AmAug.?i877.rm'}      Corrosive  Sublimate  and  Arsenic.  397 
cone  with  the  spatula  held  edgewise  against  the  slab.  After  the  powder 
is  in  its  place  a  gentle  pressure  upon  it  with  the  finger,  as  before  stated, 
will  be  of  service  in  keeping  it  together  and  causing  it  to  come  out  as 
if  moulded  to  the  form  of  the  cone.  In  many  cases  also,  the  cone 
will  retain  the  powder  sufficiently  well  to  be  inverted  without  dropping 
it  until  gently  tapped. 
1  alluded  to  this  subject  and  constructed  a  little  cone  of  paper  at  the 
last  meeting  of  the  American  Pharmaceutical  Association. 
Nashville,  June  29,  1877. 
CORROSIVE  SUBLIMATE  contaminated  with  ARSENIC. 
By  Joseph  Granville  Smith,  Ph.G. 
From  an  Inaugural  Essay. 
Experiments  made  in  the  laboratory  of  the  Philadelphia  College  of 
Pharmacy  with  commercial  corrosive  sublimate  have  demonstrated  its 
frequent  contamination  with  arsenic.  This  impurity,  which  most  likely 
is  derived  from  the  sulphuric  acid  used  in  preparing  the  mercuric  sul- 
phate, from  which  afterwards  the  mercuric  chloride  is  sublimed,  is 
usually  present  in  such  small  proportion  that  it  is  not  readily  recognized 
by  treating  the  precipitated  sulphides  with  sulphhydrate  of  ammonium  ; 
but  in  Marsh's  apparatus  or  by  Fleitmann's  test  its  presence  is  very 
easily  demonstrated. 
For  the  purpose  of  determining  the  quantity  of  the  impurity,  it  was 
endeavored  to  separate  the  two  metals  by  boiling  the  corrosive  sublimate 
with  caustic  potassa  ;  but  while  the  arsenic  was  completely  dissolved  a 
small  portion  of  mercury  likewise  entered  into  solution.  When  the 
corrosive  sublimate  was  treated  with  ammonia  water,  a  portion  of  the 
arsenic  was  persistently  retained  by  the  white  precipitate,  which  could 
not  be  removed  by  long  continued  washing,  after  which  some  mercury 
was  found  in  the  filtrate. 
Resorting  to  the  separation  of  the  sulphides  by  means  of  ammonium 
sulphhydrate,  and  oxidizing  the  sulphide  of  arsenic  to  arsenic  acid,  the 
latter  was  estimated  as  arseniate  of  magnesium  and  ammonium,  but  the 
results  from  the  same  samples  varied  to  such  an  extent  that  they  are 
deemed  unreliable.  The  following  two  methods,  however,  yielded 
figures  which  agreed  among  themselves  as  well  as  with  those  obtained 
on  repeating  the  experiments,  in  each  of  which  from  3  to  5  grams  of 
