40 PASTEUR 



with a white stone, for Mme Pasteur, down to 

 the last day of her husband's life, never ceased 

 to surround him with the tenderest and most 

 devoted care, to watch over his hours of toil 

 and his hours of rest, and to keep him in such 

 a state that he could employ his genius to the 

 full extent of its powers. 



Louis Pasteur remained on the Faculty of 

 Strasburg until 1854, and was appointed titular 

 professor of chemistry in 1852. This whole 

 period is marked by numerous researches, 

 which form the natural sequence of those that 

 he undertook in crystalography, but which ex- 

 tend far beyond that science, thanks to the 

 new perceptions that he brought to them and 

 the consequences which naturally developed 

 from them. 



From this same aspect of dissymmetry and 

 hemihedrism, he studied the aspartates and the 

 malates, shed light upon obscure questions 

 which no chemist before had successfully han- 

 dled, established the laws of molecular dis- 



