Rapid Estimation of Urea. 147 



suitable cement — common sealing-wax, for example. Thus, 

 with the aid of the two pipettes, cork, and tubing, which can 

 be easily procured through a druggist for about 3s., a medical 

 man can construct his own ureometer*. 



When in use the block g is secured to the board S, on which 

 the beaker T stands held by the wire W. 



Mode of using the Apparatus. — The vessels A and F are 

 disconnected, and F filled with water until it overflows and 

 the excess has ceased to drip from the tube under H. The 

 cork is removed from the bottle A, and two flnid-drachms of 

 the liquid to be tested measured off in a tall minim-measure, 

 and then poured into A ; one drachm of water is next used to 

 rinse the liquid adhering to the sides of the measuring-glass 

 into the bottle A : the total volume in A therefore should 

 measure about three drachms f. For a reason which will 

 presently appear, it is desirable that no more water than one 

 drachm should be employed. If a pipette delivering two 

 drachms be used, a drachm of water should be added ; but the 

 pipette need not be rinsed with it. The next step is to fill the 

 pipette B with the reagent which evolves the nitrogen of the 

 urea. For this purpose a suitable vessel (a wine-glass for 

 example) is filled with the hypobromite liquid J ; the forceps 

 D is removed from the india-rubber tube, but is placed 

 close at hand, and a piece of vulcanized tubing, five or six 

 inches long, attached to the end of the glass tube C ; suction 

 is then applied by the mouth when the curved end c of the 

 pipette is immersed in the hypobromite. The pipette is thus 

 easily filled by suction with the re-agent up to the mark b. 

 The forceps D is next applied to the connector, as shown, 

 before the lips are withdrawn from the india-rubber tube at- 

 tached to ; the suction tube may then be removed from C, 

 as the liquid is retained in B by atmospheric pressure, pro- 

 vided D pinches the tube well. Having washed the end c by 

 pouring a little water over it, the cork carrying all its apparatus 

 is securely inserted in the bottle A, the latter placed in the 

 beaker T containing enough water to cover the cork when A 

 is pressed down, and the tube E securely connected by the 



* Messrs. Yeates & Son, of Dublin, supply a neat form of my apparatus 

 ready for use. 



t The measure used should be good, the two-drachm and two-ounce 

 vessels agreeing witheach other. The amount of reliance which can be 

 placed upon the results depends in great part on the accuracy of the 

 measures. 



% This solution is prepared as follows : — Dissolve 4 ounces of the solid 

 caustic soda of the shops in 10 fluid-ounces of water. When the soda has 

 dissolved and the liquid cooled to 60° F., add gradually 1 fluid-ounce of 

 bromine. The test solution is then ready for use. It should be kept in a 

 cool place, and away from the light. 



L2 



