204  Artificial  Human  Milk.  {AmAprff;5&rm' 
young  infants  which  should  as  nearly  as  practicable  resemble  the 
mother's  supply,  when  that  supply  was  deficient  or  absent. 
The  literature  on  the  subject  was  principally  found  in  an  article 
by  Professor  Frankland  ("  Experimental  Researches,"  London,  1877, 
p.  843)..  Here  the  percentage  composition  of  human  and  cow's 
milk  was  given  as  follows  : 
table  1. 
Woman.  Cow. 
Casein,   V  . 27  4/2 
Butter,   3-5        3-8  • 
Milk-sugar,    5*0  38 
Salts  ;   -2  7 
A  glance  at  this  table  will  show  that  the  assimilation  of  the  two 
required  that  the  quantity  of  casein  present  in  cow's  milk  should  be 
decreased,  while  the  quantity  of  butter  was  maintained,  and  that  of 
milk-sugar  should  be  increased. 
In  the  case  of  the  addition  of  milk-sugar  the  increase  was  easy,  as 
a  supply  of  that  constituent  was  easily  obtained  to  augment  that 
which  was  already  in  the  natural  compound.  But  the  subtraction 
of  the  casein  was  not  so  simple  a  matter.  He  proposed,  however, 
to  accomplish  this,  to  remove  one-third  of  the  casein  from  cow's 
milk,  and  to  keep  the  butter  strength  as  it  was,  thus  giving  a  liquid 
having  a  composition  per  cent,  of : 
TABLE  II. 
Pet  Cent. 
Casein,   28 
Butter,   38 
Milk-sugar,   5'o 
Salts,   7 
The  mode  of  preparation  was  to  remove  the  cream  from  one- 
third  of  a  pint  of  new  milk  .  and  by  means  of  rennet  to  curdle  the 
skimmed  milk;  the  separated  whey  had  then  no  grains  of  milk- 
sugar  dissolved  in  it,  the  solution  being  added  to  the  remaining  two- 
thirds  of  a  pint  of  new  milk  and  the  cream  which  had  been  removed 
as  above. 
Although  very  good  results  could  be  obtained  by  this  process,  it 
had  the  disadvantage  of  being  wasteful  and  tedious.  A  simpler 
mode  of  working  was  therefore  thought  out  and  the  following  plan 
was  adopted. 
Water  was  used  in  the  place  of  the  whey,  and  extra  cream  sepa- 
