368 
Detection  of  Blood. 
/  Am.  Jour.  Pharm 
1      August,  1899. 
fest  degree  a  catalytic  and,  at  the  same  time,  "  oxygen-transferring  " 
action  towards  hydric  peroxide,  strictly  differ  from  the  coloring 
matter  of  blood  in  that  the  last-named  action  is  cancelled,  or  at 
least  most  strikingly  weakened  by  heating  to  ioo°  C,  or  also  by 
contact  with  diluted  hydrocyanic  acid  !  In  case  the  extract  of  a  pre- 
tended blood  stain  contains  such  a  substance  of  the  class  of  ferments, 
instead  of  the  ingredients  of  blood,  it  will  cease  to  show  the  guaia- 
cum-reaction,  even  after  a  shorter  digestion  at  the  temperature  of 
the  water- bath,  and  also  a  control-experiment  with  addition  of  hydro  - 
cyanic  acid  during  the  extraction  of  the  stain  will  give  essentially- 
negative  results.5  However,  the  avoiding  of  every  mistake  becomes 
rather  difficult  in  such  cases,  where  the  presence  of  even  the  smallest 
quantities  of  ferrous  oxide  or  other  ferrous  compounds  can  occur,  as, 
for  instance,  in  the  testing  of  suspected  stains  on  rusty  iron  materials. 
If  the  rust,  even  in  the  absence  of  blood,  contains  small  portions  of 
certain  ferrous  compounds,  viz.,  ferrous  carbonate  or  other  ferrous 
salts,  they  could,  by  extraction,  be  introduced  into  the  filtered  solu- 
tion, even  in  case  the  latter  had  not  taken  up  any  ferric  hydrate  or 
basic  ferric  salt;  yet  such  an  extract  of  a  stain,  even  with  the  slightest 
trace  of  ferrous  oxide,  would  cause  the  guaiacum-blue-reaction  after 
subsequent  addition  of  guaiacum  resin  and  hydric  peroxide.  A 
strict  distinction  of  ferrous  oxide  and  of  the  coloring  matter  of  blood 
is  not  very  easy  in  such  cases,  because  the  first-named  compound, 
even  in  smallest  quantities,  manifests  the  same  intense  **  ozone-trans- 
ferring "  power  as  hemoglobin  or  hematin,  which  also  contain 
iron.  It  will,  therefore,  form  the  object  of  further  experiments  to 
find  out  how  the  mentioned  casual  mistaking  in  the  guaiacum-blood- 
reaction  may  be  eliminated.  On  occasion  of  such  further  researches 
concerning  the  reaction  discussed  in  this  paper,  the  question  would 
have  to  be  treated,  whether  blood,  which,  after  drying  up  in  slow 
decomposition  on  certain  materials,  like  stone,  clay  and  rough 
metallic  surfaces,  and  after  disappearance  of  the  organic  substance 
by  the  action  of  air  and  water,  leaves  but  rusty  spots,  can  generate 
in  these  conditions  seizable  quantities  of  ferrous  compounds. 
The  above-described  method  of  extraction  of  blood  stains  with 
5  For  further  particulars  concerning  this  question  see  Ed.  Schaer's  "Contri- 
butions to  the  Chemistry  of  the  Blood  and  the  Ferments,"  Zeitschr.f.  Biologie, 
Vol.  VI  (1870),  p.  467. 
