6 
ON  ACID  NITRATE  OF  MERCURY. 
to  the  mercury  six  equivalents  oxygen  ;  whilst  two  eqs.  binoxide 
nitrogen  are  given  off  as  gas.  The  reaction  is  represented  by  the 
formula : 
3Hg  +  10  N05.  =  3  Hg02,  6  N05  +  2N02  +  2N05. 
In  the  Dublin  recipe  the  quantity  of  acid  is  insufficient,  as  will 
appear  from  the  following  calculation — 
One  and  a  half  ounces  of  distilled  water,  imperial  measure, 
weigh  656.25  grains  ;  the  same  bulk  of  acid  of  the  sp.  gr.  1.5, 
the  strength  ordered  by  the  Dublin  Pharmacopoeia  will  weigh 
984.375,  which,  according  to  Professor  Ure,  will  contain  but 
79.7  per  cent,  of  dry  acid  ;  then  984.375  x  -797  =  784,54  weight 
of  dry  acid  in  1|  ounces.  Two  ounces  of  mercury  weigh  875 
grains,  its  combining  equivalent  is  101,  while  nitric  acid  is  repre- 
sented by  the  No.  54  ;  then  in  round  numbers  7_8|^-4  =  14  J  equi- 
valents nitric  acid,  and  =  81  equivalents  of  mercury,  which 
proportion  is  evidently  insufficient  to  dissolve  the  mercury. 
I  would  propose,  as  a  correction  of  the  error,*  the  following 
*  [^Note. — After  the  above  paper  was  in  type,  and  too  late  to  consult  the 
author,  we  discovered  that  by  assuming  the  equivalent  of  mercury  as  101, 
instead  of  202,  the  old  number,  he  had  rendered  his  calculations  incorrect, 
and  the  formula  based  on  them  equally  so.  In  following  the  Dublin  Phar- 
macopoeia he  must  have  used  a  weak  acid,  probably  the  commercial  nitric 
acid  sp.  gr.  1.34,  which  will  account  for  his  ill  success.  Taking  the  numbers 
used  above  for  the  Dublin  proportions,  viz.,  875  grs.  of  mercury  and  984 
grs.  of  nitric  acid,  sp.  gr.  1.5,  the  equivalents  are  4h  Hg.  to  14|  NO5,  which 
are  as  3  Hg.  to  10  NO5. 
Now  the  author  having  adopted  101  as  the  equivalent  of  mercury,  should 
have  used  but  one  equivalent  of  nitric  acid  to  make  the  nitrate  of  the  red 
oxide  of  mercury,  whereas  he  evidently  intended  to  use  the  old  equivalent 
202  by  his  calling  the  salt  bi-nitrate  of  the  deutoxide.  In  the  recipe  pro- 
posed, the  ratio  of  equivalents  is  as  3  Hg  to  15f  NO5,  which  gives  an  excess 
of  more  than  live  equivalents  of  nitric  acid,  far  too  great  an  excess  to  render 
its  use  admissible.  In  view  of  the  fact  that  much  of  the  commercial 
white  nitric  acid  has  a  sp.  gr.  of  about  1.34,  we  have  calculated  the  following 
as  yielding  a  preparation  nearly  equivalent  to  that  of  the  Dublin  Pharma- 
copoeia. 
Take  of  Mercury,  2  ounces  (Troy). 
Nitric  acid  (sp.  gr.  1.34),  3|  (Troy). 
Dissolve  the  mercury  in  the  acid  by  aid  of  heat,  and  evaporate  the  solu- 
tion until  it  measures  two  fluid  ounces  and  a  half. — Editor  Amer.  Jour. 
Pharm.] 
