74 
ON  CHLORAL. 
ble  that  the  medical  profession  will  adopt  any  of  the  long  names  in 
making  up  their  prescriptions,  but  that  chloral  will  reign  in  all 
its  simplicity.  It  is  worthy  of  note  that  nearly  simultaneously 
with  Liebig's  discovery  of  chloral  in  Germany,  was  Guthrie's 
preparation  of  chloroform  in  the  United  States,  and  it  is  some- 
what remarkable  that,  while  the  former  is  just  coming  into 
notice  as  an  hypnotic  agent,  the  latter  has  been  employed  since 
1847  as  an  anaesthetic,  and  the  present  investigations  upon  it 
would  not  have  been  undertaken  if  it  were  not  for  its  relations 
to  chloroform.  Although  Liebig  first  prepared  chloral,  yet  we 
are  chiefly  indebted  to  Dumas  for  a  knowledge  of  its  properties 
and  constitution,  just  as  we  were  for  the  best  investigations  upon 
chloroform.  In  order  to  understand  how  chloral  can  be  made 
from  alcohol,  it  would  be  well  to  write  down  the  formulas  of 
alcohol,  aldehyd,  &c.,  and  then  trace  the  decomposition  that 
takes  place : 
Old.  New. 
Alcohol,  C^H^O^  C^H^O 
Aldehyd,  C^H^O^  C^H^O 
Chloral,  C^CPHO^  C^HCPO 
Chloroform,  C^HCP  C  HCP 
When  chlorine  is  passed  through  absolute  alcohol,  we  can  see, 
from  the  above  table,  how  it  takes  the  place  of  hydrogen,  and 
forms  hydrochloric  acid.  The  reaction  may  be  represented  by 
the  following  formula,  C^H^O+S  Cl^C^HCPO+S  HCl.  The 
actual  manufacture  of  chloral  is  attended  with  considerable 
difficulty  and  expense. 
It  is  necessary  to  pass  well  dried  chlorine  gas  through  pure 
anhydrous  alcohol  for  many  hours,  as  long  as  it  is  absorbed,  and 
to  keep  the  vessel  cool  in  the  early  stages  of  the  operation  ; 
later,  the  temperature  must  be  gradually  raised  until  the  liquid 
boils.  If  dilute  alcohol  be  employed,  instead  of  the  anhydrous, 
no  chloral  is  formed,  but,  in  its  stead,  aldehyd,  acetic  acid  and 
hydrochloric  acid  ;  hence  the  necessity  of  using  absolute  alcohol. 
It  is  also  difficult  to  prevent  the  formation  of  other  compounds, 
especially  chloride  of  carbon,  which  serve  to  contaminate  the 
chloral  and  render  its  administration  dangerous.  After  the 
chlorine  has  been  passed  through  sufficiently  long,  the  crude 
product  is  mixed  with  three  times  its  bulk  of  oil  of  vitriol  and 
