ON  COLOR  OBTAINED  FORM  COAL  TAR  PRODUCTS. 
271 
The  pieces  are  then  allowed  to  age  for  two  or  three  days, 
when,  to  fix  the  purpurate  of  lead  on  the  cotton,  and  the  pur- 
purate  of  ammonia  on  the  wool,  it  is  necessary  to  pass  the  cloth 
into  a  bath  of  bichloride  of  mercury,  composed  as  follows : 
Water  .       .       .       100  gallons. 
Bichloride  of  merury    .  6  pounds. 
Acetate  of  soda    .       .        12  pounds. 
Acetic  acid  ...  2  quarts. 
Until  recently,  all  the  green  colors  produced  on  fabrics  were 
the  results  of  blue  and  yellow  mixed  together ;  but  of  late  pub- 
lic attention  has  been  drawn  to  a  green  matter  discovered  by  the 
Chinese,  and  fixed  by  them  on  cotton.  It  has  been  ascertained 
that  they  prepare  it  by  a  long  and  tedious  process,  from  two 
plants  called  Pa-bi-lo-sa  (Rhamnus  chlorophorus}  and  Ilom-bi- 
lo-za  (Ehamnus  utilis),  and  sell  it  in  small  square  cakes,  under 
the  name  of  Luh-kaou  or  Luh-chao.  The  first  commercial  impor- 
tation of  this  color,  new  to  us,  is  quite  recent,  as  the  first  pub- 
lic sale  of  it  in  England  took  place  a  week  ago,  at  the  quarterly 
indigo  sales,  under  the  name  of  China  green  indigo.  No  sooner 
had  a  foreign  green  substance  been  brought  to  our  notice,  than 
in  Europe  we  had  succeeded  in  obtaining  also  a  green  dyeing 
substance  from  the  plants  which  surround  us,  and  Mr.  Schlum- 
berger  has  been  fortunate  enough  to  fix  on  woollen  fabrics  the 
green  chlorophylle,  or  coloring  matter  of  leaves  and  grass. 
This  discovery  will,  in  time,  prove  of  great  service  to  dyers  and 
calico  printers.  Mr.  Schlumberger's  process  consists  in  boiling 
60  lbs.  of  grass  with  25  gallons  of  water.  This  operation  is  re- 
peated, and  the  grass  then  treated  to  25  gallons  of  soda  lye, 
with  addition  of  2  to  4  lbs.  of  Mercer's  dung  substitute  (phosphate 
of  soda  and  lime).  Boil  half  an  hour,  and  then  add  excess  of 
hydrochloric  acid  ;  a  green  precipitate  falls,  which  is  separated 
by  filtration.  The  precipitate  is  dissolved  in  very  dilute  soda 
lye,  adding  a  little  of  the  substitute,  and  the  silk  or  wool  to  be 
dyed  is  dipped  in  until  the  desired  shade  is  obtained.  Stannate 
of  soda  is  the  only  mordant  which  gives  any  beneficial  results. 
M.  Pelouze  has  rendered  lately  a  great  service  to  Turkey  red 
dyers  by  enabling  them  to  use  any  oil,  instead  of  only  Gallipoli 
oil,  and  this  of  special  quality.  M.  Pelouze  has  discovered 
that  the  difference  there  was  betwixt  a  Gallipoli  oil,  which  could 
