SPONTANEOUS  DECOMPOSITION  OF  PYROXYLIN.  401 
,  CHEMICAL  RESEARCHES  ON  THE  SPONTANEOUS  DECOM- 
POSITION OF  PYROXYLIN. 
By  M.  S.  DeLuca. 
The  pyroxylin,  or  gun  cotton, employed  in  this  investigation,  was 
bought  in  Paris  in  1859,  and  preserved,  sheltered  from  the  light, 
in  a  wooden  box,  perfectly  close,  in  the  Chemical  Laboratory  of 
the  Faculty  of  Sciences,  at  Pisa.  It  was  enclosed  in  a  glass 
bottle,  stopped  with  a  cork  and  sealed  with  wax.  Its  spontane- 
ous decomposition  had  occurred  during  the  summer  of  1860,  with 
disengagement  of  nitrous  vapors. 
This  decomposed  pyroxylin  had  lost  all  its  original  properties. 
In  fact  it  had  a  white  aspect,  a  little  yellowish  at  the  sides  ;  was 
pasty  and  sticky ;  possessed  a  strong  acid  taste,  emulsionized 
with  cold  distilled  water,  and  the  emulsion  thus  formed  passed 
slowly  through  filtering  paper.  The  filtered  solution,  which  was 
limpid,  reddened  litmus,  disengaged  nitrous  vapors  when  in  con- 
tact with  copper  and  sulphuric  acid,  was  colored  strongly  yellow 
by  ammonia  and  potassa,  reduced  the  tartrate  of  copper  and 
potassa,  was  not  colored  by  an  aqueous  solution  of  iodine,  be- 
came brown  when  heated  with  sulphuric  acid,  and  gave  a  pre- 
cipitate with  an  excess  of  lime  water  which  had  all  the  charac- 
ters of  an  oxalate.  The  solution  disembarrassed  of  the  lime 
precipitate,  subjected  to  a  current  of  carbonic  acid  gas,  and 
carried  to  ebullition  to  separate  the  carbonate  of  lime,  easily  re- 
duced the  tartrate  of  copper  and  potassa. 
The  modified  gun  cotton  put  under  a  bell  glass,  with  concentrat- 
ed sulphuric  acid,  becomes  perfectly  white,  preserves  its  acidity, 
can  be  reduced  to  powder  under  the  pressure  of  the  finger, 
and  loses  38  per  cent,  of  its  weight.  In  fact,  5-346  grms.  of  this 
cotton  left  thus  in  contact  with  sulphuric  acid,  from  December 
22d,  1860,  to  June  20th,  1861,  lost  1-919  grms. 
This  cotton,  when  subjected  to  heat  lost  weight,  as  follows  : — 
Weight  of  cotton. 
Temperature. 
Total. 
Per  cent. 
Grmg. 
2-352 
...212°  to  230° 
F  
 0-791.... 
 33-2 
4-328 
230°  to  248° 
tt 
 1-632.... 
 37-7 
2-187 
248°  to  266° 
a 
 0-823.... 
,..  37-6 
2-458 
266°  to  284° 
a 
 0.605.... 
,.  41-5 
2-187 
302°  to  320° 
(C 
 0-914.... 
 41-8 
26 
