Am.  Tour,  pharm.  \       Preparation  of  Arsphenamme. 
May,  1919-       J  r 
303 
warmed  in  a  water  bath  at  40°  C,  until  the  suspension,  first  formed, 
seems  to  agglutinate  and  to  be  about 
to  settle.  The  suspension  matter 
seems  to  be  impurities,  mostly  dark 
colored,  from  the  nitro-oxyphenyl- 
arsonic  acid;  impurities  from  the 
hydrosulphite,  also  dark,  and  its  re- 
action products ;  besides  a  little  of  the 
arsphenamine  base.  The  total  weight 
of  the  suspension,  when  filtered  and 
dried,  is  rarely  more  than  three  to 
four  grams,  or  four  to  five  per  cent, 
of  the  total  yield. 
When  this  stage  is  reached,  the 
mixture  is  rapidly  filtered,  through 
hard  paper,  or  alundum  ware,  and  the 
clear,  yellow  filtrate  digested,  accord- 
ing to  Ehrlich  and  Bertheim's  direc- 
tions, at  500  to  60  0  C.  for  two  to  two 
and  a  half  hours,  when  the  base — 
diamino-dioxyarsenobenzene  —  sepa- 
rates out  as  a  yellow  precipitate. 
Some  chemists  lay  great  stress  on 
using  only  the  purest  nitro-oxyphenyl- 
arsonic  acid  and  only  to  treat  it  sub- 
sequently with  commercial  hydro- 
sulphite,  which  itself,  in  many  cases 
gives,  if  not  a  muddy  solution,  at 
least  a  dark  colored  one;  all  this  in 
spite  of  Ehrlich  and  Bertheim  point- 
ing out,  that  the  reduction,  even  with 
the  purest  nitro-oxyphenyl-arsonic 
acid,  produces  its  own  by-products. 
These  chemists  then  rely  on  bone- 
black  to  remove  all  such  impurities 
from  the  hydrochloride  in  methyl- 
alcohol  solution. 
This  preliminary  digestion  of  ours 
and  filtering  removes  the  impurities 
to  such  an  extent,  that  with  the  exception  of  a  slight  white,  mineral 
Laboratory  Anaerobic  Filter. 
The  outer  cylinder  may  be 
made  of  glass,  and  the  inner 
cone  of  "  alundum "  ware. 
When  not  completely  filled 
with  liquid,  inert  gas  such  as 
hydrogen  or  nitrogen  is  intro- 
duced and  the  position  of  the 
filter  reversed. 
