140 MEMOIR OF DR. DALTON, AND 



* ** 1st. There is no chemical union, if one of the bodies be 

 not sufficiently fluid to allow the molecules to obey the law of 

 affinity, which carries them from (mere) proximity to (actual) 

 contact. 



"2nd. Affinity takes place only among the smallest integral 

 molecules of a body. 



" 3rd. From the affinity of one substance with another, we 

 cannot know the affinity of a compound; we cannot know the 

 affinity of a compound of one of these substances, with one or 

 the other in excess. 



" 4th. The affinity of composition has no efficacy, unless it 

 can overcome the affinity of cohesion. 



" 5th. Two or more bodies, which unite by the affinity of 

 composition, form a substance which has new properties 

 distinct from those which belong to each of the bodies before 

 combination. 



"6 th. To give effect to affinities, a particular temperature 

 is necessary, which renders the action either slow or rapid, 

 invalid or efficacious." 



These feeble and incipient attempts at laws may surely sur- 

 prise us, written as they are almost within the memory of some 

 of the living. There was at this time an attempt to measure 

 the force of affinities as the only method of obtaining 

 results, and there was not yet seen the absolute necessity of 

 having bodies kept uniform by a constant and absolutely 

 similar composition, much less to bring this absoluteness of 

 composition under the forms of natural law, and we might 

 add also, logical necessity. 



It should be noticed that the remarks about saturation 

 shew that compound proportion was not in the least degree 

 understood in the present sense. Its possibility is even 

 denied. 



The aim was to find the strength of affinity. When it is 



• Remarks in italics on the various laws, from p. 567 onwards. 



