1813.] Elements of Chemical Philosophy. 37S 



subject could not be understood without eVjtering into much 

 longer details than would be coni^isteot with this article. I 

 propose publishing an essay on it in a subsequent number of this 

 journal. Mere convenience is the only reason assigned by the 

 author for pitching upon 15 to represent oxygen, if we were to 

 be directed by convenience alone there could be no hesitation in 

 choosing 10, the number proposed by Dr. Wollaston, which 

 would aiford more arithmetical facility than any other number. 

 But I conceive that a better basis may be obtained for a ground- 

 work than mere facility ; and in fact the difficulties which such 

 elementary arithmetical processes present are of too slight a 

 nature to claim much attention. 



Sir Humphry Davy terminates this part of the subject with an 

 examination of the peculiar opinions respecting affinity which 

 have been supported by Berthollet. That Berthollet in some of 

 his notions has gone much farther than he can be borne out by 

 facts is, i think, incontrovertible. Thus when he affirms that 

 substances are capable of combining in any proportion what- 

 ever, he is refuted by all the chemical compounds which have 

 been hitherto examined, excepting aqueous solutions and alloys, 

 which are more similar to mixtures than chemical compounds. 

 When he affirms that substances divide another between them, 

 according to their rate of affinity for it, and that bodies are 

 seldom or never thrown down in a state of absolute purity ; his 

 opinion is opposed by the knowledge of the determinate propor- 

 tions in which bodies combine, and by the permanency and 

 comparatively small number of chemical combinations ; but to 

 condemn all his opinions in the lump, appears to me to be going 

 just as far wrong on the one side as he has done on the other. 

 That he has succeeded in demonstrating the inaccuracy of many 

 of the old notions respecting affinity, appears to me incontro- 

 vertible : though he has not been so fortunate in establishing his 

 own. Nor are we at present in possession of any precise notions 

 respecting the strength of the affinity which different bodies have 

 for each other. 



Next follows a very neat and distinct enumeration of the phe- 

 nomena of electricity, of considerable value, especially that part 

 of it which treats of galvanism. Several important general laws 

 are stated, some of them not hitherto attended to by electri- 

 cians ; but unlucldly the whole subject is treated so briefly as to 

 preclude the possibility of giving any sketch of it. This brevity^ 

 I should think, will be felt by a beginner, and v^iii give an air of 

 obscurity to this very valuable section. 



This part of the work is concluded with some very judicious 

 observations on Analysis and Synthesis^ on the mode of experi- 

 menting, aud upon the state in which vapour exists in gases. 



