32 
Carmine. 
Am.  Jour.  Pharm. 
Jan.,  1886. 
acid  was  dibasic,  and  therefore  capable  of  forming  normal  and  acid  salts. 
Hlasiwetz  and  Grabowski  came  to  the  conclusion  that  the  carminic 
acid  as  prepared  by  the  previous  investigators  was  a  glucoside,  for  on 
treating  it  with  boiling  dilute  acid  it  was  found  to  yield  a  peculiar  kind 
of  sugar  and  a  substance  which  they  named  carmine  red,  the  analysis 
of  which  led  to  the  formula  CnH1207. 
The  results  obtained  by  the  repeated  ultimate  analysis  of  several 
samples  of  commercial  carmine  exhibited  such  a  wide  variation  that  I 
was  irresistibly  led  to  the  conclusion  that  the  formation  of  carmine 
was  the  result  of  a  species  of  physico-chemical  action,  and  that  the 
products  of  such  action  will  largely  depend  on  the  conditions  under 
which  it  takes  place.  Many  striking  examples  of  this  peculiar  reaction 
may  be  observed  in  the  dyeing  of  wool  and  other  fibres,  where  an  ex- 
tremely small  quantity  of  a  base  may  be  made  to  unite  with  varying 
proportions  of  coloring  matter.  I  am  therefore  of  opinion  that  it  is 
scarcely  possible  to  obtain  carmine  of  a  uniform  and  fixed  chemical 
composition;  consequently,  we  must  adopt  some  other  standard  by 
which  to  gauge  the  purity  of  the  commercial  article. 
This,  to  a  certain  extent,  has  already  been  decided  by  the  fact  that 
the  alumina  or  tin  compound  of  cochineal  is  readily  soluble  in  dilute 
ammonia,  whereas  the  substances  with  which  it  is  liable  to  be  adulte- 
rated are,  as  a  rule,  not  soluble  in  this  menstruum. 
It  must  not,  however,  be  assumed  that  everything  soluble  in  dilute 
ammonia  is  pure  carmine;  i.e.,  accepting  carmine  as  a  compound  of 
alumina  or  tin  with  the  coloring-matter  of  cochineal.  Tin  spirits  form 
with  aniline  scarlet  a  compound  which  very  much  resembles  carmine 
physically  and  chemically,  being  like  it  soluble  in  dilute  ammonia 
and  insoluble  in  water. 
The  foreign  substances  which  are  likely  to  be  mixed  with  carmine 
and  which  are  separated  from  it  by  means  of  dilute  ammonia,  are  ver- 
milion, chrome  red,  albuminous  or  starchy  matters,  and  uncombined 
alumina;  aniline  carmine,  not  being  separated,  must  be  tested  for  in 
the  ammoniacal  filtrate. 
The  method  adopted  in  the  examination  of  ten  samples,  the  result 
of  which  will  be  found  in  the  appended  table,  was  as  follows :— The 
quantity  taken  for  analysis  was  0'2  gram.  This  was  digested  in  dilute 
ammonia  with  frequent  stirring  for  twenty  minutes,  then  poured  on  a 
tared  filter  and  washed  with  ammonia  until  all  traces  of  carmine  had 
disappeared.    The  filter  was  dried  at  100°  C.  and  weighed,  and  the 
