269 



HO,C 



H' H0 2 C 



HO,C 



A 1 1 o - Cinnamic Acid . Uebermanns IsocinnamicAcid. Henmeijeft Isocinnamic Add . 



The discovery of the optically active forms of cinnamic acid, 

 which even in the crystalline state should exhibit the non-super- 

 posable hemihedrism usually met with in the case of optical anti- 

 podes, will, if really confirmed in future, certainly have as a conse- 

 quence, that our ordinary views about the configuration of 

 wwsaturated organic molecules, must be modified in many respects, 

 and, therefore, these investigations deserve the greatest attention 

 of workers in this field. If true, doubtless also other cases of this 

 kind must be found, where such a stereometrical isomerism occurs. 

 As Erlenmeyer has suggested, in the light of his conceptions, 

 it seems even possible to give an explanation, at least in several 

 cases, of the phenomena of autoracemisation, of partially asym- 

 metrical synthesis, and of the Wai den-in version. But a thorough 

 control of these remarkable results is highly desirable in any case, 

 before his views can be generally adopted. 



The agreement, in by far the largest number of cases, of theory and 

 experience may be considered as an argument, that the representa- 

 tion of molecules by our stereometrical formulae, as proposed by 

 and derived from the original hypothesis of Van 't Hof f and Le 

 Bel, perhaps modified in some details of secondary inpor- 

 tance, - - allow us to give a fairly exact account of the most funda- 

 mental geometrical properties of such carbon-derivatives. In this 

 respect these formulae may be conjectured as something more than 

 mere outlines, and as really corresponding in at least the most 

 salient features to the true configuration of the atoms in space. 



26. After these considerations, we may now proceed to the 

 second part of Pasteur's law, in so far as it connects the molecular 

 dissymetry with the appearance of enantiomorphous, hemihedral 

 crystal-forms of the two isomerides, and also examine more closely 

 the general validity of this conclusion. 



Since Pasteur discovered the occurrence of such enantiomorphous- 



