138  Aqueous  Mixtures  of  Chlorate  of  Potash.        {^iS' it"1. 
AQUEOUS  MIXTURES  CONTAINING  POWDERED 
CHLORATE  OF  POTASH. 
By  Johx  Rutherford  Hill,  Pharmaceutical  Chemist. 
Read  before  the  North  British  Branch  of  the  Pharmaceutical  Society, 
Edinburgh,  January  16,  18S4. 
It  is  a  common  practice  to  prescribe  gargles,  mouth  washes  and 
mixtures  containing  a  much  larger  proportion  of  chlorate  of  potash 
than  the  aqueous  menstruum  is  capable  of  dissolving,  and  the  object 
of  the  following  note  is  to  point  out  some  objections  to  this  practice, 
and  to  suggest  a  more  excellent  way. 
It  not  unfrequently  happens  that  such  gargles,  etc.,  are  ordered  to 
be  made  with  boiling  water,  but  no  discreet  dispenser  would  be  so 
foolish  as  to  follow  the  directions  of  the  prescriber  in  such  a  case, 
because,  although  the  whole  of  the  chlorate  might  thereby  be  dissolved, 
it  would,  of  course,  be  deposited  in  a  crystalline  form  as  the  solution 
cooled. 
It  sometimes  happens,  however,  that  the  proportion  of  chlorate  is 
very  near  the  quantity  which  the  menstruum  is  understood  to  be  capable 
of  holding  in  solution  at  the  normal  temperature ;  and  in  such  cases, 
I  believe,  many  dispensers  do  not  hesitate  to  facilitate  solution  by  the 
application  of  heat.  Even  in  these  instances  there  is  always  a  risk 
that  separation  of  crystals  may  ensue,  either  from  an  erroneous  calcu- 
lation as  to  the  degree  of  solubility,  or  from  the  normal  temperature 
falling  considerably  below  that  at  which  the  solubility  estimations 
were  made,  and  consequently  this  process  is  not  altogether  free  from 
objection. 
The  least  objectionable  method  is  generally  understood  to  be  that  of 
reducing  the  chlorate  of  potash  to  very  fine  powder,  using  in  all  cases 
cold  water  only  and  attaching  a  "  shake  the  bottle  label. 
If  the  chlorate  remained  in  the  condition  of  fine  powder  this  might 
meet  the  first  difficulty,  because,  though  not  in  solution,  it  would  be 
in  the  next  best  condition  for  application  to  inflamed  and  ulcerated 
surfaces.  Unfortunately,  however,  this  is  not  the  case,  and  chlorate  of 
potash  gargles,  etc.,  so  dispensed  soon  become  unfit  for  use,  owing  to 
the  rapidity  with  which  finely  powdered  chlorate  resumes  the  crystal- 
line condition. 
My  attention  had  been  frequently  directed  to  this  circumstance  by 
