﻿M. Dumas' s Remarks on Affinity. 85 



tion of their parts, as the globe of the earth and sea affects a 

 round figure by the mutual attraction of its parts by gravity. 



" Since metals dissolved in acids attract but a small quantity 

 of the acid, their attractive force can reach but to a small dis- 

 tance from them. And as in algebra, where affirmative quanti- 

 ties vanish and cease there negative ones begin, so in mechanics, 

 where attraction ceases, there a repulsive virtue ought to succeed. 

 And thus Nature will be very conformable to herself and very 

 simple, performing all the great motions of the heavenly bodies 

 by the attraction of gravitation which intercedes these bodies, 

 and almost all the small ones of their particles by some other 

 attractive and repelling power which intercedes the particles. 



"There are in nature agents capable of uniting the particles 

 of bodies, and it is the province of experimental philosophy to 

 discover these agents." 



Newton proceeds: — "All these things being considered, it seems 

 probable to me that God in the beginning formed matter in 

 solid, massy, hard, impenetrable, moveable particles, of such sizes 

 and figures and with such other properties and in such propor- 

 tion to space as most conduced to the end for which he formed 

 them ; and that these primitive particles being solids, are incom- 

 parably harder than any porous bodies compounded of them, 

 even so very hard as never to wear or break in pieces." 



In the same way that it would be difficult to define molecular 

 attraction (to which chemical affinity is referred) better than New- 

 ton did, in like manner the definition which he gives of atoms 

 would even now be the best introduction to the statement of the 

 ideas which it is possible to form of the atoms of modern che- 

 mistry, which are identical with the particles which he calls pri- 

 migenal. Chemists of the present time elude, it is true, the dif- 

 ficulty by leaving in vagueness whatever concerns the nature of 

 affinity or that of atoms. They thus obey their praiseworthy 

 habits of mind, preferring to pass over in silence subjects on which 

 certainty cannot be obtained. This reserve, however, is not 

 without inconvenience; for those commencing the study of che- 

 mistry naturally attempt to supply the silence of their masters 

 on these subjects, the only ones which the beginner can attack 

 in the absence of laboratories, and when he is not led to fix all his 

 attention on the details of experiments and the management of 

 apparatus. It is unnecessary to add that they go astray, and 

 that one of the principal obstacles to the diffusion of sound prin- 

 ciples in chemistry arises probably from the ignorance in which 

 the beginner is left as to the nature of the forces at work, and on 

 that of the atoms it is concerned with. 



"It seems to me further," adds Newton, "that these particles 

 have not only a vis inertia accompanied with such passive laws 



