Am.  Jour.  Pharm. 
July,  1915. 
The  Estimation  of  Fat. 
In  order  to  determine  whether  the  large  amount  of  cholesterol 
and  other  unsaponifiable  substances  in  the  blood  soluble  in  petroleum 
ether  has  really  a  great  deal  to  do  with  the  fluctuation  of  results, 
we  determined  the  amount  of  fat  in  the  liver  of  the  same  cow  from 
which  the  blood  was  obtained,  since  it  is  stated  by  Paton  5  that  the 
liver  contains  only  about  0.3  to  0.05  per  cent,  of  cholesterol. 
One  hundred  grammes  of  liver  were  saponified  and  made  up  to 
volume,  1000  Cc,  with  water;  100  Cc.  aliquots  representing  10 
grammes  of  sample  were  then  taken  and  analyzed. 
Table  II. 
Liver. 
Weight  of 
sample 
Weight  of 
fatty  acids 
and  unsaponi- 
fiable sub- 
stances 
Weight  of 
unsaponifiable 
substances 
Weight  of 
fatty  acids 
Weight  of 
neutral  fat 
Neutrai  fat 
• 
Grammes 
Gramme 
Gramme 
Gramme 
Gramme 
Per  cent. 
10 
O.2125 
O.OI94 
O.I931 
0.2020 
2.020 
IO 
0.2205 
O.O273 
0.1934 
0.2023 
2.023 
It  is  interesting  to  note  how  closely  these  two  results  agree, 
within  0.003  Per  cent.  The  amount  of  unsaponifiable  substances 
in  the  liver  soluble  in  petroleum  ether  is  over  10  per  cent,  of  the 
total  amount.  This  close  agreement,  it  seems  to  us,  would  indicate 
that  the  less  the  amount  of  unsaponifiable  substances,  the  less  the 
errors  introduced,  regardless  of  the  other  errors  enumerated  above. 
Table  III. 
Clear  Back  Fat  of  Pork. 
Weight  of 
sample 
Weight  of 
fatty  acids 
and  unsaponi- 
fiable sub- 
stances 
Weight  of 
unsaponifiable 
substances 
Weight  of 
fatty  acids 
Weight  of 
neutral  fat 
Neutral  fat 
Gramme 
Gramme 
Gramme 
Gramme 
Gramme 
Per  cent. 
O.2826 
O.2404 
0.0010 
O.2394 
O.2504 
88.62 
O.2826 
O.2356 
O.OOO9 
O.2347 
0.2455 
86.87 
We  next  determine  the  fat  in  a  sample  of  fresh,  clear  back  fat  of 
pork.  We  weighed  out  2.8262  grammes  and  added  50  Cc.  of  95  per 
cent,  alcohol,  and  saponified  it  for  three  hours  under  a  reflux  con- 
5D.  N.  Paton:  Jo  urn.  Physiol,  xix,  p.  191,  1895-96. 
