""VayUs™  }  Erythrocentaurin  etc.  207 
iirson  melts  into  an  amorphous  transparent  mass  ;  at  a  still  higher  tem- 
perature it  boils  and  sublimes  in  a  test  tube  unchanged.  Its  medical 
properties  have  as  yet  not  been  ascertained,  at  least  no  physiological 
experiments  have  been  made  with  it,  and  very  probably  it  is  entirely 
inert.  A  small  quantity  of  volatile  oil  was  found  in  the  aqueous  solu- 
tion of  the  ethereal  extract,  besides  some  tannic  and  gallic  acids. 
The  organic  constituents  of  Uva  ursi  as  obtained  by  this  investiga- 
tion, therefore,  are  : 
Arbutin,  and  its  product  of  decomposition,  hydrokinone  ;  ericoliuy 
ericinol,  urson  ;  (ursin,  the  diuretic  principle  of  Hughes,  was  found  to 
be  impure  arbutin  ;)  tannic,  gallic  and  malic  acids,  then  a  small  quan- 
tity of  volatile  oil,  fatty  matter,  wax,  gum,  sugar,  albumen,  coloring 
matter,  etc. 
The  test  for  arbutin  may  perhaps  serve  for  finding  this  principle, 
in  plants,  without  isolating  it,  for,  an  infusion  of  Uva  ursi,  when 
diluted  with  sufficient  water  to  make  it  perfectly  colorless,  and  then 
rendered  alkaline,  produces,  on  the  addition  of  phosphomolybdic  acid, 
the  blue  reaction  due  to  arbutin  ;  when  the  alkali  (ammonia)  is  added 
to  the  diluted  colorless  infusion,  a  color  (orange)  again  appears,  owing 
to  the  astringent  acids  present ;  this  color  must  also  be  removed  by 
again  diluting  it  with  water,  before  the  final  addition  of  the  phos- 
phomolybdic acid. 
This  test  cannot  be  applied  to  a  strong  infusion  because  phosphomo- 
lybdic acid  reacts  with  tannic  and  gallic  acids  green,  and  the  blue 
color  cannot  then  be  observed. 
ERYTHEOCENTAURIN  IN  AMERICAN  CENTAURY. 
By  John  F.  Huneker. 
(From  the  Author's  Inaugural  Essay). 
This  principle  was  discovered  in  European  Centaury  [Erythrcea 
centaurium),  a  few  years  ago,  by  M^hu,  a  French  chemist,  who  ob- 
tained it  in  the  minute  quantity  of  one  grain  in  three  thousand  grains 
of  the  herb.  The  question  very  naturally  arose,  whether  American 
Centaury  [Sahhatia  angularis)  also  contained  this  principle ;  the  ex- 
perimenter will  prove  that  it  may  be  obtained. 
The  flowers  and  leaves  of  Sahhatia  angularis  to  the  amount  of  two 
pounds  were  exhausted  with  one  gallon  of  water,  a  portion  of  which 
was  evaporated  by  a  water  bath,  and  allowed  to  stand  to  deposit  the 
