188 EXPERIMENTAL OBSERVATIONS ON 



with the percentage of invert sugar an empirical formula in which 



(y\ 

 1 -j-e J, so that the equation 



for velocity of reaction became , - = e(l +e - ) (a - x), leading on 



(tt \ a/ 



In a / #\~~] 



integration to K l (l+}= r log - -flog ( 1 +e -) . Calculating 



t ( _ (I X \ tt/ ~1 



the value of the empirical constant e from his experimental results, 

 Henri found that it varied within narrow limits around the value 



sj _ I- 'T* 



unity, and hence the above formula simplifies to K!= log 



X 



In accord with O'Sullivan and Tompson, Henri found that 

 within limits in which the enzyme was not too concentrated the 

 amount of hydrolysis in the case of invertase and cane sugar was 

 directly proportional to" the concentration of the enzyme. The 

 laws governing the velocity of reaction have also been studied by 

 Adrian Brown in the case of zymase for conversion of glucose into 

 alcohol, and for the action of invertase upon cane sugar. In the 

 case of the alcoholic fermentation it was found by this author that 

 the velocity of reaction was not represented by a logarithmic curve, 

 but by a straight line that is to say, the velocity of reaction was 

 constant. On the other hand, it was found, as in Henri's experi- 

 ments, that the velocity of reaction in the case of invertase and 

 cane sugar increased more rapidly than it ought on the basis of the 



logarithmic law, the value of K=- log - - increasing steadily 



t ci x 



throughout the series. Adrian Brown also obtained similar results 

 to those of Barth, Duclaux, and Henri for variations in concentra- 

 tion of the cane sugar in not too dilute solutions, the amount con- 

 verted showing a constant weight and not a constant proportion 

 for equal times. To explain this result, he supposed that a com- 

 pound is formed between enzyme and sugar which persists for a 

 time, and that as a result a molecule of enzyme can effect only a 

 limited number of complete molecular changes in unit time. Accord- 

 ingly, whatever the available concentration of sugar may be at any 

 given instant, no increase of conversion above a fixed maximum 

 can occur. It is hence only when the concentration of the sugar 

 falls below a certain definite level relatively to the amount of 

 enzyme present that the amount of conversion can fall below this 



