10 DETERMINATION OF SUGARS IN GRAIN AND CATTLE FOODS. 



As the addition of alum or lead for clarification neutralizes the sodium 

 carbonate, and therefore removes the agent inhibiting the enzymic 

 action, the procedure from this point must be hastened as much as 

 possible to prevent changes in the sugar content. Should the filtra- 

 tion of the clarified solution be difficult and some time be consumed 

 in obtaining a clear filtrate, it is better to throw away the solution 

 and extract the sample again, as the results are very apt to be incor- 

 rect. The few results in the following table will show the possible 

 errors in such determinations : 



Results showing errors introduced by slow filtration. 



The more time consumed from the point of clarifying to that of 

 determining the reducing sugar, the greater will be the error. Deter- 

 minations were made on the fresh extract and on the extract that 

 had stood overnight after clarification. 



A few of the results are given in the following table : 



Data showing effect on results of standing overnight. 



1 Lead acetate as a clarifier. 



Standing overnight in all cases greatly increased the reducing sugar 

 content. In some instances this increase was over 500 per cent. 

 The total sugars in all except one case (No. 7856-C) showed a marked 

 increase, but the percentage increase is far below that of the reducing 

 sugars. From the last two tables it is seen that allowing the solution 

 to stand for any length of time after clarification increases the per- 

 centage of sugars present. This increase is due, no doubt, to enzymic 



