Am.  Jour.  Pharm.  ) 
January,  1910.  j 
U.S. P.  Chemicals  and  Tests. 
3r- 
tures,  it  should  be  wholly  or  almost  wholly  dissolved  (limit  of 
quinine  or  cinchonidine  sulphate)." 
Collodion. — The  U.S. P.  8th  Revision  requires  40  Gm.  gun- 
cotton  to  be  dissolved  in  750  c.c.  ether  and  250  c.c.  alcohol,  whereas 
the  U.S. P.  1890  required  only  30  Gm.  in  the  same  amount  of  sol- 
vents. The  increased  quantity  of  gun-cotton  has  caused  some 
trouble  where  collodion  is  used  as  a  base  for  preparations. 
Glycerin. — It  is  apparently  difficult  to  eliminate  the  last  traces 
of  butyric  acid.  In  almost  every  examination  of  glycerin  a  fruity 
odor  is  noticed  when  treated  with  alcohol  and  sulphuric  acid. 
Iron  Chloride  Solution. — The  test  for  oxychloride  is  not  suffi- 
ciently exacting.  It  has  been  found  that  when  tincture  iron  chloride 
is  made  from  a  solution  which  meets  the  oxychloride  test,  the  tincture 
subsequently  becomes  turbid  owing  to  an  excess  of  oxychloride. 
Lime,  Sulphurated. — The  test  for  the  percentage  of  pure 
calcium  sulphide  is  somewhat  misleading,  as  there  is  always  iron 
present,  which  will,  on  the  addition  of  ammonia,  impart  a  brownish 
color  to  the  filtrate. 
Mercury  Oxide  Yellow. — Criticism  has  been  made  that  mercury 
oxide  yellow  contained  red  oxide,  because  it  is  not  entirely  converted 
into  white  mercuric  oxalate  when  digested  on  the  water-bath  with 
oxalic  acid  for  fifteen  minutes.  Experiments  show  that  even  if  the 
yellow  oxide  is  reduced  to  a  very  fine  powder,  a  small  portion  still 
remains  unchanged,  consisting  of  minute  lumps  of  a  fine  yellow  pow- 
der, showing  no  crystalline  appearance  under  a  lens  magnifying 
four  diameters.  This  residue  was  not  converted  to  oxalate  even 
after  heating  for  several  hours.  When  the  yellow  oxide  is  mixed 
with  a  small  quantity  of  red  oxide,  and  the  same  test  applied,  the 
residue  shows  a  decided  red  color  and  crystalline  structure.  When 
red  oxide  of  mercury  is  powdered  until  it  becomes  the  same  color 
as  yellow  oxide,  there  is  a  partial  conversion  into  oxalate  at  the  end 
of  fifteen  minutes,  but  when  treated  with  oxalic  acid  without  powder- 
ing, there  is  no  visible  diminution  of  the  red  color  at  the  end  of  two 
hours. 
Sugar  of  Milk. — Even  the  corrected  test  has  given  considerable 
trouble  in  testing  for  cane  sugar,  and  is  difficult  to  comply  with. 
However,  when  the  test  of  the  German  Pharmacopoeia  is  applied, 
samples  which  meet  the  other  U.S. P.  requirements  stand  the  German 
test  perfectly.  This  difference  is  occasioned  by  the  fact  that  the 
U.S. P.  requires  diluted  alcohol  containing  about  41^  per  cent,  by 
