Am.  Jour  Pharm. 
Sept.,  1878 
Liquor  Potass*. 
433 
by  adulteration  ;  still,  through  carelessness  or  neglect  of  the  operator, 
potassium  carbonate,  silica,  alumina  and  lime  salts  are  sometimes  found 
to  such  an  extent  that  they  will  impede  the  application  for  therapeutical 
but  more  especially  for  chemical  purposes. 
Of  seventeen  samples  of  liquor  potassas,  purchased  from  a  corres- 
ponding number  of  reputable  pharmacists,  which  I  have  examined,  I 
find  that  a  deficiency  of  strength  was  the  principal  defect.  They  are 
found  to  range  in  specific  gravity  from  1*036  (one)  to  1*065  (one)  and 
to  require  for  48  02  grams  from  38  to  50  cubic  centimeters  of  volu- 
metric solution  of  oxalic  acid. 
Made  by  the  first  process  of  the  Pharmacopoeia,  viz  ,  boiling  bicar- 
bonate of  potassium  with  lime,  the  solution  was  in  most  cases  obtained 
of  the  specific  gravity  1  -047  ;  and  when  made  by  dissolving  a  troyounce 
of  potassa  in  a  pint  of  distilled  water,  it  had  the  density  of  1*053. 
Hence  either  the  specific  gravity  as  required  or  the  formula  is 
incorrect.  But  taking  for  granted  that  the  specific  gravity  is  considered 
the  standard  for  liquid  preparations,  I  have,  after  many  experiments, 
ascertained  the  formulas  by  which  the  quantity  directed  to  be  made 
(seven  pints)  coincides  with  the  specific  gravity  1*065,  which  1  submit 
below : 
Take  of  Bicarbonate  of  potassium,  17  troyounces  and  160  grains. 
Lime,     .  .  .11         "         "160  " 
Distilled  water,  a  sufficient  quantity. 
Dissolve  the  bicarbonate  of  potassium  in  4  pints  of  distilled  water 
and  heat  the  solution  until  effervescence  ceases ;  then  add  distilled 
water  to  make  up  the  loss  by  evaporation,  and  heat  the  solution  to  the 
boiling  point.  Mix  the  lime  with  4  pints  of  distilled  water,  and, 
having  heated  the  mixture  to  the  boiling  point,  add  it  to  the  alkaline 
solution  and  boil  for  ten  minutes.  Then  transfer  the  whole  to  a  muslin 
strainer,  and,  when  the  liquid  portion  has  passed,  add  enough  distilled 
water  through  the  strainer  to  make  the  strained  liquid  measure  7  pints. 
Lastly,  keep  the  liquid  in  well  stopped  bottles  of  green  glass.  Solution 
of  potassa  thus  prepared  has  the  specific  gravity  1*065,  an^  contains 
six  and  six-tenths  per  cent,  of  hydrate  of  potassium. 
Solution  of  potassa  may  also  be  prepared  in  the  following  manner  : 
Take  of  Potassa,       ,  .  „       640  grains. 
Distilled  water,  one  pint 
28 
