O. Folin and W.S. McEllroy pare Tbe 
taken, whether this is several cc. or a fraction of 1 cc., gives the 
per cent of sugar in the urme. It 1s, of course, desirable to con- 
firm the results of the titration by a repetition. In this case the 
first addition of urine should be only 2 or 3 drops less than the 
full amount of urine required and the first boiling period should 
be 3 minutes. The titration is then finished by boiling 1 minute © 
after each subsequent addition of urine. The total boiling period 
must not be less than 4 minutes, and if it-is more than-7 the re- 
sults obtained tend to be a trifle high. 5 to 6 minutes is the time 
for which the copper value has been adjusted. 
For accurate work two precautions must be observed in con- 
nection with the drop system of sugar titration: The drops 
should be delivered at a slow rate of speed, not faster than 1 
drop per second. And the portion of the burette most used, the 
first 2 ce., should be calibrated. (1 cc. of distilled water weighs 
about 997 mg.) After the first 2 cc. of the burette have been 
calibrated by weight the remaining parts of the burette can be 
calibrated in a few minutes by means of the drop system. 
Special. Burette for Sugar Titrattons—While very satisfactory 
results are obtained in the titration of undiluted sugar urines 
by means of ordinary burettes and the drop system described in 
the preceding section, we recognize that many who do or teach 
sugar titrations will prefer to pay for fine burettes and thus do 
away with the necessity of keeping count of the number of drops 
used in each titration. Further, a small burette has the advan- 
tage that two or more titrations can be made with as little as 10 
ec. of urine or sugar solution—an important consideration when 
teaching large classes, and also for certain kinds of work, as, for 
example, for the titration of sugar in human milk. We recom- 
mend for this work 5 cc. burettes with glass stop-cocks graduated 
in 0.02 of acc.’ These burettes can be read to within 0.01 of 1 ce. 
These burettes must be filled by suction. The tips of the 
burettes are necessarily too coarse to deliver more than 25 or 30 
drops per cc. The fine accessory tips delivering 45 to 55 drops 
per cc. already described are therefore highly desirable in con- 
nection with these burettes. “In other words, the burettes should 
be used just as ordinary burettes are used in the drop system 
5 Our burettes are made by the Meyer Camera and Instrument Company, 
31-33 East 27th Street, New York. 
