Am.  Jour.  Pharro.  1 
August,  1899.  J 
Detection  of  Blood. 
365 
Inasmuch  as  guaiacum  resin,  as  well  as  the  guaiaconic 
acid,  specially  concerned  in  the  formation  of  "  guaiacum  blue,"  are 
both  easily  soluble  in  the  concentrated  chloral  hydrate  solution,  a 
simple  method  may  be  devised  for  the  extraction  of  blood  stains  and 
the  subsequent  detection  of  the  coloring  matter  of  blood.  This  modi- 
fication of  the  former  procedures  having  led  to  identical  results  in 
all  the  numerous  experiments  executed  for  this  purpose,  I  have  no 
reason  to  wait  any  longer  for  the  communication  of  a  process  which 
may  sometimes  prove  a  desirable  supplement  to  the  other  methods 
for  the  detection  of  blood. 
In  fact,  the  guaiacum  blood  test  can  be  prepared  and  managed 
on  the  simplest  terms  in  this  way,  that  first  the  colored  spots  in 
question,  after  moistening  with  a  little  acetic  acid,  are  extracted  either 
with  a  70  per  cent,  chloral  hydrate  solution  or  directly  with  a 
1  per  cent,  solution  of  guaiacum  in  aqueous  chloral  hydrate,  con- 
taining 70  to  75  per  cent,  of  the  latter.  In  regard  to  the  fact  that 
the  resin  constituents  concerned  in  the  subsequent  reaction  show  a 
marked  tendency  for  spontaneous  oxidation — as  is  sufficiently 
proved  by  the  well-known  change  of  color  in  the  air  and  light — 
this  latter  method,  on  the  whole,  seems  less  preferable  than  the 
first  named,  which  consists  in  first  extracting  the  blood  by  means  of 
chloral  solution  and  then  adding  to  the  resulting  blood  solution  about 
an  equal  volume  of  the  guaiacum  chloral  solution.  If  in  this  pro- 
cess the  blood  stain  has  been  moistened  with  acetic  acid  previous  to 
the  treatment  with  chloral  hydrate,  the  addition  of  guaiacum 
chloral  solution  to  the  chloralic  extract  of  the  stain  to  be  tested  for 
blood  will  permit  a  control  reaction,  inasmuch  as  the  casual  pres- 
ence of  nitrites  (as,  for  instance,  nitrite  of  ammonia)  in  the  respec- 
tive stain  would  at  once  cause  a  more  or  less  intense  blue  coloration 
of  the  mixture  owing  to  the  decomposition  of  these  salts  by  the 
acetic  acid,  the  nitrous  acid  coloring  guaiacum,  viz.,  guaiaconic  acid 
blue  even  in  high  dilutions.  Moreover,  if  the  chloral  extract  of 
the  stain  contains  only  blood,  the  addition  of  the  brownish-yellow 
guaiacum  chloral  solution  to  the  pale  red  liquid  derived  from  the 
stain  will  give  a  pale  brown  mixture  exceedingly  well  adapted  for  a 
decisive  zone  reaction  indicating  the  presence  of  hematin.  To 
this  blood  guaiacum  solution  in  aqueous  chloral  hydrate  a  stratum 
of  the  already  mentioned  turpentine  solution  of  Hiinefeld  or  of  an 
adequate  solution  of  hydric  peroxide  (the  indifference  of  which 
