Am.  Jour.  Pharm. 
Jan.,  1886. 
Action  of  Pyrogallol. 
41 
The  dark  brown  color  is  simply  due  to  oxidised  pyrogallol.  The 
addition  of  alkali  neutralizes  the  free  acid,  and  thus  renders  the 
formation  of  the  blue  compound  possible.  All  strong  acids  prevent 
the  formation  of  this  compound,  but  feebler  acids,  such  as  boric  and 
-acetic,  have  not  the  same  effect.  The  blue  coloration  is  due  to  the 
combination  of  partially-oxidised  pyrogallol  with  a  ferrous  salt.  If 
a  current  of  air  is  blown  through  the  blue  liquid,  or  if  pyrogallol  is 
mixed  with  a  large  excess  of  ferric  chloride  and  an  alkali  then  added, 
a  black  precipitate  is  formed  by  the  oxidation  of  the  blue  compound. 
Pyrogallol  does  not  give  any  coloration  with  amnion iacal  cuprous 
chloride  out  of  contact  with  oxygen,  but  the  introduction  of  a  trace 
of  this  gas  causes  the  formation  of  a  deep  brownish-black  compound. 
Cupric  sulphate  is  immediately  reduced  by  pyrogallol,  and  on  addi- 
tion of  an  alkali  a  black  coloration  is  produced  which  is  changed  to 
red  by  excess  of  ammonia,  and  is  destroyed  by  hydrochloric  acid. 
Cupric  acetate  gives  an  immediate  black  coloration  without  addition 
of  an  alkali.  It  is  evident,  therefore,  that  the  action  of  pyrogallol 
on  copper  salts  is  strictly  analogous  to  its  action  on  iron  salts. — Jour. 
Chem.  Soc.j  1885,  p.  1059 ;  Compt.  rend.  ci. 
Mercury  Compounds  in  the  Animal  Organism.  3  )r.  Richard 
Fleischer,  in  a  study  of  the  modification  undergone  by  preparations 
of  mercury  in  the  animal  economy,  adduces  the  following  facts  as  the 
results  of  his  experiments: — (1)  Calomel,  which  in  pure  water  is  in- 
soluble, in  the  presence  of  chloride  of  sodium  is  dissolved  and  trans- 
formed into  the  bichloride  of  mercury.  (2)  The  formation  of  mer- 
curic chloride  is  favored  by  a  high  temperature — i.  e.,  the  tempera- 
ture of  the  body.  (3)  The  amount  of  mercuric  chloride  produced  is 
minute,  but  plainly  recognizable.  (4)  Dilute  hydrochloric  acid  of  a 
strength  of  25  per  cent,  converts  only  a  minimum  portion  of  calo- 
mel into  the  bichloride.  A  solution  of  a  strength  of  4  per  cent,  is 
much  more  active.  (5)  By  mixture  of  potassium  iodide  and  calomel, 
iodide  of  mercury  is  produced.  The  double  salt  produced  is  soluble 
in  excess  of  potassium  iodide,  but  separates  in  pure  water  into  the 
insoluble  oxide  of  mercury  and  into  iodide  of  potassium.  (6)  The 
oxide  of  mercury  forms  with  chloride  of  sodium,  corrosive  sublimate 
and  caustic  soda. — Deutsche  Med.  Wochenschrift,  Sept.  3,  1885;  Med. 
Chron.,  Dec,  1885,  p.  229. 
