Amscp^i?7trm  }  Chemistry  of  Oak,  Willow  and  Elm  Barks.  455 
cent,  of  water,  and  on  analysis  gave  22*53  Per  cent-  °f  carbon,  1*35 
per  cent,  of  hydrogen,  and  53*28  per  cent,  of  lead  oxide.  By  fraction- 
ally precipitating  with  a  lead  salt,  both  these  acids  gave  salts  of  varying 
constitution.  Ulmotannate  of  lead  was  greyer  than  the  last  body  ;  and 
on  analysis  gave  21*36  per  cent,  of  carbon,  1*51  per  cent,  of  hydro- 
gen, 10*32  per  cent,  of  oxygen,  and  66*8 1  per  cent,  of  lead  oxide. 
Copper  Salts. — Quercitannate  of  copper  is  a  brown  substance,  in- 
soluble in  alcohol  and  ether,  and  sparingly  soluble  in  water.  At  no° 
it  lost  12*23  Per  cent-  °f  moisture,  and  on  analysis  gave  39*99  per 
cent,  of  carbon,  2*38  per  cent,  of  hydrogen,  28*14  Per  cent.  of  oxygen, 
and  29*49  per  cent,  of  copper  oxide.  Salitannate  of  copper  forms  a 
dark  reddish-brown  salt,  which  lost  at  1200  12*4  per  cent,  of  moisture  ; 
and  on  analysis  gave  39*36  per  cent,  of  carbon,  2*35  per  cent,  of 
hydrogen,  27*83  per  cent,  of  oxygen,  and  30*46  per  cent,  of  copper 
oxide.  Ulmotannate  of  copper  is  chocolate-brown,  and  after  drying 
at  1100  gave  39*68  per  cent,  of  carbon,  1*93  per  cent,  of  hydrogen, 
17*98  per  cent,  of  oxygen,  and  40*41  per  cent,  of  copper  oxide 
Tin  Salts. — Quercitannate  of  tin  is  a  greenish-brown  substance,  in- 
soluble in  alcohol  and  ether,  and  only  sparingly  soluble  in  water.  At 
110°  it  loses  5*98  per  cent,  of  moisture,  and  on  analysis  gave  36*32 
per  cent,  of  carbon,  2*56  per  cent,  of  hydrogen,  20*69  per  cent,  of 
oxygen,  and  40*43  per  cent,  of  stannous  oxide.  The  formula 
C30H26O13.3SnO  agrees  fairly  with  these  numbers.  Salitannate  of  tin 
is  a  chocolate-colored  body,  which  losses  7*18  per  cent,  of  moisture  at 
120°,  and  on  analysis  gives  35*17  per  cent,  of  carbon,  2*79  per  cent, 
of  hydrogen,  15*05  per  cent,  of  oxygen,  and  46*50  per  cent,  of  stannous 
oxide.  Ulmotannate  of  tin  on  drying  no°  gave  38*99  per  cent,  of 
carbon,  2*40  per  cent,  of  hydrogen,  13*66  per  cent,  of  oxygen,  and 
44*95  percent,  of  stannous  oxide. 
When  these  different  tannins  were  acted  on  by  dilute  acids  in  the 
usual  manner,  as  Grabowski  has  already  shown,  the  oak  tannin  yields 
an  easily  decomposed  saccharide  and  a  crystalline  body.  The  amount 
of  these  bodies  obtained  varies  with  the  strength  of  acid  employed.  On 
purification  the  saccharide  is  obtained  as  a  brown  substance,  forming  a 
dark-brown  bitter  svrup.  Similar  bodies  were  obtained  from  the  willow 
tannin.  On  analysis  the  saccharide  obtained  from  the  willow  tannin, 
gave  36*94  per  cent,  of  carbon,  5*19  per  cent,  of  hydrogen,  and 
57*87   per  cent,  of  oxygen.     Elm  tannin,  on  the  contrary,  yields  no 
