362 Prof. H. E. Armstrong and Dr. E. F. Armstrong. [May 9, 



The Hydrolysis of Cane Sugar. — The evidence as to the manner in which 

 the hydrolysis of cane sugar is affected by the products of change is 

 conflicting. O'Sullivan and Tompson stated, in 1890,* that the products of 

 inversion are without iniiuence on the rate of change. In 1902, however, 

 Henri asserted - )- that invert sugar retards the hydrolysis and ascribed the 

 inhibiting effect almost entirely to the fructose.J 



In the same year, Adrian Brown§ also showed that invert sugar had 

 a marked effect, whilst milk sugar had but little influence in retarding 

 inversion. 



Barendrecht has since published two communications! | dealing with the 

 influence of a variety of substances. His results are of a most contradictory 

 character and scarcely admit of rational interpretation ; it is difficult to 

 regard his radiation hypothesis seriously. 



Apparently, the difficulties which attend experiments on the subject are 

 not sufficiently appreciated. Invertase being extraordinarily active, it is 

 necessary to work with highly dilute solutions of the enzyme : minute 

 quantities of impurity therefore exercise an important influence. Unless 

 hard glass vessels are used, it is impossible to obtain consistent results. 

 A very large number of experiments have been made at various times 

 (chiefly in 1904 — 05) to test the influence of glucose, fructose, galactose, 

 mannose, dulcitol and mannitol : in many cases the results were conflicting, 

 so that the problem cannot be regarded as solved : the general impression 

 has been gained, however, that glucose and fructose alone retard the action, 

 probably to an equal extent. 



Conclusions similar to ours have been arrived at by Ford with reference to 

 the action of diastase on starch,1F and he has used amino-acids in order 

 to neutralise impurities. From this point of view, we had used glycine and 



* 'Chem. Soc. Trans.,' vol. 57, p. 927. 



t ' Compt. Kend.,' 1902, p. 917. 



| This statement was incorporated in the table given in No. III. 



§ ' Chem. Soc. Trans.,' vol. 81, p. 382. 



|| ' Zeit. Phys. Chem.,' 1904, vol. 49, p. 456 ; 1906, vol. 54, p. 367. 



IT ' Soc. Chem. Ind.,' 1904, vol. 23, No. 8 ; ' Chem. Soc. Trans.,' 1904, vol. 85, p. 980. 

 Ford expresses the opinion that the extraordinary results obtained with starch by various 

 workers are due to a lack of recognition of the important influence of traces of impurity 

 on the course of the change. The results of recent French workers justify this view. 

 According to Ford, the action of diastase attains. its maximum in neutral solution and is 

 not augmented by asparagine unless there has been a previous restriction ; this is true 

 also of the various salts which are said to accelerate the action. 



The accelerating influence of traces of acid on the activity of invertase (cf. O'Sullivan 

 and Tompson) is probably a consequence of the neutralisation of alkalinity. We are 

 inclined to think that the effects produced by salts are also of a secondary character and 

 that they do not influence the action of invertase in any specific manner. 



