556 
LARIXINIC  ACID. 
with  the  vapor  of  water,  and  is  thereby  lost.  The  highly  con- 
centrated solution  of  larixinic  acid,  obtained  in  the  way  just 
described,  on  standing,  deposits  brownish-yellow  crystals,  which 
are  impure  larixinic  acid.  This  is  to  be  pressed  between  folds 
of  blotting  paper,  and  again  to  be  crystallized  out  of  a  small 
quantity  of  water.  The  larixinic  acid  may  be  rendered  perfectly 
pure  by  subliming  it  once  or  twice.  This  is  easily  effected  by 
placing  the  larixinic  acid  between  two  watch  glasses,  or  in  any 
other  suitable  apparatus,  and  heating  it  cautiously  on  a  sand- 
bath,  or  even  on  a  water-bath,  as  the  larixinic  acid  sublimes  at 
the  very  low  temperature  of  93°  C.  The  larixinic  acid  is  a 
proximate  principle,  which  exists  ready  formed  in  the  larch. 
This  is  easily  proved  by  distilling  even  a  dilute  infusion  of  the 
bark,  when  the  liquid  which  passes  over  will  be  found  to  strike 
a  deep  purple  color  with  a  persalt  of  iron,  which  is  very  persist- 
ent. The  bark  of  old  larch  trees  contains  very  little  larixinic 
acid ;  but  the  bark  of  the  small  branches,  and  that  of  the  stems 
of  the  larch,  when  not  more  than  from  twenty  to  thirty  years 
of  age,  contains  very  considerable  quantities  of  this  sub- 
stance, the  concentrated  syrup  from  the  portions  of  bark 
yielding  more  larixinic  acid  than  an  equal  weight  of  catechu 
does  of  oxyphenic  acid.  Larixinic  acid,  after  it  has  been  puri- 
fied by  sublimation,  forms  beautifully  white  crystals,  often  more 
than  an  inch  in  length,  of  a  brilliant,  silvery  lustre,  very  much 
resembling  benzoic  acid  in  appearance.  They  sublime  at  93° 
C,  and  melt  at  153°  ;  but  its  aqueous  solutions  volatilise  at  or- 
dinary temperatures. 
The  smell  of  the  aqueous  solution  of  larixinic  acid  is  sweet- 
ish, like  that  of  a  syrup,  but  the  smell  of  the  sublimed  acid  is 
very  peculiar  and  slightly  empyreumatic.  As  larixinic  acid 
emits  a  sensible  odor  at  ordinary  temperatures,  in  this  respect 
it*  considerably  resembles  naphthaline  and  ordinary  camphor. 
The  taste  of  larixinic  acid  is  slightly  bitter  and  astringent.  It 
reddens  litmus  paper  very  slightly  ;  but  a  single  drop  of  potash 
or  ammonia,  when  added  to  a  solution  of  a  large  quantity  of 
larixinic  acid,  renders  it  alkaline.  Larixinic  acid  is  very  solu- 
ble in  boiling  water,  but  is  by  no  means  very  soluble  in  cold 
water,  87*88  parts  of  water,  at  15°  C.,  dissolving  one  part  of 
the  acid  only  ;  but  the  solubility  of  larixinic  acid  in  cold 
