HISTOHY OF THE ATOMIC THEORY. 1 39 



In this case, the affinity of composition, which produces the 

 union, takes the name of disposing affinity. 



"4th. Two or more compounds being placed in circum- 

 stances, suitable for bringing into play the respective affinities 

 of their component parts; either there is a change and new 

 products formed without our being able to determine which 

 is the most powerful affinity under which they act, or the first 

 composition remains, contrary to the order indicated by the 

 superior affinity of the principle of one of the component parts 

 to the affinity of the other. In these two cases we say that 

 they are not the relations of affinity of one body to another, 

 but affinities of concourse, otherwise called double affinities; 

 in a word, the sum of all the united affinities which are needed 

 to explain these phenomena. 



" Two bodies being put in contact, the compound which 

 results is supercompounded, or united with an excess of one of 

 the principles. This tendency to supercomposition, is some- 

 times so strong, that when the least affinity of a third body 

 interferes with it, the proportions of the first compound are 

 changed, and the neutral state destroyed. This tendency may 

 cause the production of crystals, with excess of base, in an 

 acid liquor. To distinguish this force, we shall call it the 

 affinity of a compound for an excess of one of its constituents, 

 or for shortness, affinity of excess ^ which will be enough to 

 recall the idea when it has been well grasped. However 

 paradoxical some of these propositions may appear, I have no 

 fear of their being called in question after the proofs I have 

 given ; and if they are well founded, it will readily be granted 

 that they ought to form one of the most important elements 

 in the calculation of affinities." 



Here now we have what Morveau has given, as the most 

 certain of the laws of affinities known among chemists at his 

 time. He adds, however, that they certainly scarcely deserve 

 the title. The following are additions : — 



