176 
GREEN  COLORING  MATTER  FROM  CHINA. 
must  then  be  divided  on  an  iron  plate  into  25  pills,  and  again 
rolled  in  the  iron  powder.  Finally,  they  are  covered  with  a 
layer  of  tolu,  according  to  M.  Blancard's  process. 
All  these  preparations  must  be  made  very  carefully.  M. 
Burin-Dubuisson  has  ascertained  that  the  commercial  salts  of 
manganese  frequently  contain  copper,  and  even  arsenic  ;  he 
hence  insists  on  the  necessity  of  calcining  the  sulphate  of  manga- 
nese, twice,  or  more  frequently,  at  a  dark  red  heat,  and  of  care- 
fully testing  the  solution — Amer.  Jour.  Med.  Sci.,  Oct.  1852. 
from  Bui.  de  Therap. 
ON  A  GREEN  COLORING  MATTER  FROM  CHINA. 
By  J.  Persoz. 
M.  Daniel  Kceehlin-Schone  forwarded  to  me,  last  autumn,  a 
sample  of  calico  dyed  in  China,  of  a  sea-green  tint  of  great 
stability,  requesting  me  to  examine  into  the  composition  of  this 
green  color.  All  the  attempts  to  ascertain  the  presence  of  either 
a  yellow  or  blue,  which  I  made  with  this  specimen,  met  with  no 
success  ;  and  I  was  soon  convinced,  by  isolating  the  coloring 
matter,  that  this  green  was  produced  by  a  tinctorial  substance  sui 
generis.    It  also  became  evident — 
1.  That  this  coloring  matter  was  of  a  vegetable  origin. 
2.  That  the  stuff  upon  which  it  was  fixed  was  charged  with  a 
large  quantity  of  alumina  and  with  a  little  oxide  of  iron  and  lime, 
substances  the  presence  of  which  necessarily  implied  that  the 
coloring  matter  employed  had  required  the  assistance  of  mordants 
to  make  it  adhere  to  the^ stuff. 
These  results,  so  positive,  and  yet  so  contrary,  not  only  to  all 
we  know  in  Europe  with  regard  to  the  composition  of  greens,  but 
also  to  all  that  has  been  written  on  the  processes  employed  by  the 
Chinese  in  dyeing  this  color,  necessitated  a  closer  examination  on 
my  part.  I  therefore  had  recourse  to  the  assistance  of  Mr.  Forbes, 
American  Consul  at  Canton,  to  obtain  a  specimen  of  the  substance. 
He  had  the  goodness  to  send  me  about  1  grm.  of  it. 
This  substance  is,  in  thin  plates,  of  a  blue  color,  resembling 
that  of  Javanese  indigo,  but  of  a  finer  grain,  and  differing  also 
from  indigo  in  its  composition  and  all  its  chemical  properties.  On 
