61       ON  THE  MEDICINAL  PLANTS  OF  CHEROKEE  GEORGIA. 
Ulmus.  Our  elm  does  not  yield  so  mucilaginous  a  bark  as 
that  obtained  from  the  Northern  States. 
Zingiber  does  not  bear  our  climate  well,  unless  it  be  protected 
during  the  winter.  Besides  the  plants  named,  we  have  many 
which  are  used  only  in  domestic  and  steam  practice.  With  a 
few  exceptions,  we  are  unable  to  obtain  a  home  supply  of  medi- 
cinal plants. 
From  the  Proceedings  of  the  American  Pharmaceutical  Association. 
ON  COLLODION. 
By  L.  Hofmann. 
The  author  has  occupied  himself  with  the  preparation  of  col- 
lodion for  photographic  purposes,  and  recommends  the  following 
process,  which  may  also  be  rendered  applicable  in  surgery  by 
additions,  The  best  addition  is  castor  oil,  to  deprive  the  collo- 
dion of  the  property  of  contracting  so  strongly  and  becoming 
cracked. 
1  part  of  loose,  clean  cotton-wool  is  immersed  for  a  quarter 
of  an  hour  in  a  mixture  of  20  parts  of  dry  nitrate  of  potash,  and 
30  parts  of  English  sulphuric  acid,  in  a  suitable  glass  vessel, 
capable  of  being  closely  covered  with  a  glass  plate.  During  this 
time  it  is  once  strongly  stirred.  The  mixture  is  then  poured 
into  a  pail  of  pure  water,  and  well  washed,  and  this  operation 
must  be  repeated  until  the  last  traces  of  salt  and  acids  are  re- 
moved. The  xyloidine  obtained  is  then  put  into  a  linen  cloth, 
pressed  sharply,  and  teased  out  before  drying,  so  as  to  remove 
all  knots.  The  drying  is  effected  upon  a  common  stove  in  a 
suitable  sieve. 
Schacht  has  already  recommended  the  same  proportions,  but 
has  not  prescribed  the  employment  of  the  dried  salt,  and  he  has 
also  confined  the  time  of  action  to  4-5  minutes.  Xyloidine  thus 
prepared  did  not  dissolve  so  readily  and  completely  in  the  mixture 
of  ether  and  alcohol,  and  the  preparation  in  course  of  time  lost 
the  property  of  dissolving  easily.  6  parts  of  xyloidine,  obtain- 
ed by  the  above  process,  were  dissolved  by  shaking  in  a  mixture 
of  120  parts  of  ether,  and  8  parts  of  the  most  highly  rectified 
alcohol,  and  3  parts  of  castor  oil  were  added  to  the  solution  
Chemical  Gazette,  October  15,  1856,  from  Archiv  der  Pharm. 
