FIKST DISCOVERIES. 23 



one case the deviation of the plane of polarisation was 

 to the right, while in the other it was to the left. With 

 regard to all their other properties, both chemical and 

 physical, the identity was absolute. Solubility, simple 

 refraction by solutions, double refraction by crystals, 

 the action of heat in producing decomposition, &c., 

 the similitude extended to the most perfect identity. 



The Academy of Sciences, which shows by the 

 rarity of its reports the importance which it attaches 

 to them, gave for the second time an account of these 

 new researches. M. Biot was again the reporter. It 

 was with a sort of coquetry that Pasteur brought from 

 Strasburg perfectly labelled specimens of the magnifi- 

 cent crystallisations of the double series of right- 

 handed and left-handed tartrates. By means of 

 models he was able to render the forms of these 

 crystals visible at a distance. 



M. Biot undertook to bring the subject before the 

 Academy. On the morning of the day when he was 

 to read his report he spent several hours in conversa- 

 tion with Pasteur. M. Biot became so excited during 

 the discussion that Madame Biot, with the solici- 

 tude peculiar to the wives of Academicians, requested 

 Pasteur to change the subject of conversation. 



The members of the Academy shared the enthu- 

 siasm of M. Biot. Arago moved that the report 

 be inserted in the collected memoir es of the Academy. 

 This was an exceptional honour. Arrived for the most 



