ON  CHLOROFORM. 
299 
ascertained,  the  older  statements  all  being  more  or  less  below 
the  above.  But  for  medicinal  use,  I  have  no  doubt,  it  would 
even  be  less  adapted  than  a  chloroform  of  the  specific  gravity 
1*49  to  1495,  which  has  been  adopted  in  all  recent  pharmaco- 
poeias, since  it  is  most  likely  more  prone  to  spontaneous  decompo- 
sition than  the  officinal,  which,  exposed  to  direct  sunlight,  con- 
tains free  muriatic  acid  in  a  short  time,  even  though  it  be  prepared 
from  pure  alcohol. 
It  is  not  improbable  that  in  certain  localities  chloroform  may 
be  prepared  from  very  impure  alcohol,  and,  in  consequence  of 
careless  purification  or  rectification,  may  contain  chlorinated 
compounds  decomposing  even  more  readily  than  chloroform  it- 
self. I  believe,  however,  with  Schacht,  that  a  constant  boiling 
point  is  a  very  good,  perhaps  the  best  criterion  for  the  purity  of 
chloroform.  Schacht  experimented  with  a  chloroform  of  1-4960 
sp.  gr.,  and  a  boiling  point  of  67°  C.  (152-6°  F.)  I  have  in  my 
possession  a  sample  of  sp.  gr.  1*4840,  at  66°  F.,  which  was 
rectified  in  July,  1865,  and  had  been  kept  during  this  time  in 
diffused  daylight,  in  a  well-corked  and  perfectly  dry  bottle, 
without  acquiring  the  slightest  acid  reaction.  Exposed  to  the 
direct  sunhght,  it  showed  after  two  days  no  free  acid.  Tested 
with  an  equal  bulk  of  oil  of  vitriol,  it  imparted  to  it  after  24 
hours  an  extremely  faint  yellowish  color.  Evaporated  from  filter- 
ing paper,  no  difference  in  the  odor  was  perceptible. 
It  may  be  inferred  from  this  that  chloroform  of  1-4840  sp.  gr. 
will  keep  well  in  diffused  daylight,  and,  at  least  for  a  limited 
time,  also  in  direct  sunlight.  One  pound  of  this  chloroform  was 
re-rectified  by  distillation.  Introduced  into  a  glass  retort  and 
suspended  over  a  carefully  regulated  gas  flame,  a  false  boiling 
commenced  as  low  as  62*2°  C.  (144°  F.),  and  the  greater  portion 
distilled  over  at  this  temperature,  when  the  distillation  was 
stopped,  and  the  distillate  returned  to  the  retort.  This  false 
boiling  proceeded 'from  two  or  three  points  in  the  bottom  of  the 
retort,  from  whence  minute  globules  of  vapor  arose,  which 
finally  burst  above  the  surface  of  the  liquid,  when  distillation 
commenced. 
In  the  second  experiment  with  direct  heat,  the  temperature 
