1 1 6 Analysis of Feeding Materials [183-185 



Should the temperature have altered, the specific gravity is 

 taken at the mean temperature between the two readings. 



The specific gravity is determined by means of a hydro- 

 meter or a specific gravity bottle. 



Details of Juice Analysis 



183. Glucose. — The lead acetate which has been added 

 to the diluted juice will form a heavy precipitate with the sub- 

 stances which caused turbidity, so that in the course of a few 

 hours a perfectly clear solution will be obtained, all the precipi- 

 tate having settled at the bottom of the flask. 



In a normal swede this clear solution will be of just about 

 the correct strength for treatment with Fehling's solution. 

 Remove 50 c.c. from the flask with a pipette, taking care not 

 to disturb the precipitate, and transfer to a clean, dry burette. 

 Determine the glucose with Fehling's solution exactly as de- 

 scribed in paragraphs 82-84. 



184. This method gives results sufficiently accurate for 

 most purposes. If, however, results are required of the highest 

 possible accuracy, the excess of lead should be removed from 

 the solution before titration. In this case the sugar solution 

 should not be made up to 100 c.c. immediately after adding 

 the lead acetate solution, but should be allowed to stand for 

 two hours to settle. At the end of that time 20 c.c. of a 

 saturated solution of alum should be added. This will pre- 

 cipitate the excess of lead. The solution should then be made 

 up to 100 c.c, shaken up, and allowed to settle. When quite 

 clear it must be treated as described in the last paragraph. 



185. Total Sugar. — Measure out 50 c.c. of the solution, 

 clarified for this determination, into a 4-oz. beaker, taking care 

 as before not to remove any of the sediment. Add 10 c.c. of 

 dilute sulphuric acid (1 to 4), and digest on the water bath for 



