356 
Decomposition  of  Chloroform. 
f Am.  Jour.  Pbarm. 
I        July,  1893. 
chloroform  from  decomposition  by  light.1  Though  the  direct  pro- 
ducts of  the  decomposition  of  pure  chloroform  are  only  chlorine  and 
carbon  oxychloride,  it  is  natural  that  in  the  case  of  chloroform  con- 
taining alcohol  the  chlorine  thus  eliminated  should  act  upon  the 
alcohol  present,  and  so  give  rise  to  the  production  of  hydrochloric 
acid.  Consequently,  in  the  first  stage  of  decomposition  of  chloro- 
form containing  alcohol,  hydrochloric  acid  is  always  found  in  the 
place  of  free  chlorine.  That  being  the  result,  however  minute  the 
proportion  of  alcohol  may  be,  it  is  evident  that  in  such  a  case  an 
observer  who  is  not  aware  of  the  presence  of  alcohol  in  the  chloro- 
form will  be  led  to  dispute  the  statement  that  elimination  of  free 
chlorine  is  a  primary  feature  of  the  alteration.  For  that  reason  we 
consider  it  to  be  absolutely  necessary,  in  making  experiments,  to 
ascertain  the  nature  of  the  decomposition  of  chloroform,  either  to 
make  sure  that  the  chloroform  operated  with  is  perfectly  free  from 
alcohol,  or  to  determine  how  much  is  present,  and  to  take  that  into 
account  when  interpreting  the  observed  results. 
As  we  have  found  that  sufficient  attention  is  not  generally  given 
to  this  point  and  to  th*  purity  of  the  chloroform  experimented  with, 
we  desire  to  point  out  the  following  facts  : 
Chloroform  cannot  be  absolutely  deprived  of  alcohol  in  any  other 
way  than  by  repeatedly  shaking  it  with  double  its  volume  of  fresh 
water.    This  operation  should  be  repeated  at  least  ten  times. 
To  ascertain  the  entire  absence  of  alcohol  it  is  necessary  to  have 
recourse  to  the  well-known  iodoform  test,  or  to  test  the  chloroform 
with  a  solution  of  potassium  bichromate  exactly  in  the  manner  we 
have  described,2  any  stronger  solution  being  unsuitable  for  the 
purpose. 
Chloroform  quite  free  from  alcohol  has  the  specific  gravity  1-502 
at  1 50  C.  (590  F.),  and  its  boiling  point  is  62-05°  C  (14370  F.)  at 
760  mm. 
Such  chloroform  when  exposed  to  daylight  of  sufficient  power, 
will  begin  to  decompose  within  one  or  two  hours.  But  it  must  be 
remembered  that  the  chemical  intensity  of  daylight  varies  con- 
siderably at  different  times.  In  summer  it  is,  on  an  average,  ten 
times  as  powerful  as  in  winter,  and  even  in  summer  time  days  of 
1  Pharm.  Journ.  [3],  xxii,  1041,  and  "Month,"  691;  Am.  Jour.  Phar.,  1S92, 
P-  39i- 
2  Archiv  der  Pharmacie,  186S,  vol.  134,  p.  20S  ;  Pharm.  Journ.  [3],  xxii,  1041. 
