Following Newton, he believed a gas to be made up of particles or atoms, From Dalton's Hydrogen Gas.
In water and in ethylene experiment shows that 8 parts by weight of oxygen and 6 parts of carbon, respectively, are in union with one part of hydrogen; also, if the diagrams are correct, these numbers must be in the ratio of the atomic weights of oxygen and carbon.
It is now agreed that the molecule of water contains two atoms of hydrogen and one of oxygen, so that the atomic weight of oxygen becomes 16, and similarly that the molecule of ammonia contains three atoms of hydrogen and one of nitrogen, and that consequently the atomic weight of nitrogen is 14.
Dalton believed that the molecules of the elementary gases consisted each of one atom; his diagram for hydrogen gas makes the point clear.
necessary to determine the specific gravities of the various gases referred to some one of them, say hydrogen; the numbers so obtained giving the weights of the molecules referred to that of the hydrogen molecule.
Metallic cobalt may be obtained by reduction of the oxide or chloride in a current of hydrogen at a red heat, or by heating the oxalate, under a layer of powdered glass.
On heating in hydrogen, ammonia or carbon monoxide, or with carbon or sodium, it is reduced to the metallic state.
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.
They are precipitated from their alkaline solutions as cobalt sulphide by sulphuretted hydrogen, but this precipitation is prevented by the presence of citric and tartaric acids; similarly the presence of ammonium salts hinders their precipitation by caustic alkalis.
For the quantitative determination of cobalt, it is either weighed as the oxide, C0304, obtained by ignition of the precipitated monoxide, or it is reduced in a current of hydrogen and weighed as metal.
He determined the percentages of carbon, hydrogen and oxygen in the sugar and in the products of fermentation, and concluded that sugar in fermenting breaks up into alcohol, carbonic acid and acetic acid.
Certain yeasts exercise a reducing action, forming sulphuretted hydrogen, when sulphur is present.
The gas contains a certain amount of hydrogen and oxides of carbon, also traces of nitrogen.
In order to get rid of hydrogen, some oxygen is added to the helium, and the mixture exploded by an electric spark.
approximately four times that of hydrogen.
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.
This difference amounts to about at the temperature of liquid oxygen, and about -k° at that of liquid hydrogen.
ACID-AMIDES, chemical compounds which may be considered as derived from ammonia by replacement of its hydrogen with acidyl residues, the substances produced being known as, primary, secondary or tertiary amides, according to the number of hydrogen atoms replaced.
On the other hand, they show faintly acid properties since the hydrogen: of the amido group can be replaced by metals to give such compounds as mercury acetamide (CH 3 CONH) 2 Hg.
by the addition of sulphuretted hydrogen to the nitriles, or by the action of phosphorus pentasulphide on the acid-amides.
Boron hydride has probably never been isolated in the pure condition; on heating boron trioxide with magnesium filings, a magnesium boride Mg 3 B 2 is obtained, and if this be decomposed with dilute hydrochloric acid a very evil-smelling gas, consisting of a mixture of hydrogen and boron hydride, is obtained.
It is decomposed by water, and with a solution of yellow phosphorus in carbon bisulphide it gives a red powder of composition PBI 2, which sublimes in vacuo at 210° C. to red crystals, and when heated in a current of hydrogen loses its iodine and leaves a residue of boron phosphide PB.
Borimide B 2 (NH) 3 is obtained on long heating of the compound B 2 S 3.6NH 3 in a stream of hydrogen, or ammonia gas at 115-120° C. It is a white solid which decomposes on heating into boron nitride and ammonia.
It forms slightly coloured small crystals possessing a strong disagreeable smell, and is rapidly decomposed by water with the formation of boric acid and sulphuretted hydrogen.
A pentasulphide B2S5 is prepared, in an impure condition, by heating a solution of sulphur in carbon bisulphide with boron iodide, and forms a white crystalline powder which decomposes under the influence of water into sulphur, sulphuretted hydrogen and boric acid.
On oxidation with chromic or nitric acids, or potassium permanganate, it yields nicotinic acid or (3-pyridine carboxylic acid, C 5 H 4 N CO 2 H; alkaline potassium ferricyanide gives nicotyrine, C10H10N2, and hydrogen peroxide oxynicotine, C10H14N20.
On fusion with solid potash at 250° C. it completely decomposes, giving potassium oxalate and hydrogen, C2H602-1-2KHO =K2C204+4H2.
Trans., 18 53, p. 357, 18 54, p. 321, and 1862, p. 579) showed that the statement that no internal work is done when a gas expands or contracts is not quite true, but the amount is very small in the cases of those gases which, like oxygen, hydrogen and nitrogen, can only be liquefied by intense cold and pressure.
Poulsen immensely improved this process by placing the arc in an atmosphere of hydrogen, coal-gas or some other nonoxidizing gas, and at the same time arranging it in a strong magnetic field.'
The electric arc is formed between cooled copper (positive) and carbon (negative) electrodes in an atmosphere of hydrogen or coal-gas.
Simultaneously Hermann, a German chemical manufacturer, discovered the new metal in a specimen of zinc oxide which had been thought to contain arsenic, since it gave a yellow precipitate, in acid solution, on the addition of sulphuretted hydrogen.
Cadmium vapour decomposes water at a red heat, with liberation of hydrogen, and formation of the oxide of the metal.
It does not melt at a white heat, and is easily reduced to the metal by heating in a current of hydrogen or with carbon.
Cadmium sulphide, CdS, occurs naturally as greenockite (q.v.), and can be artificially prepared by passing sulphuretted hydrogen through acid solutions of soluble cadmium salts, when it is precipitated as a pale yellow amorphous solid.
It is used as a pigment (cadmium yellow), for it retains its colour in an atmosphere containing sulphuretted hydrogen; it melts at a white heat, and on cooling solidifies to a lemon-yellow micaceous mass.
Cadmium salts can be recognized by the brown incrustation which is formed when they are heated on charcoal in the oxidizing flame of the blowpipe; and also by the yellow precipitate formed when sulphuretted hydrogen is passed though their acidified solutions.
It can also be determined as sulphide, by precipitation with sulphuretted hydrogen, the precipitated sulphide being dried at Ioo° C. and weighed.
Sulphur is present to the extent of more than i %, whence the smell of suiphuretted hydrogen when the resin is heated.
