294 
ON  CHLOROFORM. 
liquids  left  in  contact,  with  occasional  agitation,  until  sulphuric 
acid  was  scarcely  colored  on  being  shaken  with  a  little  of  the 
chloroform.  The  latter  liquid  was  then  repeatedly  agitated  in  a 
copper  can  with  a  concentrated  solution  of  carbonate  of  soda,  to 
remove  adhering  sulphuric  acid.  The  chloroform  was  separated, 
and — about  sixteen  gallons  at  one  time — subjected  to  rectification 
from  a  copper  still,  after  it  had  been  previously  diluted,  according 
to  its  specific  gravity,  with  from  eight  to  sixteen  ounces  of  alco- 
hol, to  bring  its  density  within  the  limits  allowed  by  the  pharma- 
copoeia. 
It  will  be  observed  that  the  process  of  preparing  chloroform  is 
that  of  B.  Hirsch,*  with  such  modifications  as  were  found  con- 
venient and  requisite  to  work  such  large  quantities.  The  chlori- 
nated lime  used  was  of  English  manufacture,  and  usually  con- 
tained in  the  neighborhood  of  35  per  cent,  active  chlorine  ;  the 
percentage  rarely  fell  below  30,  and  was  once  as  low  as  17f  per 
cent.  The  actual  weight  of  the  lime  compound  was  decreased 
with  the  increase  of  the  amount  of  chlorine  ;  but  if  the  latter  fell 
below  30  per  cent,  the  alcohol  was  lessened  in  proportion,  since 
experience  proved  that  more  than  800  pounds  could  not  be  con- 
veniently worked  in  the  still  at  one  time. 
The  various  wash  waters  of  the  crude  chloroform  were  always 
used  in  the  next  charge,  the  amount  of  alcohol  contained  therein 
having  previously  been  approximately  ascertained. 
Various  methods  had  been  carefully  tested  before  the  above 
process  was  finally  adopted  ;  among  them  I  may  mention  the 
quick  heating  of  the  mixture  until  it  rapidly  rose  in  the  still, 
checking  its  passing  over  by  cold  water ;  also  the  heating  of  the 
mixture  to  as  high  a  point  above  120°  (about  160°  F.)  as  could 
be  prudently  done  without  imminent  danger  of  the  charge  being 
carried  over ;  also  the  blowing  of  alcohol  under  steam  pressure 
into  a  mixture  of  chlorinated  lime  and  water,  heated  to  various 
temperatures.  All  these  methods  failed  to  give  the  good  results 
obtained  by  the  process  finally  adopted. 
From  the  few  memoranda  now  in  my  possession,  I  select  the 
following  experiments : 
*  Amer.  Journ.  Pharm.  1862,  42. 
