566 SCIENCE PROGRESS 



isolate laevoglucosan from these three substances by hydrolysis 

 by means of barium hydroxide, they consider that these com- 

 pounds are in reality derivatives of laevoglucosan, and not of 

 glucose. On this hypothesis the constitution of arbutin, 

 for example, would be represented as follows : 



OH-CH CH-OH 



CH— 0— CH 



CH a -OH CH(OH)-0-C 6 H 4 OH 



Reference has already been made in these columns to the 

 theory of alcoholic fermentation and to the products formed 

 during this complex change (Science Progress, 1919, 

 52 and 54). In a paper recently published by Neuberg and 

 Reinfurth (Berichte, 1919, 52, [B], 1677) attention is once 

 more drawn to the fact that in the presence of sulphites, especi- 

 ally calcium sulphite, the acetic aldehyde formed as an inter- 

 mediate product is fixed in form of its bisulphite compound ; 

 the available hydrogen, no longer being able to reduce the 

 aldehyde, is therefore employed in attacking other substances, 

 and glycerol therefore results in practically equimolecular 

 proportions to the amount of acetaldehyde produced. Under 

 these conditions the fermentation proceeds according to the 

 equation 



C 6 H 12 6 = CH3CHO + C 3 H 5 (OH) 3 + C0 2 , 



and about 73 and 70 per cent, of the quantities of acetaldehyde 

 and glycerol respectively required by the above equation are 

 produced. 



The separation of potato tyrosinase into two constituents 

 is described by Haehn (Berichte, 191 9, 52, [B], 2029). By 

 filtration this enzyme yields a thermolabile residue a-tyrosinase 

 and a thermostable filtrate or activator, neither of which alone 

 is active, while on reuniting these two substances, the resulting 

 mixture regains its original activity. The inactive residue 

 can also be rendered active by adding to it an aqueous 

 solution of the ash obtained by igniting the juice of potatoes 

 expressed with dilute acetic acid. 



A number of papers have recently appeared dealing with 

 the colouring-matters of plants. Everest and Hall (/. Soc. 

 Dyers, 191 9, 35, 275) have been examining the tinctorial pro- 

 perties of some anthocyans (glucosides) and their related 

 compounds the anthocyanidins, obtained from them on hydro- 

 lysis. Both classes of compounds dyed full shades on tannin- 

 mordanted cotton from a faintly acid bath, but on wool, 



