lS2 
V arieties. 
Am.  Jour.  Pharm. 
Mar.,  1879. 
pletely  saturating  wine  and  then  adding  sodium  chloride,  contains  nearly  4.  per 
cent,  of  iron. — Jour,  of  Chem.  Soc,  Nov.,  1878  ,  from  Compt.  Rend. 
Examination  of  the  "Gum"  of  the  Quebracho  Colorado  [Loxopterigium  Lo- 
rentiiy  Grisebach).  ByPEDRO  N.  Arata. — This  tree,  belonging  to  the  Anacard- 
iaceous  order,  is  indigenous  in,  and  peculiar  to,  the  northern  part  of  the  Argentine  . 
Republic.  The  so-called  gum,  or  rather  thickened  juice,  collects  in  the  cracks  and 
hollows  of  the  wood,  in  ruby-red  concretions  somewhat  resembling  colophony,  but 
more  brittle ;  it  is  easily  pulverized,  and  yields  a  brick-red  powder.  It  is  scentless, 
but  has  a  slightly  astringent  taste.  Sp.  gr.  1*3756  at  150.  It  is  easily  soluble  in 
alcohol,  acetone,  and  acetic  ether,-  dissolves  also  in  amyl  alcohol  and  acetic  acid, 
but  is  insoluble  in  benzin,  carbon  bisulphide,  chloroform  and  turpentine  oil  ;  nearly 
insoluble  in  cold  water  and  in  ether  5  nevertheless,  an  etherial  solution,  having  an 
emerald-green  color,  may  be  obtained  by  agitating  the  gum  with  ether  and  water. 
Boiling  water  dissolves  it  completely,  and  deposits  part  of  it  on  cooling.  It  dis- 
solves also  in  strong  sulphuric  acid,  and  is  precipitated  therefrom  by  water. 
Heated  in  a  platinum  capsule,  it  swells  up  and  burns,  leaving  a  shining  porous 
cinder,  which  burns  away  slowly  on  continuing  the  heat.  If  the  combustion  be 
completed  in  a  stream  of  oxygen,  the  unburnt  residue  is  scarcely  appreciable. 
A  1  per  cent,  solution  of  the  gum  in  absolute  alcohol,  in  a  layer  7  mm.  thick, 
exhibits  an  absorption-spectrum  having  a  dark  band  commencing  between  the  solar 
lines  A  and  B,  and  terminating  at  C  ;  another  extending  for  a  short  distance  on 
each  side  of  D;  and  a  third,  beginning  half  way  between  D  and  E  and  extending 
to  all  the  more  refrangible  part  of  the  spectrum.  The  same  solution  in  a  layer  25 
mm.  thick  absorbs  the  whole  of  the  spectrum,  excepting  a  narrow  space  from  C 
half-way  to  D.  A  solution  of  dragon's  blood,  which  in  some  respects  resembles 
quebracho  gum,  exhibits  a  very  different  spectrum,  containing  a  dark  band  extend- 
ing for  a  short  distance  on  each  side  of  C,  and  a  second  beginning  just  beyond  D 
and  occupying  all  the  rest  of  the  spectrum. 
Reactions. — Quebracho  gum,  subjected  to  dry  distillation,  yields  between  ioo°  and 
i2o°C.  a  distillate  which  remains  liquid  on  cooling,  and  between  2400  and  245°C. 
a  distillate  which  solidifies  to  colorless  prisms  of  pyrocatechin  (m.  p.  1050,  nearly,  b. 
p.  2400 — 2450).  The  gum  is  strongly  attacked  by  concentrated  nitric  acid,  and 
when  heated  with  the  same  acid  somewhat  diluted  with  water,  it  is  oxidized  to  oxalic 
acid  and  trinitrophenol  or  picric  acid.  Fused  with  potash  it  yields  protocatechuic 
acid,  C7H6Ot  or  C6H3(OH)2.COOH,  and  phloroglucin,  C6H603. 
The  formation  of  these  products  renders  it  probable  that  quebracho  gum  contains 
one  of  the  bodies  called  catechins  1  j  but  in  consequence  of  the  great  tendency  of 
these  bodies  to  alteration,  the  author  has  not  yet  been  able  to  obtain  satisfactory 
evidence  of  their  actual  presence  in  the  gum.    The  existence  of  a  catechin  in  an 
1  Gautier  has  shown  that  the  term  "catechin  "  usually  supposed  to  denote  a  definite  proximate  prin- 
ciple of  plants,  really  includes  several  compounds  forming  a  natural  family  of  organic  bodies  (see 
"Journal  Chemical  Society,"  1877,  ii,  892. 
