76 CLASSIFICATION OF THE SCIENCES. 



chemist. Ho docs not take his substances as Nature 

 supplies them. Before he proceeds to specify their 

 respective properties, he purifies them separates from 

 each all trace of every other. Before ascertaining the 

 specific gravity of a gas, he has to free this gas from 

 the vapour of water, usually mixed with it. Before 

 describing the properties of a salt, he guards against 

 any error that may arise from the presence of an 

 uucombined portion of the acid or base. And when 

 he alleges of any element that it has a certain atomic 

 weight, and unites with such and such equivalents 

 of other elements, he does not mean that the results 

 thus expressed are exactly the results of any one 

 experiment ; but that they are the results which, 

 after averaging riany trials, he concludes would be 

 realized if absolute purity could be obtained, and 

 if the experiments could be conducted without 

 loss. His problem is to ascertain the laws of 

 combination of molecules, not as they are actually 

 displayed, but as they would be displayed in the 

 absence of those minute interferences which cannot 

 be altogether avoided. Thus all these Abstract-Con 

 crete Sciences have for their object, analytical inter 

 pretation. In every case it is the aim to decompose 

 the phenomenon, and formulate its components apart 

 from one another ; or some two or three apart from 

 the rest. Wherever, throughout these Sciences, syn 

 thesis is employed, it is for the verification of analysis.* 



* I am indebted to Prof. Fnmkland for reminding me of au objection that may ba 



