DETERMINATION OF SUGARS IN GRAIN AND CATTLE FOODS. 



These figures show that the two methods give results that are 

 fairly comparable. In the case of the wheat, however, the sodium 

 carbonate method gave results for total sugars that are a little 

 higher than those obtained by the alcohol method. This 110 doubt 

 is due to the fact that trouble was experienced in filtering the extract 

 quickly and clearly after adding the alum, hence allowing the enzyms 

 to become active again, a point which will be considered later in the 

 discussion. 



Samples of mixed cattle foods were then examined by the two 

 methods, with the following results: 



Examination of mixed cattle foods by the two methods. 



1 This sample had undergone fermentation. 



It is to be noted that the sodium carbonate digestion method gives a 

 perceptible quantity of reducing sugars, determined from the weight 

 of the precipitated cuprous oxid. On examination of the cuprous 

 oxid precipitate obtained in the sodium carbonate digestion method 

 it was found that considerable organic matter was occluded in the 

 precipitate, and also some mineral matter. This was traced back to 

 the alum clarification, as alum does not clarify as completely as 

 lead acetate. Using neutral lead acetate instead of alum for clari- 

 fication in a second set of determinations on this material, the reduc- 

 ing sugar of the first sample came down to 0.00 and of the second 

 sample to 0.08 per cent. With the lead clarification it is seen that the 

 results compare more closely. 



With other materials, such as molasses feeds and plants, high in 

 nitrogenous bodies, when alum was used as a clarifying agent, it was 

 noted that the precipitated cuprous oxid in the direct reducing- 

 sugar determination was badly contaminated, a greenish flocculent 

 mass occurring quite often. When neutral lead acetate was used no 

 indication of this greenish precipitate was noted in the determination 

 of reducing sugars in these samples. This shows alum to be a poor 

 clarifying agent for sugar determinations by this method and indi- 

 cates that neutral lead acetate should be used for this purpose. In 

 no case, however, should lead subacetate be used as a clarifying 

 agent, as its power of precipitating reducing sugars is well known. 1 



i Intern. Sugar Journal, 1908, 10: 602. 



