ON THE HYDROLYSIS OF SUGARS. 281 



where K.jo per cent, is the inversion velocity in a 20-per-cent. solution 

 and 6.20 is the actual volume of the sugar molecules in 100 cc. of a 

 20-per-cent. solution. That is to say, • the rate of inversion is inversely 

 proportional to the space in which the molecules move.' 



He showed that this theory was in fair numerical agreement with the 

 results already published by Ostwald. 



■laqa Arrhenius, however, ignored Cohen's suggestion when he 



* pointed out in the next year tha'c the rate of inversion, cceteris 

 2)aribus, follows the osmotic pressure of the sugar in solution. That is 

 to say, the increase in inversion velocity with sugar concentration is to 

 be explained by the abnormally high osmotic pressures of strong solutions. 

 The amount of ' active sugar ' {vidti Section F) is supposed to be pro- 

 portional to the osmotic pressure of the sugar molecules. 

 -,(\n(> The author has recently demonstrated that the supposed 



abnormality of strong sugar solutions is almost non-existent when 

 a rational method of experiment is adopted, viz., the use of weight- 

 normal solutions. In this case, when the concentration of the sugar is 

 varied from 85-5 to 342 grams per 1,000 grams of water, the inversion 

 velocity increases only 3'3 per cent, instead of 38 per cent., the increase 

 observed when volume-normal solutions are used, i.e., solutions in 1 litre. 



It is probable that the inversion velocity and the osmotic pressure 

 do run closely parallel in both volume- and weight-normal solutions. 

 Morse and Frazer have recently shown that in weight-normal solutions 

 the molecular osmotic pressure is not affected by changes in concentration. 

 The author has ventured to suggest, on the basis of his determinations, 

 that some of Morse and Frazer's values ' for concentrated solutions are a 

 little too low ; the results obtained by Lord Berkeley and Mr. Hartley by 

 direct measurement of osmotic pressure appear to support this view. 



H. — Influence of added Non-electrolytes on Inversion Velocity. 

 H 1. — Non-electrolytes in General. 



The effect of various non-electrolytes on inversion, such as glucose, 

 glycerol, mannitol, &c., acquires interest from a comparison of their effects 

 in the case of the action of invertase. 



Briefly put, almost any ' foreiga ' substance affects the velocity of 

 inversion by acids, whilst the activity of an enzyme is only affected in 

 cases in which the added non-electrolyte happens to be one of the products 

 of the inversion. 2 Thus glucose retards the action of maltase on maltose, 

 whilst fructose has no effect. 



On the other hand, moderate amounts of glucose, fructose,^ and 

 glycerol, in volume-normal solution, accelerate the inversion of cane 

 sugar by acid, whilst in weight-normal solutions .some non-electrolytes 

 accelerate and some retard. 



,QQQ Arrhenius supposed that the addition of non-electrolytes 



increased the amount of his ' active sugar ' in (volume-normal) 

 solution. 



' Morse and Frazer, Am. Ckem. Journ., 1905, 34, p. 1 ; 1906, 36, p. 39. Berkeley 

 and Hartley, Phil Trans., 1906, A 200, p. 481. 



' Vide E. F. Armstrong, Proe. Roy. Sue, 1904, 73, p. 520. 

 » Armstrong and Caldwell, ibid., 1904, 74, p. 200. 



