"^"^T^ny  issr™'}    Analytical  Researches  and  Investigations.  301 
be  prepared  from  putrefied  albuminous  bodies,  such  as  fibrin,  casein^ 
the  brain,  liver,  and  muscle  flesh.  The  poisonous  substance  which 
has  recently  been  repeatedly  observed  in  urine,  the  author  believes  to 
be  identical  with  that  obtained  from  pepton. — Ber.  d.  Deutsch.  ch.  Ges, 
16,  p.  807,  from  Ztscher.f.  Physiol.  Chem.  vii,  274-281. 
On  Colocynthin.  By  Gustav  Henke. — The  author  reviews  the 
various  methods  adopted  by  earlier  chemists,  Meissner,  Braconnot, 
Vauquelin,  Lebourdais,  Herberger,  Bastick,  Hiibschmann,  and  Walz, 
for  the  obtainment  of  colocynthin,  or  the  various  impure  products 
which  have  received  this  name,  and  subsequently  describes  the  pro- 
cess followed  by  him,  and  the  true  characters  of  the  colocynthin 
obtained. 
Five  kilograms  of  commercial  colocynth,  deprived  of  the  seeds^ 
were  reduced  to  coarse  powder,  and  extracted  four  times  with  alcohol^ 
diluted  with  an  equal  weight  of  water,  with  tlie  aid  of  heat.  The  fil- 
trates were  combined,  the  alcohol  distilled  off,  and  the  residue 
extracted  with  water  and  filtered.  To  the  clear,  bright  yellow  filtrate 
a  concentrated  aqueous  solution  of  tannic  acid  was  added,  and  the 
very  abundant  white  precipitate  thus  formed  allowed  to  deposit.  As 
this  required  some  time,  its  deposition  was  accelerated  by  the  addition 
of  powdered  pumice-stone,  thereupon  the  precipitate  filtered,  well- 
washed,  and,  after  mixing  with  freshly  precipitated  carbonate  of  lead, 
evaporated  on  a  water-bath  to  dryness.  Upon  treating  with  boiling 
absolute  alcohol  the  colocynthin  becomes  immediately  dissolved,  and, 
after  evaporation  and  drying  over  sulphuric  acid,  forms  a  brittle,  colo- 
phonium-like  mass.  When  triturated,  it  forms  a  permanent,  loose, 
and  bright  yellow  powder. 
Colocynthin  is  without  action  upon  litmus,  and  is  soluble  in  20 
parts  of  cold,  or  16  parts  of  warm  water ;  it  is  likewise  very  readily 
soluble  in  alcohol,  but  more  difficultly  in  absolute  alcohol.  If  to  the 
alcoholic  solution  an  excess  of  ether  be  added,  the  colocynthin  sepa- 
rates out  in  the  form  of  white  flakes.  It  is  insoluble  in  chloroform,^ 
ether,  benzol,  carbon  bisulphide,  and  petroleum  ether.  When  heated 
on  platinum-foil  it  burns  away  without  residue.  Besides  being  soluble 
in  water  and  in  alcohol,  it  is  also  very  readily  dissolved  by  ammonia- 
water  and  an  aqueous  solution  of  chromic  acid.  Concentrated  sul- 
phuric acid  dissolves  it  in  the  cold,  forming  a  deep  red  liquid,  and, 
upon  warming,  the  colocynthin  is  immediately  destroyed ;  dilute  sul- 
phuric acid  is  without  any  action.    Concentrated  nitric  acid  dissolves 
