Vm] FOODS Al^ro FEEDING STUFFS 109 



56 REDUCING SUGARS OTHER THAN DEXTROSE. 



Proceed as directed under 54 and multiply the weight of dextrose found in 55 

 by the following factors: 



Levulose, 1.093; 

 Invert sugar, 1.046; 

 Arabinose, 0.969; 

 Xylose, 1.017; 



Galactose, 1.114. 



Total Sugars." 

 (Applicable to cattle foods.) 



57 preparation of solution. 



Place 12 grams of the material in a 300 cc. graduated flask, if the substance has an 

 acid reaction add 1-3 grams of calcium carbonate, and boil on a steam bath fori hour 

 with 150 cc. of 50% alcohol by volume, using a small funnel in the neck of the flask 

 to condense the vapor. Cool, and allow the mixture to stand several hours, prefer- 

 ably overnight. Make up to volume with neutral 95% alcohol, mix thoroughly, 

 allow to settle, transfer 200 cc. to a beaker with a pipette, and evaporate on a steam 

 bath to a volume of 20-30 cc. 



Do not evaporate to dryness, a little alcohol in the residue doing no harm. Trans- 

 fer to a 100 cc. graduated flask, and rinse the beaker thoroughly with water, adding 

 the rinsings to the contents of the flask. Add enough saturated neutral lead acetate 

 solution to produce a flocculent precipitate, shake thoroughly and allow to stand 15 

 minutes. Make up to the mark with water, mix thorough'y, and filter through a 

 dry filter. Add sufficient anhydrous sodium carbonate to the filtrate to precipitate 

 all the lead, again filter through a dry paper and test the filtrate with a little anhy- 

 drous sodium carbonate to make sure that all the lead has been removed. 



58 determination of REDUCING SUGARS. 



Proceed as directed under 26 or 29-34 respectively, employing the Soxhlet 

 modificatiin of Fehling's solution and using 25 cc. of the solution (representing 2 

 grams of the sample), prepared as directed in 57. Express the results as dextrose 

 or invert sugar. 



59 SUCROSE. 



Introduce 50 cc. of the solution, prepared as directed in 57, into a 100 cc. gradu- 

 ated flask, add a piece of litmus paper, neutralize with acetic acid, add 5 cc. of con- 

 centrated hydrochloric acid and allow the inversion to proceed at room temperature 

 as directed under 14 or 16. When inversi m is complete, transfer the solution to a 

 beaker, neutralize with sodium carbonate, return the solution to ih^ 100 cc. flask, 

 dilute to the mark with water, filter if necessary and determine reducing sugars in 

 50 cc. of the solution (representing 2 grams of the sample) as directed in 58, and 

 calculate the results as invert sugar. Subtract the per cent of reducing sugars be- 

 fore inversion from the per cent of total sugar after inversion, both calculated as 

 invert sugar, and multiply the difference by 0.95 to obtain the per cent of sucrose 

 present. 



Since the insoluble material of grain or cattle food occupies some space in the 

 flask as originally made up, it is necessary to correct for this volume. Results 

 of a large number of determinations on various materials have shown the average 

 volume of 12 grams of material to be 9 cc, and therefore to obtain the true amount 

 of sugars present all results must be multiplied by the factor 0.97. 



