ON  PYROXYLIN. 
228 
From  its  decomposing  at  about  50°,  it  maybe  asked  whether 
pyroxylin  is  not  liable  to  decompose  even  at  the  ordinary  tem- 
perature. Is  it,  for  instance,  likely  to  detonate  spontaneously 
when  kept  in  large  masses  in  magazines  ?  Several  chemists 
have  given  examples  of  the  decomposition  of  pyroxylin  at  the 
ordinary  temperature.  They  have  generally  mentioned  as  pro- 
ducts of  this  decomposition  nitrous  vapors  and  several  oxidised 
bodies  like  formic,  oxalic,  and  acetic  acids,  and  residues  of 
gummy  or  saccharine  substances,  and  have  endeavored  to  ascribe 
these  instances  of  the  alteration  of  pyroxylin  to  imperfect  wash- 
ing. 
We  will  in  the  first  place  remark  that  it  is  easy  to  wash 
small  quantities  of  materials,  and  that  as  the  destructive  action 
of  sulphuric  acid  on  pyroxylin  is  perfectly  established,  it  is 
evident  that  the  greatest  care  should  be  taken  to  eliminate  every 
trace  of  it,  and  that  consequently  the  most  careful  washing  is 
necessary. 
Without  entering  into  the  details  of  the  known  cases  of  the 
decomposition  of  pyroxylin  at  the  ordinary  temperature,  we  will 
describe  the  decomposition  we  observed  in  some  specimens  made 
in  1847,  which  had  been  washed  with  especial  care  either  in 
pure  or  alkaline  water. 
Of  twenty-eight  samples  placed  in  small  stopped  flasks,  and 
a  few  grammes  in  weight,  sixteen  underwent  alteration  of  some 
kind. 
We  took  at  hazard  one  of  the  altered  specimens,  and  examined 
it.  It  was  originally  composed  of  six  grammes  of  pyroxylin 
which  had  been  washed  in  potash  water  and  left  since  March 
17,  1850,  or  fourteen  years,  in  a  flask  imperfectly  stopped.  It 
had  left  a  residue  representing  79  per  cent,  of  a  dark  yellow 
color,  and  considerable  amount  of  acid,  but  no  sulphuric  acid. 
This  residue  dissolved  completely  in  water,  and  like  glucose  re- 
duced tartrate  of  copper  and  potash.  Its  boiling  solution  gave 
a  decided  odor  of  vinegar,  and,  what  was  very  remarkable,  dis- 
engaged ammonia  under  the  action  of  potash. 
There  are,  then,  under  the  ordinary  atmospheric  conditions, 
incontestable  instances  of  the  spontaneous  alteration  of  pyroxy- 
lin, which,  moreover,  had  been  washed  in  alkaline  water. 
Now  we  have  shown  that  pyroxylin  is  sure  to  decompose  with 
