QUANTITATIVE ESTIMATION OF SUGAR. 117 



LESSON XX. 

 QUANTITATIVE ESTIMATION OF SUGAR. 



1. By the Saccharimeter. 



Study the use of some form of saccharimeter. The portable 

 form made by Zeiss is very convenient. A coloured urine must 

 first be decolourised by acetate of lead [Lesson XVII., 12 (<?.)]. 



2. Volumetric Analysis by Fehling's Solution. 10 cc. of Fehling's 

 solution = *05 grms. of sugar. 



(a.) Ascertain the quantity of urine passed in twenty-four 

 hours. 



(6.) Filter the urine, and remove any albumin present by 

 boiling and nitration. 



(c.) Dilute 10 cc. of Fehling's solution with about five to 

 ten times its volume of distilled water, and place it in a 

 white porcelain capsule on a wire gauze support under a 

 burette. [It is diluted because any change of colour is more 

 easily observed.] 



(d.) Take 5 cc. of the diabetic urine, add 95 cc. of distilled 

 water, and place the diluted urine in a burette. 



(e.) Boil the diluted Fehling's solution, and whilst it is 

 boiling, gradually add the diluted urine from the burette, 

 until all the cuprous oxide is precipitated as a reddish 

 powder, and the supernatant fluid has a straw-yellow colour, 

 not a trace of blue remaining. This is best seen when the 

 capsule is tilted. It is not advisable to spend too much 

 time in determining when the blue colour disappears, as it 

 is apt to return on cooling. 



(f.) Read off the number of cc. of dilute urine employed. 

 If 36 cc. were used, this, of course, would represent 1 '8 cc. 

 of the original urine. 



(g.) Make a second determination, using the data of the 

 first, and in this case run in at once a little less of the dilute 

 urine than was required at first. 



