572  On  Some  of  the  Tests  for  Quinine.    { ADecTembef hi8^°" 
Beside  these  substances,  certain  vegetable  principles  and  extracts 
and  the  hydrocarbon  oils  present  fluorescent  properties. 
4.    TEST  OF  TASTE. 
The  intensely  bitter  taste  of  quinine  and  its  salts  may  serve  as  a 
test  of  its  presence.  Of  the  ordinary  preparations  of  quinine,  the 
tannate  is  the  least  and  the  free  alkaloid  next  least  bitter;  the  nor- 
mal sulphate  is  less  bitter  than  the  bisulphate,  hydrobromide  or 
hydrochloride.1 
The  taste  of  the  acid  sulphate  is  very  distinct  and  strongly 
marked  in  a  single  drop  of  a  i-iooooth  solution;  and  is  still  dis- 
tinct in  the  same  quantity  of  a  i-20000th  solution  ;  but,  according  to 
several  persons,  is  not  perceived  in  a  drop  of  a  i-50000th  solution. 
In  the  very  elaborate  investigations  of  Dr.  G.  Kerner2  on  the 
absorption  and  elimination  of  quinine,  he  found  that  when  taken 
into  the  stomach  in  0-5  gram  (7-5  grains)  doses,  it  appeared  in  the 
urine  in  fifteen  minutes  thereafter  ;  and  that  one-half  of  the  total 
quantity  taken  was  thus  eliminated  in  six  hours;  and  one-fourth  in 
the  following  six  hours ;  but  that  a  trace  might  still  be  present  in 
the  urine  at  the  end  of  seventy-eight  hours. 
Of  the  quinine  thus  eliminated  Dr.  Kerner  found  that  a  large  por- 
tion had  undergone  a  material  change,  in  that  while  it  still  possessed 
fluorescent  properties,  responded  to  the  reaction  with  chlorine  and 
ammonia,  and  with  chlorine  and  potassium  ferrocyanide,  it  no 
longer  had  a  bitter  taste,  it  now  being  tasteless.  By  experiments 
he  found  that  under  the  limited  oxydation  of  quinine  by  potassium 
permanganate,  a  substance  was  produced  which  was  tasteless  and 
corresponded  in  every  respect  to  this  eliminated  quinine.  On  analy- 
sis this  oxydation  product  was  found  to  be  dihydroxyl  quinine,  hav- 
ing the  composition  C20H24N2O2,  2OH.  From  these  results  Dr. 
Kerner  concluded  that  it  was  under  this  form  that  the  alkaloid,  in 
part  at  least,  appeared  in  its  tasteless  condition  in  the  urine. 
If  then,  in  the  absorption  of  quinine  or  under  oxydation,  this 
change  to  the  tasteless  variety  may  take  place,  it  is  easy  to  under- 
stand that  in  the  extraction  of  the  alkaloid  from  the  urine  or  the 
tissues,  this  important  corroborative  test  might  fail,  even  when  the 
chemical  tests  indicated  its  presence.    At  present  we  have  little  or 
1Prescott  Organic  Analysis,  p.  127. 
2Archiv  fur  Physiologie,  ii,  1869,  pp.  200-243;  iii,  1870,  93-165. 
