68 THE LIFE OF PASTEUR 



But allow me to tell you that, with my ideas, I look upon that 

 discovery as impossible. I do not ask for your secret ; I shall 

 await the publication of it with the greatest impatience. So 

 that is really true? You take a kilogramme of pure tartaric 

 acid, and with that you make racemic acid?' 



" ' Yes,' he said; ' but it is still ' . . . and as he had some 

 difficulty in expressing himself, I said : ' It is still surrounded 

 with great difficulties ? ' 



' ' Yes, monsieur.' 



"Great heavens! what a discovery! if he had really done 

 what he says ! But no ; it is impossible. There is an abyss 

 to cross, and chemistry is yet too young." 



Second letter, same date. " M. Eassmann is mistaken. . . . 

 He has never obtained racemic acid with pure tartaric acid. 

 He does what M. Fikentscher and the Viennese manufacturers 

 do, with slight 'differences, which confirm the general opinion 

 I expressed in my letter to M. Dumas a few days ago." 



That letter, and also another addressed to Biot, indicated 

 that racemic acid was formed in varying quantities in the 

 mother-liquor, which remained after the purification of crude 

 tartars. 



"I can at last," Pasteur wrote from Leipzig to his wife, 

 " turn my steps again towards France. I want it ; I am very 

 weary." 



In an account of this journey in a newspaper called 

 La Verite there was this sentence, which amused everybody, 

 Pasteur included : " Never was treasure sought, never adored 

 beauty pursued over hill and vale with greater ardour." 



But the hero of scientific adventures was not satisfied. He 

 had foreseen by the examination of crystalline forms, the 

 correlation between hemihedral dissymmetry and rotatory 

 power; this was, to his mind, a happy foresight. He had 

 afterwards succeeded in separating the racemic acid, inactive 

 on polarized light, into two acids, left and right, endowed with 

 equal but contrary rotatory powers ; this was a discovery 

 deservedly qualified as memorable by good judges in those 

 matters. Now he had indicated the mother-liquor as a source 

 of racemic acid, and this was a precious observation that 

 Kestner, who was specially interested in the question, confirmed 

 in a letter to the Academic des Sciences (December, 1852), 

 sending at the same time three large phials of racemic acid, 

 one of which, made of thin glass, broke in Biot's hands. But 



