AMIDOGEN AND AMIDES. 177 



cannot afterwards be separated from it by the agency of heat. 

 The compound is strictly analogous to chloride of ammonium,, 

 but contains an atom of copper in the place of hydrogen. Its 

 formula is NH 3 Cu, Cl, and it may be named the chloride of 

 cupr ammonium. This salt and many others are likewise 

 capable of combining with more ammonia, which is retained 

 less strongly, and has the relation of constitutional water to the 

 salt. The constitution of these combinations will be more mi- 

 nutely considered in another part of the work. 



Amidogen and amides. The existence of another compound 

 of nitrogen and hydrogen, containing an atom less of hydro- 

 gen than ammonia, (NH 2 ), is recognized in an important series 

 of saline compounds, although it has not been isolated. These 

 compounds are called amides, and hence the name amidogen 

 applied to their radical. When potassium is heated in am- 

 moniacal gas, the metal is converted into a fusible green 

 matter, which appears to contain the amide of potassium, while 

 an atomic proportion of hydrogen is disengaged. Amidogen 

 exists also in the white precipitate of mercury of pharmacy, 

 formed on adding ammonia to corrosive sublimate, the pro- 

 duct being a double chloride and amide of mercury (Ag 

 Cl + HgNH 2 ). 



Amides are produced in an interesting way, by the abstrac- 

 tion of the elements of water from compounds of ammonia with 

 oxygen acids. Thus, on decomposing oxalate of ammonia by 

 heat, the acid losing a proportion of oxygen, and the ammonia 

 a proportion of hydrogen, oxamide sublimes, which consists of 

 NH 2 +2CO. When ammoniacal gas and anhydrous sulphuric 

 acid vapour are mixed together, a saline substance is produced 

 which dissolves in water, but is not sulphate of ammonia, the 

 solution affording no indications of sulphuric acid. It is be- 

 lieved to be a hydrated sulphamide, or to be constituted thus, 

 NH 2 , SO 2 + HO; a compound which it will be observed con- 

 tains neither ammonia nor sulphuric acid. Similar products 

 result from the action of ammonia on dry carbonic acid, and 

 all the other anhydrous oxygen acids. The difference between 

 these compounds and the true salts of ammonia affords a 

 strong argument in favour of the ammonium theory of the 

 latter. 



The other speculative view of the constitution of the ammo- 

 nical amalgam, to which allusion has been made, is suggested 



