APPENDIX. 689 
not found in the free state as yet in the body, it may be split off from 
bile acids and hippuric acid. 
Taurin, C:H,NO.S, or GHCQG?H. 
This is an amido-isethionic acid, and may be made artificially by a 
laboratory synthesis, as well as derived from the taurocholic acid of the 
bile. It assumes the form of large prisms, soluble in water, and is a 
remarkably stable compound. Taurin has been extracted from several 
organs of the mammalian body. 
Leucin. OsHisNO. or CHs, CH2.CH:CH>.CH(NH:).CO;:H—i. e., an 
amido-caproic acid. 
This compound, which may be obtained from the pancreas, spleen, 
thymus, and thyroid bodies, the liver, etc., and occurs as a product of 
natural and artificial pancreatic digestion, and in the urine in acute 
atrophy of the liver, in thin whitish, glistening, flat crystals, soluble in 
water... Leucin is one of the chief products of the decomposition of 
nitrogenous (proteid) matter. 
/CONH: 
Asparagin. (,H.N:Os, or O.Hs(NH2)(G6, 47 ie. 
Amido-succinamic acid. 
Found in many plants—as asparagus, licorice, beets, peas, beans, ete. 
—but not in the animal body, so far as is yet. known. 
Aspartic acid (or Amido-succinie acid). 
CAH:NO, or ChH(NH)( G07. 
Found, like the preceding, most abundantly in seeds, but said also to 
occur, in minute quantity, among the products of pancreatic digestion. 
Glutaminic acid. CsH»NO.. 
Seems to occur, under similar natural conditions, to those giving rise 
to the preceding compound. It has not, however, as.yet been shown to 
arise in the digestive processes of animals. 
Cystin. CsH:NSO:. 
By some chemists this compound is believed to be an amido-acid. It 
appears occasionally in the urine, but is chiefly of importance as making 
up the greater part of certain urinary calculi in men, dogs, etc. The 
body is crystalline : insoluble in water, alcohol, and ether, but soluble 
in ammonia, other alkalies, and the mineral acids. 
Acids of the Benzine or Aromatic Series. 
Benzoic acid. C.Hs.COsH. 
The acid itself is not known to exist in the body, but may arise in 
urine, especially that of the herbivora, from fermentative decomposi- 
tion : 
C.H»NOs + H.0 = C:HsNO. + C:He0s. 
‘Hippuric acid. Glycin. Benzoic acid. 
Benzoic acid is very sparingly soluble in water, but readily dissolved 
by alcoho] and ether. 
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