LARIXINIC  ACID.  559 
is  boiled  with  a  solution  of  hypochlorite  of  lime,  no  coloration 
is  produced.  It  is  readily  attacked  by  nitric  acid,  especially 
when  assisted  by  heat ;  nitrous  fumes  are  given  off,  and  oxalic 
acid  is  the  only  fixed  product.  It  is  also  readily  attacked  by 
bromine,  especially  when  assisted  by  heat.  Abundant  vapors 
of  hydrobromic  acid  are  given  off,  the  larixinic  acid  being 
entirely  destroyed  and  converted  into  an  uncrystallisable  resin. 
The  salts  of  copper  produce  an  emerald  green  color  in  solu- 
tions of  larixinic  acid,  but  no  precipitate.  Chloride  of  manga- 
nese produces  neither  coloration  nor  precipitation.  Protosul- 
phate  of  iron  strikes  a  brownish-red  color  with  solutions  of 
larixinic  acid,  which  acquire  a  brighter  red  color  on  standing, 
resembling  meconate  of  iron.  Perchloride  and  persulphate  of 
iron  produce  a  beautiful  purple  drhlia-color,  which  is  very 
persistent,  and  stands  dilution  well.  Its  reactions  with  salts  of 
iron  are  very  characteristic  of  larixinic  acid,  which  forms  an 
excellent  reagent  for  the  detection  of  salts  of  iron,  even  in  very 
minute  quantity.  In  this  way  the  presence  of  iron,  in  tolerably 
pure  sulphate  of  copper,  can  readily  be  detected  by  the  purple 
coloration  produced.  Larixinic  acid  does  not  affect  neutral  pro- 
tonitrate  of  mercury  in  the  cold  ;  and  on  the  application  of 
heat  no  mercury  is  reduced. 
Larixinic  acid  appears  to  be  peculiar  to  the  larch-tree  ;  at 
least  I  have  not  been  able  to  find  a  trace  of  it  in  the  bark  of 
the  spruce  fir  (Abies  excelsa,}  or  in  that  part  of  the  Scotch  fir 
(Pinus  sylvestris.)  Larixinic  acid  evidently  belongs  to  that 
small  group  of  substances  of  which  pyrogallic  acid  and  pyrocat- 
echine,  the  oxyphenic  acid  of  Gerhardt,  are  the  only  other 
members  yet  known.  Larixinic  acid  is  much  less  easily  oxidi- 
sable  than  oxyphenic  acid,  which  again  is  less  easily  oxidated 
than  pyrogallic  acid.  Larixinic  acid  volatilises  at  a  much  lower 
temperature  than  either  of  these  two  substances,  from  which  it 
also  differs  in  being  a  ready -formed  proximate  principle,  and 
not  an  educt. 
Addendum. — In  consequence  of  the  extremely  feeble,  if  not 
somewhat  doubtful,  acid  properties  of  the  so-called  larixinic  acid, 
perhaps  the  name  Laraxine  would  be  more  appropriate;  but  in 
that  case  the  name  of  pyrogallic  acid  should  be  altered  to  pyro- 
galline,  and  that  of  oxyphenic  acid  to  pyrocatechine,  the  name 
originally  given  to  it  by  Zwenger, — Trans.  Royal  Society,  1862. 
36 
