286  Analytical  Researches  and  Investigations.  {^'^ATJjimi''^ 
observations  of  C.  Mann,  when  2  ])arts  of  citric  acid  and  1  part  of 
molybdic  acid  are  heated  together  in  a  ])orcelain  capsule  until  they 
begin  to  fuse,  a  dark  blue  mass  is  obtained,  which  dissolves  in  water 
with  a  slight  yellowish-brown  color.  If  strips  of  paper  are  moistened 
with  the  liquid,  and  dried  at  100°C.,  they  ap])ear  blue,  but  lose  this 
color  again  when  dipped  in  water.  The  strips  of  paper  thus  prepared 
are  adapted  for  determining  the  presence  of  water  in  alcohol  and  ether, 
the  latter  bodies  having  no  action  upon  the  blue  color ;  but  if  they 
contain  water  decoloration  ensues,  and  the  quicker  in  proportion  to 
the  amount  of  water  present. — Ihid.,  from  Archiv  der  Fharni.,  1882, 
17,  p.  122. 
Examimat;ion  of  Blood  Stains.  By  Victor  Schwarz. — The  separa- 
tion of  blood  from  its  solutions  (in  well-water,  soap-w^ater,  salt-water 
or  normal  urine)  for  the  formation  of  Teichmann^s  hsemin  crystals  by 
means  of  precipitation  is  more  successful  with  the  use  of  acetate  of 
zinc  than  with  tannic  acid.  For  the  solution  of  dried  blood  stains 
upon  linen  the  ordinarily  employed  potassium  iodide  is  well  adapted, 
and  the  obtained  liquid  is  precipitated  by  acetate  of  zinc.  The  spots 
may  also  be  extracted  by  digestion  for  48  hours  at  the  ordinary  tem- 
perature with  a  cold  saturated  solution  of  borax,  and  to  the  liquid  a 
solution  of  acetate  of  zinc  added  as  long  as  the  precipitate  appears 
colored  ;  by  the  further  addition  borate  of  zinc  will  be  precipitated, 
which  ])revents  or  retards  the  formation  of  the  haeniin  crystals  from 
the  precipitate.  By  the  previous  extraction  with  borax  the  prepara- 
tion containing  the  ha?min  crystals  must  eventually  be  warmed  again 
with  glacial  acetic  acid,  in  order  to  dissolve  foreign  substances,  before 
the  crystals  become  distinctly  visible.  The  extraction  of  mixtures  of 
blood  with  sand,  earth,  turf,  etc.,  is  best  accomplished  by  means  of  a 
cold  saturated  borax  solution,  much  less  effectually  with  potassium 
iodide,  as  the  blood  solution  with  the  latter  decomposes  very  quickly, 
so  that  after  a  few  hours  a  blood  spectrum,  which  at  first  is  plainly 
visible,  can  no  longer  be  detected.  In  o|)position  to  an  older  statement 
of  Wessel  the  author  has  repeatedly  succeeded  in  forming  the  hsemin 
crystals  from  blood  which  had  become  completely  decomposed,  and 
possessed  a  penetrating  odor. 
According  to  Struve  the  detection  of  blood  in  suspected  spots  is 
most  difficult  in  those  which  have  a  very  pale  color,  and  which  are 
only  observable  by  means  of  the  sharper  contour  of  the  edges.  In 
order  to  furnish  the  proof  a  large  segment  of  the  fabric  containing  the 
