( 311 ) 



the axes, so tliat the solution which is equally saturated with L 

 and with D is inactive, no matter how great the excess of L or D 

 with which it is in contact. 



If at another temperature a racemic combination is possible, we 

 get three solubility-curves de, efy and gh. The second regards the 

 solutions of the combination; here ƒ represents the pure solution, c 

 and f/ those which are acquired in presence of an excess oi D or L. 



At the transition temperature the curve in the middle disappears 

 (point ^1). Here too the solution is always inactive. If therefore an 

 inactive substance is a conglomerate (by which I mean a solid mix- 

 ture in which the components lie side by side separately) of L and 

 D, we shall never get as a saturated solution anything else than 

 point c] if the substance is a combination we can get three solu- 

 tions, as we dissolve it alone or with an excess of L or D. 



Phenomeva observed at evaporation. On this subject experiments 

 have lately been made by Kippikg and Pope. From the figure of 

 the solubility-curves it is easy to deduct, in the graphic manner first 

 instituted by Schreinemakers, 'that in case of the evaporation of a 

 solution containing an excess of D or L, the solution arrives at last 

 in point c — that is to say becomes inactive — in case no racemic 

 combination exists at the temperature used. If on the other hand 

 this combination does exist — we arrive with an excess of D to 

 a final point in e, with an excess of L in y. 



In this manner it would be equally possible to make out what is 

 deposited : conglomerate or combination — if in these evaporation 

 experiments care were always taken that the necessary crystallisa- 

 tionnuclei were present — a circumstance to which K. and P. have 

 paid no attention. 



Partialli/ racemic combinations. These have lately been discovered 

 by Ladenburg and been studied with a view to the solubility in 

 D- and Lstrychninetartrate. 



The symmetry of fig. 1 disappears in that case owing to the 

 unequal solubility of the two components. Consequently point A 

 will generally lie no longer on OB. It results therefrom that the 

 combination, even before its transition-temperature is reached, already 

 possesses a temperature-interval of partial decomposition. So Mr. Laden- 

 burg is wrong in the opinion that this combination in its transition- 

 temperature must furnish a solution, containing an equal amount of 

 D- and L-tartrate. 



At temperatures situated in the decomposition interval, we now 

 only get two kinds of solutions in case the combination is dissolved 

 alone and with an excess of D or L. 



