98 PROGRESS OF SCIENCE IN THE CENTURY. 



itative analysis had already attained a high degree of 

 accuracy, and even the quantitative method had 

 found excellent exponents in Proust, Klaproth, and 

 Vauquelin, Lavoisier's experiments with alcohol, oil, 

 and wax were the only ones in existence, designed to 

 ascertain the composition of organic compounds ; and 

 these, it may easily be understood, were not very ac- 

 curate/' * 



Some Factors in the Development of Organic 

 Chemistry. — The development of organic chemistry 

 which has been characteristic of the latter half of the 

 century has been influenced in many ways: — by the 

 elaboration of more perfect methods of determining 

 the composition of organic substances (Gay-Lussac, 

 Liebig, Wohler, Bunsen, Dumas, and many others) ; 

 by the clear recognition, which may be associated 

 with the name of Berzelius, that organic compounds 

 could not be separated by any hard and fast line 

 from inorganic compounds, but illustrated similar 

 laws, and might in many cases be profitably regarded 

 as derivations of inorganic compounds; by the fasci- 

 nation of the methods of synthesis which gave the 

 chemist an almost creative power; and by the enor- 

 mous practical interests involved, in connection, for 

 instance, with coal-tar products, one of the most fa- 

 miliar of the many possible illustrations. 



We may pause here for a moment to note the fine 

 instance of gradual discovery which the utilisation 

 of coal-tar affords. " Sixty years ago an obscure 

 German chemist obtained an oily liquid from coal- 

 tar oil, which gave a beautiful tint with calcium 

 chloride ; five years later another separated a similar 

 liquid from a derivation of coal-tar oil. Still later, 

 Hofmann, then a student in Liebig's laboratory, in- 

 ♦ Ladenburg, 1900, p. 112. 



