Am.  Jour.  Pharm.) 
August,  1899.  J 
Detection  of  Blood. 
369 
concentrated  solutions  of  chloral  hydrate  which,  as  is  well  known  by 
this  time,  are  also  good  solvents  for  resins,  has  induced  some  experi- 
ments in  order  to  ascertain  whether,  by  using  the  process  men- 
tioned in  the  first  part  of  this  essay,  chloral  solutions  containing 
blood  and  guaiacum  may,  by  precipitation  with  water  and  subse- 
quent filtration,  give  a  resinous  secretion  containing  blood  constitu- 
ents, showing  the  mentioned  behavior  and  applicable  to  the  guaia- 
cum-blood-reaction  after  any  time  of  conservation.  It  may  here  be 
stated,  by  the  way,  that  the  trials  performed  in  this  manner  have  but 
led  to  a  moderately  satisfactory  result,  probably  because  even  a 
diluted  chloral-solution  still  acts  as  a  solvent  on  the  resin  in  a  low, 
but  perceivable  degree  and  besides,  as  I  am  induced  to  believe, 
because  the  coloring  matter  of  blood  is  less  easily  precipitated  by 
the  secreting  resin  from  a  chloral-blood-solution  than  from  a  chiefly 
aqueous  liquid.  But,  notwithstanding  the  loss  of  material  caused  in 
that  way,  by  the  use  of  this  method  resin-covered  filters  can  be 
obtained  possessing  the  properties  quoted  in  the  beginning  of  this 
paper. 
Lastly,  it  may  be  mentioned  that — as  it  could  be  expected — the 
guaiacum  blood-test  executed  with  chloral  solution  is  thoroughly 
applicable  to  a  control-reaction,  viz.,  to  the  chemical  identification 
of  the  hemin-crystals,  which  are  of  high  importance  in  judicial 
cases.  A  specially  pure  blue  coloration  is  obtained,  when,  instead 
of  the  ordinary  guaiacum-solution,  a  solution  of  guaiaconic  acid  in 
200  to  500  parts  of  chloral-solution  (v.  s.)  is  used,  and  the  reaction 
is  observed  in  a  glass  tube  as  a  zone-reaction.  The  guaiaconic  acid, 
proposed  as  a  substitute  for  the  natural  resin  by  O.  Doebner*  in  his 
interesting  essay  on  guaiacum  resin  and  "  guaiacum-blue,"  is  just  as 
well  liable  to  spontaneous  oxidation  in  light  and  air  with  changes 
of  color ;  and,  according  to  my  observations,  its  use  is  more  con- 
venient for  the  described  zone-reactions  than  for  experiments  in 
watch  glasses  or  dishes,  where  greater  surfaces  get  into  action.  It 
is,  moreover,  obvious  that  this  special  experience  cannot  interfere 
with  the  certainly  desirable  use  of  the  guaiaconic  acid,  as  being  the 
active  constituent  of  the  resin,  in  the  numerous  other  guaiacum- 
reactions.  I  cannot  but  feel  convinced  that  the  reactions  with  gua- 
iacum resin  have  not,  in  all  respects,  met  with  the  consideration 
fi  See  Archiv.  d.  Pharmacie,  1897. 
