^'jm*'^™'}      Acidum  Phosphortcum  Dilutum.  9 
this  discussion  commended  upon  by  recent  writers.  The  "  Pharma- 
copoeia "  directs  either  of  two  processes,  directing  preferably  the  oxida- 
tion of  phosphorus  by  nitric  acid,  and  the  subsequent  dilution  to  the 
proper  specific  gravity.  The  objection  to  this  process,  we  believe, 
comes  from  only  one  source,  viz.  :  the  retail  druggist  to  whom  it  is 
both  dangerous  and  insufferably  tedious,  requiring  constant  watchful- 
ness regarding  temperature,  "  eternal  vigilance  "  being  the  only  price 
of  safety,  beside  being  a  source  of  constant  expense  through  the 
breakage  of  funnels,  capsules  and  the  other  paraphernalia  of  the  phos- 
phoric acid  apparatus  usually  found  at  the  command  of  the  pharmacist 
It  is,  however,  the  process  usually  followed  by  manufacturers,  because 
of  its  most  striking  allurement,  viz.  :  cheapness ;  and  for  their  benefit 
we  will  describe  a  piece  of  apparatus  employed  by  ourselves  for  the 
past  two  years  in  the  manufacture  of  this  preparation. 
We  place  in  the  yard  attached  to  the  laboratory  a  tub  of  twenty- 
five  gallons  capacity,  into  which  we  place  some  smooth  bricks,  and 
upon  these  we  place  a  graphite  crucible  of  say  ten  gallons  capacity, 
such  as  are  used  in  the  steel  works  for  melting  and  refining  of  cast 
steel,  and  upon  the  top  of  this  we  insert  a  funnel  and  carefully  lute 
the  edges  with  flaxseed  meal  or  clay — having  previously  placed  in  the 
crucible  the  quantity  of  phosphorus  we  wish  to  convert  into  phosphoric 
acid.  Into  the  spout  we  place  a  glass  tube  reaching  to  the  bottom  of 
the  crucible,  and  at  the  apex  insert  a  small  funnel  ;  the  apparatus  is 
now  complete  with  the  exception  of  the  method  of  applying  heat. 
On  the  upper  floors  of  the  laboratory  are  the  steam-pans  from  which 
the  condensed  steam  passes  through  the  drip-cock  either  to  the  boiler 
tank  or  to  the  ground  below.  Now  we  take  a  small  steam-pipe  and 
attach  one  extremity  to  the  drip  cock  and  allow  the  other  to  terminate 
into  the  tub  in  which  stands  the  acid  apparatus.  We  start  the  process 
by  putting  the  phosphorus  into  the  crucible,  luting  the  funnel  as  before 
described,  and  through  the  tube  in  the  spout,  adding  the  quantity  of 
nitric  acid,  slightly  diluted,  that  may  be  requisite.  We  then  allow  the 
condensed  steam  to  fill  the  tub,  and  pay  no  more  attention  to  it  excepting 
to  add  water  or  nitric  acid  as  occasion  may  require.  Through  the 
daily  use  of  the  steam-pans,  stills,  etc.,  there  is  abundance  of  condensed 
and  live  steam  passing  into  the  tub,  the  water  in  which  is  thereby  kept 
constantly  hot,  without  requiring  any  attention,  and  the  process  may 
go  on  for  weeks  without  the  slightest  danger  or  annoyance  to  the 
