332 
Carmine  Solution. 
/Am.  Jour.  Pharm. 
\      July,  1887. 
The  true  chemical  constitution  of  carmine,  in  the  present  state  of 
knowledge,  is  shrouded  in  considerable  doubt,  although  it  has  been 
made  the  subject  of  repeated  analyses  ever  since  Pelletier  and  Caven- 
ton  first  examined  it  in  1818.  One  of  the  latest  and  most  satisfactory 
researches  has  been  made  by  Messrs.  Will  and  Leymann1,  who  dissolved 
pure  carmine  red  in  50  per  cent,  acetic  acid  and  boiled  it  with  an  ex- 
cess of  bromine,  whereby  colorless  needles  of  C10H4Br4O3  were  ob- 
tained. The  acetic  acid  mother-liquor,  on  dilution  with  water,  yielded 
yellow  amorphous  floccules  which,  boiled  with  KHO,  gave  a  red 
pulverulent  salt,  the  crystalline  acid  of  which,  when  liberated,  gave 
the  formula  CnH5Br304.  It  exhibited  no  tinctorial  properties,  but 
all  its  salts  were  strongly  colored.  Further,  on  treating  the  alkali  so- 
lution with  stannous  chloride  and  supersaturating  with  HC1,  ether  ex- 
tracted a  substance,  the  solution  of  which,  on  exposure  to  air,  acquired 
a  color  similar  to  that  of  a  cochineal  solution  and,  like  the  latter,  be- 
came violet  red  on  the  addition  of  an  alkali.  The  products  obtained 
by  these  investigations  may  be  summed  up  as  having  the  formula  C10 
H803,  a  colorless  acid,  capable  of  forming  colored  salts,  as  CnH804, 
and  a  readily  oxidizable  chromogene  whose  constitution  is  unknown. 
Let  us,  for  a  moment,  following  Dechan,  briefly  review  the  results 
of  earlier  investigators  and  see  how  widely  they  differ  from  each  other. 
De  la  Rue2  first  gave  as  the  formula  of  carminic  acid  C14H1408.  This 
was  denied  by  Schutzenberger,  who  claimed  that  De  la  Rue  had  been 
experimenting  with  a  mixture  of  several  substances,  and  that  the  true 
formula  of  this  acid  was  C9H805.  Again,  Schaller  obtained  results 
which  differed  from  these  by  H20,  and  expressed  the  opinion,  that  the 
acid  was  dibasic  and  capable,  therefore,  of  forming  both  acid  and  nor- 
mal salts.  Hlasiwetz  and  Grabowsky 3  came  to  the  conclusion  that 
the  carminic  acid  of  previous  investigators  was  a  glucoside  for,  on  treat- 
ing it  with  boiling  dilute  sulphuric  acid,  it  was  found  to  yield  a  pecu- 
liar kind  of  sugar  and  a  substance  they  called  carmine  red.  Their  for- 
mula was  CnH1207.  Dechan 4  instituted  experiments  for  the  purpose 
of  determining  whether  carmine  could  be  prepared  without  the  use  of 
alum  or  tin  spirits  and  very  clearly  established  the  fact,  that  either  ot 
the  bases,  aluminium  or  tin,  were  essential  for  its  production.  Hence, 
xBer.D.  Chem.  Ges.,  1885  p.  3180-3193;  Am.  Jour.  Phar.,  1886,  p.  91. 
2Gmelin,  xiiip.  358. 
3  Jour,  de  Pharm.,  Sept.,  1866;  A.  J.  P.  1866,  p.  504. 
4  Pharm.  Jour,  and  Trans.,  Dec.  12,  1885;  A.  J.  P.,  1886,  p.  30. 
