THE JOURNAL OF PHARMACOLOGY. 



FIG. 1 



capacity of about 5 cc, by means of a stopcock having 

 a wide bore. The capacity of ^ inclusive of that of the 

 stopcock bore must be accurately determined. This 

 may be done by introducing water by means of a bu- 

 rette or pipette, noting the volume introduced. The 

 total capacity should not exceed 6 cc. The upper con- 

 tracted end of the tube B is connected with the neck of 

 a funnel-like ves.sel (C), extending several centi- 

 meters into this. It may be thus kept in place by 

 means of a perforated cork stopper. The eudiometer 

 {D) when in position must be directly above the upper 

 contracted end of B, and is fastened in this position 

 by means of a clamp. It should have a capacity of 

 50-100 cc. divided into i/iocc. 



The method is executed as follows : The lower bulb 

 of the apparatus if filled with the sample of urine, pre- 

 ferably diluted with an equal volume of distilled 

 water, noting, of course, the exact quantity of urine employed. When 

 thus filled the liquid should extend up to the distal end of the bore 

 in the stopcock. Care must be taken that no urine adheres to B. This 

 may be 'avoided by introducing the liquid by means of a pipette. The 

 stopcock is now closed and the tube B together with most of the vessel C 

 are filled with Knop's hypobromite solution. Next fill the eudiometer 

 with the same reagent, close with thumb, and invert over the contracted 

 end of iS", taking care that no air enters, and fasten in position with clamp. 

 Now open the stopcock and note the evolution of gas resulting from the 

 reaction between the urea and the reagent. The carbon dioxide liberated 

 is absorbed by the excess of alkali, while the nitrogen collects in the 

 eudiometer, displacing in this a volume of liquid equal to its own volume. 

 In about one-half "hour the reaction will have terminated, and the volume 

 of gas may now be read off. Lowering the eudiometer into a cylinder of 

 cold water, which has previously been boiled to expel gases, in such a 

 manner that the liquid in the eudiometer and that in the cylinder are on 

 the same level, will permit a most correct reading. It is furthermore 

 necessary to note the barometric pressure and temperature. From the vol- 

 ume of nitrogen so obtained, its weight is determined, and from this the 

 weight of urea. ■ The weight of nitrogen is determined after the following 

 formula : 



V. (b—b') 



0.0012566. 



V. 



760 (i +0.C03665. /) 



weight of nitrogen expressed in grammes. 



volume of liberated nitrogen expressed in cubic centimeters. 



