NOTE  ON  PYROPHOSPHATE  OF  lEON. 
215 
§17,  were  taken.  The  oil  and  lard  were  heated  to  125°  F.,  and 
the  mercurial  solution  was  also  heated,  after  solution,  to  125°, 
when  it  was  poured  into  the  oil  and  lard ;  the  temperature 
gradually  rose  to  170°,  172°,  at  which  temperature  it  remained 
»  until  effervescence  ceased.    (Loss  2-3  per  cent.) 
In  this  last  experiment  the  ointment  was  rapidly  stirred  upon 
the  addition  of  the  acid  solution,  and  afterwards  until  it  began 
to  stiffen. 
All  of  the  samples  appear  in  good  condition  ;  §1  has  evolved 
some  gas,  and  has  been  relieved  of  about  one-eighth  of  the  origi- 
nal contents.  The  remainder  has  been  pronounced  a  good  oint- 
ment by  a  competent  gentleman. 
§3  has  not  changed  since  made,  and  although  not  an  elegant 
ointment,  from  containing  many  aggregations  of  particles  of 
{2(Hgfi)'N0^),  the  salt  which,  when  the  ointment  is  not  heated 
too  high,  and  in  presence  of  a  slight  excess  of  nitric  acid  and 
finely  divided,  gives  the  beautiful  lemon  color. 
In  the  foregoing  detailed  experiments  the  writer  has  gleaned 
the  following  facts  :  that  heat,  within  certain  range  of  degrees, 
and  nitric  acid  of  at  least  sp.  gr.  1-42,  in  excess  (although  the 
Brit.  Pharm.  process  shows  too  much  acid),  is  required. 
Without  going  further  into  the  discussion  of  the  chemistry  of 
the  subject,  the  writer  begs  leave  to  submit  to  the  consideration 
of  the  College  of  Pharmacy  of  the  City  of  New  York  this  paper, 
and  four  samples  of  ointment  of  nitrate  of  mercury,  prepared  in 
accordance  with  the  foregoing  detail  of  experiments. 
NOTE  ON  PYROPHOSPHATE  OF  IRON.  ^ 
By  Robert  W.  Gardner. 
Prof.  Procter  : 
Dear  Sir  : — I  notice  a  communication  in  the  January  No. 
Journal  of  Pharmacy,  in  answer  to  Query  No.  26,  in  regard  to 
Pyrophosphate  of  Iron. 
I  have  made  pyrophosphate  of  iron  in  considerable  quantities, 
and  found  much  difficulty  at  first  in  getting  it  to  scale  properly. 
After  numerous  trials  I  discovered  m?/  error — not  the  formula's. 
I  did  not  fully  sesquioxidize  my  solution  of  tersulphatc  of  iron. 
