1156 



Journal of Applied Microscopy 



7 



r\ 



M 



A Plan for a Ureometer. 



The plan for a ureometer (or modification of Doremus' apparatus) here pre- 

 sented would, it is believed, offer some advantages as to accuracy and facility of 

 manipulation over other methods of estimating urea. 



C is a tube of about '^5 cubic centimeters capacity, closed at the upper end, 

 and accurately graduated from the upper end downward for IG c. c, to tenths of 

 a cubic centimeter. The graduation also gives urea percentages to tenths per 



cent., at 20°C, and barometric pressure of 760 mm. of 

 mercury. At the bottom of tube r is a curved neck 

 communicating with a bulb />, which opens into a tube 

 (7 ; this has a funnel top, and is of the same length as 

 tube c. The capacity of bulb ^ is about 30 c. c, which 

 quantity is indicated by a mark on tube a. 



Tube c communicates near its lower end with a 

 small tube ^/, joined at such an angle and position that 

 gas generated in ^/ will rise easily into tube c and 

 none pass into bulb />. A removable accurately fitted 

 glass stopper and stop-cock e separates tube ^ from 

 the cavity of tube r, and the capacity of tube t/ below 

 the stopper is exactly 1 cubic centimeter when the 

 stopper is inserted. A transverse perforation «, rather 

 large, passes through the stopper, so that when turned 

 in the right direction it opens free communication 

 between tubes t/ and c. When the stopper is so turned 

 that it shuts off tube //, the perforation n should open 

 into the cavity of tube r. A glass cross-bar // 



strengthens the appara- 

 tus, which is entirely of 

 glass. A separate base 

 or stand for the support 

 of the instrument can be 

 provided. 



Method of Use. — 

 The stopper, being re- 

 moved, the tube t/ is by 

 means of a dropper filled 

 with urine. The stopper 

 e is then inserted with 

 opening /i so placed as 

 to cut off tube t/ from tube r. Tube // then contains exactly 1 c. c. of 

 urine. The usual sodium-hypobromite solution is then poured into tube a, 

 up to the 30 c. c. mark. The apparatus is then tilted so that the solution runs 

 into tube r, entirely filling it ; the perforation ;/ should also be filled with the 

 solution. The apparatus being held upright, the stopper e is turned so as to 



