204 
Uva  ursi 
j  Am.  Jour.  Pharm. 
t     May  1,1871. 
from  water  ;  it  is  neutral  in  its  behaviour,  very  soluble  in  warm  or 
hot  water,  less  in  cold  water  or  alcohol,  more  in  hot  alcohol,  very 
sparingly  in  ether;  a  concentrated  solution  of  arbutin  is  precipitated 
by  strong  alcohol  or  ether  added  to  it,  but  the  precipitate  rapidly  dis- 
appears on  shaking.  Concentrated  sulphuric  acid  or  hydrochloric  acid 
added  to  the  crystals  on  a  small  plate,  gradually  dissolves  them  with- 
out change  of  color.  With  nitric  acid  the  crystals  first  turned  black,, 
and  then  slowly  dissolved,  the  acid  assuming  a  yellow  color  and 
giving  oft'  fumes  of  nitrous  acid.  Arbutin  in  aqueous  solution  does 
not  affect  an  alkaline  solution  of  sulphate  of  copper,  the  salts  of  lead, 
acetate  and  subacetate  do  not  precipitate  it,  salts  of  iron  have  no 
effect  upon  it  ;  other  reagents  for  organic  bodies  as  tannic  and  gallic 
acid,  bichloride  of  mercury,  nitrate  of  silver,  iodide  of  potassium  and 
bichloride  of  platinum  were  tried  without  any  results. 
While  experimenting  with  these  reagents,  I  accidently  found  a  very 
characteristic  and  remarkable  test  for  arbutin  ;  when  a  solution  of 
arbutin  in  water  is  rendered  alkaline  by  ammonia,  or  any  other 
caustic  or  carbonated  alkali,  and  then  phosphomolybdic  acid  is  added^ 
a  blue  color  is  produced;  in  strong  solutions  the  coloration  is  of  a  deep 
azure  blue,  but  the  bluish  hue  can  be  observed  even  in  very  dilute 
solutions.  One  grain  of  arbutin  was  distinctly  indicated  in  twenty 
pints  of  water  (1  in  140,000) ;  this  reaction  does  not  occur  with  molyb- 
date  of  ammonia,  nor  does  it  take  place  when  phosphoric  or  phos- 
phomolybdic acid  is  acted  upon  by  an  alkali  alone. 
A  solution  of  arbutin  may  be  perfectly  colorless  but  still  impure; 
when  to  an  impure  solution  of  arbutin,  ammonia  or  any  caustic  or 
carbonated  alkali  is  added,  a  deeper,  sometimes  orange  color  is  pro- 
duced, while  a  solution  of  pure  arbutin  is  not  affected  in  this  way, 
[The  author  now  describes  the  composition  and  glucoside  nature  of 
arbutin  and  the  mode  of  obtaining  hydrokinone,  the  literature  on  tiie 
subject  being  reviewed  and  compared  with  his  experiments.] 
E.  C.  Hughes,  in  an  essay  on  Uva  ursi,  published  in  the  American 
Journal  of  Pharmacy,  1847,  describes  a  crystalline  principle  whicii 
he  obtained  from  the  leaves  and  to  which  he  gave  the  name  Ursin." 
This  ursin,  although  it  has  not  been  noticed  in  European  literature,  has 
received  some  attention,  and  has  generally  been  regarded  as  a  distinct 
principle  in  American  works.  As  this  was  obtained  before  the  known 
existence  of  arbutin,  and  as  its  mode  of  preparation  is  similar  to  that 
