FOEMATION  OF  ACETYLENE  IN  INCOMPLETE  COMBUSTIONS.  263 
THE  FORMATION  OF  ACETYLENE  IN  INCOMPLETE 
COMBUSTIONS 
By  M.  Beethelot. 
Acetylene  is  formed,  as  I  have  already  proved,  at  the  expense 
of  most  organic  compounds  when  submitted  to  the  prolonged  in- 
fluence of  a  red  heat.  I  now  purpose  showing  the  formation  of 
this  same  carbide  under  a  condition  not  less  general — namely, 
incomplete  combustion. 
The  following  is  a  general  experiment  proving  this  fact  either 
with  gas  or  with  very  volatile  liquids  : — 
Take  gas  such  as  ethylene,  C4H4 ;  hydrochloric  ether,  C4H5C1 ; 
propylene,  C^H6 ;  methylic  ether,  C2H2(C2H402) ;  marsh  gas,  C2- 
H4,  &c. ;  or,  better  still,  a  very  volatile  liquid,  such  as  ordinary 
ether,  CJH4  (C4H602) ;  amylene,  C10H10;  hydride  of  amylene,  C10- 
H12  and  even  benzole,  C12HG;  acetone,  C6H602  methylformic 
ether,  C2H2(C2H204),  &c. 
Fill  a  test-tube  of  300  cubic  centimetres  capacity  with  gas,  or 
pour  into  it  a  few  drops  of  volatile  liquid ;  then  add  a  few  cubic 
centimetres  of  ammoniacal  cuprous  chloride,  set  fire  to  the  com- 
bustible vapor,  and  incline  the  tube  almost  horizontally,  rolling 
it  about,  so  as.  to  spread  the  cuprous  reagent  over  all  the  interior  ; 
cuprous  acetylide  will  speedily  be  produced.  It  is  produced  by 
the  contact  of  the  flame  from  beneath,  and  is  seen  in  the  form  of 
a  characteristic  red  precipitate. 
This  experiment  answers  especially  well  with  ordinary  ether 
and  hydride  of  amylene. 
The  amount  of  acetylene  produced  under  these  circumstances 
in  the  form  of  acetylide  is  evidently  larger  than  that  produced 
under  the  influence  of  heat  alone,  acting  on  the  same  compounds, 
The  quantity  of  acetylene  actually  produced  is,  moreover,  much 
greater  than  that  which  takes  the  form  of  acetylide,  because  the 
greater  part  of  the  acetylene  burns  almost  as  soon  as  formed, 
and  without  coming  in  contact  with  the  reagent.  I  think  it 
possible  to  deduce  from  this  experiment,  conveniently  modified, 
a  method  of  preparing  acetylene  more  advantageous  than  those 
hitherto  in  use. 
Coal  gas  is  no  exception  to  this  general  rule,  as  may  be  easily 