His researches on sebacic acid (1802) and on bile (1807), and his discovery of peroxide of hydrogen (1818) also deserve mention.
Molybdenum dioxide, Mo02, is formed by heating sodium trimolybdate, Na2M03010, to redness in a current of hydrogen (L.
Molybdenum trichloride, MoC1 31 is obtained when the pentachloride is heated to a temperature of about 250° C. in a current of hydrogen.
Molybdenum disulphide, MoS 2, is found as the mineral molybdenite, and may be prepared by heating the trioxide with sulphur or sulphuretted hydrogen.
It is readily oxidized by nitric acid, and when strongly heated_ in a current of hydrogen is reduced to the metallic condition.
Molybdenum trisulphide, MoS3, is obtained by saturating a solution of an alkaline molybdate with sulphuretted hydrogen and adding a mineral acid.
The original hypothesis of Baeyer suggested that the course of events is the following: the carbon dioxide is decomposed into carbon monoxide and oxygen, while water is simultaneously split up into hydrogen and oxygen; the hydrogen and the carbon monoxide unite to form formaldehyde and the oxygen is exhaled.
The first chemical change suggested is an interaction between carbon dioxide and water, under the influence of light acting through chlorophyll, which leads to the simultaneous formation of formaldehyde and hydrogen peroxide.
The formaldehyde at once undergoes a process of condensation oi- polymerization by the protoplasm of the plastid, while the hydrogen peroxide is said to be decomposed into water and free oxygen by another agency in the cell, of the nature of one of the enzymes of which we shall speak later.
The hydrogen of the hydroxyl group in phenol can be replaced by metals, by alkyl groups and by acid radicals.
It may be obtained from argyrodite by heating the mineral in a current of hydrogen; or by heating the dioxide to redness with carbon.
It can also be obtained by passing sulphuretted hydrogen through a solution of the dioxide in hydrochloric acid.
By heating the disulphide in a current of hydrogen, germanious sulphide, GeS, is formed.
The germanium salts are most readily recognized by the white precipitate of the disulphide, formed in acid solutions, on passing sulphuretted hydrogen.
Volcanic sulphur usually occurs as a sublimate around or on the walls of the vents, and has probably been formed in many cases by the interaction of sulphur dioxide and hydrogen sulphide.
Deposits of sulphur are frequently formed by the decomposition of hydrogen sulphide, on exposure to the atmosphere: hence natural sulphureous waters, especially hot springs, readily deposit sulphur.
Sulphur dioxide and sulphuretted hydrogen are present in volcanic exhalations and in many mineral waters.
Rhombic sulphur may be obtained artificially by slowly crystallizing a solution of sulphur in carbon bisulphide, or, better, by exposing pyridine saturated with sulphuretted hydrogen to atmospheric oxidation (Ahrens, Ber., 1890, 23, p. 2708).
rend., 188 4, 9 8, p. 1 44) obtained a form which he termed nacre (or pearly) sulphur; the same modification was obtained by Sabatier (ibid., 1885, 100, p. 1346) on shaking hydrogen persulphide with alcohol or ether.
The colloidal sulphur, Ss, described by Debus as a product of the interaction of sulphuretted hydrogen and sulphur dioxide in aqueous solution, is regarded by Spring (Rec. tra y.
Sulphuretted hydrogen, H 2 S, a compound first examined by C. Scheele, may be obtained by heating sulphur in a current of hydrogen, combination taking place between 200° C. and 358° C., and being complete at the latter temperature, dissociation taking place above this temperature (M.
To obtain pure sulphuretted hydrogen the method generally adopted consists in decomposing precipitated antimony sulphide with concentrated hydrochloric acid.
Sulphuretted hydrogen is a colourless gas possessing an extremely offensive odour.
Oxidizing agents rapidly attack sulphuretted hydrogen, the primary products of the reaction being water and sulphur.
It may be condensed and yields a solid which melts at - 55° C. Sulphuretted hydrogen decomposes it with formation of hydrofluoric acid and liberation of sulphur.
News, 1902, 86, p. 5) obtained a substance of composition S312 (which in all probability is a chemical individual) as a reddish-coloured powder by the action of sulphuretted hydrogen on a solution of iodine trichloride.
Soc., 1888, 53, p. 278) is prepared by passing sulphuretted hydrogen gas into a nearly saturated aqueous solution of sulphur dioxide at about o° C. The solution is then allowed to stand for 48 hours and the process repeated many times until the sulphur dioxide is all decomposed.
Michaels (Ber., 1897, 30, p. 1383) by distilling thebenol over zinc dust in a stream of hydrogen, or by the action of hydriodic acid and phosphorus at 220° C. on thebenol.
For example, when metallic zinc is dissolved in dilute sulphuric acid with production of zinc sulphate (in solution) and hydrogen gas, a definite quantity of heat is produced for a given amount of zinc dissolved, provided that the excess of energy in the initial system appears entirely as heat.
Thus if concentrated instead of dilute sulphuric acid acts upon zinc, the action takes place to a great extent not according to the equation given above, but according to the equation Zn +2H 2 SO 4 = ZnS04+S02+2 H20, sulphur dioxide and water being produced instead of hydrogen.
hydrogen during the action of zinc on dilute sulphuric acid) performs work equivalent to 580 cal.
The oxygen contained in the compound was deducted, together with the equivalent amount of hydrogen, and the heat of combustion of the compound was then taken to be equal to the heats of combustion of the elements in the residue.
A much better approximation to the heat of combustion of such substances is obtained by deducting the oxygen together with the amount of carbon necessary to form C02, and then ascertaining the amount of heat produced by the residual carbon and hydrogen.
Berthelot, and many other chemists, from whose researches it results that glycerin is a trihydric alcohol indicated by the formula C 3 H 5 (OH) 3j the natural fats and oils, and the glycerides generally, being substances of the nature of compound esters formed from glycerin by the replacement of the hydrogen of the OH groups by the radicals of certain acids, called for that reason "fatty acids."
The relationship of these glycerides to glycerin is shown by the series of bodies formed from glycerin by replacement of hydrogen by "stearyl" (C18H350), the radical of stearic acid (C18H350.
Some other glycerides isolated from natural sources are analogous in composition to tristearin, but with this difference, that the three radicals which replace hydrogen in glycerin are not all identical; thus kephalin, myelin and lecithin are glycerides in which two hydrogens are replaced by fatty acid radicals, and the third by a complex phosphoric acid derivative.
