216 



Of course the solution which corresponds to this transition-tem- 

 perature, does in .general not necessarily contain equal quantities 

 of the dextro- and laevogyratory compounds; this can only be 

 the case approximately when the difference of their solubilities 

 at the temperature under consideration is very slight. 



If the splitting-up of the partial racemate does not occur, or cannot 

 be produced in some way, partial racemism may therefore also 

 be an obstacle for the successful fission of a racemoid by this method. 

 Many cases of partial racemism have since been observed: strych- 

 nine-racemate, tetrahydro-papaverine-d-tartrate l ), l-menthyl-mandelic 

 ether 2 ), etc. 



Laden'burg 3 ) found for fi-pipecoline-bitartrate a partial racemism 

 at higher temperatures, while a fission occurred at lower tempera- 

 rures. For brucine-biracemate 4 ) a transition-temperature of 50 C. 

 was found, below which the partial racemate can exist, while at higher 

 temperatures fission takes place. Levi-Malvano and Mannino 

 found partial racemism with some santonine-salts 5 ), while Win da us 

 und Resau 6 ) met with a partial racemic compound in the case of 

 jB-cholestanol and pseudo-coprosterol. The number of such increases 

 from year to year. 



10. III. The third method of fission also proposed by L. 

 Pasteur 7 ), is that by means of living organisms, by bacteria, moulds, 

 yeasts, and by a number of very complicated organic substances 

 belonging to the proteids, and being named ferments or enzymes. 



Pasteur 7 ), as is well known, was engrossed by the idea that the 

 production of single optically active substances was the very prero- 

 gative of life. To this view of vitalism, which supposes that in vital 

 agency, special asymmetric forces play a directional role, a number 

 of experiments must be referred, made by him in later years, and 

 which were as unsuccessful as all other attempts made since then 



1) W. J. Pope and S. J. Peachy, Zeits. f. Kryst. u. Min. 31. 11. (1900); 

 Journ. Chem. Soc. London, 73. 902. (1898). 



2 ) A. Findlay and E. M. Hickmans, Journ. Chem. Soc. London 91.909. 

 (1907). 



3) A. Ladenburg, Ber. d. d. Chem. Ges. 27. 75. (1884). 



4) A. Ladenburg, Ber. d. d. Chem. Ges. 40. 2279. (1907). 



6) M. Levi-Malvano and A. Mannino, Atti Rend. Acad. Lincei Roma (5). 

 18. //. 144. (1909). 



6) A. Windaus and C. Resau, Ber. d. d. Chem. Ges. 48. 861. (1915). 



7) L. Pasteur, Compt. rend, de 1'Acad. d. Sc. Paris, 32. 110. (1851); 36. 26- 

 (1853); 37. 110, 162. (1853); 51. 298. (1860). 



