364 
Detection  of  Blood. 
( Am.  Jour.  Pharm. 
t     August,  1899. 
observed  by  ScJibnbein,  viz.,  that  the  coloring  matter  of  blood 
altered  by  exsiccation  even  in  higher  temperatures  still  shows  in 
unimpaired  degree  the  different  "  ozone-transferring "  properties, 
and  even  seems  to  act  more  intensely  in  some  respects,  for  instance, 
towards  a  mixture  of  peroxide  of  hydrogen  and  cyanine. 
Since  the  publication  (in  the  quoted  treatise)  of  this  modification 
in  the  methods  of  detection  of  blood  by  means  of  guaiacum,  some 
observations  on  different  points  of  solubility  of  the  red-colored 
blood  constituents,  especially  in  dry  blood,  have  taken  place,  which 
lead  to  new  propositions  concerning  a  reliable,  very  short  and  direct 
way  for  the  detection  of  blood,  and  therefore  may  be  communicated 
in  this  Journal,  after  having  been  briefly  related  in  the  pharmaceu- 
tical section  of  the  annual  meeting  of  German  naturalists  at  Bruns- 
wick in  1897.  By  occasion  of  former  studies  and  experiments  on 
the  physical  and  chemical  behavior  of  chloral  hydrate,  which  later 
on  have  been  continued  and  extended  by  a  pupil  and  assistant, 
R.  Manch,  pharmaceutical  chemist,3  a  special  solvent  power  of 
highly  concentrated,  that  is  to  say,  65  to  80  per  cent.,  aqueous  solu- 
tions of  the  said  compound  has  been  observed,  not  only  for  several 
bodies  already  known,  like  starch,  but  also  for  various  very  different 
substances,  like  certain  resins,  coloring  matters,  stearoptenes  and 
also  albuminous  matters,  especially  the  coloring  matter  of  blood.  In 
fact,  experience  showed  that  blood  stains  which  have  become  dry 
even  for  a  long  time  on  linen  or  other  similar  materials  are  ex- 
tracted in  a  relatively  short  time  by  impregnation  and  contact  with 
a  chloral  hydrate  solution  of  about  70  per  cent,  and  more  thor- 
oughly dissolved  than  by  any  other  treatment.  Even  blood  stains 
many  years  old  may,  by  this  operation — after  a  somewhat  longer 
contact  with  the  solution — be  removed  to  such  a  degree  that  their 
trace  is  but  hardly  discernible  on  the  linen.  It  may  be  observed  on 
this  occasion  that  the  solution  of  the  blood  constituents  by  aqueous 
chloral  hydrate  is  much  facilitated  if  the  blood  spots  have  been 
previously  wetted  with  small  quantities  of  concentrated  acetic  acid. 
The  use  of  this  acid  is  not  only  admissible  for  itself,  as  the  guaia- 
cum-blue  is  not  affected  by  it,  but  even  offers  a  certain  advantage 
concerning  a  reaction  of  control  to  be  mentioned  later  on. 
C.  f.  '' Ueber  physikal.-chem.  Eigenschaften  des  Chloralhydrates  u.  deren 
Verwerthung  in  pharm. -chem.  Richtung."  Inaug.  Dissertat.,  Strassburg, 
1898.    In  this  paper  a  short  chapter  is  also  dedicated  to  the  present  question. 
