3H 
The  Estimation  of  Fat. 
Am.  Jour.  Pharm. 
July,  1915. 
Table  VI. 
Clear  Back  Fat  of  Pork. 
Weight  of 
sample 
No.  of  Cc.  of 
0.0409/N 
NaOH 
Weight  of 
NaOH 
Weight  of 
fatty  acids 
Weight  of 
neutral  fat 
Fat 
Grammes 
Gramme 
Gramme 
Gramme 
Per  cent. 
O.2825 
17.62 
O.0352 
O.2437 
O.2549 
90.18 
0.2826 
17.60 
O.O35I 
O.2434 
O.2546 
90.08 
Average  per  cent.,  90.13. 
Table  VII. 
Comparison  of  Three  Methods. 
Substance 
Blood  
Blood  
Blood  
Liver  
Liver  
Liver  
Back  fat  of  pork 
Back  fat  of  pork 
Back  fat  of  pork 
Method 
Soxhlet  
Kumagawa-Suto . 
Proposed  method 
Soxhlet  
Kumagawa-Suto . 
Proposed  method 
Soxhlet  
Kumagawa-Suto . 
Proposed  method 
Fat 
0.000 
0.400 
0.263 
2.722 
2.021 
1.981 
90.13 
87.74 
90.13 
As  can  be  seen  from  Table  VII,  the  Soxhlet  method  does  not 
compare  at  all  favorably  except  when  working  with  almost  pure  fat. 
With  the  blood  the  ether  did  not  extract  anything,  while  with  the 
liver  it  extracted  35  per  cent,  of  substances  other  than  fat.  This 
agrees  with  Paton  (1895),  who  claimed  that  lecithin  is  a  constant 
constituent  of  ether  extract  of  liver.  The  Kumagawa-Suto  method 
has  many  possibilities  of  error,  as  has  been  pointed  out  previously, 
and  is  time-consuming.  The  proposed  method,  on  the  other  hand, 
is  very  short  and  by  no  means  complicated.  In  titrating,  a  molecular 
weight  has  to  be  assumed.  Kumagawa  and  Suto,  in  working  with 
fats  of  different  animal  organs,  claim  that  in  the  main  they  consist 
of  70  per  cent,  oleic  acid,  20  per  cent,  palmitic  acid,  and  10  per  cent, 
stearic  acid.  This  proportion  would  give  an  average  molecular 
weight  of  277.  The  use  of  an  arbitrary  acid  molecular  weight  of 
277  cannot  account  for  the  difference  in  the  fat  in  the  blood  from 
that  found  by  the  Kumagawa-Suto  method,  as  the  use  of  an  oleic 
acid  molecular  weight  of  282  would  raise  the  average  per  cent,  of 
fat  in  the  blood  to  only  0.270.    Similarly,  in  converting  the  acid  into 
