516 Titration Method for Sugar in Cait: 
5. per cent of sugar.and then testing the, water in the lower part 
of the burette for sugar. It contains no sugar.. For the suction 
we use a rubber tube about 30 cm. long, having.a-glass tip at the 
lower end; we attach it to the burette by means of.a small rub- 
ber stopper and a bent glass tube; since the burette needs no 
eleaning or rinsing the suction arrangements need. seldom. be 
removed. The rubber tube can of course be omitted...The 
essential point. is merely to fill the burette, Rese a Dinette, from the 
bottom by means of suction. 
Sugar Titration. 
Fill the burette as described. (by suction) to, the. zero. mark. 
Into a test-tube introduce a pebble, 5 cc. of the copper sulfate 
solution (corresponding to 25 mg. of dextrose), and 4 to 5 gm. of 
the dry salt mixture. Shake and heat until a clear solution is 
obtained; this takes usually only a. few seconds.. Add 25 drops 
of the urine and boil very gently for 2 minutes. If all the copper 
has been reduced the urine contains probably more than 5 per 
cent sugar. In that case the determination must be started 
over again. If the copper is but slightly reduced, yielding only 
a,small amount of white precipitate, add more urine, from 10 to 
25 drops depending, on, the amount of unreduced remaining. cop- 
per, .and.boil gently for another minute. If at the end of the 
second boiling period most of the copper. has been reduced, eom- 
plete the titration by the drop system, keeping count of the num- 
ber of drops added and. boiling 1 minute after each subsequent 
addition of urine. At the end of. the titration determine how 
many additional drops of urine are required. to give a, volume of 
1 or 2 cc. For example, if 37 drops were used in reducing the 
copper another 15 drops may be required to eve a volume of 1 
-.cc. and the volume of urine taken is therefore 3 5.08 11, GC. mee eee 
70 drops were used and 36 more are peedeg tbe bes a. aie of 
2 cc., then the volume of urine used is 7% of 1 cc.; If 50 drops of 
urine have not reduced most.of the copper, then the titration is 
finished by the addition of larger amounts of urine, without 
counting the drops, and at the end of the titration the volume of 
urine taken is determined, as in any other titration, by. the 
reading on the burette. 2.5 divided by the volume of. urine 
