228 MEMOIR OF DR. DALTON, AND 



He says, p. 66, § 36, " The affinity of a substance towards 

 another is always in proportion to its chemical mass, which it 

 brings with it for combination." 



Page 68. " Affinity is consequently in no way an elective 

 attraction, in the sense in which Bergman and his followers 

 have taught it." 



Page 80, § 59. " By means of affinity alone two substances 

 may combine with each other in every quantitative proportion. 

 Although this asserts quite the opposite of Bergman's theory, 

 and even appears to contradict experience, it is nevertheless a 

 perfectly natural consequence of the above. 



" For suppose A and B could combine in the proportions 

 of 5 : 7, and not as 10 : 7, if we put 7 parts of B with 10 of 

 A, then the very same thing would happen as when we put 7 

 parts of B with 5 of A ; that is, the 7 parts of B would com- 

 bine with 5 parts of A, and the other 5 parts would remain 

 uncombined. 



" If this were really possible, then it would follow clearly 

 that 10 parts of A contained no more affinity than 5 parts, 

 which however completely contradicts what is proved in § 36." 



The idea of the present law seems to have entered into his 

 mind as a conclusion to be avoided for its absurdity. 



§ 60. " But as soon as the power of cohesion or expansion 

 of two substances of a given mass, acting on each other, 

 ceases to be overpowered by their affinity, an exception con- 

 stantly takes place to this universal law, and a certain propor- 

 tion of mixture is established between the two substances, 

 which, on account of their affinity, can no longer be surpassed, 

 and consequently limits their mutual affinity. 



" But if there were a removal of the obstructions caused 

 by cohesion and expansion to the affinity of two bodies, then 

 the law would again come into action in its first unity." 



" The absorption of several gases by water, the solution of 

 salt in water, and the oxidation of metals, best establish that 

 which has been said." 



