186 Dr. Carnelley on the Influence of Atomic Arrangement 



elements or radicals, an asymmetrical form of molecule is pro- 

 duced, which must therefore be optically active. This view is 

 supported by Van t'Hoff {Bull. Soc. Clam. [2] xxiii. p. 295), 

 who finds, from the comparison of the chemical composition 

 of all known active and many inactive bodies: — (1) That every 

 organic combination which rotates the plane of polarized light 

 contains an atom of asymmetrical carbon. The converse of this 

 law, however, does not hold good. This may be attributed 

 either to the presence of two isomerides of opposite rotatory 

 power, or to the fact that asymmetrical carbon is not of itself 

 sufficient to produce optical activity, which may also depend 

 on the nature, as well as on the mutual diversity, of the atoms 

 attached to the asymmetrical carbon atom. The follow- 

 ing compounds are all optically active, and all contain an 

 asymmetrical carbon atom, which for distinction is printed in 

 black type: — 





Lactic acid CH 3 .CH(OH).COOH.' 



Malic acid COOH.CH 2 .CH(OH).COOH. 



Malamide (CONH 2 ).CH 2 .CH(OH).COOH. 



Aspartic acid COOH.CH 2 .CH(NH 2 ).COOH. 



Asparagine (COXH 2 ).CH 2 .CH(NH 2 ).COOH. 



Tartaric acid COOH.CH(OH).CH(OH).COOH. 



Tartaramide (CONH 2 ).CH(OH).CH(OH).(CO^H 3 > 



Secondary butyl carbinol...CH 3 .CH 2 .CH(CH 3 ).CH 2 (OH). 

 Methylethylacetic acid ...CH 3 .CH 2 .CH(CH 3 ).COOH. 



Hydroxyglutanic acid COOH.CH 2 .CH 2 .CH(OH).COOH. 



Glutamic acid COOH.CH 2 .CH 2 .CH(NH 2 ).COOH. 



Secondary butyl acetic acid.CH 3 .CH 2 .CH(CH 3 ).CH 2 .COOH. 



Mannitol* CH 2 (OH).(CH.OH) 4 .CH 2 (OH). 



Glucose.., CH 2 (OH).(CH.OH) 4 .COH. 



Saccharic acid COOH.(CH.OH) 4 .COOH. 



Phenylhydroxyaceticacid..C 6 H 5 .CH(OH).COOH. 



(2) Derivatives of optically active combinations lose their rota- 

 tory power when the asymmetry of their carbon atoms disappears. 

 When the contrary happens they do not generally lose it. 



These facts will in the future, no doubt, render great service 

 in determining the constitution of optically active chemical 

 compounds. 



