﻿84 M. Dumas' s Remarks on Affinity. 



"When salt of tartar per diliquium (potash) being poured into 

 the solution of any metal precipitates the metal and makes it 

 fall down to the bottom of the liquor in the shape of mud, does 

 not this argue that the acid particles are attracted more strongly 

 by the salt of tartar than by the metal, and by the stronger 

 attraction go from the metal to the salt of tartar ? And so when 

 a solution of iron in aquafortis dissolves the lapis calaminaris 

 and lets go the iron, or a solution of copper dissolves iron im- 

 mersed in it and lets go the copper, or a solution of silver dissolves 

 copper and lets go silver, or a solution of mercury in aquafortis 

 being poured upon iron, copper, tin, or lead dissolves the metal 

 and lets go the mercury, does not this argue that the acid par- 

 ticles of the aqua for tis are attracted more strongly by the lapis 

 calaminaris than by iron, and more strongly by iron than copper, 

 and more strongly by copper than by silver, and more strongly 

 by iron, copper, tin, or lead than by mercury?" 



" . . . . And when metals corroded with a little acid turn into 

 rust, which is an earth tasteless and indissolvable in water, and 

 this earth imbibed with more acid becomes a metallic salt, and 

 when some stones, as spar of lead, dissolved in proper men- 

 struums become salts, do not these things show that salts are 

 dry earth and watery acid united by attraction, and that the 

 earth will not become a salt without so much acid as makes it 

 dissolvable in water." 



I think that no chemist contemporary with Newton had such 

 just and sound notions of chemistry as are summed up in these 

 lines. It is doubtful whether any one at that time understood 

 their force and import. 



We may then regard the following considerations of Newton 

 not as vain hypotheses, but as the fruit of a very advanced expe- 

 rience, of long and substantial studies : — 



"Now the small particles of matter may cohere by the strong- 

 est attractions and compose bigger particles of weaker virtue; 

 and many of these may cohere and form bigger particles whose 

 virtue is still weaker ; and so on for divers successions, until the 

 progression end in the biggest particles, on which the operations 

 in chemistry and the colours of natural bodies depend, and 

 which by adhering compose bodies of a sensible magnitude. 



"If the body is compact and bends or yields to pression with- 

 out any sliding of its parts, it is hard and elastic, returning to its 

 figure with a force rising from the mutual attraction of its parts. 

 If the parts slide upon one another, the body is malleable or soft ; 

 if they slide easily and are of a fit size to be agitated by heat, 

 and the heat is big enough to keep them in agitation, the body 

 is fluid; and if it be apt to stick to things it is humid; and the 

 drops of every fluid affect a round figure by the mutual attrac- 



