566  United  States  Army  Laboratory.  {A51^j£biEiSS. 
succeeded  in  avoiding  silver-nitrate  stains  when  working  with  that 
commodity,  and  I  know  of  no  one  that  has.  Another  salt  that  was 
made  on  this  furnace  in  large  quantities  was 
Mercuric  Sulphate — this,  of  course,  by  the  direct  action  of  sul- 
phuric acid  on  metallic  mercury.  The  beautiful  white  salt  produced 
was  used  exclusively  for  making 
Corrosive  Sublimate.  The  perfectly  dry  salt  was  intimately  mixed 
with  chlorid  of  sodium  in  molecular  quantities  and  by  means  of  an 
Fig.  4. — Diagram  of  Corrosive  Sublimate  Apparatus. 
iron  spoon  conveyed  in  small  portions  at  the  time  into  the  sublim- 
ing or  vaporizing  tube  (C)  previously  and  continuously  heated  at  a 
proper  temperature  by  the  fire  beneath.  Here  the  interchange  of 
elementary  constituents  took  place,  mercuric  chloride  vapor  passed 
into  the  condensing  chamber  where  it  had  to  traverse  a  series 
of  shelves  with  openings  at  alternate  ends  in  the  direction  of  the 
arrows  (shown  in  detail  by  Fig.  4.),  and  was  so  perfectly  condensed, 
in  the  form  of  fine  powder,  during  its  passage  towards  the  flue,  that 
it  was  practically  all  deposited  on  the  shelves  without  appreciable 
