FIRST DISCOVERIES. 



I. 



Unlike the old professor of physics and chemistry 

 at Besan9on, one of the lecturers in the Ecole Normale 

 often took pleasure, not only in answering Pasteur's 

 questions, but in leading him on to talk over scientific 

 subjects. M. Delafosse, whose memory remains dear 

 to all his pupils, was one of those men who fail to do 

 themselves justice, or who, according to the expression 

 of Cardinal de Eetz, do not fulfil all their merit. Not 

 that circumstances have been unfavourable to them, 

 but that an invincible modesty, and a natural non- 

 chalance which finds in that modesty a shield against 

 latent self-reproach, leave them in a sort of twilight 

 in which they are content to dwell. Pupil, and after- 

 wards fellow worker, of the celebrated crystallographer 

 Haiiy, M. Delafosse had devoted himself to questions 

 of molecular physics. Pasteur, who had read with 

 enthusiasm the works of Haiiy, conversed incessantly 

 with Delafosse about the arrangements of molecules, 

 when an unexpected note from the German chemist 

 Mitscherlich, communicated to the Academy of 

 Sciences, came to trouble all his scientific beliefs. 

 Here is the note : 



' The paratartrate and the tartrate of soda and 

 ammonia have the same chemical composition, the 

 same crystalline form, the same angles, the same 



