IX 



anything, illustrate one extreme of this capacity; while carbon, 

 whose compounds number considerably more than a hundred 

 thousand, illustrates the other. The overwhelming superiority of 

 carbon in respect of its compound-forming capacity is one of the 

 cardinal facts of Chemistry. Its compounds include all substances 

 of vegetable and animal origin; thus starch, sugars, fats, and that 

 exceedingly complex group of substances, the proteins, which make 

 up the chief part of the white of egg or the protoplasm of cells, 

 are all compounds of carbon. This great group of substances 

 known as organic compounds, formed the dark continent of early 

 chemical exploration. Until about a century ago only a very few 

 of the most venturesome had dared to enter the territory at all. 

 There was a mysterious something about organic substances which 

 distinguished them from inorganic or mineral compounds, a some- 

 thing which, as a leading chemist of the time said, was easier felt 

 than defined. One distinction between the two came to be univer- 

 sally accepted, namely, that only inorganic compounds could be 

 built up in the laboratory from their elements. Organic com- 

 pounds, on the other hand, could only be formed in organisms, 

 under the influence of vital force. 



This belief received a shock in 1828 when Wohler, a 

 distinguished German chemist, accidentally discovered that 

 ammonium cyanate, commonly classed as an inorganic compound, 

 could be readily converted into urea, a typical organic substance. 

 It is not easy for us now to realize how startling this discovery 

 seemed to the chemists of that time. If a modern chemist were 

 to discover that living cells could be developed from ammonium 

 salts, the discovery would .scarcely produce a greater sensation. 

 Wohler's discovery showed that the synthesis of organic compounds 

 was possible in the laboratory and that therefore the mysterious 

 influence called vital force was not a necessary factor in their 

 formation. Why, then, would it not be possible to make, starch, 

 sugar, the fats, even muscular fibre from their elementary consti- 

 tuents ? And so this first organic synthesis opened up to the vision 

 of chemists a vista of possibilities hitherto undreamt of and 

 pointed the way to an illimitable field for investigation and 

 discovery. 



