\vrnl%T-}  Calomel  155 
The  British  process,  when  carried  out  by  experienced  hands,  is  a 
good  one,  but  by  far  too  troublesome.  The  truth  is  that  nearly  every 
pharmacist  purchases  his  calomel  from  the  wholesale  druggist,  which 
is  by  no  means  advantageous  to  the  art.  It  is  obvious  that  we  must 
either  follow  the  British  formula  or  fail  to  compete  with  the  British, 
as  long  as  no  better  process  is  presented  to  us  than  the  one  now  offi- 
cinal in  our  country.  I  think  it  might  have  been  just  as  well  not  to 
give  us  any  formula  at  all,  but  to  simply  direct  us  to  purchase  the 
preparation  as  obtained  by  Jewell's  or  Soubeiran's  processes,  (or 
rather  Henry's  and  Mohr's,)  and  to  test  that  conscientiously  before 
using  it,  although  Prof.  Wood  thinks  it  is  "  free  from  all  suspicion  of 
containing  corrosive  sublimate." 
Let  us  have,  when  such  a  thing  is  possible,  practical  formulae  which 
will  be  adopted  by  a  greater  number  of  apothecaries. 
When  metallic  mercury  is  dissolved  in  nitric  acid,  the  resulting  salt 
is,,  according  to  circumstances,  either  a  protoxide  or  a  peroxide  salt. 
3Hg  +  8NO5  =  3{Hg02  +  +  2^0, ;  or, 
6Hg  +  8N0.  =  6(HgO,N05)  +  SNO^. 
When  the  acid  is  warm,  concentrated  and  in  excess,  the  peroxide 
salt  is  formed  ;  but  when  it  is  cold,  dilute,  and  in  a  less  quantity  than 
is  necessary,  in  order  to  dissolve  all  of  the  metal,  the  result  is  a  pro- 
to-salt.  Therefore,  also,  if  a  solution  of  a  mercurial  persalt  is  mace- 
rated with  metallic  quicksilver,  some  of  the  metal  is  taken  up  which 
reduces  the  peroxide  to  a  protoxide. 
The  salt  which  is  obtained,  when  dilute  acid  acts  on  the  metal  at  a 
moderate  temperature,  is  the  neutral  protonitrate,  and  can  be  obtained 
in  a  crystalline  state  ;  according  to  the  younger  Mitscherlich,  some 
basic  salt  may  be  simultaneously  produced,  if  the  metal  is  present  in 
great  excess,  and  the  maceration  is  allowed  to  go  on  for  a  longer 
period.  When  a  more  elevated  temperature  is  applied,  a  neutral 
proto-salt  (together  witli  more  or  less  per-salt)  is  first  formed,  but, 
under  the  continued  dissolution  of  the  metal,  more  and  more  basic 
salts  are  successively  generated. 
"All  those  salts  are  soluble,  in  certain  proportions,  in  water,  but 
decompose  upon  a  further  addition  of  that  solvent,  so  that  a  yellow 
overbasic  salt  falls,  while  an  acid  one  remains  in  solution.  But,  if 
free  acid  be  added  to  their  solutions  previous  to  dilution,  no  precipitate 
or  decomposition  will  take  place. 
