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COCHINEAL  COLORING. 
greater  extent  than  20  per  cent,  at  50° ;  but  that  if  croton  oil 
has  undergone  a  chemical  change,  such  as  resinification  or  oxi- 
dation by  time  and  exposure  to  air,  or  has  been  expressed  from 
seeds  which  have  become  changed  in  the  same  manner,  then  the 
oil  is  freely  dissolved  by  the  alcohol.  It  follows  that  "  a  test 
which  is  open  to  many  weighty  objections,  both  from  the  influ- 
ence of  small  fluctuations  of  temperature,  and  for  indicating 
the  purity  of  material  liable  to  such  marked  differences  from  the 
effects  of  such  natural,  and  in  some  cases  inevitable,  chemical 
changes,  is  perfectly  useless  as  a  reliable  indication  of  purity." — 
Chem.  News,  Feb.  3,  1865. 
COCHINEAL  COLORING. 
For  the  following  formula  we  are  indebted  to  Dr.  George, 
Dickson,  of  Edinburgh  : — 
"  Cochineal  coloring  may  be  prepared  without  admixture  of 
carbonate  of  potash,  alum,  etc.,  as  follows : — 
Take  of— 
Cochineal  in  powder,  1  oz. 
Spirit  of  wine,  2  oz. 
Water,  6  oz. 
Liq.  Amraon.  Fort.,  q.  s.  (about  viij. 
«  Mix  the  spirit  and  water,  and  in  three  ounces  of  the  mixture, 
heated  to  near  the  boiling-point  in  a  flask,  infuse  the  cochineal 
for  fifteen  minutes.  Pour  the  infusion  into  another  vessel,  and 
repeat  the  process  with  three  ounces  more  of  the  mixed  spirit 
and  water ;  and  a  third  time,  with  the  remaining  two  ounces. 
Let  the  liquid  stand  till  cold,  when  some  fatty  matter  will  rise 
to  the  surface  ;  filter,  adding  spirit  and  water,  up  to  eight  fluid 
ounces.  Lastly,  add  sufficient  Liq.  Ammon.  Fort,  (about  m  i. 
to  %\y  to  change  the  infusion  to  the  desired  tint. 
"  The  objections  to  the  use  of  carbonate  of  potash,  alum, 
etc.,  are  : — 1st,  The  coloring-matter  is  thrown  down  as  a  lake, 
and  after  some  time,  forms  a  layer  at  the  bottom  of  the  con- 
taining vessel,  requiring  the  addition  of  ammonia  to  redissolve 
and  keep  it  in  solution  ;  and  2d,  it  does  not  keep  well.  On  the 
other  hand,  the  advantages  of  this  preparation  are  : — 1st,  the 
coloring-matter  remains  in  solution,  and  2d,  it  keeps  well,  and 
has  no  unpleasant  odor." — Lond.Pharm.  Journal. 
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