20 PASTEUR: THE HISTORY OF A MIND 



abundant crystallization of a paratartaric acid identical 

 with the acid of Thann with which we set out. 



To summarize, there existed there tartaric acids iden- 

 tical from the point of view of all their physical and chem- 

 ical properties, save this, that they each had their 

 special hemihedral facets and the corresponding rotary 

 power. These differences persisted in all their com- 

 pounds and formed a part of their true nature. They 

 formed their distinctive marks, which were permanent 

 and deep. 



ASPARTATES AND MALATES 



This harmonious development from a single fertile 

 idea will become still more thrilling presently when we 

 go back, as we are justified in doing, to the chemical 

 molecule from which comes the initial influence. For 

 the moment we must ask ourselves whether we are here 

 in the presence of a general or an exceptional fact. Do 

 all these different organic substances, which Biot found 

 endowed with rotary power, present hemihedral forms 

 when crystallized? Unfortunately, not many of them 

 give measurable crystals: asparagin and its different de- 

 rivatives, aspartic acid and malic acid do, however, 

 and Pasteur made haste to study them. 1 



Asparagin was at this time a rare substance. Pasteur 

 was obliged to plant vetch in the garden and cellars of 

 the Academy of Strasbourg. By known processes, from 

 the juice of these plants he extracted the asparagin which 

 he crystallized and which he showed at the same time 

 to be provided with hemihedral facets and endowed with 



1 Memoire sur les acides aspartique et malique. Ann. de ch. et de 

 phys., 3e p., t. XXXIV. 



