ON  COLLODION. 
371 
to  the  stability  of  the  salt,  and  seems  to  counteract,  in  a  remark- 
able degree,  its  proneness  to  pass  into  its  insoluble  state. 
Of  the  therapeutic  value  of  the  preparation,  of  course,  I  can 
say  nothing,  but  merely  offer  it  as  a  syrup,  holding  in  solution  a 
large  amount  of  phosphatic  salt. — Jour n.  and  Trans.  Maryland 
Col.  Pharm.,  June,  1858. 
ON  COLLODION. 
By  Charles  Caspari. 
'  Read  before  the  College,  December  3d,  1857. 
Collodion  cotton  may  be  prepared  either  by  treating  cotton  in 
a  mixture  of  nitrate  of  potash  and  sulphuric  acid,  or  with  a  mix- 
ture of  nitric  and  sulphuric  acids.  By  using  nitrate  of  potash 
and  sulphuric  acid,  I  obtained  a  good  preparation  of  collodion 
cotton  after  the  following  method  : 
Thirty-one  parts  of  sulphuric  acid  of  1.83  sp.  gr.  to  be  well 
mixed  in  a  glass  cylinder  with  twenty  parts  of  pulverized  nitrate 
of  potash.  After  the  mixture  has  cooled  to  110°  F.,  one  part 
of  cotton  freed  of  all  impurities  is  mixed  with  it,  and  allowed  to 
stand  for  about  36  or  40  hours,  in  a  temperature  of  75  to  80°  F. 
For  removing  the  acid  and  sulphate  of  potash,  the  cotton  thus 
prepared  must  be  well  washed  several  times  with  cold  water,  and 
afterwards  hot  water  poured  upon  it,  to  remove  all  sulphate  of 
potash,  which  is  retained  very  obstinately  by  the  fibres  of  the 
cotton. 
This  cotton,  after  being  strongly  pressed  and  almost  freed  of 
its  humidity  by  pressing  between  blotting  paper,  will  easily  dis- 
solve in  a  mixture  of  ether  and  alcohol. 
For  preparing  collodion  cotton  with  nitric  and  sulphuric  acids, 
I  availed  myself  of  one  or  the  other  of  the  two  following  pro- 
cesses : 
13  parts  of  Sulphuric  Acid  of  1.64  sp.  gr.,  and 
12  parts  of  Nitric  Acid  of  1.48  to  1.50  sp.  gr., 
or  14  to  16  parts  of  Sulphuric  Acid  1.83  sp.  gr., 
and  12  parts  of  Nitric  Acid  of  1.43  sp.  gr. 
The  acids  being  mixed  in  a  glass  cylinder  covered  with  a  plate 
of  glass,  and  the  mixture  cooled  to  40°  F.,  the  cotton  is  stirred 
