426 Uxp'rlmtnis showing that in Hepatilis [JuNf, 



method I have fbllowed in my experiments, and a description oi 

 the apparatus 1 have invented to operate with, may not be unac- 

 ceptable. 



Dr. Henry, in the first number of the Annals of Philosophy, 

 after having related some experiments on the urine discharged in 

 diabetes mellitus, in which he employed the nitric acid with the 

 extra'- 1 as a test of urea, says, " There is one property, however, 

 of this substance, originally pointed out by Fourcroy and Vau- 

 quelin, which enables us to detect urea, even when present in such 

 minute quantities as to escape discovery by nitric acid. Amidst i\\e 

 great variety of animal products, this appears to be the only one 

 which is decomposed, when in a state of solution, by the tempera- 

 ture of boiling water. At this low degree of heat its elements, held 

 together by a balance of affinities which is easily disturbed, arrange 

 themselves in a new order; ammonia and carbonic acid are gene- 

 rated ; and carbonate of ammonia is composed, equivalent in 

 weight to about two-thirds that of the urea. It is in the iluid, there- 

 fore, condensed during the evaporation of diabetic urine, that we 

 are to look for traces of the existence of urea ; and in this fluid I 

 have invariably found a sufficient quantity of carbonate of ammonia 

 to restore the colour of reddened litmus paper, and to precipitate 

 muriate of lime." In my search for urea 1 have generally chosen 

 this method by distilling the urine, and applying the tests to the 

 condensed iluid, in preference to the more tedious process of evapo- 

 ration for the extract, &c. In Dr. Henry's paper, {Annals of Phi- 

 losophy, No. 1.) and in his Elements of Experimental Chemistry, 

 may be found information sufficient to enable any one to accomplish 

 <he examination of urine for the above purpose with the necessary 

 precision. 



Having collected the condensed fluid, I put some of it into a 

 wine-glass, to which 1 add some solutio muriatis calcis ; if a preci- 

 pitate subside, I drop some acidum muriaticum into the liquid, 

 which, from its greater specific gravity, passes to the bottom of the 

 glass, comes in contact with the precipitate, and a brisk effer' 

 vescence follows, the decisive test of the existence of urea in the 

 urine. 



Not being provided with retorts, &c. the follewing apj)aratus is 

 what I have constructed to effijct the distillation of the urine, and it 

 answers the purpose extremely well. My retort is a Florence oil- 

 liask ; to which, by means of a perforated cork, I adapt a barometer 

 tube, which has a small part at the end next the flask, bent to rather 

 an acute angle, and at the other end a portion sufficiently long that 

 it may reach nearly to the bottom of the receiver, bent to nearly a 

 right angle, so that when the opposite ends are placed in their 

 respectives places the tube lies in an inclined plane. By means of 

 a leather collar fastened to the top of a jar, I fix in it a wide 

 mouthed bottle for a receiver. The lower end of the tube passes 

 into this, through a perforated cork, and a small short tube is passed 

 into the receiver to admit of the exit of air. 'J["Ws cork should be 



