354 
BYE  PIGMENT  FROM  QUERCITRON  BARK. 
ing  operation,  the  mordants  were  dissolved,  as  might  have  been 
expected,  in  accordance  with  the  results  obtained  by  Prof.  Cal- 
vert. This  fact  shows  further  that  the  gallic  acid  produced  by 
the  action  of  sulphuric  acid  upon  the  tannin  of  the  quercitron 
bark  is  removed  by  the  washing,  for  otherwise  the  dyeing  capa- 
bility would  be  reduced  instead  of  increased  by  this  treatment. 
By  the  treatment  of  quercitron  bark  with  sulphuric  acid  the 
color  substance  must  have  undergone  a  change,  because  the  co- 
lor is  fixed  by  mordants  only  at  a  high  temperature,  and  is  al- 
most insoluble.  An  aqueous  decoction  deposits  on  cooling  a  co- 
pious yellow  sediment,  which  appears  to  be  Rigaud's  quercitin. 
Logwood,  Lima  wood,  sandal  wood,  turmeric,  Cuba  wood,  su- 
mach, yellow  berries,  woad,  galls,  and  pomegranate  shells  were 
subjected  to  the  action  of  sulphuric  acid  in  a  similar  manner, 
then  washed,  pressed,  and  dried.  Hr.  Schlumberger  found  that 
logwood,  Lima  wood,  and  sandal  wood  were  injured  by  this  treat- 
ment, but  that  the  result  was  very  advantageous  with  the  other 
dye  stuffs.  The  most  striking  effect  was  produced  with  sumach, 
when  the  water  was  mixed  with  40  or  50  per  cent,  sulphuric  acid 
by  volume.  The  product,  which  may  be  called  sumacin,  thus 
obtained,  gives  finer  yellow,  grey,  and  black  than  quercitron,  and 
the  dyeing  capability  is  increased  fourfold  ;  when  mixed  with 
garancin  the  color  obtained  has  more  body,  and  the  violet  is  not 
injured  so  much  as  is  the  case  in  dyeing  with  an  admixture  of 
wood  containing  tannin.  Woad  likewise  acquires  a  much  greater 
dyeing  capability  by  the  action  of  sulphuric  acid,  and  the  color 
it  gives  is  purer,  but  it  requires  then  a  temperature  of  158°  F. 
for  dyeing. 
Yelk>w  berries,  Cuba  wood,  and  turmeric,  treated  in  the  same 
manner,  give  very  satisfactory  results  in  dyeing.  For  these 
substances,  the  liquid  should  contain  from  15  to  20  per  cent, 
concentrated  sulphuric  acid.  The  tannic  acid  of  nutgalls  and  of 
pomegranate  shells  is  not  all  converted  into  gallic  acid  by  the 
action  of  sulphuric  acid,  but  more  color  substance  is  set  at  liber- 
ty. The  colors  produced  with  aluminous  mordants  are  more  de- 
cidedly yellow,  and  those  produced  with  iron  mordants  are  clearer. 
A  stronger  acid  should  be  used  for  nutgalls  than  for  pomegranate 
shells  London  Pharm.  Jour.^  May],  1857. 
