INTRODUCTION. 5 



however, and the identification of its phenomena with other 

 phenomena of oxidation, the way was opened for true sci- 

 entific progress. At the same time accurate methods of ulti- 

 mate organic analysis were suggested and soon developed by 

 the followers of Lavoisier. In the hands of Berzelius, Gmelin 

 and others these soon began to furnish results. This brings 

 us to the end of the first quarter of the nineteenth century, a 

 point which marks the real beginning of our science. A pecu- 

 liar distinction between inorganic and organic bodies had 

 gradually arisen, and had come to be commonly accepted. 

 This was founded on the notion that while the former might 

 be produced by laboratory processes synthetically, for the 

 latter group nothing similar was possible. By this arbitrary 

 limitation research was naturally greatly curtailed. However, 

 in 1828, Wohler made the important discovery that urea could 

 be easily formed by warming a solution of ammonium cyanate, 

 and this was in time followed by others of equal value, point- 

 ing to the same conclusion, that the production of organic 

 compounds is in no wise dependent on the aid of a so-called 

 vital force. It was soon demonstrated that the chemist's labo- 

 ratory, no less than nature's laboratory, could take part in the 

 formation of these substances, and in the next ten years, to 

 about 1840, many products of physiological interest were 

 made. The great Wohler made many of the most fruitful 

 discoveries of this epoch, but it is to Liebig that we owe the 

 most. For many years he was busily engaged in perfecting 

 methods of analysis, and with these developed he turned his 

 attention largely to the chemical phenomena of vegetable 

 and animal life. This led to the publication, in 1840, of his 

 epoch-marking work, " Organic Chemistry in Its Relations to 

 Agriculture and Physiology." This was followed in 1842 

 by a work giving evidence of his broadened and strengthened 

 views, " Organic Chemistry in Its Relations to Physiology 

 and Pathology." These works passed through many editions 

 and were translated into several languages. In them we find 

 much that is now considered fundamental in physiology and 



