538 Royal Society. 



perfect accordance with the principles laid down by Berthollet. 

 Besides the argument founded on this universal fact, several expe- 

 riments were devised for the purpose of proving that the complete 

 precipitation of an insoluble salt on the mixing of two soluble salts, 

 was due to the insoluble compound being removed at once out of the 

 field of action on the first distribution of the elements, thus neces- 

 sitating a redivision, and so on until no more of it could possibly be 

 formed. The phenomena attending volatilization have the same 

 bearing as those connected with precipitation. If by the mutual 

 action of two salts a substance be formed, which, though soluble in 

 water, requires more water for its solution than is present, it crystal- 

 lizes out : certain experiments were noted where this action occurs, 

 and it was found that they gave testimony in favour of the same 

 views as have been supported by the preceding observations. The 

 bearing of the phenomenon of diffusion of salts upon the point at 

 issue was also examined : Malaguti's experiments were discussed ; 

 and they, as well as some observations on the solution of certain 

 bodies by others set at liberty, were found to bear testimony also in 

 the same direction. 



During the whole of the experiments on this subject, most of 

 which were performed quantitatively, no unequivocal instance oc- 

 curred of two substances having so strong an affinity for one another, 

 that they combined to the exclusion of other bodies of like kind pre- 

 sent in the same solution. After showing that some reputed excep- 

 tions are really not capable of being proved to be so, and after sug- 

 gesting some probable limitations of the action of the general law, 

 the paper concludes with the following deductions : — 



I. That where two or more binary compounds are mixed under 

 such circumstances that all the resulting compounds are free to act 

 and react, each electro-positive element enters into combination 

 with each electro-negative element in certain constant proportions. 



II. That these proportions are independent of the manner in 

 which the different elements were primarily arranged. 



III. That these proportions are not merely the resultant of the 

 various strengths of affinity of the several substances for each other, 

 but are dependent also on the mass of each of the substances pre- 

 sent in the mixture. 



IV. That an alteration in the mass of any one of the binary com- 

 pounds present alters the amount of every one of the other binary 

 compounds, and that in a regular progressive ratio ; sudden transi- 

 tions only occurring where a substance is present which is capable 

 of combining with another in more than one proportion. 



V. That this equilibrium of affinities arranges itself in most cases 

 in an inappreciably short space of time, but that in certain instances 

 the elements do not attain their final state of combination for hours. 



VI. That totally different phenomena present themselves where 

 precipitation, volatilization, crystallization, and perhaps other actions 

 occur, simply because one of the substances is thus removed from 

 the field of action, and the equilibrium that was first established is 

 thus destroyed. 



VII. That consequently there is a fundamental error in all 



