The proportion of the quantities of Silica, Oxyds of Iron, Lime,
Magnesia and Alkalies, which were washed out from (1) during its
transformation into (2) is therefore the following :

Oxygen.

Silica,                         95.58 50.58

Oxyds of Iron,            14.36                   4.40

Lime,                        21 41                   6.10

Magnesia,                   38.91                 15.51 28.65

Potash,                        0.56 0.09

Soda,                           9.90                   2.55

The proportion of the quantities of Silica, Oxyds of Iron, &c,
which were washed out from (2) during its transformation into (3),
is as follows:

B

Oxygen.

56.13
7.53
6.03

0.91 19.96
0.57
4 92

By subtraction of the quantities given in (3) from those in (1),
we get the whole quantity of substances, which were washed
away during both periods of degradation. Hence it follows the
following composition in per cent. :

Silica,

Oxyds of Iron,

Lime,

Magnesia,

Potash,

Soda,

Silica,	10612
Oxyds of Iron,	25.12
Lime,	21.13
Magnesia,	2.28
Potash,	3.36
Soda,	19.07

	Oxygen.
56.		29.1
11.5	3.5
11.9	3.4
11.6	4.3	13.5
1.	0.2
8.	2.1

100.0

It will be seen that with advancing degradation the quantities of
Silica and Lime decrease in a constant proportion, which is how-
ever not the case with Magnesia and Alkalies; the former has
been washed out almost entirely during the transformation of (1)
into (2); whilst the greatest part of the latter had not disappeared
till the transformation of (2) into (3) took place, consequently du-
ring the second period of degradation. The proportion between
the quantity of Oxygen in the bases to that in the Silicic acid is

36