330 
ON  CATECHU  AND  ITS  ACIDS. 
1.  II.  III.  IV.       V.  VI. 
C   17  102  52.58    52-46  52  78  =  17  102  61-08  60-95  61-32  61-20  61-77 
H  12    12    6-18      6-09  6-08=  9      9  5-39  5-29  5-25     5-17  5-10 
0    10    80  41-24    41-45  41-14=  7    56  33-53  33  76  33-43  33-63  33  13 
194  100-00  100-00  100-00  167  100-00  100-00  100-00  100-00  100-00 
I.  and  II.  is  the  acid  prepared  by  ether  air-dry ;  III.,  IV.  the 
same  dried  at  100°  C.  (212°  F.)  until  it  just  ceases  to  lose 
weight ;  V.,  VI.  dried  in  the  same  way  was  prepared  by  water. 
The  loss  of  the  drying  operation  is  14-34  per  cent. ;  BHO  are 
13-92  per  cent.  When  heated  for  a  longer  time  the  acid  gradu- 
ally assumes  a  yellow  and  brown  color,  and  the  loss  increased 
to  15-85  per  cent.  Such  a  yellow  acid  on  elementary  analysis, 
gave  results  closely  approaching  those  of  Svanberg  and  Zwen- 
ger— C  62-62  H  5-24  O  32-14. 
The  lead  salt  was  prepared  by  precipitating  a  warm  solution 
with  acetate  of  lead,  filtering  and  washing  quickly,  pressing  be- 
tween bibulous  paper  and  dried  on  the  water-bath.  It  had  a 
brown  color  and  could  not  be  obtained  white ;  the  results  of  the 
analysis  approached  as  near  as  could  be  to  the  formula  C17  H9  07 
+2PbO. 
All  the  above  experiments  have  been  made  with  that  variety 
of  catechu  called  Bombay  catechu.*  For  the  following  experi- 
ments Gambir  catechu  was  used,  and  the  catechuic  acid  prepared 
partly  with  ether,  partly  by  Wackenroder's  method,  by  mace- 
rating the  catechu  in  three  parts  of  cold  water  and  boiling  the 
residue  several  times  with  eight  parts  of  water ;  the  first  crystal- 
lization is  yellow,  the  others  nearly  white,  and  are  to  be  recrys- 
tallized.    The  analytical  results  are  the  same  as  above. 
White  catechin  was  now  boiled  with  diluted  sulphuric  acid 
(1HO,  S03  to  24HO)  for  three  or  four  hours.  The  cinnamon- 
colored  precipitate  was  filtered,  the  filtrate  saturated  with  car- 
bonate of  baryta,  filtered  and  precipitated  with  acetate  of  lead ; 
the  filtrate  was  treated  with  hydrosulphuric  acid  to  separate  the 
lead  in  excess,  evaporated  in  the  water-bath,  the  brown  residue 
dissolved  in  water,  again  treated  with  acetate  of  lead  and  hydro- 
sulphuric  acid,  left  a  colorless  crystalline  residue,  easily  soluble 
in  water,  consisting  chiefly  of  acetate  of  baryta,  which  was 
*  The  author's  description  corresponds  with  that  of  Pegu  and  Bengal 
calccJm,  in  Wood  and  Baehe's  Disp.,  lOfch  edit.,  199,  200. 
