POTASSIUM  CITRATE

The  employment  of  potassium  citrate  as  a
restrainer  by  way  of  substitute  for  potassium
bromide  has  met  with  favor.  Indeed,,  the
citrates  of  the  alkalies  have  some  advantages,
over  bromide  in  checking  development,  in-
asmuch as  they  work  well  with  both  high  and
low  factor  developers.  Pyro,  where  the  high-
lights of  the  image  flash  up  first,  responds
readily  to  the  checking  influence  of  bromide,
but  when  metol  is  used,  where  the  high-lights
and  middle  tones  come  out  in  rapid  succession,
bromide  is  of  little  worth  in  securing  right
contrast  in  the  negative,  and  preventing  fuit-
ness  of  ima^e.  The  citrate  of  potash  here
is  more  efficient.  It  works  with  both  high
and  low  factor-developers — and  may  indeed
be  used  more  intelligently,  because,  it  can
be  added  after  development  begins,  when
one's  judgement  is  better  able  to  determine
what  to  do.
It  would  take  considerable  experimentation
to  accurately  determine  the  equivalence  of
the  two  restrainers,  but  practically  this  is
not  needed,  as  there  is  but  little  risk  in  the
use  of  the  citrate,  unless  excessively  used,
and  this  is  not  a  likely  occurrence.  It  is  not
advisable,  however,  to  add  it  to  your  made-
up  stock  solution,  but  better  to  keep  it  ready
for  use.  Make  up  a  solution,  say,  120  grains
to  the  ounce,  and  use  a  starter,  a  dram  of
this  to  every  ounce  of  developer.
