AGRICULTURAL CHEMISTRY — AGROTECHNY. 411 



The starch liquefying capacity of the malt extracts was greater than that 

 of the raw cereals, in all probability because the amylase exists in the raw 

 cereals in the proenzym state. 



Part 2 confines itself chiefly to a study of methods for determining the starch 

 liquefying capacity, and the results indicate that Liutner and Sollied's method 

 is the best for the puri)ose. 



The effect of alcohol on invertase, C. S. HudsoK and H. S. Paine ( U. S. 

 Dept. Agr., Bur. Chem. Circ. 58, pp. 8, figs. 2). — In these investigations, " O'Sul- 

 livan and Thompson's observation that alcohol reduces the activity of invertase 

 is confirmed, and the relation between alcoholic strength and inactivation is 

 shown to be graphically a rounded curve. Alcohol is found to destroy inver- 

 tase, and the relation between alcoholic strength and rate of destruction is very 

 peculiar, as it shows a high maximum at about 50 per cent alcohol. The 

 destruction follows the course of unimolecular reactions; it is not noticeable 

 below 20 per cent alcohol at 30° C, is almost instantaneous at 50 per cent, and 

 decreases to nearly zero at SO per cent. If the alcohol contains cane sugar, the 

 destruction is much slower; thus, 6 per cent cane sugar reduces the rate of 

 destruction in 50 per cent alcohol from 0.850 to 0.009, or to about 1 per cent of 

 its original value. A mathematical theory of the progress of the inversion of 

 cane sugar by invertase in alcoholic solutions of sufficient strength to slowly 

 destroy the enzym has been woi-ked out and its conclusions found to agree with 

 the results of the experiments. In this way it has been possible to measure 

 the activity of invertase in 50 and TO per cent alcohol, where the destruction 

 plays an important role. Invertase can be precipitated by alcohol without 

 much destruction, provided the strength of alcohol in the final solution is high, 

 approximately 90 per cent. By this method of precipitation, working at room 

 temperature, a solid preparation was obtained which had 78 per cent of the 

 activity of the original solution. If cane sugar is present, invertase can be pre- 

 cipitated with no important destruction by even 70 per cent alcohol ; this 

 method of iirecipitation gave a recovery of 94 and 96 per cent of the original 

 activity." 



The destruction of the enzym invertase by acids, alkalis, and hot water, 

 C. S. Hudson and H. S. Paine {U. 8. Dcpt. Agr., Bur. Chem. Circ. 59, pp. 5, 

 figs. 2). — Measurements were made according to the method previously de- 

 scribed (E. S. R.. 23, p. 110) to determine the rate of destruction of invertase 

 by hot water, alkalis, and acids, and at different temperatures. 



From the results it is seen that as the temperature is raised the rate of de- 

 struction by acids and alkalis increases until finally at or about the temperature 

 of (>0° C. distilled water itself slowly destroys invertase, and at 65° destruction 

 by water is quite rapid. It is thus evident that the destruction of invertase 

 Ity hot water is due to the same cause as its destruction by acids and alkalis. 

 As far as is known this is the first evidence offered to explain the cause of the 

 well known destruction of enzyms by hot water. It explains why dry enzym 

 preparations can be heated without destruction to temperatures over 100°, in 

 case no water is present, since the hydrolysis does not then take place. 



In studying the influence of temperature in increasing the rates of destruction, 

 and comparing the rates of destruction in the same medium at different tem- 

 peratures, the coefficient which shows how many fold the rate increases for 

 10° in temperature is found to be (.n the average 3.1. This agrees with the 

 general observation that this factor for most chemical reactions varies between 

 2 and 4. The hydrolytic destruction of invertase by acids, alkalis, and hot 

 water thus falls in with the common types of chemical reactions. 



The results on the work of the protective action of fructose against the 

 destruction of invertase indicate " that the enzym forms a combination with 



