CHEMICAL COMPOSITION OF THE BODY. 



93 



Km. r>7. 



Taurin. 



of especial attention. They all clearly constitute successive steps in the 

 downward or retrogressive process of metamorphosis of the albuminous com- 

 pounds. 



ANIMAL QUINOIDINE. From the experiments of Dr. Bence Jones and 

 M. A. Dupre, 1 it appears there exists in the bodies of man and other verte- 

 brata a substance which can be extracted from any of the tissues by the 

 same process as quinine, when that alkaloid has been ingested and absorbed. 

 It possesses nearly the same chemical properties as quinine, and its solutions 

 o-ivo thi' well-known fluorescence characteristic of quinine. 



CHOLIC ACID, C, 4 H 40 O 5 , is obtained from glycocholic acid by the action 

 of alkalies. It crystallizes either in four-sided prisms with dihedral sum- 

 mits, in octaliedra, or in tetrahedra, which are easily soluble in alcohol, but 

 not readily in water or ether. On boiling with acids it yields dyslysin 

 (Co 4 H 36 O :! ), which is only soluble in 

 ether. Cholic acid has a pure bitter 

 taste, and when treated with nitric acid 

 it yields acetic, valeriauic, capronic, 

 oxalic, and cholesterinic acids. 



TAURIN, C.,H.NO 3 S, is found as a 

 constant constituent of the bile in com- 

 bination with cholic acid. It has also 

 been occasionally discovered in the 

 blood and urine, in the tissue of the 

 kidney, lungs, and of the striated mus- 

 cles. It forms large tasteless and col- 

 orless four- or six-sided prisms, with 

 four-sided pyramids at their extremi- 

 ties. It dissolves in fifteen parts of cold water, and the solution is neutral 

 to test-paper. Taurin is decomposed when subjected to a heat greater than 

 464 F. 



GLYCIN (Glycocol or Gum Sugar), C 2 H 3 (NH,)O 2 , is chiefly found in 

 combination with cholic acid in the bile, but it also occurs combined with 

 benzoic acid, as hippuric acid, in the blood and urine. It crystallizes in 

 large colorless rhombohedral crystals, which melt at 354 F., are easily 

 soluble in water, but with difficulty in alcohol. The solutions are acid to 

 test-paper, and sweet to the taste. It acts both as a base to acids, and as 

 an acid to alkalies. It originates as the product of the disintegration of 

 gelatin and of albumen, and has been artificially formed. 



GLYCOCHOLIC AND TAUROCHOLIC ACIDS, C, 6 H 43 NO 6 and C. 2f) H 44 NO.S. 

 When to a solution of crystallized ox-bile neutral acetate of lead is added, 

 a precipitate of glycocholic acid in combination with the oxide of lead falls, 

 and when this has been removed by filtration, 'the addition of the subacetate 

 of lead to the mother liquid causes the precipitation of the taurocholate of 

 the same metal. The amount of glycocholic acid contained in the bile of 

 man and of the carnivora is small, but in that of the ox it is abundant. 

 Both acids rotate the plane of polarized light to the right. Taurocholic 

 acid is easily soluble in water, and tastes very bitter. Glycocholic acid dis- 

 solves with difficulty. Glycocholate of soda crystallizes in acicular radiating 

 needles. Taurocholate of soda forms resinous drops. Dr. Daltou 2 observes 

 that the biliary acid or acids of the human subject are precipitated by both 

 the acetate and subacetate of lead. Pettenkofer's test for bile consists in the 

 addition of a little cane sugar, and then of a drop of sulphuric acid to the 



1 Proceedings of the Royal Society, vol. xv, No 83, p. 73. 



2 Human Physiology, 1867, p. 167. 



