PREPARATION  OF  LIQUOR  POTASS^. 
241 
ON  THE  PKEPAEATION  OF  LIQUOR  POTASS^. 
By  Theophilus  Redwood,  Ph.D. 
Professor  of  Chemistry  and  Pharmacy  to  the  Pharmaceutical  Society. 
[Note. — The  following  remarks  are  taken  from  an  elaborate  paper  by  Dr. 
lledwood,  in  the  March  number  of  the  Pharmaceutical  Journal.  After  dis- 
cussing the  history  and  some  points  involved  in  the  process,  Dr.  Redwood  re- 
commended the  following  process  as  yielding  uniform  and  satisfactory  re- 
sults.— Editor.] 
Liquor  Potassce, 
Take  of  Carbonate  of  potash, 
Hydrate  of  lime,  each  ^viiss. 
Distilled  Water,  Oiv. 
Mix  the  vslaked  lime  with  three  pints  of  the  water,  and  put 
the  mixture  into  a  green  glass  stoppered  bottle  (a  Winchester 
quart).  Dissolve  the  carbonate  of  potash  in  the  remainder  of 
the  water,  and  add  this  solution,  in  small  quantities  at  a  time, 
to  the  milk  of  lime,  shaking  the  bottle  for  some  minutes  after 
each  addition  ;  and  when  the  whole  of  the  ingredients  have  been 
thus  mixed,  continue  the  agitation  until  a  portion  of  the  filtered 
liquor  no  longer  evolves  carbonic  acid  gas  on  the  addition  of  an 
excess  of  hydrochloric  acid.  Then  filter  the  solution  through 
calico. 
This  process  differs  from  that  of  the  present  London  Pharma- 
copoeia— 1st,  in  the  substitution  of  cold  water  for  boiling  water  ; 
2d,  in  the  substitution  of  hydrate  of  lime  for  quick  lime ;  3d, 
in  the  use  of  an  increased  quantity  of  lime  ;  4th5  in  the  reduc- 
tion of  the  quantity  of  solution  ordered  to  one  half  (from  a 
gallon  to  half  a  gallon).  These  alterations  are  important. 
Thus,  by  using  cold  water  instead  of  boiling  water,  all  difficulties 
in  conducting  the  process,  including  the  selection  of  a  suitable 
vessel  in  which  to  mix  the  ingredients,  are  removed.  A  green 
glass  stoppered  bottle,  the  most  appropriate  apparatus  for  the 
purpose,  may  be  employed,  and  as  the  quantity  ordered  is  half 
a  gallon,  a  Winchester  quart  bottle,  which  every  druggist  has  in 
his  store-room,  will  just  hold  this  quantity.  By  ordering  the 
lime  to  be  weighed  in  the  state  of  hydrate,  the  use  of  bad  lime, 
and  the  impurities  which  accompany  it,  is  to  a  great  extent  pre- 
cluded.   By  increasing  the  quantity  of  lime,  provision  is  made 
16 
