Am.  Jour.  Pharm  > 
July  1, 1874.  $ 
Arhutin  in  Ericaceous  Plants. 
315 
cinium  myrtillus)*  besides  pyrocatechin,  a  neutral  crystallizable  prin- 
ciple, which  he  named  ericinon,  and  which  Hessef  believed  to  be  iden- 
tical -with  hydrokinone.  This  identity  was  subsequently  (1864) 
proven  by  Zwenger  and  Himmelmann, J  who  separated  arbutin  from 
the  leaves  of  Chimaphila  umbellata,  and  found  that  this  principle 
yields,  on  dry  distillation,  hydrokinone,  but  no  pyrocatechin,  while 
among  the  products  of  the  dry  distillation  of  kinic  acid  they  observed 
pyrocatechin,  besides  hydrokinone,  as  announced  by  Woehler  in 
1844. §  The  hydrokinone  which  is  found  in  the  dry  distillate  of 
ericaceous  leaves  is  therefore  ascribed  by  them  to  the  presence  there- 
in of  arbutin,  while  in  the  leaves  of  Vacciniece  it  is  due  to  kinic  acid, 
the  presence  of  which  has  been  proven  by  Zwenger  for  the  leaves  of 
Vaccinium  myrtillus.\\  In  1870,  E.  Claassen^f  announced  having  ob- 
tained a  crystalline  principle  from  the  leaves  of  Vaccinium  vitis  idcea? 
which  I  at  one  time**  supposed  to  be  probably  identical  with  arbutin  ; 
however,  on  comparing  his  process  with  Zwenger's  process  for  kinic 
acid,  the  two  will  be  found  identical,  except  that  Claassen  has  omitted 
the  final  treatment  with  sulphuric  acid,  thus  rendering  it  probable 
that  his  vacciniin  is  simply  kinate  of  calcium.  This  supposition  is 
confirmed  by  comparing  the  properties  of  this  so-called  vaciniin  with 
those  of  kinate  of  calcium, tf  the  main  difference  will  be  found  to  be 
that  the  latter  is  stated  to  be  nearly  tasteless,  while  vaciniin  is  of  a 
somewhat  bitter  taste  (kinate  of  potassium  is  decidedly  bitter) ; 
moreover,  the  absence  of  lime  in  vacciniin  has  not  been  proven  by 
Claassen,  for  he  merely  says  that  his  crystals  are  reduced  to  coal  by  a 
stronger  heat. 
This  position  appears  to  be  further  strengthened  by  the  results  of 
an  analysis  of  the  leaves  of  Gcaylussaeia  resinosa,  Torrey  and  Gray, 
{§.  Vaccinium  resinosum,  Lin.)  undertaken  at  my  suggestion  by  Mr. 
Hugo  Oppermann,  and  reported  in  his  inaugural  essay,  recently  pre- 
sented to  the  Philadelphia  College  of  Pharmacy.  Arbutin  could  not  be 
*  Anna],  d.  Chem.  uud  Pharm.,  cxi,  p.  215-229. 
f  Ibid.,  cxiv,  p.  301. 
X  Ibid.,  cxxix,  p.  203-208. 
I  Ibid.,  li,  p.  146. 
||  American  Journal  of  Pharmacy,  1861,  p.  128. 
1  Ibid.,  1871,  p.  297. 
**  Ibid.,  1871,  p.  235. 
ft  See  Gmelin's  Chemistry,  Cavendish  Edit.,  xvi,  p.  229. 
