44 
ON  THE  PREPARATION  OF  CHLOROFORM. 
volume  :  on  shaking  it  a  fourth  time  with  water,  the  loss  is  very 
small,  and  the  specific  gravity  of  the  chloroform  is  now  1.4D8 
to  1.499,  and  was  once  obtained  as  high  as  1.501.  The  loss  by 
weight  of  the  crude  chloroform,  equivalent  to  25  per  ct.  by 
measure  is  only  about  12  or  13  per  ct.,  because  water  removes 
chiefly  the  alcohol.  The  wash  waters  contain  a  variable 
quantity  of  chloroform,  held  in  solution  by  alcohol,  and  obtain- 
able by  distillation  and  washing.  The  product  now  contains  a 
small  proportion  of  water  and  alcohol,  and  some  heavy  chloric 
ether,*  the  latter  of  which  is  probably  the  cause  of  the  colora- 
tion of  chloroform  by  sulphuric  acid.  To  free  it  from  these  im- 
purities, the  chloroform  is  agitated  with  about  5  per  ct.  of  dry 
chloride  of  calcium,  decanted  into  a  dry  retort  and  rectified  in 
the  water-bath,  the  temperature  of  which  ought  to  be  preserved 
at  56°  R.  (158°  F.),  when  98  per  ct.  are  obtained  in  a  perfectly 
pure  state,  so  that  sulphuric  acid  has  no  effect  even  after  a  con- 
tact for  several  days.  If  the  distillation  is  then  continued  with 
a  higher  heat,  a  single  drop  of  the  distillate  will  color  several 
drachms  of  sulphuric  acid  dark-brown,  which  proves  the  correct 
separation  by  this  method.  A  black  inodorous  liquid  remains 
in  the  retort,  which  from  50  ib.  chloroform,  varies  from  a  few 
drops  to  two  ounces  in  amount.  The  chloride  of  calcium  will 
yield  when  distilled  with  water,  a  little  impure  chloroform  which 
may  be  preserved  for  subsequent  purification. 
The  author  then  gives  the  results  of  a  series  of  18  distillations, 
17  of  which  were  made  with  the  following  quantities  :  40  ft), 
chlorinated  lime  of  30  per  ct.  chlorine,  7  ft),  alcohol  of  90  per 
ct,,  160  ib.  water.  This  mixture  was  heated  to  a  temperature 
between  32°  and  37°  R.  (101  and  115°  F.)  ;  in  each  case,  the 
time  was  carefully  noted  in  which  the  thermometer  fell  to  its 
lowest  point,  also  the  temperature  to  which  the  mixture  rose 
spontaneously,  the  quantity  of  crude  chloroform  obtained,  and 
the  loss  by  volume  on  agitating  with  an  equal  bulk  of  water. 
The  following  comprises  the  entire  result  of  three  series : 
*  This  heavy  chloric  ether  which  was  formerly  officinal  in  many  European 
Pharmacopoeias,  under  the  names  of  Aether  (s.  Naphtha)  chloratus,  a. 
chloricu,  s  s.bichloricus,  is,  according  to  Schloosberger,  a  mixture  of  chloral, 
aldehyde,  acetic  ether,  &c.  Hager  prepares  it  by  distilling  a  mixture  of 
1  p.  chlorinated  lime,  5  water,  and  1  alcohol. 
