326 
MODIFICATION  OF  CHEMICAL  AFFINITY. 
lents,  and  I  believe,  in  this  case,  I  have  proved  first  that  other 
double  salts  of  platinum  exist. 
The  problem  remains  now  to  be  solved,  -which  are  the  three 
organic  radicals  contained  in  quinine.  Although  former  experi- 
ments have  thrown  some  light  on  this  question,  I  decline  now  to 
enter  into  its  discussion  before  further  experiments  have  given 
us  a  stronger  hold. 
ON  CIRCUMSTANCES  MODIFYING  THE  ACTION  OF  CHEMICAL 
AFFINITY. 
By  J.  H.  Gladstone,  Ph.  D.,  F.  R.  S. 
The  question  intended  to  be  solved  in  this  communication  is, — 
what  takes  place  when  two  binary  compounds  AB  and  CD  are 
brought  together  under  such  circumstances  that  both  they  them- 
selves and  the  products  of  their  mutual  action,  remain  free  to 
react  ?  Do  they,  according  to  a  generally  received  opinion, 
remain  unaltered,  or,  should  the  affinities  so  preponderate,  become 
simply  AB  and  CB  ?  Or  do  A  and  C,  according  to  Berthollet's 
view,  divide  themselves  in  certain  proportions  between  B  and  D, 
the  said  proportions  being  determined  not  solely  by  the  difference 
of  energy  in  the  affinities,  but  also  by  the  difference  of  the  quan- 
tities of  the  bodies?  And,  supposing  the  latter  to  be  the  correct 
view,  do  the  amounts  of  AD  and  CB  produced  by  the  reaction, 
increase  progressively  with  the  relative  increase  of  AB,  or  do 
sudden  transitions  occur,  such  as  Bunsen  and  Debus  have  recently 
observed  in  certain  cases  where  the  products  were  removed  at 
once  from  the  field  of  action  ? 
A  reply  was  sought  in  the  colors  produced  upon  mixing  differ- 
ent salts  in  aqueous  solution.  There  were  not  many  colored 
salts  suitable  for  the  purpose,  as  it  generally  happens  that  a  base 
gives  the  same  color  with  whatever  acid  it  is  combined,  and  vice 
versa  ;  but  the  compounds  of  sesquioxide  of  iron  were  peculiarly 
adapted  to  the  requirements  of  the  experiment,  as  some  are 
intensely  colored,  while  others  are  nearly  colorless. 
The  circumstances  that  attended  the  formation  of  the  blood- 
red  sulphocyanide  were  first  fully  examined.  On  mixing  known 
quantities  of  different  ferric  salts  with,  known  quantities  of  dif- 
ferent sulphocyanides,  it  was  found  that  the  whole  of  the  iron 
