RESEARCHES  ON  THE  ETHERS. 
123 
bination  is  generally  easy  with  the  energetic  acids ;  but  with  the 
organic  acids,  such  as  acetic  acid,  becomes  very  slow  and  incom- 
plete. But  with  the  aid  of  sulphuric  acid,  the  combination  is  im- 
mediately and  almost  completely  effected. 
The  author  ha^  arrived  at  the  following  results  by  employing 
close  vessels,  and  the  assistance  of  long  exposure  to  heat,  in  the 
direct  preparation  of  the  ethers: — 
At  392°-482°  F.,  the  combination  of  the  alcohols  with  the  fatty 
acids  is  effected  with  rapidity.  In  this  manner  the  author  produced 
at  482°  F.  the  following  ethers  : — 
Methylopalraitic  ether,  a  crystalline  substance, fusible  at  82°  F., 
solidifying  at  72°  F.  ; 
Elhylopalmitie  ether,  fusible  at  70o,7  F.,  solidifying  at  640,4 
F.,  and  reproducing,  by  the  action  of  potash,  palmitic  acid,  fusible 
at  142°  F.  ;  and 
Amylopalmitic  ether,  a  waxy  substance,  fusible  at  48°  F. ;  with 
potash  it  reproduces  palmitic  acid,  fusible  at  142°  F. 
The  combination  of  the  alcohols  with  the  fatty  acids  is  never 
complete,  either  for  the  alcohol  or  the  acid.  But  these  three  ethers 
are  most  abundantly  formed  in  the  presence  of  an  excess  of  acid, 
which  is  afterwards  separated  by  lime  and  ether.  When  heated 
afresh  to  500°  F.  for  fourteen  hours  with  eight  or  ten  times  their 
weight  of  palmitic  acid',  they  are  found  after  the  operation  to  have 
undergone  no  change  whatever. 
With  thirty  hours  contact  at  212°  F.,  benzoic,  acetic,  and  buty- 
ric ethers  were  produced  in  great  abundance,  especially  the  latter. 
Stearic  ether  even  begins  to  be  formed  in  102  hours,  but  in  very 
small  quantity.  The  addition  of  acetic  acid  to  the  mixture  in  the 
latter  case  causes  the  stearic  acid  to  become  completely  etherified 
in  102  hours.  This  corresponds  with  the  known  action  of  sul- 
phuric and  muriatic  acids,  only  differing  in  the  comparative  weak- 
ness of  the  acetic  acid.  It  appears  especially  in  this  case  that  the 
combination  of  the  stearic  acid  with  the  alcohol  is  induced  by  that 
which  takes  place  between  the  acetic  acid  and  the  same  alcohol. 
It  is  a  pretty  clear  instance  of  the  propagation  of  molecular  move- 
ment. 
The  ready  etherification  of  the  fatty  acids  in  an  alcoholic  liquid, 
rendered  acid  even  by  acetic  acid,  appears  to  the  author  often  to 
render  the  purification  of  these  bodies  very  delicate. 
