AmMari8P76arm'}    Presence  of  Tannin  in  Gentian  Root.  117 
water,  until  no  farther  precipitation  ensues,  being  careful  towards  the 
last  to  add  the  solution  very  gradually,  so  as  to  avoid  dissolving  the 
mercuric  iodide  in  an  excess  of  the  liquid.  Collect  the  precipitate  on 
a  filter,  wash  well  with  distilled  water,  drain  and  dry. 
The  solution  of  mercuric  nitrate  also  affords  a  very  convenient  way 
of  preparing  the  yellow  oxide  of  mercury,  and  I  submit  also  a  formula 
for  its  preparation. 
Hydrargyrum  Oxidum  Flar. 
R 
Sol.  mercuric  nitrate  (prepared  by  dissolving  mercury  in  an  ex- 
cess of  nitric  acid),       .  .       any  convenient  quantity 
Liq.  sodae,                .               .  .  .  q.  s. 
Dilute  the  solution  of  mercuric  nitrate  with  an  equal  bulk  of  water, 
and  add  liq.  sodae  until  in  slight  excess.  Collect  the  yellow  precip- 
itate, wash  well  and  dry.  Sol.  soda  is  used  here  instead  of  sol.  potassa, 
as  directed  by  the  "  Pharmacopoeia,"  on  account  of  its  cheapness,  there 
being  no  appreciable  difference  in  the  quality  of  the  yellow  oxide  ob- 
tained from  the  two  solutions. 
For  these  formulae  I  do  not  claim  any  special  originality,  but  regard 
them  only  as  affording,  by  the  aid  of  a  very  common  and  easily-made 
preparation,  a  much  more  convenient  and  practicable  method  of  pre- 
paring these  mercurials  than  any  other  process  of  which  I  have  knowl- 
edge. Their  greatest  merit  lies  in  the  fact  that  they  can  be  prepared 
with  much  economy  of  both  time  and  space,  both  important  points  to 
pharmaceutists  whose  facilities  for  manufacturing  are  of  a  rather  limited 
character. 
ON  THE  ASSERTED  PRESENCE  OF  TANNIN  IN  GENTIAN  ROOT. 
BY  JOHN  M.  MAISCH. 
[Read  at  the  Pharmaceutical  Meetings  February  i$tk,  1876.) 
The  root  of  Gentiana  lutea,  owing  to  its  importance  as  a  medicine, 
has  been  frequently  subjected  to  chemical  analysis  during  the  last  sixty 
years,  and  none  of  the  investigators  have  been  able  to  prove  the  presence 
of  tannin  in  it.  The  long  list  commences  in  1 815,  with  Schrader 
("  Berl.  Jahrb.  f.  Phar.,"  xvi),  who  is  followed  by  Henry,  and  by  Guille- 
min  and  Foecquemin  in  18 18  ("Jour,  de  Phar.,"  v) ;  in  1821  by  Henry 
and  Caventou  {ibid.,  vii) ;  in  1836  by  Denis  {ibid.,  1836,  January)  ; 
in  1837  bv  H.  TrommsdorfF  ("Ann.  d.  Phar.,"  xxi),  and  by  Claude 
