314 



Prof. R. W. Atkinson. 



due to the solution of hoji, we find as the result of the action upon the 

 maltose — 



Before heating. After heating. 



Total solid matter. ....... 2 '68 grms 2' 775 grms. 



Optical rotation 321 divns 7*3 divns. 



Specific rotatory power, p . 144°*5 .... 79°*6 



The hydrating action of hoji upon maltose is, therefore, very decided. 

 The action ceased at 79 °* 6, probably because the activity of the hoji 

 was exhausted at that high temperature. The following series of ex- 

 periments shows the progressive reduction in the specific rotatory 

 power of the solution when observed at successive intervals of time. 

 100 cub. centims. of the same solution of maltose were mixed with 

 100 cub. centims. of a freshly prepared extract of hoji, which contained 

 2-424 grms. of solid matter in solution, and which gave an optical 

 rotation of 11 divisions in a 200 millims. tube. The mixture of maltose 

 and hoji solutions was diluted to 500 cub. centims. at 15° C, and after 

 standing ten minutes a sample was withdrawn for analysis. The re- 

 mainder was placed in a water-bath heated to 45° C, and samples 

 were withdrawn after the lapse of thirty minutes, one hour, and two 

 hours, by which time all the solution had been used up. The numbers 

 given are corrected for the hoji solution added. 



Table IX. 



Time. 



Total solid 

 matter in 500 

 cub. centims. 

 (corrected for 

 koji) . 



Optical rotation 

 in 200 millims. 

 tube (corrected 

 for hoji) , 



Specific 

 rotatory power 

 of maltose 

 products. 





Grms. 



Divisions. 



144-5 





2'685 



6 5 



After 10 minutes at 15° C. . . 



2-826 



5-8 



124-2 







5-3 



111 1 



„ 1 „ „ 



| 2 -886 | 



4-7 



98-5 







3-7 



77-6 



The action is very regular, as will be seen from Curve A, which ex- 

 presses graphically the above numbers. There is no evidence at the 

 end of two hours of the action of the hoji extract upon the maltose 

 having been exhausted, and the fall in the specific rotatory power 

 would doubtless have continued to 59° if the experiment had been 

 allowed to continue longer. The fact that hoji solution thus converts 

 maltose into dextrose is evidence of the difference of this diastase from 

 that contained in malt, which, according to the experiments of Brown 

 and Heron,* has no action upon maltose. It is a point of interest to 

 * " Journal of the Chemical Society," 1879, Trans., p. 648. 



