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69
WATER-SUPPLY.
City of London would conduce to the health and
comfort of the population; and that the principles,
proposed by the Board for its collection and conveyance,
appear to me such as sanitary science, in
its present condition, should counsel for the waterservice
of the metropolis.
There is, however, one aspect of the subject
which must not pass unconsidered. Water that is
free from earthy ingredients requires a peculiar
distributory apparatus. If conveyed in leaden pipes
with access of air, or if stored in leaden cisterns,
it corrodes the metal of which they are composed,
and is liable to derive from this source an impregnation
very hazardous to life. Under certain circumstances,
especially under alternations of air and
water (such as occur in the intermittent supply) or
where organic impurities are held in solution or
suspension, or probably where from any cause uncombined
carbonic acid is present, even the hardest
waters are not free from this risk. Speaking generally,
however, it affects soft water chiefly; distilled
water most of all: and the Farnham water (in common
with all pure water) is decidedly liable to this
empoisonment, if used with leaden apparatus of conduction
and storage. In my Appendix you will find
some interesting particulars on this head; and you
will observe that with experiments conducted by
Mr. Taylor in imitation of the constant supply (i. e.
with total submersion of the metal) the formation
of carbonate of lead in the Farnham water was ex-
F