24 
Chloroform  as  Solvent,  etc. 
f  Am.  Jour.  Pharm. 
t     Jan.  1,  1873. 
ness,  adding  water,  and  repeating  the  operation  several  times,  until  a 
stopper  with  ammonia  no  longer  gives  white  fumes.  The  sufficiently 
concentrated  chromic  acid  crystallizes  in  black  warts,  exactly  similar 
to  the  plates  obtained  in  a  vacuum  by  Bolley's  method.  In  this  way 
chromic  acid,  sufficiently  pure  for  most  uses,  can  be  prepared  in  a  few 
hours. 
To  obtain  a  perfectly  pure  product  it  is  only  necessary  to  precipi- 
tate the  remainder  of  the  barium  by  adding  a  sufficient  quantity  of 
sulphuric  acid  to  the  boiling  solution. 
This  method  possesses  the  advantage  over  all  those  previously  de- 
scribed of  quickly  furnishing  all  the  chromic  acid  contained  in  the 
chromate  of  barium  used,  and  also  that  the  acid  is  absolutely  pure. 
It  can  also  be  employed  on  a  large  scale  by  observing  the  above-given 
proportions.  The  excess  of  acid  would  then  be  collected  in  a  suit- 
able distilling  apparatus  so  as  to  use  it  for  another  operation.  The 
nitrate  of  barium  could  be  used  in  making  the  chromate  of  barium, 
so  that  no  loss  would  be  sustained. 
CHLOROFORM  AS  SOLVENT  FOR  AND  MEANS  OF  SEPARAT- 
ING POISONOUS  YEGETABLE  SUBSTANCES  IN  FORENSIC 
INVESTIGATIONS. 
I.  Nowak  has  instituted  a  series  of  experiments  which  prove  that 
chloroform  quickly  and  perfectly  extracts  the  following  long  list  of 
vegetable  substances  from  alkaline  solutions,  viz. :  Strychnia,  quin- 
ia,  quinidia,  chinchonia,  caffeina,  theobromina,  emetina,  atropia, 
hyoscyamia,  aconitina,  veratrina,  physostigmia,  narcotina,  codeina, 
thebaina,  nicotina  and  conia.  It  dissolves  brucia,  colchicia  and 
papaverina  more  slowly.  Sabadillia  is  only  taken  up  by  it  when 
warm,  while  narceina  is  taken  up  from  alkaline  solutions  in  small 
quantities  only.  Picrotoxin  is  acted  upon  by  chloroform  more  readily 
from  acid  than  alkaline  solutions.  Morphia  and  solania  do  not 
dissolve  in  chloroform,  either  from  acid  or  alkaline  solutions. 
Further  experiments  also  show  that  all  those  substances  which  are 
taken  up  by  chloroform  from  aqueous  alkaline  solutions  are  again 
given  up  by  it  on  shaking  repeatedly  with  acidulated  water,  while 
fatty  and  other  foreign  substances  mixed  with  them  remain  in  the 
chloroform.  A  systematic  course  of  search  for  poisonous  vegetable 
substances,  founded  upon  the  above  facts,  was  instituted,  and  its  prac- 
ticability tested  by  actual  experiments  as  follows:  A  weighed  quantity 
