The  methods  adopted  by  Mr.  Sharpies  in  making  these  determinations  are  described  by  him  as  follows:

The  tannin  in  each  case  was  determined  in  the  rossed  bark ;  that  is,  bark  deprived  of  the  main  part  of  the  outside  coating.  The
method  employed  was  that  devised  by  Lowenthal,  which  may  be  thus  briefly  described :  A  standard  decoction  of  the  bark  is  titrated
with  permanganate  of  potash,  a  quantity  of  indigo  being  first  added  to  it.  In  a  second  portion  the  tannin  is  precipitated  by  means  of
gelatine,  and  the  gallic  acid  in  the  liquid  again  determined  by  permanganate  and  indigo.  The  difference  between  these  two  readings
gives  the  amount  of  tannin  in  the  bark,  the  value  of  the  permanganate  having  previously  been  determined  by  pure  tannic  acid,  or  by
oxalic  acid  and  calculation.
The  bark  of  the  following  species  has  been  examined :


u

93

140
160
251
256

im

261

261
267
269
272
274


Botanlaal  name.
GrOidonia  Xasianthiui.
FrosopisjnlMaia


Bhizophoia  Mangle

Exostemma  Caribsenm.
QaeToasalba

QiieTC>ns  maciocoipa


Qnerons'FTbmB

Qaercns  piinoides  (old  tree) . ..
Qnercaa  prinoides  (young  tree)

Qaercns  virens

Qaercns  Emoryl

Qaercnsmbra

Qaercns  tinotoria


Common  name.
Loblolly  Bay.    XanBay

Mesqnit.    Algaroba.    Honey

Locust.    Honey  Pod.
Mangrove


White  Oak

Burr  Oak.  MoBsyoup  Oak.
Over-cup  Oak.
Chestnut  Oak.  'Rock  Chest-
nut Oak.
Yellow  Oak.  Chestnut  Oak.
Chinquapin  Oak.
do

Live  Oak

Black  Oak

Bed  Oak.    Black  Oak

Black  Oak.  Yellow-bark  Oak.
Quercitron  Oak.  Yellow  Oak.
13.14
4.04

31.04
5.81
5.99
4.59

6.25

4.33

10.33

10.46

9.76

4.56

5.90


2.35
8.71

,6.70
7.16
0.11
8.05

3.83


6.23

8.89
15.09
4.43
6.73


275
276

277

287
t

290


384
384
384
387


391


Botanical  name.
Qnercna  Kelloggli ..
Quercus  nigra

Quercns  falcata

Quercus  densiflora..
Castanea  vulgaris,  vor.  Ameri-
cana.
