(9) 



(lecoiiiposilioii prodiicls, ai least in Ihr caso of iiivertiii. Il luis 

 ali'OcKly bccii slalod l)v ()'Sii,i,i\ an and Thompson ') ilml iiiverliii 

 separates glneose from caiiesiit'ar in a Itirolalory condition. Tankkt') 

 and SiMON ■') have afterwards elucidated this Itirotalion (jueslion. 



The l)irotatorv «-glucose is the sn^ar of the «-glncosides and the 

 semi-rotatorv y-glncosc that of the ji-glucosides; according to the 

 said authors they are the stereoisomeric lactones: 



r. HOII UOJI II JlOll 



^\\^ C — C — C — C — C - CH,()H. 



The form which in solution is stable, the /^-glucose conforms to 

 the aldehyde-formula (Tl^^OH (CH()H)^C()H. 



This conclusion is opposed by other ijivestigators such as Armstrox(}^) 

 and LowRY ^), wdio look upon the stable form not as an aldehyde 

 but as a condition of ecpiilibrium between «- and y-glucose. My 

 investigation goes in favoui- of the tirst opinio]). 



Invertin is, geiierally speaking, the enzyme of the «-giucosides. 

 Canesugar nia^^ also be considered as an «-glucoside in accordance 

 wMth the fact that on inversion, the glucose is always separated in 

 the «-modification. This «-glucose is now^ however, gradually con^ 

 verted into /^-glucose and, therefore, prevents tlie reconversion into 

 canesugar. Owing to this, all the canesugar is always finally inverted 

 by invertin. 



A continued research, liowe\'cr, showed that there may be still 

 another reason for the non-appearance of rexersal phenomena. The 

 method of preparing the in\'ertin, that is of the yeast extract was 

 found to greatly alFect the properties of the enzyme. 



At first, I used for the preparation of a powerful invertin a yeast 

 cultivated in a solution of canesugar. This yeast after being mixed with 

 "kieselguhr", was first dried in vacuum at a low temperature and 

 then for half aji hour at J 00° in an ordinary oven. 



The addition of "Ivieselguhr" facilitates very much the subsequent 

 extraction and filtration. The abo\e experiments have been made 

 each time with a freshly prepared filtrate. 



Afterwards it was found that ordinary yeast also gives an enzyme 

 with the same properties, provided it has not been dried at loo high 



^) Journ. Cliem. Soc. 1890 pag. 861. 



2) Zie Diclionnaire de Ciiimie dc Wiirlz. 2e .siii)|)l. j). 704. 



3) C. R. 1901 pag. 487. 



-^) .louin. Clicm. Soc. 1903 pag. l^O.j. 

 '") Jouin. Chem. Soc. 1903 pag. 1314. 



