cent. of water in food in order to grow and multiply. This explains why
in high altitudes and dry climates foods keep for a long time without
artificial means of preservation. It also explains why the old-fashioned
housekeeper dried fruits and why the preservation of certain meats is
accomplished by the combined methods of smoking and drying, the creosote
of the smoke given off from the wood used in this process acting as a
preservative. All the grains, which are very dry, keep for long periods
of time, even centuries, if they are protected from the moisture of the
air. Peas, beans, and lentils, as well as dried biscuits and crackers,
are all examples of how well food will keep when little or no moisture
is present.


KEEPING FOODS WITH ICE

45. Although, as has just been pointed out, moisture is required for the
growth of some micro-organisms, both moisture and warmth are necessary
for the growth of most of the organisms that cause molding,
putrefaction, and fermentation. It is definitely known, also, that in
winter or in cold climates food can be kept for long periods of time
without any apparent change; in fact, the lower the temperature the less
likely are foods to spoil, although freezing renders many of them unfit
for use. These facts are what led up to the scientific truth that
keeping foods dry and at a low temperature is an effective and
convenient method of preventing them from spoiling and to the invention
of the refrigerator and other devices and methods for the cold
storage of foods.

46. THE REFRIGERATOR.--For home use, the refrigerator offers the most
convenient means of keeping foods in good condition. As is well known,