36 
ON  PYROXYLIN. 
5.  That  buds  produce  rather  more  carbonic  acid  than  fully- 
developed  flowers,  which  is  explicable  by  the  greater  vitality  of 
the  buds. 
6.  That  flowers  left  in  inert  gas  disengage  small  quantities 
of  carbonic  acid. 
7.  Finally,  the  pistil  and  stamens,  which  possess  the  greatest 
vitality  of  any  part  of  the  flower,  consume  the  greatest  quantity 
of  oxygen,  and  produce  the  largest  proportion  of  carbonic 
acid. — London  Chemical  News^o.  251,  from  Comptes  Rendm, 
Iviii.  1206,  64. 
ON  PYEOXYLIN. 
By  MM.  Pelouze  and  Maurey. 
The  attempts  made  during  the  last  twenty  years  to  substi- 
tute gun-cotton  for  ordinary  powder  for  fire-arms  and  mines 
have  resulted  in  most  opposite  conclusions.  In  France,  after 
numerous  experiments,  it  has  been  discarded  on  account  of  its 
detrimental  effect  on  the  metal  of  fire-arms  and  accidents  from 
spontaneous  combustion  and  explosion,  first  brought  into  notice 
by  a  memoir  presented  by  us  to  the  Institute  in  1849. 
In  Austria,  General  Lenk  has  continued  to  occupy  himself 
with  the  manufacture  and  use  of  this  explosive  material.  He 
prepares  it  by  a  process  which  has  been  followed  on  a  large 
scale  at  Hirtenberg,  and  which  remained  for  some  years  a  pro- 
found secret.  But  during  the  last  year,  papers  on  this  subject 
have  been  published  by  German  chemists  and  by  General  Lenk 
himself. 
It  would  appear  from  these  papers  that  the  Hirtenberg  py- 
roxylin does  not  decompose  spontaneously,  like  that  made  in 
France  at  the  Bouchet  powder  factory,  and,  moreover,  differs 
from  the  latter  in  its  composition,  and  in  the  circumstance  that 
its  explosive  power  may  be  regulated  by  particular  arrange- 
ments. We  will  now  examine  the  value  of  these  assertions, 
giving  the  results  of  some  experiments  and  analysis  we  have 
made  with  the  co-operation  of  MM.  Faucher  and  Chapoteaut. 
Processes  followed  at  Hirtenberg  and  at  Bouchet — The  py- 
roxylin made  at  Hirtenberg  by  General  Lenk's  process,  is  like 
