COMPOUNDS OF MTi:xiKN WITH 11 YI>i;n<;KN AND OXYGEN 287 



t,.i'i<li\ X. 2 O, f ' 7 is similar to water in its volumetric composi- 

 tion. Two volumes of nitrous oxide are formed from two volumes of 

 nitrogen and one volume of oxygen, which may be shown by the common 



vitriol acid is also used. In Kngland alone more than 1000 million kilograms of 

 chamber acid arc produced by this method. The formation of sulphuric acid by the 

 action of nitric acid was discovered by Drebbel, and the first lead chamber was erected 

 by Roebuck, in Scotland, in the middle of the last century. The essence of the process 

 was ably brought to light at the beginning of this century, when many improvements 

 were introduced into practice. 



67 Hyponitrous acid, corresponding with nitrous oxide (as its anhydride), is not 

 known in a pure state, but its salts are known. They are prepared by the reduction of 

 nitrous land consequently of nitric) salts by sodium amalgam. If this amalgam be 

 added to a cold solution of an alkaline nitrite until the evolution of gas ceases, and 

 the excess of alkali saturated with acetic acid, an insoluble yellow precipitate of silver 

 hyponiti ite. X AgO, will be obtained on adding a solution of silver nitrate. The hyponi- 

 trite is insoluble in cold acetic acid, and decomposes when heated, with the evolution of 

 nitrous oxide. If rapidly heated it decomposes with an explosion. It is dissolved 

 unchanged by feeble mineral acids, whilst the stronger acids (for example, sulphuric 

 and hydrochloric acids) decompose it, with the evolution of nitrogen, nitric and nitrous 

 acids remaining in solution. Among the other salts of hyponitrous acid, HNO, the salts 

 of lead, copper, and mercury are insoluble in water. This is almost all that is at 

 present known (according to the researches of Divers) concerning this compound, which 

 in its composition and reactions presents a certain analogy to hypochlorous acid. 

 There is even reason to think that the composition of silver hyponitrite, AgNO, is more 

 complex than was at first supposed. As a substance which has not been sufficiently 

 fully invest iuated, hyponitrous acid must be ranked with those compounds which yet 

 present much that is doubtful. It is evident from the very method of its formation that 

 it belongs to the class of compounds which are intermediate between the oxygen and 

 hydrogen compounds of nitrogen. If its composition be N HO, then perhaps it =NH 3 , 

 in which two equivalents of hydrogen are replaced by oxygen (see p. 258). A substance 

 of this composition, containing the hydrogen combined with the nitrogen, should most 

 probably be isomeric, and not identical, with the true hydrate of nitrous oxide, because 

 in the latter the hydrogen would be in the form of hydroxyl. Among such insufficiently 

 investigated compounds which, however, are of great interest we must rank amidogen^ 

 or lujdrazhic. X\>H 4 , which was prepared by Curtius (1887) by means of ethyl diazo- 

 acetate, or triazoacetic acid. Curtius and Jay (1889) showed that triazoacetic acid, 

 CHNo.COOH (the formula should be tripled), when heated with water or a mineral 

 acid gives (quantitatively) oxalic acid and amidogen (hydrazine), CHN 2 .COOH + 

 2ELO = C. 2 O..,(OH)o + N.,H 4 i.e. (empirically), the oxygen of the water replaces the nitro- 

 gen of the azoacetic acid. The amidogen is thus obtained in the form of a salt. 

 With acids amidogen forms very stable salts of the two types, N 2 H 4 HX, and N 2 H 4 H.^X,, 

 as, for example, with HC1, HUSO 4 , &c. These salts are easily crystallised ; in acid solu- 

 tions they act as powerful reducing agents, evolving nitrogen ; when ignited they are 

 decomposed into ammoniacal salts, nitrogen, and hydrogen; with nitrites they evolve 

 nitrogen. The sulphate, N.,H 4 ,H. 2 SO 4 , is sparingly soluble in cold water (8 parts in 100 

 of water), but is very soluble in hot water ; its specific gravity is 1'378, it fuses at 254, 

 with decomposition. The hydrochloride, NoH 4 ,2HCl, crystallises in octahedra, is very 

 soluble in water, but not in alcohol ; it fuses at 198, evolving hydrogen chloride, and 

 forming the salt N 2 H 4 HC1 ; when rapidly heated it decomposes with an explosion ; with 

 platinie chloride it immediately evolves nitrogen, forming platinous chloride. By the 

 action of the alkalis the salts N 2 H,,2HX give hydrate of amidogen, N 2 H 4 ,H 2 O, 

 which is a fuming liquid, boiling at 119, almost without odour, and whose aqueous 

 solution corrodes glass and india-rubber, has an alkaline taste and poisonous properties. 

 The reducing capacities of the hydrate are clearly seen from the fact that it reduces the 



