358  COMBINATION  OF  GLYCERINE  WITH  ACIDS. 
between  fatty  substances  and  ethers  was  first  pointed  out  by  M. 
Chevruel. 
M.  Pelouze  has  attempted  the  inverse  operation,  that  of  reuniting 
glycerine  with  the  acids,  in  the  same  manner  as  alcohol  is  com- 
bined with  these  substances.  He  has  succeeded,  on  the  one  hand, 
in  obtaining  by  direct  union  sulphoglycerates  and  phosphoglycerates 
analogous  to  the  sulphovinates*  ;  on  the  otherf ,  in  combining 
glycerine  with  butyric  acid,  the  most  readily  etherizable  of  all  the 
acids. 
Butyrine,  the  only  neutral  fatty  substance  which  has  hitherto 
been  reproduced,  is  obtained  by  indirect  etherification,  by  causing 
either  sulphuric  or  hydrochloric  acid  to  act  upon  a  mixture  of  gly- 
cerine and  butyric  acid. 
.1  have  succeeded  in  combining  glycerine  with  other  acids, 
namely,  the  acetic,  valerianic,  benzoic  and  sebacic  acids,  and 
others.  The  process  which  furnished  these  compounds  is,  with 
some  modifications,  that  which  is  employed  to  etherize  the  fatty 
acids,  and  which  furnished  butyrine  to  MM.  Pelouze  and  Gelis.  I 
mix  the  dry  acid  with  syrupy  glycerine,  heat  the  mixture  to  212° 
F.,  pass  through  it  a  current  of  hydrochloric  acid  gas  during  several 
hours,  keeping  the  mixture  at  that  temperature,  and  then  allow  it 
to  cool  in  the  current  of  gas.  I  then  leave  the  whole  at  the  ordi- 
nary temperature  for  several  hours,  days,  or  even  weeks,  if  neces- 
sary repeating  the  action  of  the  hydrochloric  acid.  After  the  lapse 
of  a  longer  or  shorter  time,  the  compound  is  produced  ;  to  isolate 
it,  it  is  only  necessary  to  saturate  the  mixture  with  carbonate  of 
soda.    It  is  purified  by  repeated  washings  and  the  usual  processes. 
The  above-mentioned  compounds  are  oleaginous,  and  scarcely, 
if  at  all,  soluble  in  water.  They  are  neutral  substances,  incapable  of 
uniting  immediately  with  the  alkaline  carbonates.  Alkalies  attack 
them  slowly,  saponifying  them;  in  this  way  they  all  regenerate 
the  acid  from  which  they  are  derived,  the  glycerine  being  isolated. 
They  may  also  be  decomposed  in  an  analogous  manner  by  satu- 
rating their  alcoholic  solutions  with  muriatic  acid,  a  process  em- 
ployed by  Rochleder  for  the  extrication  of  the  glycerine  from 
castor  oil.  In  this  manner,  after  a  repose  of  twenty-four  hours, 
glycerine  and  the  ether  of  the  acid  employed  are  obtained.  All 
*  Berzelius  subsequently  prepared  the  tartroglycerates. 
t  Memoire  sur  l'acide  butvrique,  par  MM.  Pelouze  et  Gelis. — Ann  de 
Chim.  et  de  Phys.,  3rd  series,  x. 
