ing the
usual filter of iron, charcoal, sponge, and gravel or sand. If this water
has a free current of air passing over it, it will acquire more sparkle
and character; but as a rule it is flat and unpleasant in flavor, being
entirely destitute of the earthy salts and the carbonic-acid gas to be
found in the best river or spring water.

Distilled water comes next in purity, and is, in fact, identical in
character with rain-water; the latter being merely steam, condensed into
rain in the great alembic of the sky. But both have the curious property
of taking up and dissolving _lead_ wherever they find it; and it is for
this reason that lead pipes as leaders from or to cisterns should _never_
be allowed, unless lined with some other metal.

The most refreshing as well as most wholesome water is river or spring
water, perfectly filtered so that no possible impurity can remain. It is
then soft and clear; has sufficient air and carbonic acid to make it
refreshing, and enough earthy salts to prevent its taking up lead, and so
becoming poisonous. River-water for daily use of course requires a system
of pipes, and in small places is practically unavailable; so that wells
are likely, in such case, to be the chief source of supply. Such water
will of course be spring-water, with the characteristics of the soil
through which it rises. If the well be shallow, and fed by surface
springs, all impurities of the soil will be found in it; and thus to _dig
deep_ becomes essential, for many reasons. Dr. Parker of England, in some
papers on practical hygiene, gives a clear and easily understood statement
of some causes affecting the purity of well-water.

"A well drains an extent of ground around it, in the shape of an inverted
cone, which is in proportion to its own depth and the looseness of the
soil. In very loose soils a well of sixty or eighty feet will drain a
large area, perhaps as much as two hundred feet in diameter, or even more;
but the exact amount is not, as far as I know, precisely determined.

"Certain trades pour their refuse water into rivers, gas-works;
slaughter-houses; tripe-houses; size, horn, and isinglass manufactories;
wash-houses, starch-works, and calico-printers, and many others. In houses
it is astonishing how many instances occur of the water of butts,
cisterns, and tanks, getting contaminated by leaking of pipes and other
causes, such as the passage of sewer-gas through overflow-pipes, &c.

"As there is now