209 



15 C. 1 ). The transition-temperature for the racemate (minimum) 

 evidently lies between 8 and 15 C., and the formation of the race- 

 mate from the antipodes must be an endothermic reaction. 



A similar case 2 ) must be the spontaneous fission of the triclinic 

 racemoid of dimethyl-dioxyglutaric acid: CH 2 [C(OH)(CH 9 ).(COOH)] 2 

 into its triclinic active components, when crystallising from a solution 

 in ether; from an aqueous solution the enantiomorphous salts could 

 not, however, be obtained, - - which proves that the special nature 

 of the solvent also plays a role in the matter. 



For ammonium-bimalate the transition-temperature was deter- 

 mined by Kenrick 3 ) at 75 C. He was also the first who demon- 

 strated that in the field of stable occurrence of the racemate, its 

 solubility is influenced by the addition of one of the two components. 



3. The relations which exist in these and similar cases with 

 respect to the solubility of the y 

 components and the racemic 

 compound, were first elucidated 

 by Bakhuis Roozeboom 4 ) 

 in 1899. 



The graphs of fig. 159 and 

 1 60 give an easy survey of these 

 relations. On the axis OX the 

 solubility of the dextrogyratory 

 component is represented by 

 Oa, on the axis OY that of the 

 laevogyratory component by 



b' 



Ob. The curve amb is the solu- a-' a 



bility-curve for a temperature Fig. 159. 



of t C., which in fig. i$ p is 



thought above, in fig. 160 below the transition-remperature of the 

 racemate, because of the fact that fig. 159 is drawn for the case 

 that the transition-temperature is a maximum temperature, in fig.ido 

 a minimum temperature for the racemate, in the sense explained 

 above. The solid phases in equilibrium with the saturated solutions 

 amb, are here the dextro-, and the laevogyratory components. 



!) E. Fischer and L. Beensch, Ber. d. d. Chem. Ges., 29, 2927, (1896). 



2 ) N. Zelinsky (Crystallographical investigations by R. Prendel), Ber. d. d. 

 Chem. Ges., 24, 4014, (1891). 



3 ) F. B. Kenrick, Ber. d. d. Chem. Ges., 30, 1794, (1897); J. H. Van 't Hoff 

 and H. M. Dawson, Ber. d. d. Chem. Ges., 31, 528, (1898). 



4) H. W. Bakhuis Roozeboom, Zeits. f. phys. Chemie, 28, 494, (1899). 



