^"^(^lyi^Gcd  BeseaTches  and  Investigations.  597 
following  manner :  From  4  to  8  grams  of  tlie  fatty  acid  mixture  to  be 
tetedj  according  to  the  greater  or  less  amount  of  neutral  fat,  are 
dissolved  by  the  aid  of  heat,  in  a  flask  of  about  300  cubic  centimeters 
capacity,  in  50  cubic  centimeters  of  strong  alcohol ;  after  the  addition 
of  a  few  drops  of  phenolphtalein  sokition,  alcoholic  one-half  normal 
alkali  solution  is  added  from  a  burette  until  the  red  color  no  longer 
immediately  disappears  upon  agitation,  and  the  solution  is  then  diluted 
with  150  cubic  centimeters  of  water.  An  alcohol  is  thus  formed  of 
from  20  to  25  per  cent.,  in  which  the  neutral  fats  are  practically 
insoluble,  while  the  potassium  soaps  dissolve  to  a  perfectly  clear  liquid. 
After  cooling,  60  to  100  cubic  centimeters  of  ether  are  added,  the  flask 
closed  with  a  cork,  and  actively  agitated,  and  then  allowed  to  repose 
until  the  soap  solution  below  the  etherial  layer  has  become  perfectly 
clear.  The  larger  portion  of  the  clear  soap  solution  is  then  removed 
from  the  flask  by  means  of  a  pipette,  with  the  precaution  not  to  remove 
the  supernatant  etherial  layer,  subsequently  largely  diluted  with  water 
and  heated  to  boiling  until  the  ether  and  alcohol  have  become  perfectly 
dissipated.  The  fatty  acids  are  afterwards  liberated  by  means  of  dilute 
sulphuric  and  hydrochloric  acids,  and  when  they  have  become  perfectly 
separated  as  au  oily  layer  they  are  washed  with  hot  water  until  the 
latter  no  longer  shows  an  acid  reaction,  and  afterwards  allowed  to  cool. 
If  the  fatty  acids  solidify' to  a  compact  mass  this  is  removed  without 
consideration  of  the  portions  that  remain  attached  to  the  sides  of  the 
vessel ;  if,  however,  the  fatty  acids  remain  liquid  the  larger  part  is 
removed  by  means  of  a  pipette.  The  equivalent  weight,  or  the  weight 
which  is  exactly  saponified  by  1  liter  of  normal  alkali,  is  now  deter- 
mined, after  the  fatty  acids  have  been  previously  carefully  dried ;  one- 
half  normal  alcoholic  potassa  solution  being  applied  in  the  process  of 
filtration. 
The  number  of  (;ubic  centimeters  of  normal  alkali  required  for  the 
neutralization  of  tlie  free  fatty  acids  in  the  normal  mixture  of  fats, 
multiplied  by  the  thousandth  part  of  the  equivalent  weight  thus  found, 
gives  the  amount  of  the  therein  contained  fatty  acids,  and  therewith 
also  the  amount  of  the  admixed  neutral  fat. — Ibid.,  from  Dingl.  Polyt. 
■Jour.,  244,  p.  303. 
A  nev)  MetJ tod  of  Detecting  and  Removing  thelm/purities  of  Chloroform. 
By  Ivon. — Potassium  permanganate  is  reduced  by  im[)ure,  but  not 
by  ])ur()  chloroform.  A  solution  of  1  gram  of  potassium  perman- 
ganate in  10  grams  of  an  alcoholic  potassa  solution  and  250  grams  of 
-water,  whi(;h  possesses  a  beautiful  violet  color,  assumes  immediately 
