268 Mr. G. C. Foster on Chemical Nomenclature. 



concealing, the fact that it is in reality a double decomposition, 

 just as truly as the change which occurs on mixing potassic 

 chloride with argentic nitrate. 



Possibly Professor Williamson might reply to this, that he 

 never asserted that double decompositions could not occur 

 between acids and bases ; but that is not now the precise ques- 

 tion. If the impossibility of correctly describing the reaction 

 which takes place between the two bodies NHO 3 and HKO as 

 the combination of an acid with a base is a reason for not calling 

 NHO 3 nitric acid, the like impossibility in the case of the 

 bodies (C 2 H 3 0) 2 and H 2 is an equally good reason for not 

 calling (C 2 H 3 O) 2 acetic acid. 



Nevertheless, although it appears to me that the only consis- 

 tent and logical sense in which the word acid can be used, is 

 the sense denned by Laurent and Gerhardt, it seems to me 

 unnecessary to retain it at all as a strictly scientific term. I 

 most fully agree with what Professor Williamson says in a pas- 

 sage which follows immediately the one last quoted : — 



"I hold that it is inconsistent and highly inconvenient to 

 apply to the double decompositions which take place between 

 hydrogen-salts of acid properties and hydrogen-salts of basic 

 properties, any terms which conceal the fact of their close ana- 

 logy with other double decompositions ; and that the hydrogen- 

 salts ought to be designated by terms similar in form and gene- 

 ral arrangement to the terms applied to the salts of other metals." 



If we regard the salts of hydrogen as constituted like the salts 

 of any other metal, the application to them of the name acid 

 becomes incorrect if it implies any peculiarity of constitution, 

 and superfluous if it does not. When we want to speak of acids 

 as a class, they are accurately and conveniently indicated as 

 hydrogen-salts ; while individual acids may equally well be de- 

 noted by such names as hydric sulphate, hydric nitrate, hydric 

 chloride, &c, the systematic adoption of which is urged by Dr. 

 Williamson. 



The word acid will certainly long remain as a part of popular, 

 and even of ordinary chemical language, and hence the im- 

 portance of trying to ascertain its correct application ; but its 

 strictly scientific significance has passed away. It indicates a 

 distinction to which we now know that no real difference cor- 

 responds. 



Lastly, it is necessary to say a few words as to the nomencla- 

 ture of the substances upon which Dr. Williamson is wishful to 

 bestow the name acid. The term " anhydride/' by which Laurent 

 and Gerhardt designated these bodies, has been very justly ob- 

 jected to on the ground that, in applying it to any object, we 

 merely state that that object is not one of an infinite number of 



