302 
ON  CHLOROFORM. 
in  diffused  daylight,  and  (for  a  limited  period,  at  least)  also  in 
sunlight,  if  free  from  moisture ;  in  the  presence  of  moisture  de- 
composition will  set  in,  if  exposed  to  sunlight. 
3.  Chloroform  of  1490  sp.  gr.  and  above  can  be  kept  un- 
altered only  in  the  dark  ;  if  decomposition  should  take  place  in 
the  dark,  it  must  have  commeyiced  before  the  total  exclusion  of 
light. 
In  view  of  these  facts,  there  are  but  two  ways  for  preserving 
chloroform  for  medicinal  use  :  either  to  keep  it  totally  excluded 
from  the  light  from  the  moment  it  has  been  rectified,  if  the  offici- 
nal specific  gravity  is  adhered  to ;  or  to  reduce  it  to  about  1*475 
by  the  addition  of  alcohol,  as  I  have  suggested  heretofore. 
The  former  alternative,  I  believe,  has  been  adopted  by  several 
governments  in  Europe,  where  the  pharmacist  is  now  compelled 
to  preserve  it  in  dark  closets  and  in  black  bottles,  impervious  to 
light. 
In  our  country  this  care  would  scarcely  appear  to  be  necessary, 
since  very  few  pharmacists  rectify  the  chloroform  they  use  in 
their  practice,  but  rather  leave  it  to  the  large  manufacturer,  who, 
to  judge  from  specimens  obtained  without  selection  at  various 
times  from  different  sources,  aim  to  get  it  of  such  a  density  that 
light  has  no  effect  on  it.  In  my  experience,  the  purified  chloro- 
form met  with  in  our  commerce  is  generally  below  1*48 ;  its 
density  occasionally  approaches  1*49,  which  point  it  very  rarely 
exceeds. 
A  case  has  been  related  to  me  of  the  shipment  to  California  of 
a  considerable  quantity  of  chloroform,  a  number  of  years  ago, 
which  arrived  there  in  a  damaged  condition  in  consequence  of 
spontaneous  decomposition.  This  and  similar  occurrences  may 
have  directed  the  attention  of  our  manufacturers  to  this  point  at 
an  early  date,  and  suggested  to  them  the  necessity  of  reducing 
the  density  of  their  product. 
The  rectification  of  chloroform,  if  intended  for  internal  use, 
ought  never  to  be  omitted  by  the  pharmacist.  Our  pharmacopoeia 
allows  the  presence  of  a  minute  proportion  of  those  compounds 
which  react  upon  sulphuric  acid,  and  upon  careful  examination 
but  very  little  chloroform  will  be  found  in  our  market  which  is 
totally  free  from  these  compounds, — a  fact  which  will  be  revealed 
