534 Dr. E. F. Armstrong and Mr. E. J. Caldwell. [Apr. 5, 



tion are attracting both sugar and acid molecules, that there is so to 

 speak competition between the Water and the sugar for the acid : there 

 will, therefore, be at any given temperature an equilibrium between 

 water, sugar and acid, depending on the relative proportions of these 

 three constituents ; a change in any one of them will necessarily also 

 change the position of the equilibrium and therefore also the proportion 

 of the combination of acid and sugar present. 



At any moment during hydrolysis, the sugar is not susceptible to 

 change as a whole : only the active system, formed by the combination 

 of acid and sugar, including some limited number of water molecules, 

 is concerned. 



In the experiments hitherto made the proportion of acid molecules 

 present has always been large, so that the magnitude of the active 

 system present cannot have been negligible compared with the total 

 amount of sugar : in such cases it was not to be expected that the 

 change would prove to be a linear function of the time. If, however, 

 a proportion of acid be used in some degree corresponding to the pro- 

 portion of enzyme which is commonly used, it is to be expected that a 

 linear period will be apparent. 



To test this point experiments were made in which N/100 hydrogen 

 chloride was used to hydrolyse a gramme-molecular proportion of cane 

 sugar at 20° : in every case distinct indication was obtained that, at first, 

 equal amounts of sugar were changed in successive equal intervals of 

 time, change proceeding according to the logarithmic law only during 

 the later stages. 



It does not appear desirable to put forward our results relating to 

 this question at present, as we are not satisfied with the degree of 

 refinement we have reached in our experiments : to determine the law 

 for very small proportions of acid, it will be necessary to make exact 

 observations and especially to regulate the temperature with excessive 

 care, as slight differences in temperature produce relatively great 

 changes. 



Effect of Altering the Amount of Acid. — It is well known in the case 

 of cane sugar that an increase in the proportion of acid used to effect 

 hydrolysis is followed by a more than proportionate increase in the 

 rate of change. The effect of an increase in the amount of acid must 

 obviously be to disturb the equilibrium in the direction of increasing 

 the magnitude of the active system ; it may be supposed that, on 

 the whole, when the amount of acid is increased, the sugar is the 

 greater gainer and that the increase in the active system is, therefore, 

 more than proportionate to the increase in the amount of acid. 



Effect of Altering the Amount of Hydrolyte. — Any considerable 

 increase in the amount of sugar present must have the effect of 

 diminishing the attraction exercised by the water upon the acid and 

 consequently must increase the stability of the combination of sugar 



