160 
RESEARCHES  ON  PYROXYLINE. 
The  water  in  which  the  precipitation  takes  place  contains 
nitrate  of  ammonia,  but  very  little  organic  matter.  This  fact 
deserves  attention.  The  elementary  analysis  shows,  in  fact,  that 
the  new  combination  only  differs  from  pyroxyline  by  containing  1 
equiv.  less  nitric  acid. 
I  have  ascertained  that  the  new  substance  is  constant  in  its  com- 
position. I  have  analysed  the  product  immediately  after  its  preci- 
pitation, and  also  after  forty-eight  hours'  contact  with  water.  The 
composition  did  not  vary. 
In  six  analyses  for  the  determination  of  the  carbon  and  hydrogen, 
and  three  others  in  which  I  determined  the  nitrogen  by  the  process 
of  M.  Dumas,  I  obtained  concordant  results ;  the  average  of  the 
four  elements  is  in  hundredths, — carbon,  28*216  ;  hydrogen,  3*575  ; 
nitrogen,  10*777;  oxygen,  57*432.  The  substance  had  been  dried 
at  212°  F.  Taking  into  consideration  the  formation  of  nitrate  of 
ammonia  in  the  reaction,  and  admitting  the  formula  attributed  to 
pyroxyline  by  M.  Pelouze,  (Comptes  Rendus,  xxiv-  p.  2,)  namely, 
C24  H  7  O17  5N05,  the  substance  examined  by  me  would  be  formed 
according  to  the  equation — 
C21  H  O'7,  5N05+NH3+HO==N05,  NH4  04-  C"4  H17  O7 ,4N05. 
If  we  take  this  last  formula  for  that  of  the  new  compound,  its  theo- 
retical centesimal  composition  is, — carbon,  28*070  ;  hydrogen, 
3-315;  nitrogen,  10*916;  oxygen,  57*699. 
Between  68°  and  212°  F.,  100  parts  of  the  substance  lost,  by 
the  average  of  two  determinations,  1*727  of  water.  This  number 
supposing  H  =  1,  represents  9*015  of  water  for  the  quantity  of 
substance  expressed  by  the  formula  C'1  H17  O17,  4N05,  that  is  to 
say,  1  equiv.  of  water.  The  formula  of  the  new  substance,  at  the 
temperature  of  68°  F.,  is  therefore  C24  H17  O17,  4NO\  HO,  or, 
dividing  it  by  2 — 
C12  H9  O9,  2N05  =  C12  H°  (2N04)2  O1  , 
that  is  to  say,  the  formula  of  cane-sugar,  in  which  2N04  takes  the 
place  of  2H. 
Conclusion. — Several  formulae  are  attributed  to  pyroxyline. 
The  new  compound,  by  its  composition  as  well  as  by  the  circum- 
stances of  its  formation,  confirms  the  formula  of  M.  Pelouze. 
The  following  is  the  molecular  formula  which  I  propose  for 
pyroxyline :— C24  H17  X4  O24,  NO5* ; 
