the rate of this incomplete inversion of cane sugar by invertase in 50 

 per cent alcohol is recorded. The quantity of cane sugar present (A) 

 is expressed in degrees, A = 4S.l (1.267) = 61.6, and the quantity of 

 cane sugar present at any time t is A z = r + 48.7 (0.267), where r is 

 the reading of the solution. The value of & 2 is taken from Table 4 as 

 0.009. 



TABLE 5. Course of the incomplete inversion of cane sugar by invertase in 50 per cent 



alcohol. 



The values of lc l in the last column, as calculated from Equation 4, 

 are sufficiently constant to show that the reaction follows the laws 

 that were assumed in the theory, within the limits of the present 

 experimentation. It was found that the activity of the invertase 

 when no alcohol was present was Jc l = 0.0080; if this rate in pure water 

 is taken as 100, the rate in 50 per cent alcohol is then 11. Similar 

 experiments have shown that in 70 per cent alcohol the rate of inver- 

 sion, on the basis of 100, is 8. These values for the activity in 50 and 

 70 per cent alcohol are included in Table 1. 



THE PRECIPITATION OF INVERTASE BY ALCOHOL. 



Alcohol precipitates invertase, and it is in this way possible to pre- 

 pare a solid enzym, though nothing regarding its purity can be predi- 

 cated at present. It is a fact, however, that such solid invertase 

 preparations are usually of low enzymotic activity. The reason for 

 this is apparent from the results of this investigation, for unless the 

 alcoholic precipitation is performed in very strong alcoholic solution 

 the invertase is rapidly destroyed by the alcohol. There are three 

 ways by which this destruction can be lessened ; one is to use strong 

 alcohol in large proportion, another is to work at low temperatures, 

 and the third is to have cane sugar present in the solution to protect 

 the invertase from destruction. In order to test the first method, 50 

 cc of invertase liquor which had been dialyzed until it contained 

 only 1 per cent of total solids was mixed with 500 cc of 95 per cent 

 alcohol at 25 C., and after half an hour the coagulated precipitate was 



a The Clerget factor at 30 C; see U. S. Dept. Agr., Bureau of Chemistry Cir. 50, p. 3 

 [Cir. 58] 



