in future lessons.

~4.~ Still another use for water is to dissolve and wash out of our
bodies, through the sweat of the skin, and in other ways, the waste and
worn-out particles which are no longer of any use.

~5. Impure Water.~--Most waters have more or less substances dissolved
in them. Water which has much lime in it is called hard water. Such
water is not so good to drink, or for use in cooking, as soft water.
That water is best which holds no substances in solution. Well-water
sometimes contains substances which soak into wells from vaults or
cesspools. Slops which are poured upon the ground soak down out of
sight; but the foul substances which they contain are not destroyed.
They remain in the soil, and when the rains come, they are washed down
into the well if it is near by. You can see some of the things found in
bad water in the illustration given on opposite page.

~6.~ It is best not to drink iced water when the body is heated, or
during meals. If it is necessary to drink very cold water, the bad
effects may be avoided by sipping it very slowly.

~7. Tea and Coffee.~--Many people drink tea or coffee at their meals,
and some persons think that these drinks are useful foods; but they
really have little or no value as foods. Both tea and coffee contain a
poison which, when separated in a pure form, is so deadly that a very
small quantity is enough to kill a cat or a dog. This poison often does
much harm to those who drink tea or coffee very strong for any great
length of time.

[Illustration: A DROP OF IMPURE WATER MAGNIFIED.]