— 22 



that amygdalin, when treated with emulsin, yields primarily d-benz- 

 aldehyde cyanohydrin, because the products obtained in the splitting- 

 up process were almost all more strongly dextrorotatory than those 

 prepared synthetically. 



It will be seen that the results obtained by Feist are in sharp 

 contradiction to those of Auld. 



Further experiments by Feist served to solve the problem whether 

 (as had previously been assumed to be the case), water produces a 

 racemisation or a decomposition of d-benzaldehyde cyanohydrin. It was 

 found that pure cyanohydrin preserved its originally ascertained rotation 

 of [«]d ~J- 14,0° even after 20 days. But if, of the same cyanohydrin, 

 2 g. which, when dissolved in 10 cc. ether, showed a rotation of -J- 2° 

 (in a 1 decim. tube), was left, after evaporation of the ether, for 8 days in 

 contact with 1 00 cc. water under occasional stirring, the cyanohydrin, when 

 once more dissolved in ether, had a rotation of -f-0,5 (in a 1 decim. 

 tube). In this experiment hydrocyanic acid could not be detected in 

 the aqueous solution, so that in any case no decomposition had occurred. 



Upon comparing those glucosides known up to the present, which, 

 when decomposed, yield benzaldehyde and hydrocyanic acid, it will be 

 found (as stated by E. Bourquelot 1 ) at the VII. International Con- 

 gress for Applied Chemistry), that these bodies may be divided into 

 two classes, viz., those which, when hydrolysed, form one, and those 

 which form two, molecules of glucose, 



a) 2 mol. glucose: — amygdalin and W0-amygdalin, 



b) 1 mol. glucose: — mandelic nitrile glucoside, prulaurasin and 

 sambunigrin. 



Taking into account the rotation of the mandelic acid which is 

 formed during decomposition, as well as the products resulting from 

 treatment with baryta, the following table may be drawn up to show 

 graphically the mutual relationships of the above-named glucosides: — 



I. 



1-mandelic acid 



yields 



a) amygdalin 



isomerism "~~~ 



(partial hydrolysis) 



\ 



b) mandelic nitrile 



glucoside 



isomerism 



II. 



i-mandelic acid 

 yields 

 ' w0-amygdalin 



(partial hydrolysis) 



t 

 prulaurasin 



III. 



d-mandelic acid 



yields 



unknown 



sam- 

 bunigrin 



x ) Journ. de Pharm. et Chim. VI. 29 (1909). 576. 



