15 



also necessary in taking the sample for analysis, as the material 

 which falls to the bottom of the stock bottle is often far richer in 

 starch than the lighter fibrous material that rises to the top. 



VI. "Some Notes on the Chemistry of Starch and its 



Tranformations." W. A. Davis. Journal of the 

 Society of Dyers and Colourists, July, 1914. 



It is shown that taka-diastase, the enzyme of Aspergillus 

 Oryzae converts starch first into dextrins, then into maltose and 

 finally into dextrose. After a few hours all the dextrin has dis- 

 appeared and the product consists of maltose and dextrose only ; the 

 amount of dextrose gradually increases with the time. It is con- 

 sidered that taka-diastase contains maltase as well as the ordinary 

 enzymes of malt diastase and that this converts the maltose into 

 dextrose. No evidence could be obtained that taka-diastase con- 

 verts starch directly into dextrose. 



The departure of the hydrolysis from a simple logarithmic 

 curve, is ascribed to the occurrence of several successive stages. 



VII. "The Action of Cold Concentrated Hydrocloric Acid 



on Starch and Maltose." A. J. Daish. Transactions 

 of the Chemical Society, 1914. 105, 2053. 



The action of cold fuming hydrochloric acid (D 15 1*210) on 

 starch appears to be essentially the same as that brought about by 

 taka-diastase. The first stages — the formation of soluble starch, 

 dextrose, and maltose — are, however, passed through very rapidly 

 and after 135 minutes 86 per cent, of the theoretical quantity of 

 dextrose has been formed. The action is apparently limited by the 

 rate of hydrolysis of the maltose, since this is hydrolysed to dextrose 

 not much more rapidly than starch itself. 



When dextrose is dissolved in ordinary concentrated or fuming 

 hydrochloric acid a certain amount of synthetic action always occurs, 

 even when only 1 per cent, of the sugar is present. This fact, and 

 the destruction of some of the dextrose, makes it impracticable to 

 utilise cold fuming hydrochloric acid in the accurate estimation of 

 starch or cellulose. 



VIII. "The Velocity of Hydrolysis of Starch and Maltose 



by Cold Concentrated and Fuming Hydrochloric 

 Acid. A. J. Daish. Transactions of the Chemical 

 Society, 1914. 105, 2065. 



When fuming hydrochloric acid acts on maltose at the ordinary 

 temperature the velocity coefficient is practically constant through- 

 out the change ; the action is unimolecular. But when either the 

 fuming or ordinary concentrated acid acts on starch or soluble starch 

 the velocity coefficient is not constant but rises continuously 

 throughout the change ; the departure from the ordinary logarithmic 

 law is ascribed to the occurrence of successive stages. The trans- 

 formation of cellulose by fuming hydrochloric acid is an extreme 

 instance of an action occurring in successive stages, and the velocity 

 co-efficient also shows considerable variation at different periods. 



