ON  THE  MEAT  BISCUIT  OF   GAIL  BORDEN. 
227 
have  been  discovered  to  exist  in  flesh,  and  the  various  salts  which 
form  an  important  ingredient  of  its  juice. 
In  the  part  which  flesh,  taken  as  food,  plays  in  nutrition,  it 
is  now  generally  admitted,  that  the  fat  serves  as  respiratory 
food,  the  carbon  and  hydrogen  of  which  it  is  composed  com- 
bining with  oxygen  in  the  course  of  the  circulation,  and  be- 
coming converted  into  carbonic  acid  and  water,  and  thus  main- 
taining the  animal  temperature.  What  escapes  oxidation  is 
either  stored  away  directly  as  fat,  for  the  future  use  of  the  sys- 
tem, or  passes  out  of  it  with  the  various  excretions.  The  fibrin 
and  albumen  serve  mainly  to  nourish  the  muscles,  imparting  by 
their  decomposition  strength  and  activity  to  the  body  and  main- 
taining the  activity  of  the  heart  and  of  the  various  other  mus- 
cles of  organic  life. 
It  cannot  consequently  be  admitted  that  the  meat  biscuit,  or 
any  similar  preparation,  contains  the  whole  nutriment  of  the 
flesh  from  which  it  is  made ;  on  the  contrary,  the  fibrin,  the 
albumen,  and  the  fat,  which  in  reality  constitute  its  most  nutri- 
tive portions,  are  removed,  and,  for  all  purposes  of  nutrition,  lost. 
What,  then,  are  its  advantages,  and  what  purpose  does  it  really 
serve  in  the  human  economy. 
"Fresh  meat  when  incinerated,"  says  Liebig,  " leaves  three 
and  one-half  per  cent,  of  the  weight  of  the  dried  flesh  as  salts. 
Meat,  exhausted  by  boiling,  leaves  hardly  one  per  cent.  Ten 
pounds  of  fresh  meat  yield  in  all,  42.93  grms.  (two  and  a  half 
oz.  avoirdupois,  or  662.8  grains ;)  but  when  these  ten  pounds  are 
exhausted  by  lixiviation  and  boiling,  544.7  grains  of  the  662.8 
enter  the  soup,  and  there  remains  in  the  meat  only  118  grains. 
The  fresh  meat  contains  in  its  ash  upwards  of  40  per  cent,  of 
potash,  the  exhausted  flesh  only  4.78  per  cent,  of  that  alkali." 
It  is  on  the  presence  of  these  salts,  we  believe,  that  the  restora- 
tive effects  of  soup  and  of  extracts  of  flesh  mainly  depend.  They 
are  essential  ingredients  of  the  body,  and  are  necessary  in  the 
minute  chemical  changes  of  which  vital  activity  is  the  product ; 
they  are  constantly  passing  away  with  the  excretions,  and  re- 
quired to  be  constantly  renewed ;  and  in  the  form  of  aliment 
under  consideration,  they  are  presented  to  us  in  a  condition  and 
in  proportions  best  suited  for  immediate  assimilation. 
Liebig  attributes  much  of  the  effect  of  extract  of  flesh  to  the 
kreatinine,  a  nitrogenous  compound,  somewhat  analogous  to 
