COLOR  TESTS  FOR  STRYCHNIA,  ETC. 
517 
The  consideration  of  the  properties  of  gelatinous  colloids 
appears  to  show  that  osmose  is  principally  an  affair  of  the  de. 
hydration  of  the  gelatinous  septum  under  influences  having  a 
catalytic  character,  and  that  the  phenomenon  is  independent  of 
diffusion.  The  colloidal  septum  is  capable  of  hydrating  itself 
to  a  higher  degree  in  contact  with  pure  water  than  in  contact 
with  a  saline  solution.  Colloidal  septa,  swollen  in  consequence 
of  contact  with  dilute  acid  or  alkali,  appear  to  require  increased 
sensibility  to  osmose,  in  consequence  of  their  unusually  high 
degree  of  hydration. — London  Pharm.  Journ.  August^  1861, 
from  Proceedings  of  the  Royal  Society, 
ON  THE  COLOR  TESTS  FOR  STRYCHNIA,  AND  THE  DIAGNOSIS 
OF  THE  ALKALIES. 
Being  the  substance  of  part  of  the  Croonian  Lectures  for  1861,  delivered  at  the  Royal 
College  of  Physicians. 
By  William  A.  Guy,  M.  B.,  Cantab. 
Fellow  of  the  College,  and  Professor  of  Forensic  Medicine,  King's  College,  London. 
[The  following  is  the  conclusion  of  a  series  of  papers  published  on 
this  subject  in  the  Pharmaceutical  Journal.  We  have  not  space  for  all, 
and  refer  those  of  our  readers  who  desire  to  examine  the  whole  series,  to 
that  work.  Vols.  2d  and  3d,  new  series,  now  in  course  of  publication. — Ed. 
Am.  Jour.  Ph.] 
The  last  of  the  four  questions  proposed  for  solution  in  my 
first  communication  still  remains  to  be  discussed.  It  relates  to 
the  diagnosis  of  the  alkaloids,  and  was  expressed  in  the  follow- 
ing terms  :  Is  it  possible  by  means  of  the  color-tests,  or  by  any 
simple  modification  of  them,  to  distinguish  the  alkaloids  from 
each  other  ? 
Before  proceeding  to  examine  this  question,  I  must  briefly 
refer  to  what  I  have  already  stated  respecting  the  color-tests. 
These  tests,  as  commonly  understood,  are  compound  tests,  con- 
sisting first  of  the  reaction  of  the  alkaloid  with  sulphuric  acid, 
and  then  of  the  reaction  of  the  peroxides  of  lead  and  manga- 
nese, the  bichromate  of  potash,  the  ferricyanide  of  potassium, 
and  the  permanganate  of  potash,  with  the  mixture  of  the  alka- 
loid and  sulphuric  acid. 
The  sulphuric  acid  produces  in  strychnia  no  change  of  color. 
