252 Mr. J. J. Waterston on Chemical Notation in 



and N = 14, we have j^ = Tnv7> an( *14<r + V = 8*5; hence# = i, 



and y = \^. Ammonia is thus expressed by N^H 1 ^, which 

 means that a gas-molecule of ammonia is composed of half a gas- 

 molecule of nitrogen united to one and a half gas-molecule of 

 hydrogen. 



In some cases of composite bodies, the components separate 

 on boiling or sublimation. When this happens, the specific gra- 

 vity of the vapour reveals the fact, as in the following instance. 



In sal-ammoniac the weight of ammonia is to the weight of 

 muriatic acid as 1 to 2'235. Its vapour-density is 13*5 

 (N*H^) = 8-5, H*Cl*=18-5. Hence 



from which we find x — y — \\ and following the usual formula, 

 we might say half a gas-molecule of ammonia unites with half a 

 gas-molecule of muriatic acid to form one gas-molecule of muri- 

 ate of ammonia ; or if this splitting of (N* H 1 ^ into two (N* H*), 

 and H*C1* into two (H*C1*), is inadmissible, we have the alter- 

 native of the two whole molecules remaining separate, and the 

 ammonia and acid vapour forming a simple mixture w T ith specific 



gravity 13*5, equal to the mean of the two ~ = 13*5 . 



The same is the case with the nitrous, formic, and acetic ethers, 

 but not so with the oxalic and succinic ethers. 

 The three first are 



O^N + H 4 C 2 . HO* 38 + 37 __ „„ 1 

 2 = ~~2 67 *> 



O^CH + H 4 C 2 .HO*_ 37 + 37 



= 67 j 



2 2 



OHc 2 H 3 + H 4 C 2 .HO* 51 + 37 



44. 



2 2 



The two last 



1 *C + H 4 C 2 .HO*=73, 



1 *H 2 C 2 + H 4 C 2 .HO i =87. 



It will be remarked that the symbols and notation, compared 

 with the vapour-density, reveal such facts without any effort of 

 the attention. 



Mr. Odling advocates Gerhardt's system of notation; but 

 although it is nominally based, like that of Berzelius, on the so- 



