PUKITY  OF  SULPHATE  OF  QUININE  OF  COMMERCE.  45 
Sulphocyanide  of  potassium  is  not  usually  kept  by  druggists, 
but  may  readily  be  made  thus  : — 
Cyanide  of  potassium  (fused), 
Sublimed  sulphur,  of  each  120  grains. 
Distilled  water,  an  ounce  and  a  half. 
Boil  in  a  glass  flask  for  fifteen  minutes,  filter,  and  make  up  the 
quantity  to      ounces  with  sufficient  distilled  water. 
This  notice  of  the  qualitative  analysis  ought  not  to  be  passed 
without  mentioning  a  very  good  application  of  Prof.  Stokes' 
fluorescent  test  for  the  discovery  of  quinine  and  other  subs- 
tances possessing  the  property  of  epipolism. 
A  small  Geissler's  vacuum  tube  is  surrounded  by  a  longer 
glass  tube  which  is  capable  of  being  closed  by  a  cork,  an  ar. 
rangement  that  permits  the  tube  to  be  filled  and  emptied  as  an 
ordinary  phial  bottle.  When  any  bark  is  suspected  to  contain 
quinine,  etc.,  an  acid  or  alcoholic  infusion  is  put  into  the  outer 
tube,  and  a  spark  from  the  RuhmkorfTs  coil  passed  through. 
Instantly  the  fluorescent  salt,  whatever  it  may  be,  will  show  its 
presence  in  the  most  gorgeous  manner. 
By  this  method  twenty-seven  samples  of  barks  were  qualita- 
tively tested  in  a  couple  of  hours  that  were  supposed  to  con- 
tain a  new  alkaloid,  which  occurs  in  on  Australian  tree  pos- 
sessing very  peculiar  fluorescent  properties. 
The  process  most  applicable  for  the  quantitative  analysis  of 
sulphate  of  quinine  i3  that  by  means  of  the  iodide  of  potassium 
reaction,  recommended  by  Dr.  De  Vry  some  time  since.  The 
following  was  the  arrangement  employed  in  the  present  in- 
stance : — 
Into  a  tube  containing  120  minims  of  distilled  water  and  16 
minims  of  dilute  sulphuric  acid  (British  Pharmacopoeia),  add 
twenty  grains  of  the  sulphate  of  quinine  to  be  tested.  When 
dissolved  add  80  minims  of  solution  of  hydrate  of  soda  (1  to 
12)  and  300  minims  of  pure  sulphuric  ether  mixed  with  six  min- 
ims of  alcohol. 
Agitate  well,  and  lay  aside  for  twelve  hours  ;  decant  the 
ethereal  solution  and  evaporate  for  the  quinine.  To  the  re- 
maining aqueous  solution  add  just  sufficient  acetic  acid  to  neu- 
tralize the  alkali,  and  precipitate  with  solution  of  iodide  of 
potassium  (1  to  4),  filter,  dry,  and  weigh  the  hydriodate  of 
