Water is one of the most abundant elements in nature. As rivers, lakes,
seas, and oceans, it covers three-fourths of the earth’s surface. It
even enters largely into the formation of the solid rocks. The clearest
and purest air contains it in large quantities as an invisible gas;
while in clouds, fogs, and mists, it appears in the form of minute
drops.
Water also forms a very considerable part of all vegetable productions,
and constitutes about _three-fourths_ of the human body, as well as
other animal tissues. The blood and the brain are each about four-fifths
water, while the fluid secretions and excretions contain more than
nine-tenths of their weight of this limpid fluid.
=Chemical Composition.=—The chemist designates water as hydrogen oxide,
and represents it by the chemical formula, H_{2}O, which signifies that
it is composed of the two gases, hydrogen and oxygen, in the proportion
of two volumes of the former to one of the latter. Both of these gases
are colorless, transparent, tasteless, and odorless. Hydrogen is the
lightest gas known; oxygen is the great supporter of combustion and
animal life and heat. Water is produced by the burning, or oxidation, of
hydrogen, a process attended with very little light, but most intense
heat. The two gases are explosive when mixed.
=Physical Properties.=—Water exists in three states; viz., as a solid,
in the form of ice; as a liquid, its most common form; and as a vapor,
in the form of steam. When in the last condition, the gaseous, it is
invisible. That to which the term steam is very commonly applied, is not
steam, but water in a state of fine division, or mist.
Below 32° F., pure water exists in the form of ice. Between 32° and
212°, it is a liquid. At 212°, it is converted into vapor. Water also
slowly evaporates at all temperatures below 212°, being absorbed and
held in solution by the air.
Water possesses the greatest specific heat of any substance. By specific
heat is meant the actual amount of heat required to elevate its
temperature a given number of degrees. For example, it requires ten
times as much heat to raise a pound of water 1° in temperature as to
elevate a pound of copper 1° in temperature. To raise the temperature of
a pound of lead 1°, requires only one-thirtieth as much heat as to
produce the same effect upon a pound of water. Water absorbs more heat
by elevation of temperature than any other substance. In passing from
the solid to the liquid state, it absorbs a vast amount of heat without
any elevation of temperature. The same thing occurs in the conversion of
water into steam or vapor by evaporation. In the evaporation of one
pound of water, as much heat is absorbed, or rendered latent, as would
suffice to raise nearly a thousand pounds of water one degree in
temperature. This heat is abstracted from surrounding objects; and,
hence, evaporation is one of the most powerful means of producing cold.
The effect is the same, no matter what the temperature at which
evaporation occurs.
Water is not the best conductor of heat, but it conducts much more
readily than air, and readily communicates its heat to bodies with which
it comes in contact, also abstracting heat when of a lower temperature,
when changing from a solid to a liquid state, or from the liquid to the
gaseous condition.
One of the most useful properties of water is its power to dissolve
numerous substances, its solvent properties being nearly universal. To
this property it owes its value as a cleansing agent.
=Pure Water.=—Absolutely pure water is not found in nature. Rain water
is the nearest approach to it; but even this gathers impurities of
various sorts as it falls through the air, and often becomes very
unwholesome by the absorption of foul gases and the collection of dust
in this way. For any use connected with the human body, the purest water
is always preferable to any other. Filtered rain water and distilled
water are the purest forms of water attainable.
=Hard Water.=—Water is said to be hard when it will not produce a good
lather with soap, but forms curds instead. Hardness is due to the
presence of earthy salts in the water; salts of lime—chalk and
gypsum—are the most common. Ten grains per gallon of any of these salts
is sufficient to render water hard and unfit for use, though some waters
furnished to cities for general use contain from 70 to 160 grains per
gallon of solid matter. Hard water is unfit for cleansing purposes
because its mineral ingredients form insoluble compounds with fatty
substances. When mixed with soap, the lime or other mineral takes the
place of the soda or potash in the soap, and forms an insoluble curd,
instead of a lather.
=Mineral Water.=—Water containing in solution salts of iron, magnesia,
or other metallic elements, as well as sulphur, arsenic, iodine, or any
compound of these or other elements which are capable of imparting a
nauseous or saline taste, an unpleasant odor, or medicinal properties,
has been much employed for the cure of all sorts of chronic ailments.
Such waters are totally unfit for general use for drinking or cooking
purposes, and certainly possess no particular advantages as cleansing
agents. Whether they are useful as medicines is a medical question which
we do not purpose to consider here; but one would naturally suppose that
water which is unfit to cleanse the outside of the body could not be of
very great utility as an internal application.
=Magnetic Water.=—Within the last few years, the scientific world has
been startled with the alleged discovery of “magnetic wells” and
“magnetic springs” in various parts of the country. The claim has been
made and stoutly defended by interested parties that the water furnished
from these sources is magnetic in character, and possesses wonderful
healing virtues on that account. The truth in the matter, when viewed in
the light of science, seems to be that the water of these much-lauded
wells is no more magnetic than any other water; the magnetic phenomena
are all explicable by well-known laws of physics, without attaching to
the water any magnetic properties. A close examination shows that the
iron pipe through which the water passes is the only magnetic object.
The supposition that the pipe derives its magnetism from the water is
both unnecessary and illogical. In the first place, any iron pipe or rod
placed vertical in the ground—or, better, placed parallel to the earth’s
axis—will spontaneously become magnetic. The production of magnetism is
greatly favored by the friction of flowing water, and by jarring, as
beating with a hammer. In the second place, the water possesses no
magnetism to impart. In view of these facts, the conclusion is
inevitable that so-called magnetic water has no existence except in the
minds of certain persons whose credulity greatly exceeds their
scientific knowledge.
“Magnetic” wells and springs are ingenious humbugs. Thousands of people
are duped by them. Hundreds are benefited by getting well washed, and by
enjoying recreation and pleasant social surroundings. The curative
effects are attributed to the imaginary magnetism, while other more
tangible agents are the real means of cure.