528  Plants  Yielding  Tanning  Materials.  {^'SS^im^ 
ing  to  some  authorities,  and  36-4  per  cent,  according  to  others. — - 
Ericaceae. 
Oak  {Quercus). — There  are  seventy  to  eighty  species  of  oak,  com- 
prising 275  varieties,  about  half  of  which  inhabit  the  old  world  and 
half  the  new  world.  The  hard  oak  dominates  in  Europe,  and  of 
its  two  varieties,  Quercus  pednncidata  and  Quercus  sessiliflora,  the 
latter  has  the  bark,  which  is  richer  in  quercitannic  acid.  Of  other 
oaks,  the  following  are  given  :  Q.  Tanza,  8  per  cent,  of  tannin  in 
its  bark;  Q.  Cerris  (hairy-cupped  oak),  10  per  cent,  of  tannin  in 
bark;  Q.  Ilex  (evergreen  oak),  10  per  cent,  of  tannin  in  bark  ;  Q. 
Suber  (cork  oak),  10  per  cent,  of  tannin  in  bark;  Q.Ballota,  10 
per  cent,  of  tannin  in  bark;  Q.  Mirbeki,  12  per  cent,  of  tannin  in 
bark;  Q.  cocci/era  (kermes  oak),  15  per  cent,  of  tannin  in  bark  ; 
sEgilops  (valonia),  8  per  cent,  of  tannin  in  bark;  Q.  infectoria  ;  Q. 
glomerata  (Russian  oak).  The  above  are  African  and  European. 
Of  American  oaks  may  be  mentioned  :  Q.  alba  (white  oak),  7-85 
per  cent,  of  tannin  in  bark  ;  Q.  tinctoria  (black  oak),  6-47  per  cent, 
of  tannin  in  bark;  Q.  rubra  (red  oak),  5-55  per  cent,  of  tannin  in 
bark;  Q.  coccinea  (scarlet  oak),  7-78  per  cent,  of  tannin  in  bark. 
It  may  be  generally  stated  that  oak  bark  contains  from  7  to  18  per 
cent,  of  quercitannic  acid,  while  the  wood  and  leaves  contain  5-7 
per  cent. — Cupuliferae. 
Chestnut  [Castanea  vesca),  abundant  in  Southern  Europe  and 
North  America  ;  the  wood  contains  68  per  cent,  of  water  when 
felled,  43  per  cent,  three  months  after  felling,  the  bark  being  left 
on,  and  35  per  cent,  five  months  after  sawing  and  stripping.  The 
wood  and  bark  contain  4  to  12  per  cent,  of  tannin  (castanea  tannic 
acid). — Cupuliferae. 
Cornelian  cherry  [Cornus  mascida,  dogwood)  grows  in  Europe,, 
especially  France;  its  bark,  leaves  and  fruit  contain  19-9  per  cent, 
ot  tannin  according  to  Gassincourt,  and  8-9  per  cent,  in  the  bark 
according  to  some  other  analysts. — Cornaceae. 
Carob  (Ceratonia  Siliqua,  Linn.)  grows  in  Spain,  Italy,  France,. 
Algiers  and  Egypt.  Its  fruit  (St.  John's  bread)  contains  50-55  per 
cent,  of  tannin. — Leguminosae. 
Carob  of  Judcea  (Pistacia  Terebinthus,  Linn.)  grows  in  the  Levant, 
and  gives  rise  to  horn-shaped  galls  which  contain  25  per  cent,  of 
tannin,  and  are  called  "  caroubes." — Anacardiaceae. 
Conocarpus  arborea  and  C.  racemosa. — West  Indies  and  Brazil ; 
