530  Dilute  Phosphoric  Acid,  {^HTc.'^^'ln.. 
reaction  between  such  spiteful  elements  as  phosphorus,  bromine  and 
nitric  acid,  and  then  by  actual  experiment  with  the  same,  cautiously 
conducted,  has  arrived  at  certain  definite  results,  which  has  led  him  to 
propose  a  new  formula  for  this  desirable  purpose,  the  whole  modus 
operandi  of  which  was  published  in  the  various  pharmaceutical  journals 
for  October  of  this  year,  being  an  abstract  from  his  interesting  and 
valuable  paper  read  at  the  last  meeting  of  the  Pharmaceutical  Associa- 
tion, and  which  it  is  not  necessary  for  me  to  repeat  here. 
Professor  Maisch,  in  our  journal  for  November,  has  correctly 
reported  the  result  of  my  first  experiment  in  this  direction,  and  it 
proved  certainly  a  very  striking  one,  leaving  a  deep  impression  upon  me 
which,  no  doubt,  will  be  permanent.  The  result,  however  (I  can  as- 
sure you),  was  not  at  all  satisfactory,  and  as  soon  after  as  I  recovered 
trom  my  confusion,  I  repeated  the  experiment,  not,  however,  in  the 
same  way,  but  according  to  a  modification  suggested  to  me  by  Professor 
Markoe,  which  is  likewise  given  in  the  Journal  of  Pharmacy  for  the 
present  month. 
The  result,  I  am  pleased  to  report,  was  very  satisfactory,  everything 
proceeding  quietly  and  slowly  as  there  stated,  the  application  of  heat 
being  unnecessary.  At  the  close  of  the  operation  and  when  all  the 
phosphorus  had  disappeared,  the  evaporation  was  carried  on  by  heat  as 
directed  in  the  Pharmacopoeia. 
This  final  part  of  the  process  here,  as  well  as  in  the  usual  method,  I 
have  found  the  most  disagreeable  feature  of  the  whole  proceeding,  re- 
quiring the  temperature  to  be  carried  up  to  420°  F.,  at  least,  before  the 
whole  of  the  free  nitric  acid  can  be  driven  ofl^,  and  the  vapors  of  acid 
at  this  temperature  prove  exceedingly  annoying.  When  entirely 
inodorous,  the  fire  should  be  withdrawn  and  the  syrupy  concentrated 
solution  allowed  to  cool,  previous  to  being  diluted  with  water.  At  the 
temperature  of  60°  the  dense  acid  made  as  above  was  found  to  have  the 
gravity  of  70°  B.,  nearly  twice  as  heavy  as  water,  and  required  about 
fifteen  times  its  bulk  of  water  to  reduce  it  to  the  proper  gravity  of 
1*056.  I  will  only  add  that  the  final  evaporation  of  this  acid  cannot 
be  performed  in  enamelled  iron  vessels,  as  by  experiment  I  found  the 
enamel  to  be  dissolved  off  when  the  temperature  was  much  over  300°. 
Porcelain  alone  should  be  employed. 
