301 



the cm n}>l< A of which forms a system of causes non superposable 

 with its mirror-in 1. 1 -. Indeed, if we compare these postulati-.n^ 

 with the conditions hitherto created in the very few direct 

 r\|>< riincnts of this kind, we must come to the conclusion, that 

 no serious and well thought-out attempts in this direction must 

 be neglected in future. 



Some of the plans to be followed have already been shortly 

 indicated in Chapter V\ and some of these experiments have 

 now been started in the author's laboratory. But no experiments 

 in other laboratories should be left untried, as this problem is 

 an extremely important one for the general development of our 

 scientific conceptions in this sphere of research, and the experi- 

 mental evidence brought by others can only be adopted gratefully, 

 as a help in overcoming the very great experimental difficulties 

 of these investigations. 



All attempts, even those well thought-out, to bring about a 

 total asymmetric synthesis directly, have up till now only met 

 with negative results. 



In 'Meyer's experiments the benzoyl- formate of Ja^vogyratory 

 amyl-alcohol was reduced to the corresponding mandelate by sodium- 

 amalgama, in a magnetic field of 180 C. G. S., while a beam of 

 polarised light passed through the solution parallel to the lines 

 of force. The result was that only racemic mandelic acid could be 

 obtained. This negative result cannot be wondered at, as the 

 experiment is badly conceived. 



For this reduction does not really 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 

 I 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 ray/-salts, and --as the 

 author stated, - - in many cases by that of ferri-salts too 8 ). The 

 desired dissymmetry of the physico-chemical causes was obtained 

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

 magnetic field, or by producing circularly polarised light with the 



1) F. Henle and A. Haakh, Bcr. d. d. Chem. Ges. 41. 4261. (1908). 



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



