UlSTOKY OF THE ATOMIC THEORY. 163 



mon solvent as a force, which acts more slowly or more 

 rapidly on one or the other. It follows, then, that the more 

 rapidly a common solvent unites with a body, the greater 

 must be its degree of combination, and we obtain therefore 

 this law. 



" The affinity of bodies tvith a common solvent is in the 

 inverse ratio of the time taken to dissolve. 



Page 31. "We have now a universal law, according to 

 which the affinity of bodies or their rank in the series is 

 decided, and we obtain at once this important advantage, 

 that we not only know that the union of a common solvent 

 is greater or less with any body, but also how much greater 

 or less it is, because the difference of the time of solution shews 

 the difference of the combination. Therefore amongst a number 

 of bodies, the combination of one with a common solvent may 

 be considered as a quantity which may be expressed by a 

 fixed number, if we take the smallest in such a series as unity ; 

 and by this means we are able to give a correct explanation 

 of all phenomena. 



Page 46. " This important question, then, remains, why 

 a solvent, when it is only moderately diluted, does not in the 

 least attack certain metals, but as soon as another metal is 

 dissolved in it, with which it naturally has a less affinity, a 

 ready solution of the first takes place. Page 47. Because 

 here the powers meet which assist each other. 



Page 72. " The circumstances under which this metal (iron) 

 is dissolved by vitriolic acid are these, that the acid must not 

 be strong. When both unite, iron vitriol is formed, which loses 

 the most of its acid in the fire, as well as by frequent solution 

 in water. A small bored cylinder of Styrian steel of 102 

 grains was put into half an ounce of the spirit of vitriol, diluted 

 with an equal quantity of water, exactly as with the zinc ex- 

 periments; there remained 46 J grains of steel, and 55 J grains 

 were dissolved in the half ounce of the spirit of vitriol. 



