STEREO-CHEMISTRY AND PHYSIOLOGY 461 



attributable to the special arrangement of atoms in space. For 

 example, Chabrie's 1 experiments on the toxicity of the tartaric 

 acids are stated by Cushny 2 to be unreliable, as the toxic 

 agent in this case is really the hydrogen ion and not the 

 acid itself. Since the configuration of the acid's molecule 

 influences its ionization, however, it should in this way have 

 some effect upon its toxicity also. Chabrie's figures are given 

 below. They are calculated in the following way : Let x 

 be the weight of acid required to kill one kilogram weight 

 of an animal in one minute, p the weight of acid, and w the 

 weight of animal used, and t the time required to kill deter- 

 mined by experiment, then 



1 __ 1000 p. T 

 x w 



X 



Laevo-tartaric acid 34*26 



Dextro „ „ 104*24 



Racemic acid 165 "2 5 



Meso-tartaric acid 1 96-27 



It will be seen from a comparison of these figures with 

 Brion's results, which have already been given, that there is 

 no close connection between the two. 



Owing to their applications in medicine, the behaviour of 

 compounds of the tropine series has been investigated with 

 more thoroughness than that of other isomers. The parent 

 substance, tropine, has the following structure : 



CH 2 *CH CH, 



I I 



*CH.OH N.CH 3 



I I 

 CHo -x-CH CHo 



in which three carbon atoms (marked with asterisks) are 

 asymmetric. When tropine (melting-point 62 ) is treated with 

 sodium amylate, it is converted into an isomeric body, pseudo- 

 tropine (melting-point 108 ). The two compounds have exactly 

 the same structure, and the difference between them is due, 

 probably, to the different arrangement of the — CH.OH — radicle. 

 Ladenburg 3 has suggested another explanation depending 



1 Chabrie, Compt. rend., 116, 1410 (1893). 



2 Cushny, Jonrn. Physiol., 30, 193 (1904). 



3 See Ladenburg, Per., 26,854(1893); 36, 3694 (1903); and Groschuff, ibid. 34, 

 2974 (1904), for examples of this type of isomerism. 



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