THE VANGE MINERAL WATER. 225
responding sodium and potassium salts. They are found both
near the surface and throughout the clay to its base. The deep
wells or bores are nearly all abandoned, but some are still to be
found about Mundon, Althorne, Stow Maries, and Bulphan.
At the last named place the water contains also a considerable
amount of common salt.
Two wells may be sunk in the same parish, yet the waters
be markedly different. A single example will suffice. In the
parish of Althorne are two wells about a mile apart. In both the
water is derived from the basement-bed of the London Clay
which formation here is about 300 feet thick. These waters
were both sulphated, but differed considerably, as the following
analyses show :—
Within a mile the same stratum yields a water which contains
no trace of calcium or magnesium sulphates and comparatively
small quantities of sodium sulphate.
A bored well near Wick House, on Bulphan Fen, gave the
following results—in parts per 100,000.
These deep well-waters have never been used medicinally,
but in past times shallow well-waters, rich in sulphates, have
acquired a reputation, notably at South Weald, Upminster, and
Hockley. The following analyses of these waters are taken