222 Mr POWER'S THEORY OF 



confirmed by those experiments which demonstrate the almost infinite 

 subdivision of matter by repeated dilution, experiments which are 

 familiar to every one. This infinite subdivision is, in fact, involved in 

 the mathematical conception upon which this theory is founded, namely, 

 that in the state of mixture the two fluids may be regarded as 

 coexisting within the same volume, each with a diminished density. 

 This conception cannot of course be a rigorous representation of nature ; 

 but is sufficiently so for the application of La Place's theory, or, which 

 comes to the same thing, for the summation of the attractions by the 

 principles of the Integral Calculus. 



18. In cases of simple mixture, unattended with a chemical change, 

 the ultimate segments of the opposite fluids, though in an extreme 

 state of subdivision, have a separate and independent existence, which 

 renders it highly probable, that the volume of the mixed fluids should 

 equal the sum of the volumes of the unmixed fluids. This supposi- 

 tion has been made in the preceding theory, and I find by experiment 

 that in mixtures of treacle and water it is accurately true. The same, 

 I believe, is true in all cases of simple mixture, where no chemical 

 result takes place, such as the precipitation of solids, or the disengage- 

 ment of heat or other volatile constituents. To liquids whose union 

 is accompanied by such phenomena the present theory is inapplicable, 

 not only on account of the penetration of dimensions, with which 

 such phenomena are generally attended, but on account of the change 

 of affinities, which the escape of some of the constituents must 

 necessarily produce, including heat, which, regarded as a chemical 

 constituent, is as important as any. 



19. The addition of a third fluid to one of the liquids, by altering 

 the chemical affinities-, must likewise alter the capillary aflfinities, which 

 are only a different modification of the same corpuscular attractions 

 which produce the former. It is not surprising then, that Dutrochet 

 should have discovered some substances which accelerated the process 

 in his experiments, and others which retarded it or stopped it 

 altogether. 



