ix SCIENTIFIC MOTIVE 249 



Wohler, whose discovery of calcium carbide, though 

 forgotten for a generation, laid the foundation of a great 

 industry, was the first chemist to prepare from inorganic 

 materials in the laboratory a substance Carbamide 

 previously known only as a product of vital action. All 

 the complicated chemical bodies which occur in animal 

 and vegetable life consist mainly of the elements carbon, 

 hydrogen, oxygen and nitrogen. About one hundred 

 and fifty thousand organic compounds are now 

 known, and have mostly been produced artificially by 

 chemists. 



This vast development of organic synthesis is due 

 chiefly to the discovery by Prof. August Kekule in 1858 

 of the characteristics of atomic structure of organic 

 compounds. His laws did for organic chemistry what 

 Kepler's laws and Newton's theory of gravitation did 

 for astronomy ; they revealed the system upon which 

 the immense number of natural substances may be 

 built up from a few elements, and enabled chemists to 

 predict the consequences of different arrangements of 

 these elements. As an architect may produce different 

 edifices by the use of a few building stones, so the chemist 

 is able to construct almost numberless compounds from 

 three or four elementary constituents. 



To one untrained in experimental science, nothing can be 

 more uninteresting than a laboratory of organic chemistry. To 

 stand over furnaces on a hot day, it may be, burning minute 

 quantities of white or brown powders in long tubes ; to watch 

 uninviting liquids for crystals which are very slow to appear ; 

 to separate liquids from coloured solids an operation which 

 often interferes with the beauty of the fingers ; to inhale 

 odours which may be of the violet or the meadow-sweet, but 

 usually are not all this must be dreary enough to the untrained 

 mind, the mind incapable of responding to the chemist's idea. 

 How different to the chemist. He is trying to unravel the 



