HALOID BASES AND SALTS. 237 



bases by the circumstance that they cannot be so readily separated 

 from their acids by simple or double elective affinity. The haloids 

 cannot be decomposed by stronger acids, nor yet by stronger 

 bases ; it requires a more considerable time and a more prolonged 

 action of heat to resolve them into their proximate constituents, 

 than is necessary for ordinary salts. 



In these decompositions of the haloid salts we constantly find 

 that the base, during its liberation, combines with water, and is 

 thus separated as a hydrate (for instance, not as oxide of ethyl but 

 as alcohol, not as oxide of methyl but as pyroxylic spirit, not as 

 oxide of lipyl but as glycerine). Conversely the haloid bases in 

 uniting with acids give off all their water, so that they always 

 form perfectly anhydrous salts a fact of which chemists have 

 long availed themselves, in order to ascertain the composition of 

 organic acids in the anhydrous state ; (the combinations of such 

 acids with oxide of ethyl or oxide of methyl, being submitted 

 to examination.) 



We should fall into a great error if we were to conclude from 

 the peculiar relations of the haloids that organic bodies are consti- 

 tuted on entirely different principles from mineral bodies ; for the 

 chemical laws deduced from pure inorganic compounds meet with 

 their fullest application in these compound organic matters ; it is, 

 however, inorganic chemistry which teaches us, that the smaller 

 the chemical attraction between two substances, with so much the 

 more difficulty can they combine with one another, but when once 

 combined, they often resist the most powerful decomposing agents ; 

 we need only refer by way of illustration, to the relations of silicic 

 and phosphoric acids to alumina and zirconia. A natural law 

 admits of no exceptions, and if the principles taking their origin 

 in inorganic chemistry be true natural laws, they must be applied 

 in their fullest extent to the chemical combinations of organic 

 matters. 



The true nature of the acid salts of the haloid bases was also 

 for a long period not recognised ; these substances were regarded 

 as peculiar acids, whose consideration led indeed very materially to 

 the theory of conjugated acids and conjugation ; but there is an 

 essential difference between an acid haloid salt and a conjugated 

 acid. We have already seen that in the conjugated acids, the true 

 acid has lost none of its saturating capacity, while in these acid 

 haloids half of the acid is always saturated by the haloid base : we 

 know, for instance, that sulphovinic acid cannot, by any possibility, 

 be regarded as a conjugated acid, since only half of the sulphuric 



