Am.  Jour.  Pharm.  ) 
April,  1885.  / 
Rhododendron  Maximum. 
165 
The  residue  on  the  filter,  after  treating  the  etherial  extract  with 
water,  was  composed  chiefly  of  resin,  associated  with  chlorophyll  and 
other  coloring  matter. 
The  alcoholic  tincture  obtained  by  macerating  the  powdered  leaves 
which  had  been  previously  exhausted  by  petroleum  spirit  and  ether 
was  evaporated  to  an  extract,  which  was  then  treated  with  water  and 
filtered. 
The  residue  left  on  the  filter  was  well  washed  and  dissolved  in  hot 
alcohol,  which  on  cooling  deposited  an  apparently  amorphous  mass, 
ursone;  upon  redissolving  in  alcohol,  microscopic  needles  were 
obtained,  which  upon  addition  of  sulphuric  acid  turned  black,  redden- 
ing the  acid,  and  became  yellow  with  nitric  acid,  giving  off  nitrous 
acid  fumes. 
The  aqueous  filtrate  was  concentrated,  treated  w^ith  acetate  of  lead, 
filtered,  the  filtrate  freed  from  lead  by  sulphuretted  hydrogen,  concen- 
trated to  a  syrupy  consistence,  again  diluted  somewhat,  and  treated 
with  animal  charcoal,  then  concentrated  and  set  aside,  when  a  deposit 
of  acicular  crystals  was  obtained,  which  proved  to  be  arbutin.  An 
alkaline  solution  of  the  crystals  gave  the  sky-blue  color  with  phospho- 
molybdic  acid.  Sulphuric  acid  dissolved  them  without  change  of  color, 
but  nitric  acid  turned  yellow,  with  the  evolution  of  nitrous  acid  fumes. 
The  precipitate  obtained  with  lead  acetate  was  suspended  in  water, 
the  lead  removed  by  sulphuretted  hydrogen,  the  filtrate  heated  to 
expel  excess  of  sulphuretted  hydrogen,  and  treated  with  solution  of 
gelatin,  when  a  bulky  precipitate  was  obtained,  which,  after  washing 
with  water,  became  black  on  the  addition  of  an  iron  salt,  thus  showing 
it  to  be  tannin. 
A  second  portion  of  the  leaves  was  treated  with  water,  and  the  infu- 
sion boiled  and  strained,  leaving  a  flocculent  residue  of  albumen  on 
the  strainer.  The  clear  liquid  was  then  concentrated  and  treated  with 
solution  of  acetate  of  lead,  the  precipitate  separated  by  a  filter,  and 
the  filtrate  freed  from  lead  by  sulphuretted  hydrogen ;  the  filtrate  was 
heated  to  expel  excess  of  sulphuretted  hydrogen,  treated  with  animal 
charcoal  to  remove  coloring  matter,  concentrated,  and  set  aside,  when 
crystals  of  arbutin  were  deposited,  showing  the  reactions  mentioned 
above. 
The  lead  precipitates  contained  tannin  and  gallic  acid,  and  some 
arbutin  was  extracted  from  the  sulphide  of  lead,  and  obtained  in  crys- 
tals.   The  mother-liquors  of  arbutin  seem  to  contain  ericolin. 
