682 ANIMAL PHYSIOLOGY. 
These neutral fats are insoluble in water and cold alcohol, soluble in hot 
alcohol, ether, chloroform, etc. 
By the action of caustic alkalies or superheated steam they may be 
readily decomposed into glycerin and their fatty acids. 
Saponification may be thus represented : 
0.0C.CisHa1 
CHs < 0.00.CisHs: + 3KOH = CsH;(OH)s + 8CisHs1.COsK. 
0.0C.CisHs1 
Palmitio. Glycerin. Potassium pa‘mitate. 
It:is known that fats are not only emulsified in the alimentary tract, 
but split up into their component fatty acids and glycerin. A certain 
proportion of soluble soaps are formed and taken into the blood; some 
insoluble soaps appear in the fzeces. 
But the chemical changes of fats, destructive and constructive, effect- 
ed by the organs that prepare food to become blood, are doubtless very 
complex, and in large part as yet unknown. 
Glycolic Acid Series. 
CH:0H 
CH.OH’ 
glycols being C,H.,4.0.—i. e., the glycols are diatomic alcohols, from 
which acids may be obtained by oxidation, thus : 
Glycol may be formulated thus : the general formula of the 
CH.OH ,_COH 46 
éu,0H +’ ~ Gaon ***”’ 
Glycol. Glycolic acid. 
By additional oxidation a member of the glycolic series may be con- 
verted into one of the oxalic series, thus : 
CO.H : 
22> 2 P] H O. 
GH.OH + O2 = (CO2H)s + Ha 
Glycolic acid. Oxalic acid. 
, ‘ /OH 
1. Lactic acid. CsHoOs or C2Hs’ 46,77: 
Exists in four isomeric conditions, three of which have been found in 
the mammalian (human) body. These have the following properties in 
common: Are sirup-like in consistence, colorless, soluble in water, alco- 
hol, and ether ; have an extremely sour taste and a strong acid reaction. 
They form salts (lactates) with the metals. (a) Ordinary lactic ger in 
active ethylidene-lactic acid, a hydroxyl-propionic acid, on..cHQE. 
This is the form of lactic acid that occurs in the fermentation of milk. 
It is found in the contents of the stomach, intestines, and pathologically 
in the urine. (b) Ethylene-lactic acid. This isomer of lactic acid 
occurs, though there is some doubt about the subject, in muscle. (Cc) 
Sarcolactic acid, active ethylidene-lactic acid, CHs.CH(Q6,m- This 
acid may be readily obtained from flesh, and is therefore found in abun- 
dance in the “meat extracts.” It is the only one of the lactic acids 
