Mixture, and its Effects. 95 



which render this theory very unsatisfactory. 

 Nitric acid, for example, dissolves silver, and 

 not gold ; aqua regia, or nitro-muriatic acid, 

 gold, and not silver; the gold is the denser of 

 the two. 



In the dissolution of solid bodies in fluids, 

 they tell you, the reason why a solid body con- 

 tinues equally suspended without subsiding from 

 the fluid, is, that the division of the bodies is so 

 minute, that the weight of the particles is not 

 sufficient to overcome the resistance of the fluid. 

 This, however, does not explain the dissolution, 

 nor the dispersion of the solid particles through 

 the fluids. 



The last theory I shall mention is that of Sir 

 Isaac Newton, which is now generally received, 

 and for which I refer to the thirty-first query at 

 the end of his Optics. 



Sir Isaac Newton supposes that the phaeno- 

 mena of chemical solution arise from a disposi- 

 tion in the particles of one body to unite with 

 the particles of another. Thus, when two bodies 

 on being mixed unite with effervescence, &c. 

 the cause of this phenomenon he supposes to be 

 a powerful attraction between them, which dis- 

 poses them to unite very strongly with a rapid 

 and accelerated motion ; whence the visible ef- 

 fects in the attraction which obtains between the 

 particles of the fluid and solid; this attraction is 

 more powerful than that which binds the par- 

 ticles of the solid together. In consequence of 



