ON  THE  PREPARATION  OF  GUN-COTTON. 
533 
above  described,  and  especially  that  which  directly  after  being 
washed,  is  strongly  pressed  and  then  freed  as  much  as  possible 
from  adhering  moisture  between  bibulous  paper,  dissolves  very 
readily  in  a  mixture  of  seven  or  eight  parts  of  ordinarily  pure 
ether,  and  one  part  of  absolute  alcohol.  The  solution  may  be  di- 
luted with  an  equal  quantity  or  even  more  ether,  without  any  sep- 
aration of  the  dissolved  substance.  The  perfectly  dry  collodion 
wool  dissolves  rather  slowly  in  the  mixture  of  alcohol  and  ether, 
a  character  presented  more  especially  by  the  wool  prepared  at  low 
temperatures.  But  when  the  dry  collodion  wool  is  moistened  with 
water,  and  then  well  pressed,  it  dissolves  as  readily  as  when  fresh 
made.  The  collodion  wool  which  is  prepared  wTith  mixtures  either 
of  nitrate  of  potash  or  monohydrated  nitric  acid,  with  the  so-called 
single  quantity  of  sulphuric  acid,  and  at  a  higher  temperature,  is 
but  little  dissolved,  and  for  the  most  part  only  disintegrated  by  a 
mixture  of  eight  parts  anhydrous  ether  and  one  part  absolute  alco- 
hol ;  that  prepared  wTith  mixtures  either  of  nitric  acid,  nitrates  of 
potash  or  soda,  with  the  double  quantity  of  sulphuric  acid,  and  at  a 
temperature  of  about  86°  F.  is  not  even  distintegrated  by  this  mixure 
of  ether  and  alcohol,  and  appears  to  be  insoluble  in  it.  Ether,  free 
from  wTater  and  alcohol,  dissolves  scarcely  any  collodion  wool,  even 
when  it  contains  water.  The  same  is  the  case  with  absolute  alco- 
hol and  watery  spirit  in  reference  to  collodion  wool  prepared  at 
temperatures  much  below  104°  or  122°  F. 
The  collodion  wool  prepared  w7ith  a  mixture  of  thirteen  parts, 
S03  3  HO+  twelve  parts  N05  HO  and  one  or  two  parts  cotton  wTool 
by  digesting  for  two  hours  at  104°  or  122°  F.,  dissolves  in  abso- 
lute alcohol,  and  gives  a  thick,  clear  solution,  like  ordinary  good 
collodion  solution  made  with  a  mixture  of  ether  and  alcohol.  This 
alcoholic  solution  evaporates  very  slowly,  and  leaves  upon  the  glass 
plate  a  clear,  colorless,  hard  layer. 
The  mixtures  A  D  F  yielded  collodion  wool,  which  admitted  of 
being  dried  at  212°  F.  without  decomposing,  and  of  being  kept 
for  years  without  alteration.  The  author  was  unable  to  arrive  at 
any  corresponding  results  by  the  analysis  of  collodion  wool  which 
had  been  purified  by  means  of  carbonate  of  soda. — Pharm.  Journ. 
Aug.  1853,  from  Bullet,  de  St.  Petersburg,  vol.  xi.,  p.  210. 
