AFebr°aYr'vT?9^m'}      Camparative  Composition  of  Milks.  59 
cent,  of  fat  when  mother's  milk,  and  fully  50  per  cent,  when  cow's 
milk  has  been  ingested  (the  moist  feces  contain,  of  course,  less  fat — 
J.  W.  E.).  The  function  of  the  fecal  fat  is  probably  to  protect  the 
mucous  surfaces  of  the  intestinal  tract,  and  to  facilitate  the  expul- 
sion of  the  feces."  ("  The  Fat  Question  in  its  Relation  to  the  Pro- 
duction and  Cure  of  Infantile  Marasmus,"  by  Heinrich  Stern,  Arch, 
of  Ped.,  1905,  431.) 
PERCENTAGE  COMPOSITION  OF  THE  SALTS  OF  MILKS 
Sodium  Chloride,  NaCl  
Potassium  Chloride,  KC1  
Mono-potassium  Phosphate,  KH2?04 
Di-potassium  Phosphate,  K2HP04  
Potassium  Citrate,  K3CeH507  
Di-magnesium  Phosphate,  MgHP04  . 
Magnesium  Citrate,  Mg3  (C6H50:)  2.. 
Di-calcium  Phosphate,  CaHP04  
Tri-calcium  Phosphate,  Ca3  (P04)  2—- 
Calcium  Citrate,  Ca3  (CttH507)  a  
Lime  combined  with  proteids  
Calcium  Silicate,  CaSi03  
Calcium  Sulphate,  CaS04  
Calcium  Carbonate,  CaC03  
Magnesium  Carbonate,  MgC03  
Potassium  Carbonate,  K2C03  
Potassium  Sulphate,  K2S04  
Iron  Oxide  and  Alumina  
Human  Milk 
Cow's  Milk 
Harrington  and  Kinnicutt, 
Soidner,  quoted 
quoted  by  Rotch 
by  Leach 
21.77 
10.62 
12.05 
9.16 
12.77 
9.22 
5.47 
3.71 
4.05 
Calcium  Phosphate 
7.42 
23.87 
8.90 
23.55 
5.13 
1.27 
2.25 
2.85 
3.77 
23.47 
8.33 
0.37 
100.00 
100. CO 
Rotch  gives  an  analysis  of  the  ash  of  human  milk  (six  quart 
sample)  by  Harrington  and  Kinnicutt,  and  a  statement  expressing 
an  approximation  to  the  relative  proportions  of  salts  in  the  form  in 
which  they  occur  in  milk  (as  stated  above),  but  it  is  very  obvious 
that  the  conclusions  from  the  analysis  are  practically  valueless, 
because  no  account  whatever  was  taken  of  the  organic  matter 
present  in  the  salts  of  the  milk. 
As  Soidner  has  shown,  nearly  one-third  of  the  salts  of  cow's  milk 
are  alkali-citrates  and  alkali-earth  citrates,  and,  as  LefTmann  states 
"  Citric  acid  (as  citrates)  is  a  normal  constituent  of  the  milk  of  various 
animals.  In  human  milk  the  quantity  is  about  0-5  gramme  to  the 
liter;  in  cow's  milk,  from  1  to  1-5  grammes.  It  is  not  dependent 
upon  the  citric  acid  present  in  the  food." 
