Am.  Jour.  Pharni. 
Jan.,  1886. 
Carmine. 
conditions  were  scrupulously  adhered  to.  I  have  subsequently  learned 
that  my  efforts  in  this  direction  had  been  anticipated  by  Hugo  Miiller, 
who  tried,  but  evidently  in  vain,  to  obtain  carmine  by  Cenette's  pro- 
oess ;  the  only  and  invariable  result  being  a  rich  crop  of  mould. 
From  the  results  obtained  by  using  the  above  methods  I  have  come 
to  the  conclusion  that  carmine  is  not  a  true  chemical  compound,  but 
that  it  is  a  complex  mixture  of  several  compounds.  Experiments  in- 
stituted for  the  purpose  of  determining  whether  carmine  could  be  pre- 
pared without  the  use  of  alum  or  tin  spirits  have  very  clearly  estab- 
lished the  fact  that  either  of  the  bases,  aluminium  or  tin,  is  necessary 
for  its  production. 
Composition  of  Carmine. — Some  authorities  state  that  carmine  is 
simply  the  alumina  salt  of  carminic  acid ;  but  this  does  not  increase 
our  knowledge  of  its  exact  composition,  and  no  two  investigators  have 
been  able  to  agree  as  to  what  the  true  constitution  of  this  acid  is. 
Pelletier  and  Caventou,  in  a  communication  to  the  Institute  de  France 
(1818),  gave  the  following  as  the  percentage  composition  of  the  color- 
ing matter  of  cochineal : — 
Carbon.         Hydrogen.         Oxvgen.  Nitrogen. 
49-33  6-66  4045  3'56 
Warren  de  la  Rue  submitted  this  substance  to  a  careful  examination 
and  succeeded  in  separating  the  coloring  matter  in,  what  he  considered, 
a  pure  state,  and  at  the  same  time  discovered  that  the  substance  now 
known  as  nitro-coccusic  acid  was  one  of  the  products  of  the  decompo- 
sition of  cochineal.  The  pure  coloring  matter  was  named  carminic 
acid,  and  its  composition  as  determined  by  W.  de  la  Rue  is : — 
Theory.  Found.  Formula.  Adopted. 
C  ,...54-19  54-13            168-  C14 
H  ..  4-52  4-62              14"  H14 
0  41-29  41-25.           128-  0  8 
wow       ioo-oo  ~m- 
This  agrees  with  the  composition  of  copper  carminate  as  analyzed 
by  the  same  investigator. 
Schutzenberger,  in  his  investigations  on  the  constitution  of  carminic 
acid,  noticed  a  considerable  variation  in  the  composition  of  carminic 
acid  of  different  preparations.  He  came  to  the  conclusion  that  W.  de 
la  Rue  had  been  experimenting  on  a  mixture  of  several  substances. 
The  composition  of  carminic  acid  as  determined  by  Schutzenberger  is 
C9H805,  which  differs  very  materially  from  that -given  by  W.  de  la  Rue. 
Schaller  in  his  researches  obtained  results  which  differ  from  those  of 
Schutzenberger  by  H20.    He  also  gave  it  as  his  opinion  that  carminic 
