COLOR  TESTS  FOR  STRYCHNIA,  ETC. 
525 
kaloid.  I  tried  this  reaction  in  the  case  of  fourteen  alkaloids 
and  active  principles,  comprising  all  the  more  active  poisons  of 
this  class,  together  with  the  less  important  principles,  emetia 
and  meconine,  and  found  the  alkaloids  to  differ  from  each  other 
in  the  amount  of  carbonaceous  deposit.  With  strychnia,  aconi- 
tina  and  veratria,  for  instance,  the  deposit  of  carbon  was  less 
abundant  than  with  brucia,  morphia,  atropia  and  the  other  poi- 
sonous alkaloids.  But  the  difference  was  not  such  as  to  justify 
me  in  using  it  as  a  diagnostic  property.  So  also  with  the  direct 
application  of  heat  to  the  alkaloids  themselves.  Strychnia, 
morphia,  atropia,  cantharidine,  meconine,  picrotoxia  and  del- 
phinia,  after  melting,  deposited  but  a  scanty  carbonaceous  ash  ; 
while  emetia,  aconitina  and  digitaline  yielded  an  abundant  ash  ; 
and  brucia,  elaterine,  veratria  and  solanine,  yielded  an  ash  in- 
termediate in  quantity.  This  test,  again,  though  fairly  applica- 
ble to  the  few  cases  in  Table  I.,  did  not  seem  admissible  as  a 
diagnostic  on  a  larger  scale.  Indeed,  the  tables,  though  care- 
fully compiled  and  based  on  carefully  conducted  experiments, 
are  open  to  the  obvious  objection  that,  with  different  specimens 
and  different  quantities  of  the  alkaloids,  and  with  different  speci- 
mens of  sulphuric  acid,  we  may  obtain  differences  of  tint,  and 
more  or  less  ready  development  of  color  under  increase  of  tem- 
perature. The  majority  of  the  reactions,  however,  will,  I  be- 
lieve, be  found  constant  for  all  specimens  of  fair  average  purity. 
One  alkaloid,  hyoscyamia,  which  I  was  not  able  to  procure,  is 
omitted.* 
Of  the  two  tables,  Table  I.  affords  the  best  illustration  of  a 
table  of  elimination.  For  the  sake  of  brevity,  and  for  other 
reasons  already  explained,  the  figures  1,  2,  3,  are  added  to  the 
words  describing  the  colors  developed  by  the  tests.  These 
figures  indicate  different  degrees  of  intensity.  In  comparing 
strychnia  with  brucia,  for  instance,  the  figure  (^)  attached  to  the 
word  yellow"  opposite  strychnia  in  the  third  column  means  a 
faint  yellow  color,  less  in  degree  than  that  indicated  by  the 
figure  opposite  brucia  in  the  same  column.  So  the  word 
<'  brown  "  with  the  annex  ^  in  the  same  column  opposite  escu- 
*  In  the  lectures  at  the  College  of  Physicians  a  table  was  used  which 
showed  the  colors  actually  produced  by  the  action  of  the  several  reagents 
on  these  poisonous  alkaloids  and  active  principles. 