It is then converted into the lead salt, which is decomposed by sulphuretted hydrogen and the solution is carefully concentrated (Th.
Heating spirits of hartshorn, he was able to collect "alkaline air" (gaseous ammonia), again because he was using mercury in his pneumatic trough; then, trying what would happen if he passed electric sparks through the gas, he decomposed it into nitrogen and hydrogen, and "having a notion" that mixed with hydrochloric acid gas it would produce a "neutral air," perhaps much the same as common air, he synthesized sal ammoniac. Dephlogisticated air (oxygen) he prepared in August 1774 by heating red oxide of mercury with a burning-glass, and he found that in it a candle burnt with a remarkably vigorous flame and mice lived well.
Even prior to the discovery of petroleum in commercial quantities, a number of chemists had made determinations of the chemical composition of several different varieties, and these investigations, supplemented by those of a later date, show that petroleum consists of about 84% by weight of carbon with 12% of hydrogen, and varying proportions of sulphur, nitrogen and oxygen.
Natural gas is found to consist mainly of the lower paraffins, with varying quantities of carbon dioxide, carbon monoxide, hydrogen, nitrogen and oxygen, in some cases also sulphuretted hydrogen and possibly ammonia.
It may be more conveniently prepared by passing the vapour of sulphur over red hot charcoal, the unccndensed gases so produced being led into a tower containing plates over which a vegetable oil is allowed to flow in order to absorb any carbon bisulphide vapour, and then into a second tower containing lime, which absorbs any sulphuretted hydrogen.
When heated with water in a sealed tube to 150° C. it yields carbon dioxide and sulphuretted hydrogen.
A mixture of carbon bisulphide vapour and sulphuretted hydrogen, when passed over heated copper, gives, amongst other products, some methane.
Carbon bisulphide combines with primary amines to form alkyl dithiocarbamates, which when heated lose sulphuretted hydrogen and leave a residue of a dialkyl thio-urea, CS 2 +2R NH 2 - R NH CSS NH 3 RCS(NHR)2+H2S; or if the aqueous solution of the dithiocarbamate be boiled with mercuric chloride or silver nitrate solution, a mustard oil (q.v.) is formed, R.NH CSS NH3R+HgC12-Hg(R NH CSS)2->2RNCS-}-HgS+H2S.
Carbon monosulphide, CS, is formed when a silent electric discharge is passed through a mixture of carbon bisulphide vapour and hydrogen or carbon monoxide (S.
Ruthenium dichloride, RuC1 2, is obtained (in solution) by reducing the sesquichloride by sulphuretted hydrogen or zinc. It is stable in the cold.
the relative weights of atoms. He took hydrogen, the lightest substance known, to be the standard.
For example, one volume of oxygen combined with two of hydrogen to form two volumes of steam, three volumes of hydrogen combined with one of nitrogen to give two volumes of ammonia, one volume of hydrogen combined with one of chlorine to give two volumes of hydrochloric acid.
4 The following are the symbols employed by Dalton: which represent in order, hydrogen, nitrogen, carbon, oxygen, phosphorus, sulphur, magnesia, lime, soda, potash, strontia, baryta, mercury; iron, zinc, copper, lead, silver, platinum, and gold were represented by circles enclosing the initial letter of the element.
Hence the gaseous atoms of hydrogen and oxygen could not have parts.
the amount of an element which can combine with or replace unit weight of hydrogen, came into favour, being adopted by L.
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.
the weight contained in a molecule of hydrochloric acid, thus differing from Avogadro who chose the weight of a hydrogen molecule.
The elements are usually divided into two classes, the metallic and the non-metallic elements; the following are classed as non-metals, and the remainder as metals: Of these hydrogen, chlorine, fluorine, oxygen, nitrogen, argon, neon, krypton, xenon and helium are gases, bromine is a liquid, and the remainder are solids.
Thus, the affinity of hydrogen and oxygen for each other is extremely powerful, much heat being developed by the combination of these two elements; when binary compounds of oxygen are decomposed by the electric current, the oxygen invariably appears at the positive pole, being negative to all other elements, but the hydrogen of hydrogen compounds is always disengaged at the negative pole.
Hydrogen and oxygen are, therefore, of very opposite natures, and this is well illustrated by the circumstance that oxygen combines, with very few exceptions, with all the remaining elements, whilst compounds of only a limited number with hydrogen have been obtained.
Thus, i part by weight of hydrogen unites with 8 parts by weight of oxygen, forming water, and with 16 or 8 X 2 parts of oxygen, forming hydrogen peroxide.
An acid (q.v.) is a compound of hydrogen, which element can be replaced by metals, the hydrogen being liberated, giving substances named salts.
An alkali or base is a substance which neutralizes an acid with the production of salts but with no evolution of hydrogen.
A base may be regarded as water in which part of the hydrogen is replaced by a metal, or by a radical which behaves as a metal.
An acid is said to be monobasic, dibasic, tribasic, &c., according to the number of replaceable hydrogen atoms; thus HNO 3 is monobasic, sulphuric acid H 2 SO 4 dibasic, phosphoric acid H 3 PO 4 tribasic.
An acid salt is one in which the whole amount of hydrogen has not been replaced by metal; a normal salt is one in which all the hydrogen has been replaced; and a basic salt is one in which part of the acid of the normal salt has been replaced by oxygen.
The distribution of weight in chemical change is readily expressed in the form of equations by the aid of these symbols; the equation 2HC1+Zn =ZnCl2+H2, for example, is to be read as meaning that from 73 parts of hydrochloric acid and 65 parts of zinc, 136 parts of zinc chloride and 2 parts of hydrogen are produced.
Thus, the symbols 14 2 and P4 indicate that the molecules of hydrogen and phosphorus respectively contain 2 and 4 atoms. Since, according to the molecular theory, in all cases of chemical change the action is between molecules, such symbols as these ought always to be employed.
Thus, the equation 2112+02 =2H20 not only represents that certain definite weights of hydrogen and oxygen furnish a certain definite weight of the compound which we term water, but that if the water in the state of gas, the hydrogen and the oxygen are all measured at the same temperature and pressure, the volume occupied by the oxygen is only half that occupied by the hydrogen, whilst the resulting water-gas will only occupy the same volume as the hydrogen.
In other words, 2 volumes of oxygen and 4 volumes of hydrogen furnish 4 volumes of water-gas.
