ON  THE    STRUCTURE    OF  GALLS. 
451 
with  perchlorate  of  potash,  with  which  it  is  isomorphous,  the  latter 
salt  crysallizes  in  splendid  red  crystals,  when  a  small  quantity  of 
permanganate  of  potash  is  added  to  its  solution.  With  equal  parts 
of  the  twtt'salts,  the  crystals  are  nearly  black. 
Gregory's  (J.  Pharm.  xxi.,  312  ;  also  Ann.  Pharm.,  xv.,  237) 
consists  in  adding  to  a  finely  divided  mixture  of  eight  parts  of 
peroxide  of  manganese  and  seven  parts  of  chlorate  of  potash,  a 
solution  of  ten  parts  of  hydrate  of  potash  in  a  very  small  quantity 
of  water,  evaporating  to  dryness;  igniting  the  finely-pounded 
mass  in  a  platinum  crucible  over  a  spirit-lamp  till  the  whole  of  the 
chlorate  of  potash  is  decomposed  (for  which  a  low  red  heat  is  suf- 
ficient,) and  proceeding  as  described  above.  It  is  readily  decom- 
posed by  organic  matter,  so  that  if  it  is  required  to  filter  the  solu- 
tion previous  to  crystallization,  the  neck  of  the  funnel  should  be 
filled  with  asbestos. 
The  composition  of  permanganate  of  potash,  according  to 
Mitscherlich,  is 
By  calculation.  By  expeiirnent. 
K  0    47.2    29.65    30.385 
Mn207  .  .  .  112.0    70.35    69.580 
KO  Mn2  07    159.2  100.00  99.065 
The  crystals  are  soluble  in  sixteen  parts  of  water  at  60°. 
The  dose  generally  found  to  agree  best  with  the  stomach  is  about 
three  grains  given  in  three  or  four  tablespoonsful  of  water  three 
times  a  day,  a  little  before  meals;  much  larger  doses  (as  much  as 
ten  or  twelve  grains,)  however,  have  been  given,  but  the  dose 
should  be  gradually  increased. — Pharm.  Jour.,  July  1,  1853. 
RESEARCHES  UPON  THE  STRUCTURE  OF  GALLS. 
By  M.  De  Lacaze  Duthiers. 
The  author  commences  by  stating,  that  former  writers  upon  the 
vegetable  pathological  productions,  named  galls,  have  only  con- 
sidered their  forms,  the  plant  upon  which  they  are  found,  and  the 
insects  which  cause  them.  Their  structure  and  development  have 
been  completely  neglected. 
Galls  are  generally  considered  as  purely  cellular  masses.  This 
is  an  error,  for  they  contain  the  principal  elements  and  tissues  which 
