1835.] on Urine. 5 



under my observation was 1.000148; that of the heaviest 

 1048. The former was voided by a hysterical patient, 

 the latter by a man labouring under confirmed diabetes. 

 In this disease the specific gravity of the urine has been 

 observed as high as 1*052. When the individual is in per- 

 fect health the specific gravity of the urine varies from 

 1-0093 to 1'0192, depending in some measure upon the 

 quantity of liquid taken into the stomach. The mean 

 specific gravity during perfect health, I have found to be 

 1 '013859. The highest specific gravity of urine from a 

 healthy individual that I ever met with was 1-0266. 



The mean quantity of urine voided in 24 hours is about 

 3-J^lbs. avoirdupois, but it varies very much even in the 

 same individual, soinC'times amounting only to 2-1331bs. 

 and sometimes to 4-8571bs. 



The colouring matter of urine has never been obtained 

 in a separate state ; we are consequently ignorant of its 

 nature. From an observation of Dr. Prout, it would seem 

 that urine contains two different colouring matters. When 

 urine is filtered through urateof ammonia, it communicates 

 a brown colour to that salt, but if we continue to pass the 

 same urine through different portions of urate of ammonia, 

 it at last ceases to communicate any tint to it, yet the 

 colour of the urine continues of as lively a yellow as ever. 

 Urine then it would seem contains a matter which gives a 

 brown colour to urate of ammonia, and another to which it 

 is indebted for its yellow colour. 



The yellow^ colouring matter is precipitated from urine 

 by nitrate of silver. If we wash the precipitated matter it 

 appears almost black. When dilute nitric acid is poured 

 upon it, both the colouring matter and oxide of silver are 

 dissolved, and the acid assumes the colour of urine. I 

 have not prosecuted this experiment, though it seems to 

 point out a method by which the colouring matter might 

 be insulated. If the silver precipitate were washed and then 

 put into water, and a current of sulphuretted hydrogen 

 passed through the liquid, it is probable that the silver 

 would be converted into sulphuret, while the colouring 

 matter would dissolve in the water. 



Urine when recently voided always contains an acid, at 

 least partly in an uncombined state; for it converts vege- 



