water stands on the window-sill or other finished wood. Rain water
absorbs more or less carbon dioxide from various sources, and soaking
into the soil often comes in contact with lime, magnesia and other
compounds. Water saturated with carbon dioxide will dissolve these
substances, forming carbonates or other salts which are soluble; such
water is known as "hard."

Water for domestic uses is called either "hard" or "soft," according
to the amount of salts which it may contain. When soap is added to
hard water, the new compound formed by the union of the lime with the
fatty acid of the soap is insoluble, and is deposited upon the surface
of any article with which it comes in contact. This is the reason why
"hard" water requires more soap when used for laundry work. It is much
better to soften the water by the addition of alkalies, ammonia or
sal-soda before using for laundry purposes than to depend entirely
upon soap for cleansing.

Another important material used in the laundry is soap. In purchasing
soap, it is safer to choose the make of some well-known firm, who have
a reputation to lose if their products are not good; and for anything
stronger than soap, it is better to buy sal-soda and use it knowingly
than to trust to the various packages so extensively advertised.
Washing soda should always be dissolved in a separate vessel, and
added to the water to be used. Ammonia may be used, but its too
frequent use will yellow bleached fabrics. Borax is an effectual
cleanser, disinfectant and bleacher. It is more expensive than ammonia
or soda but is the safest alkali to use. Turpentine is valuable in
removing grease; 1 tbsp. to a quart of water will serve for washing
silks and other delicate materials. It should never be used in hot
water.