296 THE URINE. 



causes the sediment to be red of various hues, according to the 

 proportions ; and, when the colouring matter is absent, as in hectic, 

 the sediment is pink. b 



Various odorous and coloured principles pass off with the urine ; 

 as turpentine, balsams, asparagus, on the one hand, and red fruits, 

 cactus opuntia, rhubarb, indigo, &c. on the other. Mercury, iron, 

 and prussiate of potass will enter into it ; as well as tartaric, oxalic, 

 gallic, succinic, benzoic, malic, and citric acids, or at least these 

 will render it acid. Alkaline borates, carbonates, silicates, chlo- 

 rates, and nitrates, also pass off by the kidney. But the neutral 

 salts of potass and soda with vegetable acids are decomposed ; the 

 alkali only, in the state of carbonate, being found in the urine. 

 Mineral acids, alcohol, camphor, empyreumatic animal oil, musk, 

 cochineal, turnsol, le vert de vessie, and orcanette, with the oxides 

 of iron, and preparations of lead and bismuth, when taken, are 

 not found in it. c 



The urine may be deranged as remarkably as the sweat. For it 

 is sometimes blue, from containing indigo not taken into the 

 system, as I have seen through the kindness of Dr. Prout, and from 

 other substances ; and blueness of it appears to be produced some- 

 times by Prussian blue swallowed. Sometimes it is black, perhaps 

 from containing a peculiar acid, called melanic, without any 

 danger to the health. Dr. Prout has shown me two specimens of 

 this, in which the sediment was perfectly black ; and it may con- 

 tain not only the albumen and red particles of the blood, but 

 absolutely sugar, and occasionally new substances found nowhere 

 else. 



The urine of birds is generally discharged with the faeces, becomes solid by 

 exposure to the air, and contains a large quantity of biurate of ammonia. Urea 

 exists in the urine of carnivorous birds, not in that of the herbivorous. Dr. Wol- 

 laston found the uric acid to be only ^ in a goose feeding on nothing but grass ; 

 and in birds taking nothing but animal food, to constitute nearly the whole mass. 

 That of serpents is discharged only once in some weeks, is of a caseous consist- 

 ence, and likewise becomes perfectly solid afterwards. It is almost entirely uric 

 acid, and superurates of potass, soda, and ammonia. d The urine of the turtle 



r> Gultstonian Lectures delivered before the College of Physicians. London 

 Med. Gazette, 1833. 

 c Berzelius, 1. c. 

 d Dr. Prout, Thomson's 4nnak of Philosophy. Dr. Davy, Phil. Trans. 1818- 



