348 



S|)ecially tlio group of tlie o.n'iiK's fiiruislies several examples. In 

 tliis respect we may meiilion in llio liist place aretaldo.riiii studied 

 bv Dlnstan and Dymonu'), and lalei' more closely examined by 

 Carvkth '). 



Furtlier may be meutioned hciizdldo.cim. For wiiicli the first data 

 liave beeu giveu by Bkckmann "), tlie discoverer ol' tiie isomeric com- 

 versions oF these substances. This substance was more closely in- 

 vestigated by Cameron'), whose results were later tested and im- 

 proved by ScHOEVERs's study'). TIakveth') investigated also another 

 oxim, viz. miisoldorim, of which Beckmann') had also found two 

 isomers. 



A very interesting substance is the henzUortlLOcarbonic acid, of 

 which Graebe and Jüillard ') found two distinctly different 

 crystallized products, one wliite. the other yellow. 



While enautiotropy is a very frequently occurring phenomenon 

 in anorganic chemistry, we find this phenomenon only exceedingly 

 rarely mentioned in the organic literature. We should nndoubtedly be 

 mistaken if we snpposed that it must be inferred from this that 

 the phenomenon of enautiotropy in organic region is met with only 

 by great exception. In the first place this circumstance is much 

 sooner to be ascribed to this that on account of the slight velocity 

 of conversion between the tlifferent kinds of molecules of organic 

 substances, the phenomenon of enantioti'Opy manifests itself much 

 less easily, aiul in the second place to the absolute absence of an 

 accurate systematic investigation in this direction. 



It is, however, known of beiLzilorthoatrhon'u- ac'ul that it is enantio- 

 tropic. Soch") has namely demonstrated this with certainty, and 

 considerably extended Graebe"s'°) investigation. 



We have further a \ery important group of allotropic substances 

 \vilh distinct transformation in the keto- and end corn pounds. 



WoLE ") devoted an investigation to fonni/fphenyl acetic eater, of 



I) Journ. chem. Soc. 61, 470 (1892); 65, 206 (1894). 

 ») .lourn. phys. chcm. 2, 159 (1898). 



») Jiei-. 20, 2768 (1887); 37, 3042 (1902). 



<■} .lourn. phys. chem. 2, 409 (1898). 



*) Dissertatie 48. 



«) Jouin. phys. chem. 3, 4:37 (1899). 



7) lier. 23, 2103 (1890). 



«) Bar. 21. 2003 (1888). 



») JourE. phys. cliem. 2, 364 (1898). 



"•) Bar. 23, 1344 (1890). 



II) Jouin. pliys. chem. 4, 123 (1900). 