One other instance may be given; the equation 2NH3=N2+3H2 represents the decomposition of ammonia gas into nitrogen and hydrogen gases by the electric spark, and it not only conveys the information that a certain relative weight of ammonia, consisting of certain relative weights of hydrogen and nitrogen, is broken up into certain relative weights of hydrogen and nitrogen, but also that the nitrogen will be contained in half the space which contained the ammonia, and that the volume of the hydrogen will be one and a half times as great as that of the original ammonia, so that in the decomposition of ammonia the volume becomes doubled.
It is often convenient to regard compounds as formed upon certain types; alcohol, for example, may be said to be a compound formed upon the water type, that is to say, a compound formed from water by displacing one of the atoms of hydrogen by the group of elements C 2 H 5, thus - H C2H5 O H O H Water Alcohol.
Changes of the first and second kind, according to our views of the constitution of molecules, are probably of very rare occurrence; in fact, chemical action appears almost always to involve the occurrence of both these kinds of change, for, as already pointed out, we must assume that the molecules of hydrogen, oxygen and several other elements are diatomic, or that they consist of two atoms. Indeed, it appears probable that with few exceptions the elements are all compounds of similar atoms united together by one or more units of affinity, according to their valencies.
The combination, as it is ordinarily termed, of chlorine with hydrogen, and the displacement of iodine in potassium iodide by the action of chlorine, may be cited as examples; if these reactions are represented, as such reactions very commonly are, by equations which merely express the relative weights of the bodies which enter into reaction, and of the products, thus Cl = HC1 Hydrogen.
they appear to differ in character; but if they are correctly represented by molecular equations, or equations which express the relative number of molecules which enter into reaction and which result from the reaction, it will be obvious that the character of the reaction is substantially the same in both cases, and that both are instances of the occurrence of what is ordinarily termed double decomposition H2 + C12 = 2HC1 Hydrogen.
Thus, in the production of hydrochloric acid from hydrogen and chlorine 22,000 calories are developed; in the production of hydrobromic acid from hydrogen and bromine, however, only 8440 caloriesare developed; and in the formation of hydriodic acid from hydrogen and iodine 6040 calories are absorbed.
We may suppose that in the formation of gaseous hydrochloric acid from gaseous chlorine and hydrogen, according to the equation H2 +C1 2 = HCI+HC1, a certain amount of energy is expended in separating the atoms of hydrogen in the hydrogen molecule, and the atoms of chlorine in the chlorine molecule, from each other; but that heat is developed by the combination of the hydrogen atoms with the chlorine atoms, and that, as more energy is developed by the union of the atoms of hydrogen and chlorine than is expended in separating the hydrogen atoms from each other and the chlorine atoms from one another, the result of the action of the two elements upon each other is the development of heat, - the amount finally developed in the reaction being the difference between that absorbed in decomposing the elementary molecules and that developed by the combination of the atoms of chlorine and hydrogen.
In the formation of gaseous hydrobromic acid from liquid bromine and gaseous hydrogen H2+Br2=HBr+HBr, in addition to the energy expended in decomposing the hydrogen and bromine molecules, energy is also expended in converting the liquid bromine into the gaseous condition, and probably less heat is developed by the combination of bromine and hydrogen than by the combination of chlorine and hydrogen, so that the amount of heat finally developed is much less than is developed in the formation of hydrochloric acid.
Lastly, in the production of gaseous hydriodic acid from hydrogen and solid iodine H2 - 1 - 12=HI+HI, so much energy is expended in the decomposition of the hydrogen and iodine molecules and in the conversion of the iodine into the gaseous condition, that the heat which it may be supposed is developed by the combination of the hydrogen and iodine atoms is insufficient to balance the expenditure, and the final result is therefore negative; hence it is necessary in forming hydriodic acid from its elements to apply heat continuously.
Thus, chlorine enters into reaction with hydrogen, and removes hydrogen from hydrogenized bodies, far more readily than bromine; and hydrochloric acid is a far more stable substance than hydrobromic acid, hydriodic acid being greatly inferior even to hydrobromic acid in stability.
When two substances which by their action upon each other develop much heat enter into reaction, the reaction is usually complete without the employment of an excess of either; for example, when a mixture of hydrogen and oxygen, in the proportions to form water 2E12+0, =20H2, is exploded, it is entirely converted into water.
In 1784 Henry Cavendish thoroughly examined hydrogen, establishing its elementary nature; and he made the far-reaching discovery that water was composed of two volumes of hydrogen to one of oxygen.
Sulphuretted hydrogen and nitric oxide were discovered at about the same time.
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.
Thenard discovered hydrogen dioxide, one of the most interesting inorganic compounds known, which has since been carefully investigated by H.
Of other phosphorus compounds we may here notice Gengembre's discovery of phosphuretted hydrogen (phosphine) in 1783, the analogy of which to ammonia was first pointed out by Davy and supported at a later date by H.
Theoretical speculations were revived by Lavoisier, who, having explained the nature of combustion and determined methods for analysing compounds, concluded that vegetable substances ordinarily contained carbon, hydrogen and oxygen, while animal substances generally contained, in addition to these elements, nitrogen, and sometimes phosphorus and sulphur.
Lavoisier, to whom chemistry was primarily the chemistry of oxygen compounds, having developed the radical theory initiated by Guyton de Morveau, formulated the hypothesis that vegetable and animal substances were oxides of radicals composed of carbon and hydrogen; moreover, since simple radicals (the elements) can form more than one oxide, he attributed the same character to his hydrocarbon radicals: he considered, for instance, sugar to be a neutral oxide and oxalic acid a higher oxide of a certain radical, for, when oxidized by nitric acid, sugar yields oxalic acid.
Berzelius, in 1813 and 1814, by improved methods of analysis, established that the Daltonian laws of combination held in both the inorganic and organic kingdoms; and he adopted the view of Lavoisier that organic compounds were oxides of compound radicals, and therefore necessarily contained at least three elements - carbon, hydrogen and oxygen.
Instances had already been recorded of cases where a halogen element replaced hydrogen with the production of a closely allied substance: Gay Lussac had prepared cyanogen chloride from hydrocyanic acid; Faraday, hexachlorethane from ethylene dichloride, &c. Here the electronegative halogens exercised a function similar to electro-positive hydrogen.
