MINERAL WATERS AND MEDICINAL SPRINGS OF ESSEX. 205
" These mineral stones are found of several colours, as green, grey, blue,
white. Upon experiment, they appear to contain iron, sulphur, salt, and a
considerable quantity of an earthy or stony matter. Some of them, especially
the blueish sort, are so rich in iron that, being only powdered and applied to the
magnet, without any previous calcination, many particles thereof are readily and
briskly attracted by it.
"The variegated stratum contains iron, sulphur, marine salt, nitre, and a
large proportion of a smooth bolar earth."
Mr. Dalton, criticising the foregoing statement, writes :—
" The water came, no doubt, from the Glacial Gravel or, possibly,
from the River-gravel of the Blackwater. The London Clay is
immediately below. A bed of clay derived from the London
Clay, with little or no alteration or admixture, seems to divide
the gravel into an upper layer of oxidised 'common' gravel and
a lower layer of blue and sulphurous gravel. It is not impossible
that this bed of clay marks the junction of the glacial and post-
glacial deposits, here over-lapping with undefmable limit. The
injudicious digging alluded to above probably admitted water
from the river-gravel, causing dilution of a true 'mineral' water
previously impregnated with carbonate of iron from pyrites (the
'iron-stones' spoken of by Taverner) and derived from the
Glacial Gravel."
Taverner next turns to the nature of the water :—
" The spring rises perpendicularly [he says40] into a small receptacle and is
brought up by a pump; the water, when fresh, being perfectly limpid and clear.
It has a very strong ferrugineous smell and taste ; and, though it wants that
peculiar brisk and picquant taste from whence, perhaps, chalybeate waters
might obtain the appellation of Acidulae, yet it is not destitute of a spirit, which
manifests itself in a certain remarkable freshness and makes the water very
agreeable to the palate and stomach, as the loss of it [i.e., of the "spirit"]
renders it disagreeable to both. It has, besides, a particular taste—much easier
distinguished by the palate than described—proceeding, probably, from the salts
or sulphur it contains, or being, perhaps, the joint effect of both. If suffered to
stand some time exposed to the air, it grows vapid and milky ; a variegated scum
arises upon its surface; and, at length, depositing a brownish sediment, it loses
its chalybeate taste and its power of tinging with galls."
Thus far as to the well itself and the appearance of the water
it supplied. Taverner next discusses at great length the chemical
nature of the water. Thus, Chapter IV. describes41 in great
detail fourteen "Experiments" he made to test its properties.
In Chapters V. to IX., these Experiments are discussed exhaus-
tively.42 Chapter V. deals with the water in general ; Chapter VI.,
40 Essay, pp. 7-8.
41 Op. cit. pp. 8-19.
42 Op. cit., pp. 20-58.