244 ELEMENTARY PHYSIOLOGY. [XXIIL 



FeUing's fluid may conveniently be taken, the 

 cupric salt in this is just reduced by '05 gram of 

 sugar. 



Preliminary estimation. Take 20 c.c. of urine, 

 dilute it to 100 c.c. with water, and put the diluted 

 urine in a burette. Into a small porcelain dish, 

 measure accurately 10 c.c. of Fehling's fluid, add 

 about 10 c.c. of sodium hydrate and 30 c.c. of 

 water ; place this on a piece of wire gauze over a 

 small Eunsen burner to boil, as soon as it boils 

 run in the urine from the burette in such amount 

 that the fluid does not cease to boil, and stir 

 continuously. When the fluid undergoes a distinct 

 change of colour, the urine should be added more 

 slowly, and as soon as the fluid turns bright yellow 

 or brick red, the amount of urine added (a c.c.) 

 should be noted. 



Second estimation. The Fehling's fluid is measured 

 out and diluted as before, a—'b c.c. of diluted urine 

 run into it and the mixture boiled. It is then put 

 aside to allow -the precipitate to partially settle; 

 as soon as there is a sufficient fluid free from 

 precipitate, the colour of the fluid should be 

 noted. If it is still blue, "1 c.c. urine is added, the 

 mixture again boiled, the colour of the fluid noted, 

 and so on until the fluid is no longer blue. If the 

 fluid is colourless after adding a — 5 c.c. of diluted 

 urine ; a fresh portion of Fehling's fluid must be 

 measured out a — 1 c.c. of diluted urine added and 

 the process given above repeated. This ought not 



