CHEMICAL PHENOMENA IN LIFE 



4 Laws " in Chemistry and Physics ? If the 

 conditions of a certain kind of experiment are 

 kept exactly the same, the experiment must in- 

 variably lead to the same result. Thus the same 

 result is shown, however often a physical or 

 chemical phenomenon of a certain kind is repeated 

 in Nature itself or by the hand of the experiment- 

 ing scientist. Single results, as they are produced 

 by arbitrary human action, vary. In a great 

 number of them we may already distinguish a 

 considerable number of average values. Suppose 

 this action is repeated infinitely often, mathematics 

 teach us that we may consider the average result 

 as the true and final value, and we may believe 

 this an equivalent of a Law of Nature. We see, 

 therefore, that Law in Chemistry and Physics 

 is the expression for the probability of the result 

 when a process repeats itself infinitely often. 

 Thus a phenomenon in Nature, such as the free 

 falling of bodies or the chemical reaction between 

 sodium chloride and nitrate of silver, may with the 

 greatest certainty be expected to take in every 

 case the same course which we have observed even 

 upon only one occasion. Chance and probability 

 are there excluded, and the full certainty of a 

 Law of Nature is given. Chemistry in consequence 

 may apply the means of mathematical calcula- 

 tion to the course, and the final results of chemical 

 change in matter. It belongs, as we say, to the 

 Exact Sciences. 



