﻿92 M. Dumas's Remarks on Affinity. 



Proust, who maintained the contrary, succeeded in establishing 

 his view. Dalton's atomic theory, soon confirmed by Gay-Lus- 

 sac's laws of gaseous combination, by Wollaston's experiments 

 on salts in various degrees of saturation, by Berzelius's immense 

 researches, and especially by the simple and constant ratios which 

 he pointed out, in salts of the same acid and in the same state 

 of saturation, between the oxygen of the base and that of the 

 acid — all these striking events have powerfully contributed to 

 lead chemists to continue to regard affinity as having a character 

 of its own and as having almost nothing to borrow from general 

 attraction ; for, in fact, what links are to be established between 

 general attraction (acting directly as the masses and inversely 

 as the square of the distance, obeying without discontinuity 

 all changes in mass, all changes in distance) and chemical 

 affinity ? 



Viewed with regard to masses, affinity does not admit that 

 combination can neither be effected below a certain minimum 

 nor above a certain maximum. Between these two extreme limits 

 the atomic theory, confirmed in this respect by the universal ex- 

 perience of chemists, just as little allows that combinations may 

 be indefinitely multiplied ; far from that, it limits the number, 

 and only admits those w T hich are represented by atoms united in 

 simple ratios, represented by whole numbers, as 1 : 1, 1 : 2, 2 : 3, 

 2 : 5, 2 : 7. 



If it be true that the experiments of MM. Marignac and De- 

 bray have rendered certain the existence of compounds formed 

 in accordance with more complex ratios, even in mineral che- 

 mistry, still nothing indicates that their formation takes place 

 according to a law of continuity, and that in this respect they 

 disaccord with the fundamental principle of the atomic theory. 



Thus the reciprocal action exerted by the atoms of bodies, 

 attractive at inappreciable distances, less so as they separate, 

 becoming zero, or even repulsive when the sign is changed — 

 this, according to Newton, is the most faithful image of affinity. 



But to make the effects agree with the incontestable results on 

 which the atomic theory is founded, we must add, with Newton, 

 that the figure of the atoms should be taken into consideration. 

 It is not difficult to understand, in fact, that the action exerted 

 by the peculiarities in the shape of the atoms may limit the pro- 

 duction of their compounds, and restrict them to uniting in 

 simple ratios expressed by whole numbers. 



Ampere in his youth had proposed to the chemists of his time 

 a doctrine of chemical combination which both appealed to the 

 principles of the Newtonian attraction and the laws of crystallo- 

 graphy : it excited but little interest ; it represented neither the 

 absolute ideas of affinity as then understood, nor the ideas of 

 chemical dualism as the interpreters of Lavoisier understood it, 



