FIEST DISCO VEEIES. 19 



Balard. It might be said without exaggeration 

 that the Academy was astounded. At the same 

 time there were many members who were slow to be- 

 lieve in this discovery. Charged with drawing up the 

 report, M. Biot began by requiring from Pasteur the 

 verification of each point which he had announced. 

 To this verification M. Biot brought his habitual pre- 

 cision, which was associated with a kind of suspicious 

 scepticism. 



In one of his lectures Pasteur thus described his 

 interview with M. Biot : ' He made me come to his 

 house, where he put into my handssome paratartaric 

 acid which he had carefully studied himself, and found 

 perfectly neutral as regards polarised light. It was 

 not in the laboratory of the Ecole Normale, it was in 

 his own kitchen, and in his presence, that I was to pre- 

 pare this double salt with soda and ammonia procured 

 by himself. The liquor was left slowly to evaporate, 

 and at the end of ten days, when it had deposited 

 thirty or forty grammes of crystals, he begged me to 

 go over to the College de France to collect the crystals 

 and to extract from them' specimens of the two kinds, 

 which he proposed to have placed, the one on his right 

 hand, the other on his left, desiring me to declare if I 

 was ready to re-affirm, that the crystals to the right 

 would turn the plane of polarisation to the right and 

 the others to the left. This declaration made, he 

 said that he would charge himself with the rest of 



