20 



be understood as maintaining that it is in fact an albumen. But it differs 

 from the albumens only in not being precipitated by hydrogen fer- 

 rocyanide (ferrocyanide of potassium -f- glacial acetic acid). 



Rosenthaler also reports on experiments with emulsin made by him on 

 a series of aldehydes and ketones in order to determine whether emulsin 



i. is capable of producing the asymmetrical addition of hydro- 

 cyanic acid to the aldehydes and ketones. 



2. has a general effect of hastening the absorption of hydrocyanic acid. 



3. affects the equilibrium of the reaction. 



The table which accompanies the paper shows that most aldehydes 

 yield active, and the ketones only inactive, hydroxynitriles. The follow- 

 ing yield dextro-rotatory nitriles: acetic aldehyde, zsobutylic aldehyde, 

 heptylic aldehyde, octylic aldehyde, furfurol, o-methoxybenzaldehyde, 

 anisic aldehyde, cuminol, piperonal, o-nitrobenzaldehyde, cinnamic 

 aldehyde, phenyl acetic aldehyde, w^phthalic aldehyde, terephthalic 

 aldehyde. Citral and o-phthalic aldehyde yield laevorotatory nitriles, 

 and the following yield inactive nitriles: chloral, salicylic aldehyde, 

 m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, p-nitrobenzaldehyde, 

 methyl-ethylketone and acetophenone. 



In his experiments on the displacement of the equilibrium of 

 reaction towards the nitriles, Rosenthaler met with experimental dif- 

 ficulties which he ascribes to the fact that commercial emulsin contains 

 both s- and d-emulsin. He hopes, later on, to be able to repeat his 

 experiments with s-emulsin of the greatest possible purity. 



The views expressed by Rosenthaler to which we made reference 

 in our last report 1 ), and which are confirmed in the paper quoted 

 above, and amplified by the examples cited therein, are endorsed by 

 S. J. M. Auld 2 ). That investigator, on the basis of experiments of 

 which the results have lately been published, concludes that (assuming 

 primarily benzaldehyde-cyanohydrin to be formed at all when amygdalin 

 is split up by emulsin), such a formation can only take place to a 

 limited extent and for a short period. Parallel - experiments in the 

 splitting -up and synthesis of benzaldehyde from amygdalin, or the 

 constituent under the influence of emulsin, showed that the synthesis 

 proceeds much more rapidly than does the decomposition. For instance, 

 a solution of 2 g. of amygdalin and 0,2 g. emulsin in 50 cc. water 

 was extracted with ether after standing for 3 hours. The evaporation- 

 residue dissolved in chloroform had a rotation of -|- o° c/, while 

 2 g. benzaldehyde, 0,8 g. hydrocyanic acid and 1 g. emulsin, dissolved 

 in 50 cc. water and treated in the same manner, after 3 hours had 

 a rotation of -{- o°5i'. 



*) Biochemische Zeitschrift 1908, 238; Report April 1909, 17. 

 *) Journ. chem. Soc. 95 (1909), 927. 



