528 
RECOGNITION  OF  BLOOD-SPOTS  ON  LINEN. 
stuff,  and  each  fragment  extracted  separately  with  distilled  water. 
The  spots  on  the  coarse  cloth  had  already  begun  to  decompose, 
as  it  had  lain  a  long  time  buried  in  dung.  The  filtered  fluid  from 
it  had  a  dingy  brownish-red  color.  By  the  employment  of  the 
reagents,  such  as  liquid  chlorine,  ammonia,  nitric  acid  and  tincture 
of  galls,  which  are  particularly  adapted  for  the  detection  of  albu- 
men, the  proper  reactions  were  certainly  obtained ;  but  as  the 
fluid  was  not  of  a  pure  red  color,  they  were  not  so  distinct  as  to 
enable  the  presence  of  blood  to  be  determined  with  perfect  cer- 
tainty. With  the  second  fluid  from  the  pillow-cover,  which  had 
a  dark  violet  color,  from  the  bad  blue  which  was  produced  by  log- 
wood, these  reagents  could  not  be  employed.  The  author  en- 
deavored to  produce  cyanide  of  potassium  with  the  supposed 
blood-spots  of  these  stuffs.  For  this  purpose,  having  first  ascer- 
tained, in  a  well-known  manner,  that  they  contained  no  wool,  he 
roasted  a  red  fragment  of  the  coarse  linen  in  a  porcelain  crucible 
until  it  could  be  rubbed  to  powder ;  this  powder  was  mixed  with 
some  carbonate  of  potash,  and  strongly  heated  to  redness.  The 
calcined  mixture  was  extracted  with  distilled  water,  and  a  little 
solution  of  a  salt  of  protoxide,  and  another  of  peroxide  of  iron, 
mixed  with  the  filtered  fluid,  by  which  means  a  precipitate  of 
indeterminate  color,  consisting  of  protoxide  and  peroxide  of  iron, 
precipitated  by  the  excess  of  carbonate  of  potash  and  protoper- 
cyanide  of  iron,  was  produced.  A  little  dilute  sulphuric  acid 
was  now  added,  by  which  the  oxides  of  iron  were  dissolved ; 
whilst,  on  the  other  hand,  the  protopercyanide  of  iron,  which  is 
insoluble  in  sulphuric  acid,  made  its  appearance  with  its  blue 
color.  THe  same  result  was  obtained  with  a  piece  of  the  checked 
stuff  on  which  red  spots  existed,  but  not  with  fragments  of  the 
stuffs  which  presented  no  appearance  of  blood-spots. 
The  experiments  were  also  frequently  repeated  with  other 
blood,  and  furnished  satisfactory  results  even  with  the  smallest 
quantities. 
The  operation  also  suceeds  when  a  piece  of  stuff  spotted  with 
blood  is  boiled  with  solution  of  caustic  potash,  the  fluid  evaporated 
to  dryness  and  calcined,  and  then  treated  with  iron  salts  and 
sulphuric  acid.  This  method  may  also  be  employed  when  blood- 
spots  are  found  upon  metallic  objects ;  the  spots  are  dissolved 
from  the  metal  by  solution  of  potash. — Qhemical  Gazette, 
August,  X85±,.from  Archiv.  der  Pharm.,  lxxviii.  p.  21. 
