8 



lysis has here no advantage over that by invertase. An experiment 

 was 'performed in which a 10 per cent solution of very pure recrys- 

 tallized raffinose, of specific rotation 123 (circular), was hydrolyzed 

 with the stock invertase solution, and the rotation was found to change 

 to 67.6 at 20 C., where it remained constant. 



THE ACTION OF INVEBTASE ON OTHER ACID-HYDBOLYZABLE 



SUBSTANCES. 



The stock solution of invertase has been found to be entirely inca- 

 pable of hydrolyzing lactose, maltose, starch, dextrin, cellulose, pen- 

 tosans, amygdalin, or salicin. So far no action on any substances 

 except cane sugar and raffinose has been detected, but it appears prob- 

 able that the tetrasaccharid stachyose, which occurs in some plants, 

 would be split into fructose and a trisaccharid. 



SUMMABY. 



The enzym invertase accomplishes a complete inversion of cane 

 sugar and is without action on starch, dextrin, maltose, lactose, pen- 

 tosans, and natural glucosids. A procedure for preparing stock solu- 

 tions of invertase from pressed yeast has been worked out and the 

 solutions found to be permanent in inverting power, the measure- 

 ments having been made now for a period of fifteen months. The 

 invertase inverts only in an acid medium and the best acid to use is 

 found to be acetic. Full directions for the method of analysis are 

 given and the possible errors due to the slight rotatory power of the 

 invertase solution and the mutarotation of the invert sugar are investi- 

 gated and means taken to avoid them. The formula for the percent- 



nr T 



age of cane sugar is found to be - 77 X 100, where S and /are 



141.7- | 



the direct and invert readings of the solution, Tthe temperature, and 

 141.7 the inversion constant, which differs from that for the inversion 

 by hydrochloric acid, i. e., 142.7. This difference is shown to be due 

 to the influence of the acidity on the rotation of invert sugar, as the 

 hydrochloric acid solutions give after neutralization the invertase 

 constant 141.7. It is found that raffinose is hydrolyzed by invertase 

 and that its specific rotation is thereby reduced from 123 to 67.6; 

 raffinose accordingly interferes with the estimation of cane sugar by 

 the use of invertase, just as it also interferes when the inversion is car- 

 ried out with hydrochloric acid. Determination of cane sugar in pure 

 cane sugar, Louisiana molasses, and in bagasse by the invertase method 

 of hydrolysis give percentages which agree with those obtained by the 

 hydrochloric acid hydrolysis. The sotol plant (Dasylirion texanum) 

 is shown to contain only a trace of cane sugar, but 13 per cent of an 

 unknown carbohydrate which is being further investigated. 



Cir. 50. 







