192 GENERAL CONDITIONS OF SCIENTIFIC RESEARCH. 



afterwards evolved from them by intellectual processes. 

 The man who discovers a.great scientific truth, as Oersted 

 discovered the fundamental fact of electro-magnetism or 

 Faraday found that of magneto-electricity, may be con- 

 sidered to have rendered comparatively easy the discovery 

 of all the scientific knowledge wrapped up in it. The 

 man also who discovers a fact upon which is afterwards 

 built a manufacturing process may be similarly considered 

 to have laid the foundation, and thus rendered possible 

 the existence and development, of that particular practical 

 invention ; for instance, I discovered that phosphorus was 

 decolourised by chlorine, and rendered possible the present 

 process of bleaching phosphorus based upon it. 



Discoveries of great general principles are important 

 also because they largely enable us to predict events and 

 to foretell the probable effect of proposed new experiments. 

 Men of science, both in experimental physics and chemistry, 

 look forward to the time when those sciences shall, like 

 astronomy, be placed upon a mathematical and mechanical 

 basis, and when they shall be able to predict the pheno- 

 mena of their respective subjects by means of geometrical 

 and mechanical principles, as astronomers can in the case 

 of eclipses, &c. It is partly this expectation which causes 

 such great interest to be taken by scientific investigators 

 in discoveries in molecular physics, especially those which 

 reveal to us new principles of molecular motion or of 

 internal structure of inanimate substances. 



The more complex sciences, and particularly the con- 

 crete ones, are more liable than the elementary ones to 

 yield inconclusive results, because of the greater degree of 

 complexity of their phenomena ; it is, however, always 

 possible in every science, if a research has been carefully 

 made, to draw from it conclusions which are proved by 

 the evidence. Eesearches which yield only negative results 



