AmsStf/i?8h7arm"}     Quantitative  Estimation  of  Glycerol.  467 
to  about  200  c.c. ;  decompose  the  soap  with  dilute  sulphuric  acid, 
filter  off,  and  estimate  insoluble  fatty  acids  as  usual.  Vigorously  boil 
the  filtrate  and  washings  (amounting  to  about*  500  c.c.)  in  a  covered 
beaker  or  basin,  down  to  one  half,  add  25  c.c.  strong  sulphuric  acid 
(suitably  diluted)  and  50  c.c.  standard  bichromate.  Heat  to  near 
boiling  for  two  hours,  and  titrate  back  the  excess  of  bichromate  with 
excess. of  ferrous  sulphate,  and  ultimately  the  latter  ^vithdecichromate 
using  ferricyanide  as  indicator.  Calculate  from  the  chromate  con- 
sumed the  amount  and  percentage  of  glycerin. 
Finally,  I  will  add  a  few  results  obtained  on  applying  the  method 
to  a  few  fats  : 
Olive  oil...  ,.    10*26  per  cent,  glycerin. 
Cod  liver  oil   9  87  per  cent. 
Linseed  oil  <   10*24  and  10-20  percent. 
Butterine   10-01  per  cent. 
Butter   12-40  and  11-96  per  cent. 
Of  course,  I  am  fully  aware  that  other  substances,  should  they  be 
present,  might  reduce  bichromate  as  well  as  the  glycerin  does.  The 
analogous  objection  applies  to  Dr.  Muter' s  and  Mr.  Fox's  processes  ;  I 
have,  however,  convinced  myself  that  soluble  fatty  acids,  like  butyric, 
do  not  act  upon  bichromate,  nor  do  fatty  acids  of  higher  molecular 
value. 
The  method  may  not  be  theoretically  perfect,  but  it  may  commend 
itself  for  its  simplicity  and  rapidity  in  cases  of  fluids  which  cannot 
contain  anything  but  glycerin  and  soluble  fatty  acids. 
QUANTITATIVE  ESTIMATION  OF  GLYCEROL.1 
By  K.  Diez. 
The  methods  hitherto  employed  for  the  estimation  of  glycerol  in 
wine  and  beer  consist  in  dissolving  it  out  usually  by  alcohol  and 
ether  from  a  mixture  of  the  beverage  with  chalk,  and  finally  weighing 
the  glycerol.  Neubauer  and  Borgmann  (1879)  found  that  the  glycerol  so 
obtained  contained  2  per  cent,  of  mineral  constituents  and  0*4  per  cent, 
of  nitrogen.    Champion  and  Pellet  (1873)  devised  a  method  in  which 
1  Zeit  physiol.  Chem.,  xi.,  472-484.  Eeprinted  from  Jour.  Chem.  Soc,  August, 
1887,  p.  750. 
