58 
Comparative  Composition  of  Milks. 
Am.  Jour.  Pliarm, 
February,  1908. 
juice  does  not  act  on  fat,  but,  on  the  contrary,  on  fatty  tissue,  dis- 
solving the  cell  membrane,  and  setting  the  fat  free."  (Hammar- 
sten's  Ph'y  Chemistry,  1896,  166.)  The  percentage  of  sugar  re- 
mains practically  stationary,  the  sugar  evidently  not  being  an  inter- 
fering factor  in  the  digestion  of  proteids  or  fat. 
To  determine  accurately  the  composition  of  human  milk,  a  sample 
of  the  entire  quantity  from  both  breasts  should  be  analyzed,  which 
is  rarely  done ;  hence,  to  a  degree,  the  widely  varying  results 
published  ot  analyses  of  human  milk. 
PERCENTAGE   COMPOSITION   OF  THE  FATS   OF  MILKS 
(Fats  as  Fatty  Acid  Glycerides,  Olein,  Palmitin,  Stearin,  etc.) 
Fat  of  Human  Milk  (Stern) 
f  Acid  Butyric, 
"  Caproic, 
"  Caprylic, 
"  Capric, 
Acid  Laurie, 
"'  Myristic, 
"  Palmitic, 
"  Stearic, 
C4H802  1 
C6H1202  I 
C8H1602  , 
C10H20O2j 
\  1-4 
C14H2802  I 
C16H3202  \& 
Ci8H3602 
Dioxystearic,  C18H3604 
Oleic, 
C18H3402  49.4 
Fat  of  Cows'  Milk  (Brown; 
5.45] 
2.09 
0.49 
0.32 
!.35 
2.57] 
9.89  J 
38.61  ^53.90 
1.83  J 
1.00  J 
32.50 
Fat  of  Human  Milk. — Very  small  amount  of  volatile  fatty  acids ; 
oleic  acid  forms,  practically,  one-half  of  the  non- volatile  acids ;  of 
the  solid  fats,  myristic  and  palmitic  acids  occur  in  larger  amounts 
than  stearic  acid. 
Fat  of  Cow's  Milk. — Volatile  fatty  acids,  about  six  times  that  of 
human  milk ;  oleic  acid  constitutes  nearly  one-third  of  the  non- 
volatile acids  ;  of  the  solid  fats,  palmitic  and  stearic  acids  predom- 
inate. 
The  rancidity  "  of  milk-fat  (butter)  is  due  to  the  oxidation  of 
the  glycerides  of  the  volatile  fatty  acids. 
The  fat  of  human  milk  is  always  incompletely  absorbed  by  the 
infant  economy,  the  fat  content  of  dry  feces  ranging  between  10  and 
20  per  cent.  The  younger  the  infant  the  larger  the  amount  of  un- 
absorbed  fat.  "  During  the  first  week  of  life  the  dried  feces  contain 
(Die  Faeces.    Schmidt  and  Strasberger,  1903  ;  by  Blauberg)  40  per 
