and chiefly on the use of the word Acid. 267 



the name anhydride to acids, and leaving bases, however anhy- 

 drous they might be, entirely unprovided with a corresponding 

 name " (page 424) ; but I am not aware from what part of his 

 writings such a limitation can be inferred. It is quite true, 

 however, that Laurent and Gerhardt pointed out that, as a matter 

 of fact, the bases which took part in a great many reactions were 

 not anhydrous oxides (as they had hitherto been commonly re- 

 presented) but hydrates, and that they laid great stress upon the 

 importance of recognizing this fact in the chemical equations by 

 which those reactions were expressed. 



But not only can I not admit that original usage is in favour 

 of that application of the terms " acid M and (i base " which Dr. 

 Williamson recommends ; it appears to me that one at least of 

 the arguments by which he tries to show that the salts of hy- 

 drogen ought not to be called acids, can be used with equal force 

 against the employment of that name in the sense which he de- 

 fends. In page 426 he says, — 



" But it is not only true that the bodies misnamed anhydrides 

 are acids ; it is equally true and certain that the hydrogen-salts 

 cannot with any consistency be called acids : for when two hy- 

 drogen-salts — say hydric nitrate and potassic hydrate — react on 

 one another, we cannot call the process a combination of nitric 

 acid with potash, without putting in the background, and to 

 some extent concealing, the fact that water is formed, quite* as 

 much as potassic nitrate. Learners of chemistry who have been 

 told that an acid is a thing which combines with a base, natu- 

 rally and consistently wish to omit any mention of the water in 

 their description of the process, and they have to be told that 

 this supposed acid really is a salt of hydrogen possessing acid 

 properties, and the so-called base is a hydrogen-salt with strongly 

 basic properties, the two on coming together undergoing double 

 decomposition, just as truly as potassic chloride when mixed 

 with argentic nitrate." 



Without dwelling upon the facts that chemists who call 

 hydrogen-salts acids, do not want to call the process above de- 

 scribed " a combination of nitric acid with potash," and that 

 they- would not tell learners of chemistry that " an acid is a 

 thing which combines with a base," we may remark that a pre- 

 cisely similar difficulty would in some cases arise for learners 

 from the adoption of Dr. Williamson^ definition of acids. When 



acetic « acid," (C 2 H 3 O) 2 O, aceto-benzoic « acid," q' ^5 o } °> 



or thiacetic " acid," (C 2 H 3 O) 2 S, reacts with a base, say water, 

 H 2 (which is the first base in the list of examples on page 429), 

 we cannot call the process a combination of the acid with the 

 base, without putting in the background, and to some extent 



T2 



