THE FATS. 19 
Under the influence of superheated steam, mineral acids, and in the 
body by means of certain ferments (for instance, the fat-splitting 
ferment <»f the pancreatic juice), a fat combines with water and splits 
into glycerin and the tatty acid. The following equation represents 
what occurs in a fat, taking tripalmitin as an example: — 
C 3 H 6 (O.Cy I :; ,< ( ) > 3 +3] L< ) = ( \,H,( OH) 3 +3C 16 H 31 ( '< ).OH 
(palmitin — a fat) (glycerin) (palmitic acid —a 
fatty acid) 
Saponification. — In the process of saponification much the same sort 
of reaction occurs, the final products being glycerin and a compound of 
the base with the fatty acid, which is called a soap. 
Suppose, for instance, that potassium hydrate is used, we get — 
C 3 H fl (().C,-H :;1 ( !( >) 3 +3KHO = C 3 H 5 (OH) 3 +3C 15 H 31 CO.OK 
(palmitin — a fat) (glycerin) (potassium palmitate 
— a soap) 
To separate the neutral fats from one another, they have always to be 
saponified ; this can be accomplished by potassium hydrate, or still 
better by sodium alcoholate (Kossel, Obermiiller, and Kriiger). 1 On 
evaporation of the alcohol, the soaps are dissolved in water, and pre- 
cipitated by sugar of lead ; the lead compound of oleic acid is solul >le in 
ether: the remaining soaps are treated with soda on the water bath, 
dried, dissolved in alcohol, and separated by fractional precipitation with 
barium acetate or barium chloride. 
In the decomposition of fat, propionic, acetic, and formic acids may 
be found, which are absent from the fat in the fresh condition. This 
occurs when the fat becomes rancid, and is also produced by putre- 
factive organisms in the alimentary canal. The process is one of 
oxidation, and the way in which lower terms of the series are produced 
may be illustrated by the following equations: — 
C :j H A+O., = C,H 4 0,+C0 2 +H 2 0. 
(propionic acid) (acetic acid) 
C,H 4 (\+0 3 =CH 2 2 +C0 2 +H 2 0. 
(acetic acid) (formic acid) 
2CH 2 0,+0 2 =2C0 2 d-2H 2 0. 
(formic acid) 
EmtihificaJion, — Another change that fats undergo in the body is very 
different from saponification. It is a physical rather than a chemical 
change ; the fat is broken up into very small globules, such as is seen in 
the natural emulsion — milk. 
The fats of milk resemble in a general way those of adipose tissue, 
but there is a considerable admixture of glycerides lower in the series 
(see " Milk "). 
The fats of marrow are also like those of adipose tissue. As will be 
noticed in the table on p. 17, bone marrow is the tissue which is richest 
of all in fat. 
Eylert 2 described a new fatty acid in the marrow of ox-bone which he 
called medullic acid, but this was shown by Mohr 3 to be only stearic acid. 
1 Numerous papers in vols, xiv., xv. , and xvi. of Ztschr. f. physiol. Chem., Strassburg. 
2 Vrtljschr. f. prakt. Pharmakol., Bd. ix. S. 330. 
3 Ztschr. f. physiol. Chem., Strassburg, 1890. Bd. xiv. S. 390. 
