318 



For this reduction does not essentially depend on the presence of 

 the magnetic field, nor on that of the light-energy; it is no photo- 

 chemical reaction in which the luminous energy is the necessary 

 condition for starting it ; and, moreover, the strength of the magne- 

 tic field applied, is much too small for such experiments. 



Henle and Haakh 1 ), therefore, tried a characteristic photo- 

 chemical process: the decomposition of some carboxylic acids by 

 light under production of carbon-dioxide, which reaction is appre- 

 ciably accelerated by the presence of uranyl-salts, and, - - as the 

 present author stated, also in many cases by that of ferric salts 2 ). 

 The desired dissymmetry of the physico-chemical causes was obtained 

 either by rotating the plane of a beam of polarized light by a 

 magnetic field, or by producing circularly polarized light with the 

 aid of a mica-lamella, of V 4 A, as often used in optics. In this way 

 the transformation of methyl-ethyl-cyano-acetic acid into methyl-ethyl- 

 aceto-nitrile, and that of symmetrical dichloro-dimethyl-succinic acid 

 into dichloro-dimethyl-propionic acid, was studied by them. The 

 results were negative, and only optically inactive products were 

 obtained in the reactions. 



Such an experiment was carried out with circularly polarized 

 light alone by Freundler 3 ), who studied the formation of amyl- 

 o-nitroso-benzoate from racemic diamyl-acetale of o-nitro-benzaldehyde 

 in a solution of r-amyl-alcohol: 



/\ rTJ /OC 5 H n /\ ^^ f ^ n ^ 



\OC 5 H n 

 N0 2 > C 5 H U .OH H- 



After an exposure of 400 hours, however, no optical activity whatso- 

 ever could be detected. Analogous experiments with solutions of 

 copper-tartrates, made by Cotton 4 ), had no better results. Experi- 

 ments with d- and l-potassium-cobalti-oxalates, which are reduced 

 by light-radiation into cobalto-oxalate and carbon-dioxide, are started 

 in the author's laboratory with the purpose of proving a different 

 reaction-velocity in the case that dextro-, resp. laevogyratory 

 circularly-polarized light is used. 



*) F. Henle and A. Haakh, Ber. d. d. Chem. Ges., 41, 4261, (1908). 



2 ) F. M. Jaeger, Proceed. Kon. Ak. van Wet. Amsterdam, 14, 342, (1911). 



3 ) P. Freundler, Bull, de la Soc. Chim. Paris, (4), 1, 657, (1907); Ber. d. d. 

 chem. Ges., 42, 233, (1909). 



4) A. Cotton, Journ. de Chim. phys., 7, 81, (1909). 



