14 Dr. E. J. Mills on the First Principles of Chemistry. 



Having harvested such dynamic units, and classified them 

 upon a common scale, we should certainly see a new calculus 

 and a new nomenclature. Instead of Daltonian atomic weights, 

 we should have the realities which I have termed bergmannics ; 

 and chemical substances, instead of being named dually, on 

 the current system, would be called by their bergmannic sym- 

 bol. Chemistry is now in the same position as we should be, 

 if, with the sovereign, the shilling, the penny, &c. in circula- 

 tion, we were unable to express the value of one in terms of 

 the others. For the common " equivalents " are not, so far 

 as we know, equivalents at all. They are defined, for instance, 

 as the weights of Li, Na, Ag, &c. that will displace H in the 

 expression HC1. We might as well say that the value of the 

 loads in a railway truck are always equivalent, whether the 

 load consists of air, of hay, or bullion. It is sufficiently obvious 

 that the real equivalent of a body is that which performs the 

 unit of work, however that unit may come to be defined *. 



The law of decrease of chemical energy throws considerable 

 light upon this question of equivalence. Let, for example, the 

 "successive steps" in the chlorination of benzol be one and 

 the same kind of operation throughout ; let + B represent 

 that chemical property of benzol (it is enough to assume one) 

 which is reduced by chlorination, and — C that chemical pro- 

 perty of chlorine which accumulates on the benzol by chlori- 

 nation ; also let /3 be a factor less than 1, y a factor greater 

 than 1. The law in question leads, at its simplest, to the 

 equation 



y being the sum of the aforesaid properties after a stage x of 

 chlorination. Thus the residues B/3* and C7* form geometric 

 series, the actual " valencies " of which decrease therefore by 

 a common factor, not alter by a uniform difference. In other 

 words, the arithmetical series of valencies, 



(C 6 H 5 )', (C 6 H 4 )", (C e H 3 )'", &c, 

 (5C1 2 )*, (4 CI,)™, (3C1 2 )« &c, 



is inconsistent with the law. This result affects the entire 

 doctrine of substitution. It also justifies Erlenmeyer's remark, 

 that there cannot really be any such thing as a polybasic acid. 

 (11) The following summary will serve to exhibit in a clear 

 light the difference between the chemical principles I advocate 



* One instance of such a definition might be, — The equivalent of a sub- 

 stance is that weight of it which, in a tube of unit capacity, liberates the unit 

 weight of iodine in the unit of time. 



