514  Notes  on  the  Mydriatic  Alkaloids.  {^ovimbe^SS1, 
(1)  Vitalis1  Test. — This  test,  as  is  well  known,  consists  in  treating 
the  solid  alkaloid  or  one  of  its  salts  with  a  drop  or  two  of  nitric 
acid,  evaporating  to  dryness  on  a  water-bath,  and  treating  the 
cooled  residue  with  a  drop  of  a  strong  alcoholic  solution  of  potas- 
sium hydroxide,  when  a  deep  violet  coloration  is  produced. 
On  comparing  the  above  samples  of  the  three  alkaloids,  in  equal 
but  varying  quantities,  side  by  side,  under  this  test,  no  appreciable 
difference  was  observed  in  the  results.  It  has  been  stated  by  some 
writers  that  under  this  test  atropine  yields  a  yellow  coloration, 
whereas  hyoscyamine  yields  a  purple  color  ;  but  this  difference  did 
not  exist  in  the  preparations  examined. 
(2)  Auric  Chloride. — This  reagent  throws  down  from  aqueous 
solutions  of  salts  of  the  alkaloids,  even  when  quite  dilute,  a  bright 
yellow  precipitate  of  the  aurochloride  of  the  alkaloid.  The  precipi- 
tate from  hyoscine,  being  the  least  soluble  of  these  gold  salts,  is 
notably  greater  in  quantity,  and  it  more  promptly  assumes  the  crys- 
talline form  than  the  precipitate  from  like  solutions  of  either  of  the 
other  two  alkaloids. 
If  a  drop  of  a  i-iooth  solution  of  the  alkaloids  be  treated  "with 
a  drop  of  the  reagent,  the  hyoscine  solution  yields  a  very  copious 
precipitate  and  soon  the  mixture  becomes  a  solid,  confused  crystal- 
line mass.  The  precipitate  from  atropine  stands  next  in  quantity, 
that  from  hyoscyamine  being  least.  No  marked  difference  was  ob- 
served in  the  color  of  the  precipitates,  even  on  spontaneous  evapo- 
ration to  dryness. 
A  drop  of  a  i-ioooth  solution  of  the  alkaloids  gave  with  the  rea- 
gent, very  uniformly  in  the  case  of  hyoscine,  a  precipitate  which 
quickly  formed  crystalline  lamina  or  leaves ;  whilst  that  from  atro- 
pine formed  minute  granules,  and  that  from  hyoscyamine  crystalline 
blocks  or  masses. 
(3)  Bromine  Test. — As  we  have  pointed  out  elsewhere,  a  solution 
of  bromine  in  bromohydric  acid  throws  down  from  solutions  of  at- 
ropine and  of  hyoscyamine,  even  when  highly  dilute,  a  yellow 
amorphous  precipitate  which  is  soon  converted  into  characteristic 
crystals,  no  marked  difference  being  observed  between  the  reaction 
of  the  two  alkaloids.  With  an  aqueous  solution  of  hyoscine,  the 
reagent  produces  a  voluminous  yellow  precipitate  which  soon  be- 
comes converted  into  minute  globules ;  these  change  to  large  yellow 
drops,  which  slowly  dissolve  to  a  colorless  solution.    In  no  instance 
