552 
TESTING  FOR  STRYCHNIA,  BRUCIA,  ETC. 
chromate  of  strychnia,  that  no  crystals  can  be  obtained  by  pre- 
cipitation with  the  weak  acid  liquor  previously  alluded -to. 
Chromate  of  lead  never  can  (except  at  first  sight)  be  mistaken 
for  either  chromate  of  strychnia  or  brucia,  because,  first,  it  is 
always  in  the  amorphous  or  powdery  state ;  and  secondly,  no 
color  is  developed  on  the  addition  of  sulphuric  acid. 
It  is  therefore  evident  that  the  production  of  chromate  of 
strychnia  in  one  or  other  form,  and  its  reaction  with  sulphuric 
acid,  renders  it  a  faultless  and  invaluable  toxicological  method, 
and  enables  us  to  pronounce  with  certanity  respecting  the  alka- 
loid, since  no  other  comports  itself  in  a  similar  manner. 
In  reference  to  the  precipitation  of  strychnia,  it  would  appear, 
judging  from  'the  J  very  high  equivalent  of  strychnia  (343),  that 
a  very  small  quantity  of  the  chromic  salt  is  necessary  for  that 
purpose,  as  may  be  verified  by  experiment.  Every  three-and-a- 
half  out  of  four  parts  of  chromate  of  strychnia  may  be  said  to  be 
the  proportion  of  real  strychnia.*  4 
It  has  been  asserted  since  the  trial,  that  the  non-detection  of 
strychnia  in  the  body  of  John  Parsons  Cook,  was  owing  to  the 
antimony  which  was  known  to  have  been  taken  by  the  deceased 
having  somewhat  interfered  with  the  tests.  Such  a  supposition 
is,  in  my  opinion,  truly  absurd.  Nothing,  I  conceive,  can  more 
incontestably  disprove  this  fallacy,  than  either  of  the  following 
additional  new  tests  for  the  detection  of  strychnia. 
If  we  mix  one  part  of  a  saturated  solution  of  the  yellow  cyanide 
of  potassium  (containing  twelve  grains  to  each  drachm  of  water) 
with  two  parts  of  a  solution  of  the  acetate  of  strychnia,  or  if  we 
take  say  thirty  drops  of  the  solution  of  strychnia  diluted  with 
sixty  or  ninety  drops  of  water,  and  then  drop  in  one  minim  only 
of  the  solution  of  the  ferrocyanide  of  potassium,  and  agitate  the 
mixture  for  a  few  seconds,  an  abundance  of  minute  yellowish- 
white  silky  crystals  of  the  ferrocyanide  of  strychnia  is  formed. 
This  is  a  very  beautiful  compound  test,  and  is  best  shown  as 
follows  :— I  first  take  a  very  small  portion  of  powdered  protosul- 
phate  of  iron,  and  laying  upon  it  a  little  of  the  dried  ferrocyanide 
*  It  may  be  a  point  for  consideration  how  far  chromate  of  potash  in 
solution  maybe  useful  in  neutralizing  the  effect  of  any  of  the  free  strychnia 
existing  in  the  stomach. 
