14 DETERMINATION OF SUGARS IN GRAIN AND CATTLE FOODS. 



SUMMARY. 



A method of preparing an extract for sugar determinations in 

 grains, cattle foods, and vegetable material in general is given on 

 page 3, depending on boiling the product with 50 per cent alcohol. 

 A comparison of the results obtained by this method using various 

 classes of materials is given with that of a method depending on the 

 extraction of the sugars with water at room temperature to which a 

 percentage of sodium carbonate is added to inhibit enzymic action. 

 A study of the limitations of the two methods is made, in which it is 

 shown that the alcohol method will give satisfactory and comparable 

 results on material, whether it is analyzed immediately or after stand- 

 ing for some time, while to obtain true and concordant results with the 

 sodium carbonate method the most careful attention must be given 

 to certain details of manipulation. In the sodium carbonate method, 

 after neutralizing the sodium carbonate by clarifying with alum or 

 lead, the work must be carried on with dispatch as the enzyms again 

 become active; (2) the acidity of the sample must be determined and 

 the quantity of sodium carbonate thereby regulated, or the accuracy 

 of the results will probably be affected; (3) normal lead acetate 

 should be used instead of alum for clarification under most circum- 

 stances, otherwise an error is introduced. Taking these points into 

 consideration, it is the opinion of the authors that the alcohol method 

 is to be preferred in general sugar work, but when a long, comparable 

 series of results is to be obtained on samples of the same kind of mate- 

 rial, the sodium carbonate method might be used advantageously, 

 provided it is run with dispatch and the greatest care is exercised in 

 its operation; and, most important of all, the results obtained by its 

 use should compare with those obtained by alcohol digestion. Some 

 materials, however, can not be analyzed by the sodium carbonate 

 method because clear filtrations are not obtainable even with lead 

 clarification. 



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