CLE A VAGE PRODUCTS OF THE BILE ACIDS. 379 
It crystallises in colourless rhombohedra, or in four sided prisms, which have 
a sweet taste and dissolve easily in cold water (1 in 4'3) ; in alcohol and other 
they are insoluble. Glycocoll, like other amido-acids, can act chemically, either 
as a base or an acid in forming compounds with acids and liases respectively. 
As a type of these combinations with bases, the copper compound may be 
taken. When freshly precipitated cupric hydrate is added to a warm con- 
centrated solution of glycocoll, it dissolves to form a deep blue solution, which 
is not reduced on boiling ; on cooling this solution, or on adding alcohol and 
allowing to stand, line dark blue needles crystallise out of the composition 
(XH 2 .CH 2 .COo) 2 Cu,H,0. Glycocoll has been obtained synthetically by the 
action of ammonia on monochloracetic acid thus : — 
NH 8 + CH,.C1— COOH = CH 2 .(XtL)— COOH + HC1. 
Taurine, is amido-isethionic acid, also called amido-oxyethylsulphonic 
acid (NH2.C2H4.SO.jOH). 1 It occurs in the body, apart from the bile, only 
in minute and inconstant traces : it has been stated to occur in the lungs 
and kidneys of oxen, in some of the organs of cold-blooded animals, and 
in inconstant traces, probably due to the decomposition of taurocholates, 
in the intestine. The presence of sulphur in its molecule shows it to be 
formed from proteids in the body; but the intermediate steps in its 
formation are unknown. 
Taurine is very easily crystallised, and forms large colourless prismatic 
prisms with a glassy glance, 2 without any taste, and gritty between the teeth, 
neutral in reaction and very stable, not being altered by a temperature of 
240 °C. ; heated above this temperature they melt and decompose in so doing. 
It is much less soluble in cold water than glycocoll, but still easily soluble 
(1 in 15*5), and still more so in hot water; in alcohol and ether it is insoluble. 
It is soluble in concentrated sulphuric and nitric acids without decomposition, 
and the latter acid may even be boiled off, leaving it unaffected ; neither is it 
affected by boiling with aqua regia. To alkalies also it is much more stable 
than glycocoll ; it is not affected by weak alkalies, and only by continued 
boiling in strong alkaline solution is slowly broken up into ammonia, acetic, 
and sulphurous acids ; so that it is one of the most stable of the organic 
compounds found in the body. Taurine is also a much more neutral substance 
in its chemical behaviour than glycocoll ; it does not combine at all with acids, 
and its affinity for bases is very feeble. An amorphous mercury compound is 
however obtained by boiling a solution of taurine with freshly-precipitated 
mercuric oxide. 3 
The constitution of taurine is shown by its synthesis from chlorethyl- 
sulphonic acid by the action of ammonia. 4 
,C,H 4 C1 (UI.XH, 
SO/ + 2 NH 3 =SO/ +NH 4 C1 
x OH x OH 
This synthesis, as well as the fact that taurine is not saponified by 
dilute alkalies, shows that taurine is not an ester but a sulphonic 
derivative ; that is, that the sulphur atom is united directly to carbon, 
and not indirectly by oxygen. Taurine may also be obtained by heating 
1 The amido-oxyethyl radicle is directly united to sulphur in the molecule. 
2 Gmelin, " Verdammg nach Verauchen," S. 60. 
3 Lang, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1876, Bd. vi. S. 74. 
4 Kolbe, Ann. d. Chem., Leipzig, 1862, Bd. cxxii. S. 33. 
