Studies on Enzyme Action. 195 



[D 7050, 8010.] 



" Studies on Enzyme Action. VI. The Sucroclastic Action of 

 Acids as contrasted with that of Enzymes. Part II." By 

 EDWAED FKANKLAND ARMSTRONG, Ph.D., Salters' Company's 

 Eesearch Fellow and EGBERT JOHN CALDWELL, Cloth workers' 

 Scholar, Chemical Department, City and Guilds of London 

 Institute, Central Technical College. Communicated by Pro- 

 fessor H. E. ARMSTRONG, E.E.S. Eeceived August 26, 1904. 



D 7050. Hydrolysis of Cane Sugar by very Dilute Acids. 



In accordance with the theory put forward in our former paper,* it 

 was to be expected that on hydrolysing cane sugar with sufficiently 

 dilute acids the course of the change would not follow the simple 

 logarithmic law but that it would approximate, during the earlier period, 

 to a linear function of the time. This supposition has been confirmed 

 by experiments made very carefully to test this point. 



Experimental Method : In order that hydrolysis should be about half 

 completed in 10 hours by N/500 chlorhydric acid, it was necessary to 

 work at about 40. At this temperature, when so weak an acid is used, 

 the solution does not show any trace of colour even after 4 days, 

 which may be regarded as evidence that no decomposition of the 

 levulose into acid substances has occurred. In order to maintain the 

 temperature at 40, a stream of water was passed through the jacket 

 of the polarimeter tube in which the hydrolysis was carried out. The 

 water was taken from the mains at nearly 18 and passed through a 

 metal vessel, about 2 litres in capacity, in which it was heated by 

 a Bunsen burner to 30. It was then passed through a metal vessel 

 holding about 5 litres containing an Ostwald thermoregulator ; in 

 this the temperature of the water was raised to about 39. The 

 final adjustment was performed by a very sensitive Ostwald thermo- 

 regulator with fluted sides to make it respond quickly to changes in 

 temperature; this was placed in a cylindrical Dewar vacuum vessel, 

 which it almost filled. After passing through a thin copper drum 

 holding about 150 c.c., the water circulated through the regulator, 

 cooling being prevented by the vacuum jacket; the temperature of 

 the water in the drum was maintained at 40 by means of a flame 

 controlled by the regulator. This arrangement proved to be eminently 

 satisfactory in observing slow rates of change, although the extreme 

 variation of the temperature was nearly ^jj-th of a degree, the 

 period of the variations was only 1 minute, so that in experiments 

 extending over several hours the temperature variation was of no account. 



' Boy. Soc. Proc.,' vol. 73, p. 526. 



