22 PASTEUR: THE HISTORY OF A MIXD 



we have several series of well-ordered crystals in which 

 the correlation between the two hemihedrisms and the 

 direction of the rotary power is always clear. In the 

 nialates, on the contrary, the inclination of the facets 

 and the direction of the rotation are sometimes contrary, 

 and thus there disappears, apparently at least, this beauti- 

 ful harmony which had so charmed us in the tartrates. 



If Pasteur had commenced with malic acid he would 

 have needed all his perseverance in order to disentangle' 

 himself from the midst of so many contradictory facts. 

 But at the point which he had reached his ideas were too 

 well grounded and his experience already too great for 

 him to be astounded by these particular variations in the 

 direction of rotation of the malates. He had discovered 

 quite parallel phenomena in asparagin, which neverthe- 

 less remained always the same, and also in the aspartates. 

 He had even found examples of it in the tartrates, for 

 the left-handed calcium tartrate dissolved in chlorhydric 

 acid gives a rotation to the right. 



It is under conditions like these, where the judgment is 

 wavering, that the discernment of the scientific man 

 reveals itself. Without being embarrassed by the 

 differences between the malates and the tartrates, he 

 saw and aimed at one thing only, the resemblances which 

 he had perceived and pointed out, and he concluded with 

 a fine tranciuillity that if there was a common atomic 

 grouping between the right-handed tartaric acid of the 

 grape and the malic acid of the sorb-tree, there must 

 also occur a common atomic grouping between the left- 

 handed tartaric acid and a malic acid still unknown, 

 which would be the left of the malic acid of the sorb-tree. 

 And thus little by little was born in his hands that science 

 of the arrangement of atoms which has since attained so 

 much importance. Wherever he went Pasteur was an 

 initiator. 