Dumas went no further that thus epitomizing his observations; and the next development was made in 1836 by Auguste Laurent, who, having amplified and discussed the applicability of Dumas' views, promulgated his Nucleus Theory, which assumed the existence of " original nuclei or radicals " (radicaux or noyaux fondamentaux) composed of carbon and hydrogen, and " derived nuclei " (radicaux or noyaux derives) formed from the original nuclei by the substitution of hydrogen or the addition of other elements, and having properties closely related to the primary nuclei.
von Hofmann continued the investigation, and established their recognition as ammonia in which one or more hydrogen atoms had been replaced by hydrocarbon radicals, thus formulating the " ammonia type."
Williamson showed how alcohol and ether were to be regarded as derived from water by substituting one or both hydrogen atoms by the ethyl group; he derived acids and the acid anhydrides from the same type; and from a comparison of many inorganic and the simple organic compounds he concluded that this notion of a " water-type " clarified, in no small measure, the conception of the structure of compounds.
Taking as types hydrogen, hydrochloric acid, water and ammonia, he postulated that all organic compounds were referable to these four forms: the hydrogen type included hydrocarbons, aldehydes and ketones; the hydrochloric acid type, the chlorides, bromides and iodides; the water type, the alcohols, ethers, monobasic acids, acid anhydrides, and the analogous sulphur compounds; and the ammonia type, the amines, acid-amides, and the analogous phosphorus and arsenic compounds.
From similar investigations of valerianic acid he was led to conclude that fatty acids were oxygen compounds of the radicals hydrogen, methyl, ethyl, &c., combined with the double carbon equivalent C2.
This description, although not absolutely comprehensive, serves as a convenient starting-point for a preliminary classification, since a great number of substances, including the most important, are directly referable to hydrocarbons, being formed by replacing one or more hydrogen atoms by other atoms or groups.
into two groups: (r) those exhibiting properties closely analogous to the aliphatic series - the polymethylenes, and (2) a series exhibiting properties differing in many respects from the aliphatic and polymethylene compounds, and characterized by a peculiar stability which is to be associated with the disposition of certain carbon valencies not saturated by hydrogen - the " aromatic series."
Gomberg's triphenyl-methyl play no part in what follows), it is readily seen that the simplest hydrocarbon has the formula CH 4, named methane, in which the hydrogen atoms are of equal value, and which may be pictured as placed at the vertices of a tetrahedron, the carbon atom occupying the centre.
The equivalence of the four hydrogen atoms of methane rested on indirect evidence, e.g.
Three such compounds are possible according to the number of valencies acting directly between the carbon atoms. Thus, if they are connected by one valency, and the remaining valencies saturated by hydrogen, we obtain the compound H 3 C CH 3, ethane.
This compound may be considered as derived from methane, CH 4, by replacing a hydrogen atom by the monovalent group CH 3, known as methyl; hence ethane may be named " methylmethane."
In methane and ethane the hydrogen atoms are of equal value, and no matter which one may be substituted by another element or group the same compound will result.
Thus the thio-alcohols or mercaptans (q.v.) contain the group - CH2 SH; and the elimination of the elements of sulphuretted hydrogen between two molecules of a thio-alcohol results in the formation of a thio-ether or sulphide, R 2 S.
An important class of compounds, termed amines (q.v.), results from the condensation of alcohols with ammonia, water being eliminated between the alcoholic hydroxyl group and a hydrogen atom of the ammonia.
It was long supposed that the simplest ring obtainable contained six atoms of carbon, and the discovery of trimethylene in 1882 by August Freund by the action of sodium on trimethylene bromide, Br(CH 2) 3 Br, came somewhat as a surprise, especially in view of its behaviour with bromine and hydrogen bromide.
This symbol is in general use; it is assumed that at each corner there is a CH group which, however, is not always written in; if a hydrogen atom be substituted by another group, then this group is attached to the corner previously occupied by the displaced hydrogen.
From these nuclei an immense number of derivatives may be obtained, for the hydrogen atoms may be substituted by any of the radicals discussed in the preceding section on the classification of organic compounds.
It has already been stated that benzene derivatives may be regarded as formed by the replacement of hydrogen atoms by other elements or radicals in exactly the same manner as in the aliphatic series.
Although Kekule founded his famous benzene formula in 1865 on the assumptions that the six hydrogen atoms in benzene are equivalent and that the molecule is symmetrical, i.e.
These results may be graphically represented as follows: numbering the hydrogen atoms in cyclical order from i to 6, then the first thesis demands that whichever atom is substituted the same compound results, while the second thesis points out that the pairs 2 and 6, and 3 and 5 are symmetrical with respect to 1, or in other words, the di-substitution derivatives 1.2 and 1.6, and also 1.3 and 1.5 are identical.
The proof is divided into two parts: (1) that four hydrogen atoms are equal, and (2) that two pairs of hydrogen atoms are symmetrical with reference to a specified hydrogen atom.
These three acids yield on heating phenol, identical with the substance started with, and since in the three oxybenzoic acids the hydroxyl groups must occupy positions other than I, it follows that four hydrogen atoms are equal in value.
Therefore there must be another pair of hydrogen atoms, other than 2 and 6, which are symmetrical with respect to 1.
Soc. 61, p. 367): If the hydrogen compound of the substituent already in the benzene nucleus can be directly oxidized to the' corresponding hydroxyl compound, then meta-derivatives predominate on further substitution, if not, then orthoand paraderivatives.
Applying this notion to benzene, let us consider the impacts made by the carbon atom (I) which we will assume to be doubly linked to the carbon atom (2) and singly linked to (6), h standing for the hydrogen atom.
The transformation is not one of the oxidation of a hexamethylene compound to a benzenoid compound, for only two hydrogen atoms are removed.
that the hydrogen atoms must all lie in one plane.
The proof of this statement rests on the fact that if the hydrogen atoms were not co-planar, then substitution derivatives (the substituting groups not containing asymmetric carbon atoms) should exist in enantiomorphic forms, differing in crystal form and in their action on polarized light; such optical antipodes have, however, not yet been separated.
Ladenburg's prism formula would give two enantiomorphic ortho-di-substitution derivatives; while forms in which the hydrogen atoms are placed at the corners of a regular octahedron would yield enantiomorphic tri-substitution derivatives.
Two parallel triangular faces are removed from a cardboard model of a regular octahedron, and on the remaining six faces tetrahedra are then placed; the hydrogen atoms are at the free angles.
