Affinity and Dissected (Structural) Formula. 403 



pounds and their constituents are related, viz. that, by the action 

 of a weight 2(w/) of some other body or series of bodies upon a 

 weight 2(w) of the compound, a series of weights collectively 

 equal to ^(w + w 1 ) of new products is formed, precisely the 

 same weights of the same products respectively being formed 

 when the weight %(w l ) of these other bodies acts on the weights 

 w lf Wo, w 3 , . . . of the constituents severally. 



In these two cases different amounts of work are gained. If 

 the work gained by the action of the weight 2,(w l ) of the reacting 

 bodies on the weight £(**) of the compound examined be H 

 calories, whilst that gained by the action of the weight 2) (V) of 

 the reacting bodies on the weights w x , w$, w 3 , ... of the consti- 

 tuents be H' calories, the affinity of the constituents in the com- 

 pounds is given by the equation 



H'— H 



F= _, calories per unit of weight of compound. 



In this way the affinity of the constituents in a compound 

 may be indirectly determined ; in many cases, indeed, this indi- 

 rect method is the only one practicable. 



5. By the conventional use of the terms Combination, Com- 

 pound, Constituent, Affinity, &c, no question is raised or begged 

 as to whether the constituents are actually present as such in the 

 compound : they may be bodily present (as a hypothetical atom 

 of any kind must be bodily present unchanged in qualities in 

 every molecule into which it may be conceived as entering), or 

 they may not (the kind of matter of which the compound is com- 

 posed being viewed as homogeneous throughout, and differing 

 from that of each and all of its constituents in the same way 

 that these differ from one another); the question is not in any 

 way raised or decided by the language used to express the ob- 

 served facts. 



6. It not unfrequently happens that more than one homoge- 

 neous substance is known which is capable of being generated 

 by the coalescence of the same forms of matter, the difference 

 between these different compounds of the same ingredients being 

 that the weights w lt w 2 , w 3 , ... of the constituents that go to 

 make up a weight X(w) of one compound are not all in the same 

 ratios relatively as are the weights w\, w'^, iv' 3 , ... of the same 

 constituents respectively that go to make up a weight %(w f ) of 

 another of these compounds; i. e. the ratios 



w l w 2 w 3 



w c2 iv 3 w 4 ' 



are not all equal to the ratios 



w\ W 1 ^ IV 1 



W'c> IV'a W 



. severally. 

 2D 2 



