Am.  Jour.  Pharm.  1 
July,  1915.  J 
The  Estimation  of  Fat. 
313 
petroleum  ether  (boiling-point  300  to  500  C),  and  about  10  or 
15  Cc.  of  95  per  cent,  alcohol  are  added.  This  is  titrated  with  N/20 
alkali,  using  about  two  drops  of  a  1  per  cent,  solution  of  phenol- 
phthalein  as  indicator.    The  end-point  is  sharp  and  distinct. 
With  a  sample  of  blood  an  alcohol  extraction  should  first  be  made 
as  recommended  by  Shimidzu.7 
With  a  safnple  rich  in  fat  we  recommend  that  saponification  be 
brought  about  in  the  presence  of  alcohol,  using  a  reflux  condenser 
to  prevent  loss  of  alcohol  during  boiling;  after  saponification  the 
alcohol  can  be  driven  off  by  boiling. 
The  following  tables  give  the  determination  of  the  fat  in  blood, 
liver,  and  clear  back  fat  of  pork  by  the  proposed  method : 
Table  IV. 
Blood. 
Weight  of 
sample 
No.  of  Cc.  of 
0.0400/ N 
NaOH 
Weight  of 
NaOH 
Weight  of 
fatty  acids 
Weight  of 
neutral  fat 
Fat 
Grammes 
Gramme 
Gramme 
Gramme 
Per  cent. 
20 
3.60 
O.OO72 
O.O498 
O.052I 
O.260 
20 
3-50 
O.OO70 
O.0484 
O.0506 
0.253 
10 
1.85 
O.OO37 
O.0256 
0.0268 
O.268 
9-5 
I.78 
O.OO36 
O.0246 
O.O258 
O.272 
Average  per  cent.,  0.263. 
Greatest  variation  from  average,  3.7  per  cent. 
Least  variation  from  average,  0.95  per  cent. 
This  fat  determination  shows  very  concordant  results,  and, 
although  it  differs  from  the  average  of  five  determinations  of  the 
same  sample  by  the  Shimidzu  modification  of  the  Kumagawa-Suto 
method,  it  will  be  noted  that  the  greatest  variation  from  the  average 
is  only  3.7  per  cent.,  compared  with  a  corresponding  variation  of 
28  per  cent,  in  the  results  from  the  Kumagawa-Suto  method. 
Table  V. 
Liver. 
Weight  of 
sample 
No.  of  Cc.  of 
0.0409/N 
NaOH 
Vv'  eight  of 
NaOH 
Weight  of 
fatty  acids 
Weight  of 
neutral  fat 
Fat 
Grammes 
Gramme 
Gramme 
Gramme 
Per  cent. 
IO 
1345 
0,0265 
O.1834 
O.I918 
I.918 
10 
13-50 
O.0270 
O.1842 
O.I927 
I.927 
10 
14.50 
O.O290 
0.2005 
0.2097 
2.097 
Average  per  cent.,  1.981. 
7  Shimidzu :  Loc.  cit. 