Zeit., 1905, 29, p. 30), assumed the six carbon atoms to occupy six of the corners of a cube, each carbon atom being linked to a hydrogen atom and by single bonds to two neighbouring carbon atoms, the remaining valencies being directed to the unoccupied corners of the cube, three to each, where they are supposed to satisfy each other.
If a-naphthylamine and a-naphthol be reduced, the hydrogen atoms attach themselves to the non-substituted half of the molecule, and the compounds so obtained resemble aminodiethylbenzene, C 6 H 3 NH 2 (C 2 H 5) 21 and oxydiethylbenzene, C 6 H 3.
From the pyrone ring the following series of compounds are derived (for brevity, the hydrogen atoms are not printed): Penthiophene gives, by a similar introduction of nitrogen atoms, penthiazoline, corresponding to meta-oxazine, and para-thiazine, CH 2 CH 2o CH CO „ .„0 C ?
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.
In his earlier experiments he burned the substance in a known volume of oxygen, and by measuring the residual gas determined the carbon and hydrogen.
Sulphuretted hydrogen, recognized by its odour, results from Sulphides containing water, and hydrosulphides.
The solution is filtered and treated with an excess of sulphuretted hydrogen, either in solution or by passing in the gas; this precipitates mercury (mercuric), any lead left over from the first group, copper, bismuth, cadmium, arsenic, antimony and tin as sulphides.
The solution is filtered off, boiled till free of sulphuretted hydrogen, and ammonium chloride and ammonia added.
The precipitate formed by sulphuretted hydrogen may contain the black mercuric, lead, and copper sulphides, dark-brown bismuth sulphide, yellow cadmium and arsenious sulphides, orange-red antimony sulphide, brown stannous sulphide, dull-yellow stannic sulphide, and whitish sulphur, the last resulting from the oxidation of sulphuretted hydrogen by ferric salts, chromates, &c. Warming with ammonium sulphide dissolves out the arsenic, antimony and tin salts, which are reprecipitated by the addition of hydrochloric acid to the ammonium sulphide solution.
Filter from the bismuth hydrate, and if copper is present, add potassium cyanide till the colour is destroyed, then pass sulphuretted hydrogen, and cadmium is precipitated as the yellow sulphide.
If copper is absent, then sulphuretted hydrogen can be passed directly into the solution.
The solution is boiled till free from sulphuretted hydrogen and treated with excess of sodium hydrate.
The elements which play important parts in organic compounds are carbon, hydrogen, nitrogen, chlorine, bromine, iodine, sulphur, phosphorus and oxygen.
Carbon is detected by the formation of carbon dioxide, which turns lime-water milky, and hydrogen by the formation of water, which condenses on the tube, when the substance is heated with copper oxide.
Carbon and hydrogen are generally estimated by the combustion process, which consists in oxidizing the substance and absorbing the products of combustion in suitable apparatus.
The process is therefore adapted to the simultaneous estimation of carbon,hydrogen, the halogens and sulphur.
Oxygen, nitrogen, hydrogen and carbon monoxide have the value 1.4; these gases have diatomic molecules, a fact capable of demonstration by other means.
the amount which is equivalent to one part of hydrogen; and (2) a factor which denotes the number of atoms of hydrogen which combines with or is equivalent to one atom of the particular element.
The substitution of a hydrogen atom by the hydroxyl group generally occasions a rise in boiling-point at about Ioo°.
An ethylenic or double carbon union in the aliphatic hydrocarbons has, apparently, the same effect on the boiling-point as two hydrogen atoms, since the compounds C 0 H 2 „ +2 and CoH2n boil at about the same temperature.
158.6 calories; this means that the replacement of a hydrogen atom by a methyl group is attended by a constant increase in the heat of combustion.
We assume that each carbon atom and each hydrogen atom contributes equally to the thermal effect.
By subtracting the value for CH 2, which may be derived from two substances belonging to the same homologous series, from the molecular refraction of methane, CH 4, the value of hydrogen is obtained; subtracting this from CH 2, the value of carbon is determined.
Thus oxygen varies according as whether it is linked to hydrogen (hydroxylic oxygen), to two atoms of carbon (ether oxygen), or to one carbon atom (carbonyl oxygen); similarly, carbon varies according as whether it is singly, doubly, or trebly bound to carbon atoms.
molecular weight, is constant for isomers, and that two atoms of hydrogen were equal to one of carbon, three to one of oxygen, and seven to one of chlorine; but these ratios were by no means constant, and afforded practically no criteria as to the molecular weight of any substance.
We may therefore regard the nitrogen atoms as occupying the centres of a cubic space lattice composed of iodine atoms, between which the hydrogen atoms are distributed on the tetrahedron face normals.
Coplanar substitution in four hydrogen atoms would involve the pushing apart of the iodine atoms in four horizontal directions.
It has to some extent the character of a secondary amine; the hydrogen of the imino group can be replaced by potassium.
Hydrochloric acid at once bleaches it with liberation of sulphuretted hydrogen and milk of sulphur.
The existence of sulphuretted hydrogen in great quantities below loo fathoms, the extensive chemical precipitation of calcium carbonate, the stagnant nature of its deep waters, and the absence of deep-sea life are conditions which make it impossible to discuss it along with the physical and biological conditions of the Mediterranean proper.
This gave rise to a production of sulphuretted hydrogen which is found in the deposits, as well as in the deeper waters.
There is thus a minimum circulation in the greater depths causing there uniformity of temperature, an absence of the circulation of oxygen by other means than diffusion, and a protection of the sulphuretted hydrogen from the oxidation which takes place in homologous situations in the open ocean.
-> CH3C6H5CONHC6H51 N OH Syn-phenyltolylketoxime CH3 C6H4 C C6H5 CH3C6H4NH000,H5 HO N A nti-tolylphenylketoxime In the case of the aldoximes, that one which most readily loses the elements of water on dehydration is assumed to contain its hydroxyl radical adjacent to the movable hydrogen atom and is designated the syn-compound.
The conversion of nitrogen into ammonia by electricity has received much attention, but the commercial aspect appears to have been first worked out by de Hemptinne in 1900, who used both the spark and silent discharge on mixtures of hydrogen and nitrogen, and found that the pressure and temperature must be kept low and the spark gap narrow.
