ELEMENTS OF COMPOSITION. 



49 



discovered long ago as a constituent of the bile. It crystallizes with the 

 fundamental form of a right rhombic prism (whose lateral angles are 

 respectively 111 and 68 16'), in colourless six-sided prisms, with four 

 and six facets on their extre- 

 mities (fig. 31, a}. From im- 

 pure solutions it separates in 

 irregular sheaf-like masses (&). 



Taurin has no eifect upon 

 vegetable colours; it is toler- 

 ably soluble in water, but insol- 

 uble in alcohol and ether. The 

 great stability of the substance 

 is remarkable : even boiling in 

 mineral acids in which it dis- 

 solves does not decompose it. 

 Taurin is not precipitated from 

 its solutions by tannic acid and 



the metallic salts. The sulphur n * 31 - Cr >' stals of tanrin - 

 it contains was for a long time 

 overlooked ; .it is contained in it in a different combination to that 

 which exists in cystin. 



Taurin has recently been produced artificially. It is related to 



{OTT 

 SO H 



Isethionate of ammonium, when heated up to 200 C., according to 

 8trecJcer, yields taurin, with the loss of one molecule of water. 



a, well-formed six-sided 

 priMns; b, irregular sheaf-like masses from an im- 

 pure solution. 



S0 3 NH 4 



NH 

 SO,H 



Thus taurin is an amido-sulfethylenic acid. 



Kolbe obtained it also by the action of ammonia upon chlorethyl- 

 sulphuric acid. 



Taurin may be obtained by the splitting up of one of the two biliary 

 acids, and contains all the sulphur of the bile. It also becomes free 

 on the decomposition (commencing in the body) of this acid known as 

 taurocholic, and appears- thus in abnormal as well as putrid bile, and in 

 the lower portion of the intestinal canal (Frerichs). Tt has been also 

 met with by Cloetta in the juices of renal and pulmonary tissue. 

 As obtained from the latter source, it was formerly described by Verdeil 

 as pulmonic acid. The suprarenal capsule contains it also (Holm), though 

 the blood does not. 



At present we are uncertain as to the origin of taurin ; but it has all 

 the nature of a decomposition product, and there can be hardly any 

 doubt (from the fact of its containing sulphur) that it is derived from 

 albuminous matters, a considerable quantity of the sulphur of the latter 

 being present in it. 



In regard to its farther changes, an observation has been made by 

 Buchner of great physiological interest. Taurin, otherwise so stable, splits 

 up by the action of a ferment (namely, the mucus of the gall-bladder) 

 in the presence of alkalies, into carbonate of ammonium, sulphurous, 

 and acetic acids. The latter acid, combined with an alkali, is changed 

 into a carbonate, and the sulphurous acid in combination with sodium 

 becomes later converted by oxidation into sulphuric acid, so that in 



