40 PASTEUR: THE HISTORY OF A MIND 



power will be contrary to that of one of the tartrates, 

 and will exalt that of the other. What will be the out- 

 come of this internal conflict on the physical and chem- 

 ical properties of the compound? It does not seem, 

 a priori, that it will be expressed externally in the same 

 way as the harmonious dissymmetry of the tartrates. 

 What does experiment say? 



Impelled by this ingenious and original idea, which, 

 let us remark, was, moreover, from the point of view 

 of the history of his mind, a logical consequence of his 

 conceptions, Pasteur tried, in fact, to combine with 

 active malic acid and its compounds, the right- and left- 

 handed tartaric acids and their compounds, asparagin 

 with the two tartaric acids, etc. Between the different 

 substances thus produced he actually determined some 

 differences greater than those existing between the 

 corresponding substances formed by means of inactive 

 bodies. But the results are clearer when one combines 

 the tartaric acids with the organic alkalies of plants, 

 quinine, cinchonine, brucine, strychnine, etc., endowed 

 also with the rotary power. The identity of the chem- 

 ical properties which existed in the tartrates with 

 mineral bases disappears. The right- and left-handed 

 tartrates of the organic alkalies are no longer either equally 

 soluble or equally hydrated. They bear very unequally 

 the action of heat, and they lose more or less easily their 

 water of crystallization. If by chance their chemical 

 formula is the same their crystalline forms are different 

 and incompatible. Finally, sometimes, with aspara- 

 gin, for example, combination is possible with the right- 

 handed body, impossible with the left. As for their 

 rotary powers, instead of being equal and opposite, as in 

 the case of the combinations of the tartaric acids with 

 mineral bases, there may be either addition or subtrac- 

 tion, and the resultant deviation is very different in the 