Schlutius in 1903 employed Dowson gas as a source of hydrogen, and induced combination by means of platinum and the silent discharge.
p. 862), calcium is heated in a current of hydrogen, and nitrogen passed over the hydride so formed; this gives ammonia and calcium nitride, the latter of which gives up its nitrogen as ammonia and reforms the hydride when heated in a current of hydrogen.
Nascent hydrogen reduces it to hydroxylamine (q.v.), whilst solutions of hypochlorites oxidize it to nitric acid.
Nitrogen combines with hydrogen to form ammonia, NH 3, hydrazine, N 2 H 4, and azoimide, N 3 H (qq.v.); the other known hydrides, N 4 H 4 and N5H5, are salts of azoimide, viz.
Nitrosyl chloride, NOC1, is obtained by the direct union of nitric oxide with chlorine; or by distilling a mixture of concentrated nitric and hydrochloric acids, passing the resulting gases into concentrated sulphuric acid and heating the so-formed nitrosyl hydrogen sulphate with dry salt: HN03+3HCl=NOC1+C12 +H 2 O; NOC1 + H2S04 = HCl + NO SO 4 H; NO SO 4 H + NaC1 = Noci+NaHS04 (W.
The oxide dissolves slowly in acids; it is not reduced by hydrogen and is infusible.
It is reduced by nascent hydrogen to the secondary alcohol C6H5.CH.OH.CH3 phenyl-methyl-carbinol, and on oxidation forms benzoic acid.
Perfectly pure distilled sea-water dissociates, to an infinitesimal degree, into hydrogen (H) and hydroxyl (HO) ions, so that one litre of such water contains 1 X 10 7, or 1 part of a gram-molecule of either hydr010,000,000 gen or hydroxyl (a gramme-molecule of hydrogen is 2 grammes, or of hydroxyl 17 grammes).
The putrefaction of the latter sets free sulphuretted hydrogen, which then acts on the iron compounds, precipitating ferrous sulphide.
The albumins contain in all cases the elements carbon, hydrogen, nitrogen, sulphur and oxygen; their composition, however, varies within certain limits: C= 50-55%, H = 6.9-7'.3%,N = 15-19%,S =0.32.4%7 0=1 92 4%, General char- crystallized albumin is C = 51.48%, H = 6.76%, N= acters.
THIAZOLES, in organic chemistry, a series of heterocyclic compounds containing the grouping shown below; the replaceable hydrogen atoms in which are designated a, (3 and µ.
The volume of the hydrogen was about double that of the oxygen, and, since this is the ratio in which these elements are combined in water, it was concluded that the process con sisted essentially in the decomposition of water.
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 batteries which use acids as the electrolyte, a film of hydrogen tends to be deposited on the copper or platinum electrode; but, to obtain a constant electromotive force, several means were soon devised of preventing the formation of the film.
Constant cells may be divided into two groups, according as their action is chemical (as in the bichromate cell, where the hydrogen is converted into water by an oxidizing agent placed in a porous pot round the carbon plate) or electrochemical (as in Daniell's cell, where a copper plate is surrounded by a solution of copper sulphate, and the hydrogen, instead of being liberated, replaces copper, which is deposited on the plate from the solution).
Now this ratio is the same as that which gives the relative chemical equivalents of hydrogen and copper, for r gramme of hydrogen and 31.8 grammes of copper unite chemically with the same weight of any acid radicle such as chlorine or the sulphuric group, SO 4.
If, as is now usual, we take the equivalent weight of oxygen as our standard and call it 16, the equivalent weight of hydrogen is I o08, and its electrochemical equivalent is I 044 X 5.
In aqueous solutions, for instance, a few hydrogen (H) and hydroxyl (OH) ions derived from the water are always present, and will be liberated if the other ions require a higher decomposition voltage and the current be kept so small that hydrogen and hydroxyl ions can be formed fast enough to carry all the current across the junction between solution and electrode.
At the electrodes, however, the small quantity of hydrogen and hydroxyl ions from the water are liberated first in cases where the ions of the salt have a higher decomposition voltage.
The water being present in excess, the hydrogen and hydroxyl are re-formed at once and therefore are set free continuously.
If the current be so strong that new hydrogen and hydroxyl ions cannot be formed in time, other substances are liberated; in a solution of sulphuric acid a strong current will evolve sulphur dioxide, the more readily as the concentration of the solution is increased.
The hydrogen at the cathode is developed by the secondary action 2Na+2H 2 O =2NaOH+H2.
A better basis of comparison would be the ratio of the actual to the limiting conductivity, but since the conductivity of acids is chiefly due to the mobility of the hydrogen ions, its limiting value is nearly the same for all, and the general result of the comparison would be unchanged.
It is evident that the undissociated part of each acid must eventually be in equilibrium with the free hydrogen ions, and, if the concentrations are not such as to secure this condition, readjustment must occur.
In order that there should be no change in the states of dissociation on mixing, it is necessary, therefore, that the concentration of the hydrogen ions should be the same in each separate solution.
In order that the solutions of these should be isohydric and the concentrations of the hydrogen ions the same, we must have a very large quantity of the feebly dissociated acetic acid, and a very small quantity of the strongly dissociated hydrochloric, and in such proportions alone will equilibrium be possible.
Some acetic acid is formed, and this process will go on till the solutions of the two acids are isohydric: that is, till the dissociated hydrogen ions are in equilibrium with both.
In dilute solution such substances as hydrochloric acid and potash are almost completely dissociated, so that, instead of representing the reaction as HC1+KOH = KC1 d-H20, we must write The ions K and Cl suffer no change, but the hydrogen of the acid and the hydroxyl (OH) of the potash unite to form water, which is only very slightly dissociated.
But, on the other hand, if a few drops of acid be placed in the vessel with the platinum, bubbles of hydrogen appear, and a current flows, zinc dissolving at the anode, and hydrogen being liberated at the cathode.
When we use platinum electrodes in acidulated water, hydrogen and oxygen are evolved.
When this compound is acted on by water, hydrogen peroxide and levulinic aldehyde are formed, the aldehyde being subsequently oxidized by the hydrogen peroxide, forming levulinic acid.
They are silicates, usually orthosilicates, of aluminium together with alkalis (potassium, sodium, lithium, rarely rubidium and caesium), basic hydrogen, and, in some species magnesium, ferrous and ferric iron, rarely chromium, manganese and barium.
to the extent of 4 to 6%, and rather less in the other species, is expelled only at a high temperature; it is therefore water of constitution, existing as basic hydrogen or as hydroxyl replacing fluorine.
