fefMpP":}  Groton  Chloral.  151 
more  of  the  attention  of  medical  men,  so  that  the  requirements  of  it 
somewhat  exceed  the  first  demand  for  its  predecessor  when  sold  at 
about  the  same  price. 
Crotonic  chloral  was  discovered  somewhat  accidentally  by  Drs.  Gr. 
Kraemer  and  A.  Pinner. f  These  gentlemen  were  undertaking  ex- 
periments on  the  action  of  chlorine  on  aldehyde,  chiefly  in  the  hope 
of  thus  obtaining  chloral,  and  of  being  able  to  utilize  the  valueless 
residue  from  the  first  runnings  obtained  in  the  distillation  of  crude 
spirit,  which  consists  mainly  of  alcohol,  aldehyde  and  paraldehyde. 
Chlorine  was  passed  into  aldehyde,  at  first  carefully  cooled  in  a 
freezing  mixture,  and  only  heated  to  100°  at  the  close  of  the  reac- 
tion. The  first  few  bubbles  caused  the  separation  of  a  small  quan- 
tity of  solid  met-aldehyde,  whether  originally  present  in  the  aldehyde 
or  formed  by  the  reaction,  is  undecided.  After  a  short  time  evolution 
of  hydrochloric  acid  set  in  and  every  trace  of  chlorine  was  absorbed. 
With  100  grams  of  aldehyde,  at  the  end  of  twenty-four  hours,  no  fur- 
ther absorption  took  place  even  at  100°.  The  resulting  brown  mass 
•consists  of  two  layers :  a  lower,  darker,  almost  solid  ;  and  an  upper, 
lighter-colored,  liquid  layer.  The  latter  is  a  saturated  solution  of 
hydrochloric  acid  and  the  bodies  of  the  lower  layer  in  water.  As  it 
was  found  impossible  to  separate  these  two  well,  the  whole  was  sub- 
mitted to  distillation.  A  considerable  quantity  passed  over  between 
D0°  and  100° ;  the  thermometer  then  rose  rapidly  to  160°,  and  the 
main  product  distilled  over  between  this  and  180°  ;  the  temperature 
again  rose  to  about  240°,  but  only  decomposition  products  were  ob- 
tained, and  a  considerable  carbonaceous  residue  remained  in  the  flask. 
By  means  of  fractional  distillation  the  portion  boiling  at  160°  to  180° 
was  quickly  purified,  and  a  body  boiling  at  163°  to  165°  was  isolated, 
which  proved  to  be  crotonic  chloral. 
The  specimen  I  have  here  was  produced  by  passing  perfectly  dry 
chlorine  gas  over  pure  aldehyde  (C2H40) — the  action  is  very  violent, 
and  many  precautions  have  to  be  taken  to  prevent  explosion  and  to 
condense  the  volatile  products  of  the  reaction,  and  still  to  allow  the 
enormous  quantities  of  hydrochloric  acid  gas  to  escape.  After  a  time 
the  liquid  thickens ;  at  this  stage  the  current  of  chlorine  can  be  passed 
through  the  liquid.  After  another  interval  it  becomes  necessary  to 
warm,  and  at  last  to  boil  the  liquid  through  which  the  chlorine  is 
t  Ann.  Ch.  Pharm.,  clviii,  37. 
