CHEMICAL AFFINITY. JSQ 



The forces of affinity, though also the same in kind, are still more 

 numerous than those of sensible attraction ; for instead of three, 

 they amount to as many as there an- heterogeneous bodies. The 

 rate, indeed, at \v' ' *ht , vary when the distance of the attracting 

 bodies increases _>r 'iminishes, is probably the same in all. and so 

 is also their variations as far ;is it regards the mass. But even 

 when both of these ' ircumstances, as far as we can estimate them, 

 are the same, the affinity of two bodi< s for a third is not the same. 

 Thus barytes has a stronger affinity for sulphuric acid than potash 

 has : for if equal quantities of each be mixed with a small portion 

 of s'llphuric a*.id, the barytes seizes a much greater proportion of 

 the acid than the potash does. This difference in intensity extends 

 to ".articles of all bodies ; for there are scarcely any two bodies 

 whose particles have precisely the same affinity lor a third; and 

 scarcely any two bodie.s. the particles of each ol which cohere to- 

 gether with exactly the same force. 



It is this difference in intensity which constitutes the most im- 

 portant characteristic mark of affinity, and which explains the dif. 

 ferent decompositions and changes which one body occasions in 

 others. 



Thus it appears at first sight, that there are as many different 

 affinities as there are bodies ; and that affinity, instead of being 

 one force like gravitation, which is always the same when the cir- 

 cumstances are the same, consists of a variety of different forces, 

 regulated, indeed, by the same kind of laws, but all of them dif. 

 ferent from each other. These affinities do not vary like magne. 

 tism and electricity, though the mass continues the same, but are 

 always of equal intensity when other circumstances are equal. 

 Hence it is reasonable to conclude, that these affinities cannot, 

 like magnetism and electricity, depend upon peculiar fluids, the 

 quantity of which may vary ; but that they are permanent forces, 

 inherent in every atom of the attracting bodies. 



12. It is very possible that this variation of intensity, which 

 forms so remarkable a distinction between affinity aud gravitation, 

 may be only apparent and not real. For even in gravitation the 

 intensity varies with the distance and the ma>s, and the same vari. 

 ation holds in affinity. But as the attraction of affinity acts upon bo* 

 dies situated at intensible distances from each other, it is evident 

 that, strictly speaking, we have DO means of ascertaining that 

 distance ; and coujequently that it may vary without our discover. 



