42 
ON  CHLOROFORM. 
With  regard  to  the  product,  there  is  considerable  uncertainty, 
owing  to  the  great  difference  in  the  quality  of  the  chloride  of 
lime  employed  ;  it  is  necessary  that  the  chloride  should  be  ren- 
dered alkaline  by  means  of  lime,  otherwise  formic  acid  is  not  so 
readily  produced, — it  also  prevents,  in  a  great  measure,  the 
action  being  so  violent  when  the  ingredients  are  mixed ;  and  the 
chloroform  that  passes  over  is  rarely  contaminated  with  chlorine, 
which  is  frequently  the  case  when  the  lime  is  omitted.    I  have 
occasionally  added  a  weak  solution  of  chlorine  instead  of  water, 
and  a  larger  quantity  of  lime :  but  neither  by  this,  nor  by  any  of 
the  other  processes  I  have  tried,  have  I  obtained  a  result  so  uni- 
form or  satisfactory,  as  by  the  foregoing.    The  chloroform,  when 
thus  carefully  prepared,  answers  to  the  following  tests  :    It  is 
exceedingly  bright  and  transparent  in  any  moderate  temperature, 
possessing  a  highly  penetrating  aromatic  odor  ;  when  dropped 
upon  the  hand  it  rapidly  evaporates,  leaving  no  faint  unpleasant 
odor  behind.    It  is  not  affected  by  litmus  or  turmeric  paper  ; 
when  dropped  into  water  the  greater  part  immediately  sinks, 
leaving  a  little  floating  on  the  surface,  which,  after  a  time,  sinks 
also,  imparting  a  sweetish  taste  to  the  water.    It  has  a  specific 
gravity  of  1,500,  which  is  the  best  test  of  its  strength  ;  when 
agitated  with  sulphuric  acid,  the  acid  becomes  colored  yellow, 
the  chloroform  loses  its  fine  odor  and  undergoes  decomposition, 
which  takes  place  still  more  rapidly  if  allowed  to  remain  in  con- 
tact with  the  acid,  giving  off  a  gas  somewhat  resembling  hydro- 
chloric.   If  it  contains  the  smallest  amount  of  alcohol  or  spirits 
of  wine,  on  the  addition  of  a  little  bichromate  of  potash,  and  a 
few  drops  of  sulphuric  acid,  the  green  oxide  of  chromium  is 
formed,  which  floats  on  the  surface,  and,  if  allowed  to  evaporate 
spontaneously,  the  aldehyd  which  is  formed  thereby  can  be  easily 
recognized.    It  is  miscible  with  alcohol ;  if  rather  more  than  13 
parts  of  chloroform  and  6  parts  of  alcohol,  (-835  S.  G.,)  be  mixed, 
they  will  unite  and  give  a  specific  gravity  of  about  1,200,  and  if 
more  chloroform  be  added,  they  will  separate.  When  it  contains 
the  smallest  amount  of  water,  it  will  become  clouded  with  every 
variation  of  temperature. 
It  is  quite  evident  that  the  carbonizing  or  charring  of  the 
volatile  oil  by  concentrated  sulphuric  acid,  which  is  said  to  have 
caused  nausea  &c>,  in  peculiar  sensitive  persons  (even  when  agi- 
