THE  AMERICAN 
JOURNAL  OF  PHARMACY. 
SEPTEMBER,  1884. 
.    PRECIPITATES  IN  FLUID  EXTRACTS.1 
By  J.  U.  Lloyd. 
Head  at  the  thirty-second  annual  meeting  of  the  American  Pharmaceutical 
Association  at  Milivaukee,  and  communicated  by  the  author. 
In  our  last  paper  (for  a  brief  abstract  see  "Am.  Jour.  Phar.,"  1883,  p. 
086)  we  were  led  to  bring  forward  an  experiment,  wherein  by  evaporating 
a  solution  of  a  mixture  of  the  salts,  chloride  of  sodium  and  chloride  of 
ammonium,  a  separation  of  these  substances  was  effected — one  (chloride 
of  sodium)  being  deposited  near  the  bottom  of  the  evaporating  dish ; 
the  other  (chloride  of  ammonium)  being  mostly  deposited  at  the  surface 
of  the  liquid,  or  even  above  the  surface  line,  by  the  familiar  creeping 
process.  The  examination  of  these  deposits  demonstrated  that  the 
lower  part  of  the  lowest  deposit  was  more  than  half  chloride  of  sodium, 
while  the  upper  deposit  contained  but  two-thirds  of  one  per  cent,  of 
1  Query. — "  Is  there  any  method  whereby  a  solvent  can  be  perfectly  freed 
from  a  substance  in  solution,  without  evaporating  the  liquid,  precipitating 
the  dissolved  matter  in  an  insoluble  form,  or  changing  the  liquid  (as  adding 
alcohol  to  water)  ?" 
This  question  was  addressed  to  several  of  our  foremost  scientists,  and 
without  any  information  being  furnished  as  to  another  known  method.  In 
connection  with  this  subject,  it  is  proper  to  state  that  for  many  years  it  has 
been  known  that  charcoal  will  separate  certain  organic  matters  from  solu- 
tion ;  and,  according  to  the  experiments  of  Mr.  Witt  (1856),  it  was  shown 
that  22  per  cent,  of  chloride  of  sodium  was  taken  from  a  solution  of  that 
substance  by  nitration  through  If  feet  of  sand.  These  facts  are  related  to 
the  experiments  which  follow,  and  to  which  we  can  rind  none  similar  on 
record.  Indeed,  quotations  from  our  acknowledged  authorities  show  that 
the  phenomenon  herein  brought  forward  has  been  generally  overlooked. 
We  will  cite  as  follows  : 
Filtration. — "The  mechanical  separation  of  a  liquid  from  the  undis- 
solved particles  floating  in  it." — Ure. 
"  The  separation  of  suspended  matter  is  effected  on  the  small  scale  for 
laboratory  purposes  by  filtration  through  porous  paper." — Boseoe  &  Schor- 
lemmer. 
"The  mechanical  separation  of  fluid  from  solid  matters  mixed  with 
them.  The  pores  of  the  paper  permit  the  fluid  to  pass  through  ;  whilst  tin- 
solid  matter,  being  prevented,  remains  behind."— Galloway. 
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