time in air or oxygen.
The imports are chiefly articles of food, textiles, and metals and hardware.
The Indies were expected to supply precious metals and raw materials, and to take all manufactures from the mother country.
In the Arctic and Pacific coast provinces, about Lake Superior, in Virginia and North Carolina, as well as in ruder parts of Mexico and South America, metals were cold-hammered into plates, weapons, rods and wire, ground and polished, fashioned into carved blocks of hard, tenacious stone by pressure or blow, overlaid, cold-welded and plated.
It dissolves slowly in water, and the aqueous solution is reduced by most metals with precipitation of osmium.
It combines with the chlorides of the alkali metals to form characteristic double salts of the type OsC1 4.2MC1 (osmichlorides).
By his example and patronage the art of working in metals was greatly stimulated.
Metals were used for money at an early stage of civilization, and are well suited to the purpose, owing to their great intrinsic value and their durability, indestructibility, divisibility and rarity.
The best metals for coinage are gold, silver, platinum, copper, tin, nickel, aluminium, zinc, iron, and their alloys; certain alloys of gold, silver, copper and nickel have the best combination of the required qualities.
In England, in the middle ages, the king was accustomed to send in to the mint the produce of his own silver mines, and claimed the exclusive privilege of purchasing the precious metals.
The right of levying seigniorage, however, was sometimes waived by the king to encourage his subjects to bring gold and silver to the mint, and several instances are recorded in which the aid of alchemists was called in to effect the transmutation of baser metals into gold.
Here A is the iron cover surrounding the furnaces, B is the revolving lid of a furnace, save time and to reduce the loss of the precious metals.
The monometallic salts of the alkalis and alkaline earths may be obtained in crystal form, but those of the heavy metals are only stable when in solution.
The font was at first always of stone, but latterly metals were often used.
In this way there arose central boards for wool, cotton, oil and fat, hides and leather, and various metals - to name only the more important materials.
In the Ligore ware the hammered ground-work is inlaid with a black composition of sulphides of baser metals which throws up the pattern with distinctness.
The city's foreign trade is light (the value of its imports was $859,442 in 1907; of its exports $664,525), but its river traffic is heavy, amounting to about 3,000,000 tons annually, and being chiefly in general merchandise (including food-stuffs, machinery and manufactured products), ores and metals, chemicals and colours, stone and sand and brick.
Davy, inspired by his successful isolation of the metals sodium and potassium by the electrolysis of their hydrates, attempted to decompose a mixture of lime and mercuric oxide by the electric current; an amalgam of calcium was obtained, but the separation of the mercury was so difficult that even Davy himself was not sure as to whether he had obtained pure metallic calcium.
In its chemical properties it closely resembles barium and strontium, and to some degree magnesium; these four elements comprise the so-called metals of the "alkaline earths."
The hydrogen in ammonia is capable of replacement by metals, thus magnesium burns in the gas with the formation of magnesium nitride Mg3N2, and when the gas is passed over heated sodium or potassium, sodamide, NaNH 2, and potassamide, KNH 2, are formed.
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.
The aqueous solution is strongly acid to litmus and dissolves most metals directly.
The salts of hydrofluoric acid are known as fluorides and are easily obtained by the action of the acid on metals or their oxides, hydroxides or carbonates.
The fluorides of the alkali metals, of silver, and of most of the heavy metals are soluble in water; those of the alkaline earths are insoluble.
They found that the absorbing powers of the metals, and therefore, by the principle of exchanges, their radiating powers also, are proportional to the square roots of their electric conductivities.
Previous to the war the present Czechoslovak territories were responsible for 92% of the sugar produced by Austria-Hungary, for 46% of the spirits, beer 57%, malt 87%, foodstuffs 50%, chemicals 75%, metals 60%, porcelain too %, glass 90%, cotton goods 75%, woollen goods 80%, jute 90%, leather 70%, gloves 90%, boots 75%, paper 60%.
Such was the case not only with some metals, such as lead, zinc, copper, but still more strikingly with textile materials such as wool, flax, and the like, and most of all with agricultural products such as grain, meat and meat products, timber.
He himself was an alchemist; and believing the transmutation of metals to be a possibility, he carried out experiments in the hope of effecting it; and he was instrumental in obtaining the repeal, in 1689, of the statute of Henry IV.
Eltekow, Ber., 1878, 11, p. 414); by the action of metals on the halogen compounds Cn.H 20 Br 2 i by boiling the aqueous solution of nitrites of the primary amines (V.