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CHAPTER VII. 



THE URINE. 



THE urine is an extremely complex fluid, but the relative 

 proportions of its different constituents are not very variable. 

 The following are the ordinary constituents of healthy human 

 urine : urea ; uric acid ; [hippuric acid] ; extractive matters, 

 embracing alcohol- extract, spirit-extract, and water-extract, 

 with their respective constituents; mucus; brown colouring 

 matter of the urine (hsemaphsein) ; red colouring matter of the 

 urine (uroerythrin) ; carbonic, lactic, hydrochloric, sulphuric, 

 phosphoric, silicic, and hydrofluoric acids; 1 soda; potash; 

 ammonia ; lime ; magnesia ; and peroxide of iron. 



Recently discharged urine ordinarily possesses the mean tem- 

 perature of the body ; it is of an amber yellow colour, perfectly 

 transparent, has a well-marked acid reaction, and exhales a 

 peculiar but not disagreeable odour, which it loses on cooling. 

 Its specific gravity fluctuates from 1005 to 1030, the average 

 being about 1012-5. It has a saline and disagreeably bitter 

 taste ; it undergoes no apparent change upon being heated to 

 the boiling point, and its behaviour towards reagents is depen- 

 dent upon that of its various constituents, although modified by 

 the very dilute state in which they occur. Acids, with the 

 exception of the oxalic, which produces a turbidity, throw down 

 no precipitates ; the free alkalies, on the contrary, throw down 

 the phosphate of lime; the salts of baryta, silver, and lead, 

 cause precipitates ; so also does tannin, but in a less degree. 



When urine is left to itself for some time, slight nebula, con- 

 sisting of mucus, are formed in it, which gradually descend to 

 the bottom. Soon after the appearance of this phenomenon, 

 an unpleasant odour is developed; instead of an acid, an alkaline 



1 [In addition to these constituents, two new acids, to which no names have been 

 yet assigned, have been described by Pettinkofer and Heintz.] 



ii. 8 



