Prof. Graham on the Constitution of Salts. 897 



stallization, but which Mr. Graham distinguishes as constitutional 

 water. Now it appears that metallic oxides may be substituted for 

 this constitutional water ; and it is in this way that subsalts come to 

 be produced. Thus the salt called subnitrate of copper is really a 

 nitrate of water with three atoms oxide of copper attached to that 

 combination in the place of water of crystallization. The nitrate of 

 water, or nitric acid of specific gravity 1*42, the nitrate of copper, 

 and the subnitrate of copper, are all of similar constitution, and are 

 represented by analogous formulae, viz , 



HN 11% 

 Cu N W, 



HNCu'. 



These formulae illustrate the constitutional neutrality of salts. In 

 each of them we have one atom only of oxide in the relation of base 

 to the acid, (which is expressed by placing its symbol to the left of 

 the symbol of the acid ;) while in each salt we have three atoms of 

 oxide in another and totally different relation to the acid. Certain 

 salts appear to be capable of combining with anrrvdrous acids, and 

 then a new order of saline combinations is produced. The sulphate 

 of potash and chloride of potassium absorb anhydrous sulphuric 

 acid without decomposition, as has been proved by H. Rose. The 

 red chromate of potash is analogous to Rose's salts, but more per- 

 manent. It is not a true fo'chromate of potash, but a binary com- 

 bination of chromic acid with the neutral chromate of potash with- 

 out any water. The red chromate of potash is therefore not an ex- 

 ception to the law, that all salts are neutral in composition. It is 

 well known that all the ordinary salts of ammonia contain an atom 

 of water, which forms part of the base, and that they may be repre- 

 sented as containing the oxide of a hypothetical radical ammonium. 

 Mr. Graham considers water as the true base of these salts, and that 

 ammonia is not a base itself, but belongs to a class of bodies which 

 may be called basic adjuncts, which admit of being attached to the 

 oxide of hydrogen or to the oxides of metals, the only true bases. 

 Thus the sulphate of ammonia is truly the sulphate of water, with 

 ammonia as a basic adjunct. The sulphovinates contain sulphate of 

 water, with defiant gas as a basic adjunct. The nature of the con- 

 stitution of the combinations of dry salts with ammonia can now be 

 explained. In these combinations the metallic oxide is in the place 

 of the basic water of the ordinary ammoniacal salts. Thus, chlo- 

 ride of hydrogen (muriatic acid) combines with one atom of ammo- 

 nia; chloride of copper does the same thing, and the ammonia can- 

 not be expelled or separated by heat in either case. These combi- 

 nations are represented by analogous formulae : 



NH 3 H CI, and 

 Nff Cu CI. 



Anhydrous sulphate of copper absorbs, at an elevated tempera- 

 ture, half an atomic proportion of ammonia, and retains it by a most 

 powerful affinity. It is curious that in similar circumstances oil of 