The ammonium salt is then converted into the lead salt by precipitation with lead acetate and the lead salt decomposed by sulphuretted hydrogen.
It may be artificially prepared by leading sulphur vapour over lead, by fusing litharge with sulphur, or, as a black precipitate, by passing sulphuretted hydrogen into a solution of a lead salt.
But the most delicate precipitant for lead is sulphuretted hydrogen, which produces a black precipitate of lead sulphide, insoluble in cold dilute nitric acid, less so in cold hydrochloric, and easily decomposed by hot hydrochloric acid with formation of the characteristic chloride.
The critical temperature (if there is one) was not reached in Faraday's experiment; possibly even the temperature of -250 C., which by the use of liquid hydrogen has now become accessible, might still be too high.
4 No record can be found of experiments with manganese at the temperature of liquid air or hydrogen; probably, however, negative results would not be published.
Soc. Proc., 1902, T 1, 49, 39) in oxygen, hydrogen and air at low pressures, and by C. D.
The mass of each is about 3 7 1 o T th part of that of a hydrogen atom, and with each is indissolubly associated a charge of negative electricity equal to about 3.1 Xio '° C.G.S.
Nascent hydrogen reduces them to primary alcohols, and phosphorus pentachloride replaces the carbonyl oxygen by chlorine.
Thioaldehydes are also known, and are obtained by leading sulphuretted hydrogen into an aqueous solution of acetaldehyde.
1866, 97, p. 37) by reducing the chloride with hydrogen; it has more recently been prepared by H.
tetroxide, Cb204, is obtained as a black powder when the pentoxide is heated to a high temperature in a current of hydrogen.
It is a white amorphous infusible powder, which when strongly heated in sulphuretted hydrogen, yields an oxysulphide.
Columbium oxysulphide, CbOS 3, is obtained as a dark bronze coloured powder when the pentoxide is heated to a white heat in a current of carbon bisulphide vapour; or by gently heating the oxychloride in a current of sulphuretted hydrogen.
Potassium fluoxy percolumbate, K2Cb02F5 H20, is prepared by dissolving potassium columbium oxyfluoride in a 3 ° solution of hydrogen peroxide.
The hydrogen in the primary and secondary nitro compounds which is attached to the same carbon atom as the nitro group is readily replaced by bromine in alkaline solution.
The orthocompound melts at Io 5° C. and boils at 218° C., the para-compound melts at 54° C. and boils at 230° C. Meta-nitrotoluene (melting at 16° C.) is obtained by nitrating acetparatoluidide and then replacing the amino group by hydrogen.
It abolished the conception of life s an entity above and beyond the common properties of matter, and led to the conviction that the marvellous and exceptional qualities of that which we call " living " matter are nothing more nor less than an exceptionally complicated development of those chemical and physical properties which we recognize in a gradually ascending scale of evolution in the carbon compounds, containing nitrogen as well as oxygen, sulphur and hydrogen as constituent atoms of their enormous molecules.
From the solution the arsenic, copper, &c., are precipitated by sulphuretted hydrogen as sulphides, which are filtered off.
Uranous Compounds.-Uranium dioxide, UO 2 (Berzelius's metal), is a brown to copper-coloured powder, obtained by heating U308 or uranyl oxalate in hydrogen.
The chloride is very hygroscopic. By heating in hydrogen it yields the trichloride, UC1 3, and by direct combination with chlorine the pentachloride, UC1 5.
By electrolysis it yields uranium dioxide as a pyrophoric powder, and peruranic hydroxide, U04.2H20, when treated with hydrogen peroxide.
Solutions of uranyl salts (nitrate, &c.) behave to reagents as follows: sulphuretted hydrogen produces green uranous salt with precipitation of sulphur; sulphide of ammonium in neutral solutions gives a black precipitate of UO 2 S, which settles slowly and, while being washed in the filter, breaks up partially into hydrated UO 2 an sulphur; ammonia gives a yellow precipitate of uranate of ammonia, characteristically soluble in hot carbonate of ammonia solution; prussiate of potash gives a brown precipitate which in appearance is not unlike the precipitate produced by the same reagent in cupric salts.
There is reason to believe that carbonic acid is always one of these waste products, while the others contain the remainder of the carbon, the nitrogen, the hydrogen and the other elements which may enter into the composition of the protoplasm.
Stannous sulphide, SnS, is obtained as a lead-grey mass by heating tin with sulphur, and as a brown precipitate by adding sulphuretted hydrogen to a stannous solution; this is soluble in ammonium polysulphide, and dries to a black powder.
Stannic sulphide, SnS 2, is obtained by heating a mixture of tin (or, better, tin amalgam), sulphur and sal-ammoniac in proper proportions in the beautiful form of aurum musivum (mosaic gold) - a solid consisting of golden yellow, metallic lustrous scales, and used chiefly as a yellow "bronze" for plaster-of-Paris statuettes, &c. The yellow precipitate of stannic sulphide obtained by adding sulphuretted hydrogen to a stannic solution readily dissolves in solutions of the alkaline sulphides to form thiostannates of the formula M 2 SnS 31 the free acid, H2SnS3, may be obtained as an almost black powder by drying the yellow precipitate formed when hydrochloric acid is added to a solution of a thiostannate.
Stannous salt solutions yield a brown precipitate of SnS with sulphuretted hydrogen, which is insoluble in cold dilute acids and in real sulphide of ammonium, (NH 4) 2 S; but the yellow, or the colourless reagent on addition of sulphur, dissolves the precipitate as SnS 2 salt.
Stannic salt solutions give a yellow precipitate of SnS 2 with sulphuretted hydrogen, which is insoluble in cold dilute acids but readily soluble in sulphide of ammonium, and is re-precipitated therefrom as SnS2 on acidification.
Crum was probably the first to recognize that some hydrogen atoms of the cellulose had been replaced by an oxide of nitrogen, and this view was supported more or less by other workers, especially Hadow, who appears to have distinctly recognized that at least three compounds were present, the most violently explosive of which constituted the main bulk of the product commonly obtained and known as guncotton.
How much of the hydrogen and oxygen are in the hydroxylic (OH) form cannot be absolutely stated, but from the study of the acetates at least three hydroxyl groups may be assumed.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.