Relations of tJic Elements. 229 



In a former lecture, we referred to the change of 

 affinity under varied conditions, as in the case of 

 carbon, and the formation of nitric acid from 

 ammonia, in the presence of a base to neutralize it. 

 These are only isolated examples of changes of 

 which every chemist avails himself in chemical 

 analysis. 



He learns in what condition each element is 

 weak, and when it is strong ; he learns the changes 

 that every element produces in combination with 

 every other ; and as he questions Nature she gives 

 unvarying answers in change of color, change of 

 form, and in the evolution of light or heat or electri- 

 city. And when he finds the elements combining by 

 exact weight and measure, and their order of affin- 

 ity so established, that he can foretell the order 

 and proportion of their combination when thrown 

 together, and count with absolute certainty upon 

 the composition and properties of every compound, 

 he has another proof of the adaptation of the laws 

 of matter to mind. The laws of the invisible atoms 

 have been discovered by men, and those secret 

 changes which constitute the basis of chemical 

 science, ordained from the beginning of the world, 

 are among the most certain subjects of human 

 knowledge. It seems impossible that one should 

 enter into the rich inheritance which chemistry 

 now opens to her students without recognizing in- 

 finite wisdom in the relations of the elements to each 

 other, and a provision in them for man as an intel- 

 lectual being, that he might comprehend there the 



