Nitric  acid  of  Sp.  Gr.  1  -4,  converts  it  into  oxalic  acid  and  nitro-

coccusic  acid,  which  is  Cie  ^  Q4  I  Oe  +  2  aq.,  apparently  de-
rived from  an  acid  Ci6  Hs  Oe  by  replacement  of  3  eq.  of  hydrogen
by  3  eq.  of  N  0  * .  It  forms  yellow  tables,  soluble  in  water,  and


ALKALOIDS   OR   ORGANIC   BASES.  379

colouring  the  skin  yellow.  Its  salts  are  also  yellow,  and  detonate
when  heated.  The  silver  salt  is  soluble  in  water.
It  will  be  remembered  that  under  anisic  acid,  Cis  Hs  0&,  we
mentioned  two  acids,  nitranisic  and  dinitranisic  acid,  in  which
1  and  2  eq.  of  hydrogen  were  respectively  replaced  by  1  and  2  eq.
of  N  0* .  The  acid  just  described  has  the  formula  of  trinitranisic
acid,  and  there  is  nothing  in  its  properties  inconsistent  with  the
idea  that  it  may  be  that  substance,  which  apparently  is  not  formed
by  the  action  of  nitric  acid  on  oil  of  anise,  or  oil  of  estragon.
The  finest  crimson  and  scarlet  dyes  are  made  from  cochineal,
according  as  the  mordant  is  alumina  or  tin.
Kermes  is  a  dye-stuff  similar  in  its  origin  and  properties  to
cochineal,  but  inferior  in  beauty  of  tint.  It  is  derived  from
Coccus  ilicis.
The  red  colouring  matter  of  stick-lac,  which  is  also  used  as  a
dye,  has  similar  properties.  Lac  is  produced  on  certain  plants  by
the  puncture  of  an  insect.
ACTION  OF  NTTKIC  ACID  ON  ALOES.
This  action  so  much  resembles,  in  some  points,  the  action  of
nitric  acid  on  indigo,  that  it  may  be  properly  mentioned  here.
