28 PASTEUR 



that were to give him the high title of Doc- 

 tor of Science. He initiated himself into the 

 practical manipulation of the laboratory, he 

 trained himself in those infinitely delicate ex- 

 periments which, if they are to be profitable 

 and fruitful, demand calmness and unremit- 

 ting attention. With a profound sense of reali- 

 ties he recommenced, as a test of his own ac- 

 curacy, the experiments of La Provostaye in 

 tartaric acid and the tartrates, seeking above all 

 to learn whether, by following the same pro- 

 cedure, he would obtain the same results. 



For Louis Pasteur this was a period of intel- 

 lectual fermentation, in which ideas flowed to 

 his brain in extraordinary abundance, some of 

 them perhaps still confused, but for the most 

 part new and destined to open up unforeseen 

 paths to science. On the 23d of August, 1847, 

 he defended his theses for the doctorate, which 

 were piously dedicated to his father and 

 mother, the one in chemistry treating of Re- 

 searches into the Capacity of Saturation of Ar- 

 senious Acid and forming a Study of the AT- 



