^Vct'l  mr'  }        Oolor  of  Fluorescent  Solutions.  463 
the  precipitate  of  theine  to  form.  If  the  alkaline  solution  is  very  con- 
centrated the  precipitate  will  collect  on  the  surface,  but  on  adding  a 
little  water  it  will  subside,  the  supernatant  liquid  is  then  decanted, 
the  deposit  redissolved  in  distilled  water,  evaporated  over  a  water  bath 
to  dryness,  and  finally  crystallized  from  a  boiling  solution  in  alcohol, 
which  is  distilled  off  and  allowed  to  evaporate. 
Theine  obtained  in  this  way  is  sufficiently  pure  for  medicinal  use. 
Two  pounds  of  Rio  coffee  yielded  104  grains.  It  seems  strange  that 
the  decided  therapeutic  value  of  this  agent  has  thus  far  failed  to  bring 
it  into  more  general  use  by  the  profession. 
The  above  arrangement  is  not  expensive,  costing  two  dollars  and  a 
half,  and  is  also  useful  for  some  similar  purposes,  such  as  the  prepara- 
tion of  baccag  juniperi  tostae,  glandes  quercus  tostae,  etc.,  in  fact 
for  the  torrefaction  or  incineration  of  many  organic  substances.  A 
domestic  process  such  as  this,  of  almost  weekly  occurrence  in  every 
family,  is  thus  turned  into  an  interesting  and  profitable  pharmacal 
operation. 
To  avoid  repetition,  the  reader  is  referred  for  some  further  points 
of  information  on  the  subject,  to  the  article  above  mentioned. — The 
Pharmacist^  August,  1871. 
Chicago,  July,  1871. 
OBSERA^ATIONS  ON  THE  COLOR  OF  FLUORESCENT  SOLUTIONS. 
By  Henry  Morton,  Ph.  D., 
President  of  the  Stevens  Institute  of  Technology. 
As  the  result  of  a  series  of  experiments  to  be  presently  described, 
I  have  come  to  the  curious  conclusion  that  all  the  familiar  fluorescent 
solutions,  such  as  the  tincture  of  turmeric,  of  agaric,  of  chlorophyl, 
and  the  solution  of  nitrate  of  uranium,  emit  light  of  the  same  color 
by  fluorescence,  namely,  blue  identical  with  that  developed  by  acid 
salts  of  quinine.  This  blue,  however,  as  is  well  known  in  the  case  of 
quinine,  is  not  of  a  single  tint  or  refrangibility,  but  yields  a  continu- 
ous spectrum,  in  which  the  more  refrangible  rays  predominate. 
My  attention  was  first  drawn  to  the  subject  by  observing  that  a 
specimen  of  mixed  asphalt,  which  is  here  largely  used  in  the  prepa- 
ration of  pavements,  yielded  a  light-yellow  solution  with  alcohol, 
which  fluoresced  blue,  and  an  orange  solution  with  turpentine,  which 
fluoresced  green.    It  at  once  occurred  to  me  that  the  green  color  was 
