104 
volume of water : the washings should be passed 
through blotting paper, and evaporated to dryness. 
The relative weights of the salt obtained will indi- 
cate very nearly the relative quantities of alkali 
they contain. 
The value of marine plants in producing soda 
may be estimated in the same manner, with suffi- 
cient correctness for all commercial purposes. 
Herbs, in general, furnish four or five times, and 
shrubs two or three times, as much pot-ashes as 
trees. The leaves produce more than the branches, 
and the branches more than the trunk. Vegetables 
burnt in a green state produce more ashes than in 
a dry state. 
The following table # contains a statement of the 
quantity of pot-ashes afforded by some common 
trees and plants. 
10,000 parts of Oak 
Oak 
15 
Elm 
39 
Beech 
1 2 
Vine 
55 
Popular 
7 
Thistle - 
53 
Fern 
62 
Cow Thistle 
196 
Wormwood - 
730 
Vetches 
275 
Beans 
200 
Fumitory 
790 
The earths found in plants are four; silica or 
* It is founded upon the experiments of Kirwan, Vauquelin, 
and Pertuis. 
