Dixon and Ball — Heat produced during Inversion of Sucrose. 163 



Summary. 



Estimations of the thermal changes due to the action of enzymes when 

 obtained from the heats of combustion are inaccurate, as the values obtained 

 are so close to the limits of experimental error for the heats of combustion 

 values. 



A differential calorimeter, in which the temperature is measured by 

 means of a thermocouple, was used for the determination of the heat 

 produced by the action of invertase on sucrose. 



A value was obtained which agrees closely with that previously given by 

 Brown and Pickering. The mean of all the results is 3'8.3 cal. per gm. 

 mol. 



Attempts to obtain a value for the heat of reaction during the hydrolysis 

 of maltose have not yet been successful. 



Eefekekces. 



(1). Beoavn, H. T., and PiCKERraa, S. V. Thermochemistry of Carbohydrate 

 Hydrolysis. Trans. Chem. Soc, 1897, vol. Ixxi, p. 783. 



(2). Stohmann and Langbein. Jour. Pract. Chem. (2), xlviii, p. 305. 



(3). Dixon, H. H. A Thermo-electric Method of Cryoscopy. Proc. Pioy. 

 Dub. Soc, 1911, vol. xii, p. 49. 



(4). Hill, A. V. A New Form of Differential Micro-calorimeter for the 

 Estimation of Heat Production in Physiological, Bacteriological, 

 or Ferment Actions. Jour. Physiol., 1911, No. 43, p. 216. 



(5). Eaoult, F.-M. Compt. Eend., 1897, Tom. cxxv, p. 751. 



(6). Davis, W. A. The Use of Enzymes and Special Yeasts in Carbo- 

 hydrate Analysis. Jour. Soc. Chem. Indus., Feb. 29, 1916, 

 vol. XXXV, p. 201. 



