A\Jn°T;mfM'}  Varieties.  37 
On  Bromide  of  Potassium. — Dr.  Falieres. — A  great  portion  of  this  memoir 
relates  strictly  to  the  therapeutics,  but,  as  regards  the  testing  of  the  purity 
of  bromide  of  potassium  and  its  preparation  more  especially  for  medicinal  pur- 
poses, the  following  suggestions  are  made : — 1  grm.  of  bromide  of  potassium, 
previously  pulverized,  and  put  into  a  glass-stoppered  bottle,  is  dissolved  in  from 
30  to  40  grms.  of  distilled  water.  To  this  solution  is  added  a  solution  of  nitrate 
of  silver,  containing  1'427  grms.  of  that  salt.  When  the  precipitate  has  settled, 
there  is  added  to  the  liquid,  by  means  of  a  burette,  a  drop  of  a  decinormal  so- 
lution of  nitrate  of  silver,  which,  if  the  bromide  is  pure,  will  not  produce  any 
further  precipitate — the  fact  being  that  1  grm.  of  the  bromide  requires  precisely 
1*427  grms.  of  nitrate  of  silver  for  precipitation,  while  1  grm.  of  chloride  of 
potassium  requires  2*279  grms.  of  the  argentic  nitrate.  It  is  clear,  however, 
that  the  bromide  will  have  to  be  tested  for  the  absence  of  iodide,  carbonate, 
and  sulphate  of  potassium,  and  of  nitrate  of  soda.  As  regards  the  preparation 
of  bromide  of  potassium,  the  author  proposes  the  following  process  : — 100  grms. 
of  bicarbonate  of  potassa  are  dissolved  in  500  grms.  of  water  ;  to  this  solution, 
80  grms.  of  pure  bromine  are  added,  and,  as  soon  as  the  effervescence  ceases, 
there  is  also  added  a  mixture  of  90  parts  of  pure  distilled  water  and  30  parts  of 
liquid  ammonia  (sp.  gr.  =  0.875).  The  liquid  is  next  evaporated  to  dryness, 
care  being  taken  to  apply  a  gentle  heat  as  long  as  any  vapors  of  carbonate  of 
ammonia  are  given  off.  The  residual  saline  mass  is  next  ignited,  so  as  to  con- 
vert the  bromate  of  potassa  into  bromide  of  potassium  ;  the  salt  thus  obtained 
is,  after  cooling,  re-dissolved  in  pure  distilled  water,  an  aqueous  solution  of  bro- 
mine added  to  this  solution,  which  is  next  evaporated  for  crystallization.  By 
the  addition  of  the  ammonia,  bromide  of  ammonium  is  first  formed,  and  this 
salt,  acting  upon  the  undecomposed  carbonate  of  potassa,  converts  it  into  bro- 
mide, while  carbonate  of  ammonia  is  volatilized. —  Chemical  News,  Dec.  8,/rom 
Journal  de  Pharmacie  et  dt  Chimie,  October,  1871. 
Cure  for  Corns. — Bathe  the  feet  we'll  in  warm  water,  then  with  a  sharp  in- 
strument pare  off  as  much  of  the  corn  as  can  be  done  without  pain  or  causing 
it  to  bleed,  and  dress  once  a  day  with  the  following  salve  : 
R.    Black  Oxide  of  Copper,    ....     gr.  15, 
Lard,  .  .  .  .  .  .        5  s.  M. 
—  Chem.  and  Drug.,  Lond.,  Nov.  15,  1871. 
Extract  of  Horse  Chestnut  Wood. — For  dyeiug  heavy  black  upon  silk,  an  ex- 
tract of  horse-chestnut  wood  has  recently  acquired  great  importance,  it  is 
preferred  to  nut  galls  or  divi  divi  for  this  purpose.  To  what  particular  princi- 
ple in  the  wood  is  to  be  ascribed  the  important  property  of  which  use  is  now 
made  has  not  been  determined  with  certainty. — Ibid. 
Chloroform  and  Glycerin. — Dr.  W.  Murdock,  of  New  York,  recommends  the 
following  formula  as  a  convenient  mode  of  administering  chloroform  :  Glycerin, 
six  ounces  ;  chloroform,  two  ounces.  This  solution  is  clear,  and  not  unpleasant 
in  taste  or  odor.  One  drachm  contains  fifteen  minims  of  chloroform. — Atlanta 
Med.  and  Surg.  Journ.,  Nov.,  1871. 
