C1IKMICAL BASIS (] TIIK ANIMAL 1J>I)Y. 107 



tain ( -onstitnents of the brain substance, and was named by 



him ceivhrosc, is really identical with galactose. 1 



(ialaetose is fermentiblr with yeast, ItuL less readily so than is 

 dextrose. 



I. Glycuronic acid. C,H 10 O 7 . [COH -,< II .< Mi ,,<<>< >H]. 



This acid was first obtained as a compound, campho-gljCUIOnic 

 acid, in the urine of do^s after the administration of camphor,- 

 and sul)sequently as urochloralic acid after tin- administration 

 hloral. :; Sine.- then it has been found in urine a> ethereal or 

 iducose-like compounds, with an extensive series of members of 

 the fatty or aromatic series after the introduction of the ap- 

 propriate substances into the animal body. 4 It is probable 

 that traces of compounds of this acid occur normally in urine, 

 sine,- tin- excretion is usually slightly la-vo-rotatory, and it is 

 known that indol and skatol which are formed in the alimentary 

 canal readily reappear in the urine as compounds of glycu- 

 ronic acid; viz. indoxyl- and Bkatoxyl-glycuronic acid, when intro- 

 duced into the body. The compounds of glycuronic acid are 

 all la-vo-rotatory, and some of them reduce metallic salts on 

 boiling, and may hence lead to errors in the determination of 



i in urine. 



Glycuronic acid does not occur in the free state in the animal 

 body. Chemically it is closely related to dextrose; when oxi- 

 di>ed with bromine it yields saccharic acid, 6 C 6 H 10 O8, [COOH - 

 (i I. OH) 4 -COOH], an acid which is also readily obtained by 

 the oxidation of dextrose with nitric acid. Saccharic acid can he 

 converted into glycuronic acid by reduction with sodium amal- 

 ^am.' ; Like dextrose, glycuronic acid is dextro-rotatory, but to a 

 extent, (a) = -f- 194, reduces Fehling's Huid to the same 

 tit as does dextrose, and forms with phenyl-hydra/.in a yellow 

 -talline compound which melts at 114 115. The acid jv 

 known only as a syrup soluble in alcohol and water. When 

 boiled in the latter solvent it loses a molecule of water and yields 

 an anhydride (lactone), CH 8 0, which is crystalline, insoluble in 

 alcohol, soluble in water, dextro-rotatory, ami reduces Fchling's 

 fluid powerfully. 



I Thierfcldcr, '/A. f. />// //W. f '/,///, 15,1 \i\. ( 1-vn. s. ^t'.i Hrown and Murri-. 

 Jl. CA .1. i MI. (is'.to), p. 57. 



n M.-x.-r, 7.1. /: phi/ai'ol. Cli> w IM. in. (IH7H), S. 422. 

 rin K . H.,,1. IM.'vi. (|HS L .), S. l-o 



4 For vory full li.t ..f tin- \;iri..ii( Htilwtances which when introduced into tlu> body 

 n-:i|ip-;ir in the urine as paired compounds itli ^Ixcuronic acid, and for references 

 to date (l-'.iit) to the literature "f the .-iitij-M-t, see Neiiliauer u. Vo^el, //iiriniini' 

 Kd. i\ l-'iu. p. nr, 



'> Thierfelder. /.' / ,>l,,/xiol. Cliem. Bd. xi (1887), S. 388. Sec also Bd. MII ' 

 (I88'.r, - 



1 i- u Pilot v, If,;-. ,1. ,1 chem Gciell. Jahrg. xxiv. (1891). S. :,ji. 



