RESEARCHES  ON  PYROXYLINE. 
159 
RESEARCHES  ON  PYROXYLINE. 
By  A.  Bechamp. 
We  frequently  encounter  difficulties,  in  preparing  soluble  pyroxy- 
line.  In  obtaining  that  employed  by  me,  I  followed  the  process 
of  MM.  Gaudin  and  Mialhe.  1  have  ascertained  that  if  the  mixture 
of  sulphuric  acid  and  nitre  be  cooled  previously  to  the  immersion 
of  the  cotton,  the  pyroxyline  obtained  is  strongly  fulminating,  but 
insoluble  in  ether.  On  recommencing  the  same  operation  with  the 
same  materials,  but  at  the  temperature  naturally  developed  by  the 
reaction,  the  product  obtained  was  both  fulminating  and  soluble. 
Again,  ihe  insoluble  pyroxyline  formed  in  the  first  operation  became 
soluble  after  being  immersed  in  the  hot  mixture  of  the  acid  and 
nitrate. 
The  condition  necessary  for  constantly  obtaining  soluble  pyroxy- 
line is  therefore  to  operate  whilst  the  mixture  is  hot. 
When  a  stream  of  ammoniacal  gas  is  passed,  for  at  least  half  an 
hour,  through  a  solution  of  2  parts  of  pyroxyline  in  30  parts  of 
alcohol  of  spec.  grav.  0  845,  the  viscous  solution  becomes  perfectly 
fluid. 
In  this  ammoniacal  solution,  sulphuretted  hydrogen  gas  produces 
a  yellow  precipitate,  which  is  insoluble  in  alcohol  of  spec.  grav. 
0*833.  This  precipitate  is  complex  ;  it  contains  a  portion  which 
is,  and  another  which  is  not  soluble  in  water.  According  to  some 
of  its  reactions,  I  thought  it  like  a  sulphuretted  compound. 
When  the  ammoniacal  solution  is  poured  suddenly  into  15  or  20 
times  its  volume  of  water,  a  white  powder,  completely  insoluble 
in  water,  is  precipitated  ;  it  is  not  altered  by  remaining  for  forty- 
eight  hours  in  water.    Its  properties  are  as  follows: — 
Dried  at  68°  F.  in  vacuo  over  sulphuric  acid,  it  is  very  persist- 
ent. It  is  light,  inodorous  and  tasteless.  It  becomes  electric  by 
friction.  Heated  in  a  tube,  it  does  not  fulminate  so  soon  as  pyroxy- 
line ;  it  evolves  nitrous  vapors,  and  leaves  a  residue  of  carbon. 
Heated  with  fuming  muriatic  acid,  it  is  gradually  dissolved,  dis- 
engaging'chlorine  in  abundance.  Concentrated  sulphuric  acid  dis- 
solves it,  without  apparent  disengagement  of  gas.  The  nitro-sul- 
phut  ic  mixture  does  not  appear  to  produce  any  change  in  it.  I 
have  not  yet  ascertained  whether  or  not  the  pyroxyline  was  re- 
generated. 
