and Laboratory Methods. 



1157 



make communication between tubes d and c. Tube d and perforation // should 

 be large enough to enable the fluids to mix readily. The rapidity with which 

 the fluids mix can be controlled by the stop-cock. The urine mixes with the 

 test solution, the urea is decomposed, and the nitrogen evolved rises into the 

 upper part of tube c. When the reaction is complete and the temperature has 

 subsided to that of the room, water is added to (or removed from) tube a until 

 the level of the fluid in the two arms is the same. The amount of gas in tube c 

 is then read ofi^, and from it the amount of urea can be calculated ; or the per- 

 centage of urea can be read directly from the graduation. 



The advantages of this method would be as follows : The measured amount 

 of urine ( 1 c. c.) is obtained accurately and easily, as it were automatically. 

 None of the gas generated is lost, but all is saved in tube c for measurement. 

 The equalization of the level of the fluid in the two arms equalizes the hydro- 

 static pressure and thus gives an accurate reading of the amount of gas free 

 from that source of error. The graduation in cubic centimeters enables the 

 urea to be calculated with the greatest nicety, applying any corrections for tem- 

 perature and barometric pressure ; while for localities near the sea level and 

 ordinary room temperatures the percentage graduation on the tube (in the sketch 

 given on the theoretical basis) gives a direct reading of sufficient accuracy. 

 The apparatus is compact, not cumbersome, easily kept clean, and always in 

 working order. It combines accuracy with facility of manipulation. 



J. B. Nichols, M. D. 

 Washington, D. C. 



A Device for Supporting Pasteur Flasks. 



Pasteur flasks are difficult to'handle on account of their peculiar shape. A 

 collar of asbestos, cork, or straw is ordinarily used, but has to be fitted closely 



to the base in order to keep the flask erect. 



The photograph shows a device for supporting 

 these flasks, which permits greater freedom and 

 safety in manipulation than is obtained with the 

 ordinary collar support. The device consists of a 

 solid disk of wood about 5^ inches in diameter 

 and 2 inches in thickness. This is hollowed out in 

 the center, leaving a concavity into which the base 

 of the flask fits. One end of a piece of heavy brass 

 wire is fastened into the margin of the base, the 

 other end of the wire is bent so that the bend of the 

 tube of the flask fits into it loosely. The wire sup- 

 ports the flask in the erect position, so that the base 

 of the flask need not fit closely into the hollowed 

 wooden base. Katherine E. Golden. 



