On the Mechanical Energy of Chemical Actions. 269 



things which it might be, but we do not say what it is. This, 

 again, is a term by the total abandonment of which I venture to 

 think that the language of chemistry would be improved rather 

 than impoverished. The so-called anhydrides are exclusively 

 oxides (or sulphides) ; and there seems to be no good reason for 

 applying to them a nomenclature different from that which is 

 employed for other bodies of the same class. By simply calling 

 these bodies what everyone admits that they are, namely, 

 oxides, we avoid all the objections that can be urged against 

 calling them either acids or anhydrides, and we obtain names — 

 such as sulphurous oxide, sulphuric oxide, acetic oxide, benzoic 

 oxide — which are at once intelligible to every chemist. 



In support of this suggestion, I may be allowed to quote in 

 conclusion part of a letter received a short time ago from Mr. 

 Watts, a gentleman whom all recognize as a high authority on 

 such a subject : — 



" I quite agree with you that oxide is a much better term than 

 anhydride for things like SO 3 , P 2 O 5 , &c. Indeed I should have 

 denoted them in that way throughout the ' Dictionary/ had it 

 not been that some vested interests seemed to stand in the 

 way. I allude to terms like carbonic oxide, nitric oxide, &c, 

 which, being already appropriated, could not be applied to the 

 anhydrides CO 2 and N 2 O 5 . But the difficulty may be com- 

 pletely got over by calling CO carbonic oxide, CO 2 carbonic 

 dioxide, N 2 O 5 nitric pentoxide, &c. As to the term ' acid/ I 

 really don't see why it should not, as you suggest, be superan- 

 nuated altogether, excepting as a trivial name for certain well- 

 known compounds which people in general will perhaps never 

 be induced to call by any other name." 



XXXVIII. On the Mechanical Energy of Chemical Actions. 

 By Dr. H. W. Schroder van der Kolk*. 



IN a communication on "Dissociation," M. H. Sainte-Claire 

 Deville sets out from the view that all chemical compounds 

 are ultimately decomposable into their constituents by a suffici- 

 ently elevated temperature f. He supposes the molecules thus 



* Translated from Poggendorff's Annalen, vol. cxxii. p. 439 (July 1864), 

 by G. C. Foster, B.A. The author says, in a foot-note to the original, 

 " This paper wa| already written when I again encountered the same ideas 

 in Clausius's recently published paper (Pogg. Ann. vol. cxxi. p. 1), where 

 he says that in the principle of Transformations a general natural tendency 

 to transformations in one definite direction expresses itself, and that this 

 tendency comes into account also in the changes of state of material 

 bodies." 



t Fortschritte der Physik, 1860, p. 379. Phil. Mag. S. 4. vol. xx. p. 448. 



