572  United  States  Army  Laboratory.  [ASmS£m^' 
oxidizing  the  ferrous  sulphate  solution  with  nitric  acid.  On  this 
furnace 
MonseVs  Solution  (Ferric  Sulphate)  was  also  prepared  in  large 
quantities,  while 
Solution  of  Ferric  Chloride  was  oxidized  on  this  furnace  by  the 
action  of  nitric  acid  on  a  solution  of  ferrous  chloride,  prepared  by 
the  direct  action  of  hydrochloric  acid  on  metallic  iron  (card  teeth) 
and  acidulated  after  filtration  with  the  required  amount  of  HC1. 
Syrup  of  Squill  was  another  preparation  made  on  this  furnace, 
mainly  because  of  the  facility  offered  by  the  crane  (L)  in  placing 
the  large  enameled  kettles  used  for  boiling  the  syrup  on  the  fire 
and  again  removing  them.  The  last  furnace  to  mention  is  that  on 
the  interior  in  the  southeast  corner  of  the  room,  indicated  by  (//). 
This  was  used  for  minor  operations,  such  as  making  permanganate 
of  potash,  benzoic  acid  from  benzoin  by  sublimation,  etc.,  neither  of 
which  were  prepared  in  appreciable  quantities.  Aside  from  occa- 
sional crucible  operations,  the  kettles  and  sand  baths  being  remov- 
able, these  furnaces  were  used  principally  for  boiling  lead  plaster. 
Finally 
Gun  Cotton  was  not  the  least  important  of  the  products  turned 
out  in  the  Furnace  Room,  notwithstanding,  or  possibly  because  of, 
its  inflammable  nature.  This  was  made  in  large  stone-ware  jars,  by 
the  process  then  given  in  the  U.S.P.,  which  directed  the  immersion 
of  the  cotton  in  a  mixture  of  nitrate  of  potash  and  sulphuric  acid 
for  twenty-four  hours,  at  a  certain  temperature.  I  soon  found,  how- 
ever, that  operating  in  pound  quantities  was  a  very  different  problem 
from  operating  with  ounces,  that  the  prescribed  temperature  was 
probably  within  proper  limits  in  pharmacopceial  quantities,  but 
totally  beyond  control  when  applied  on  a  manufacturing  scale. 
While  engaged  in  the  laboratory  of  the  Messrs.  Wyeth,  I  had  an 
experience  which  served  me  a  good  purpose  here.  I  had  frequently 
prepared 
Citrine  Ointment,  which  at  that  time  was  directed  to  be  made  by 
the  direct  action  of  acid  solution  of  mercuric  nitrate  on  neatsfoot  oil, 
with  good  success,  obtaining  a  golden  yellow  ointment.  Being 
required  to  make  a  quantity  of  50  pounds  or  more,  the  whole  quan- 
tity was  started  according  to  the  official  directions,  the  neatsfoot  oil 
being  brought  to  the  required  temperature.  After  the  addition  of 
the  acid  nitrate,  reaction  of  course  set  in  promptly ;  but  it  failed  to 
