238 HALOID BASES AND SALTS. 



acid contained in it is in a state to saturate a base, just as in 

 bisulphate of potash only half of the acid can be engaged in satu- 

 rating the base. Notwithstanding this very striking difference, 

 many of the acid haloid salts are, unfortunately, still ranked 

 amongst the conjugated acids. 



Moreover, these acid salts are distinguished from the other 

 known acid salts of other bases by the difficulty with which the 

 true base can be separated from the compound ; indeed, the sepa- 

 ration is here, for the most part, more difficult to accomplish by 

 strong affinities than in the neutral haloid salts. The acid haloids 

 have, however, very many properties in common with one another; 

 they are either solid and crystallisable, or liquid, and, like most of 

 the acid salts in mineral chemistry, always contain 1 atom of water 

 from which they cannot be separated without total decomposition, 

 except by means of a base ; further, however volatile the acid and 

 the base may be, these acid salts cannot be distillled or sublimed 

 undecomposed ; and, lastly, it is worthy of remark that their com- 

 binations with bases are almost without exception soluble in 

 water, even though the acid in question formed ever so insoluble a 

 salt with a base, (as, for instance, in the case of sulphate of oxide 

 of ethyl and baryta.) 



Amongst the haloid bases there is a series of homologous 

 bodies of high interest in relation to theoretical chemistry, but 

 scarcely falling within the sphere of zoo-chemistry. These are the 

 bodies already mentioned in p. 40, possessing the general formula 

 C n H n+ jO, and standing in a definite relation to the acids of the first 

 group. 



There is, however, another haloid base of more importance in 

 zoo-chemistry, but homologous to no other body with which we 

 are acquainted, the oxide of lipyl, which, in combination with the 

 fatty acids, constitutes the fats which hold so prominent a place in 

 physiological chemistry. There are many other haloid bases, but 

 for the most part only some of their combinations, namely, their 

 acid salts, have been examined ; and in their isolated as well as in 

 their hydrated state they are yet unknown. Hence, we have here 

 only to consider oxide of lipyl and its combinations, and oxide of 

 cetyl, which is homologous to the group of ethers. 



