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HISTORY OF REFRIGERATION 319
the slow influx of heat from above through the cooled dense
air, or from below through the badly conducting straw, and
the water freezes. The desert traveller carries water in a
porous canvas water bag so as to have, through slow evapo-
ration, a supply of drinking water sufficiently palatable to
dampen his parched lips and cool his throat.
The use of saltpetre mixed with snow for cooling and
freezing liquids was known and employed at a remote period
in India. In 1607 Tancrelus mentioned the use of this mix-
ture to freeze water, and in 1626 Santono mentioned the use
of common salt and snow to freeze wine. At about that same
time, in Italy, iced fruits put in an appearance at table, and
during the 17th century a method of congealing cream was
discovered.
Lord Francis Bacon, English scientist, philosopher and
statesman (1561-1626), appreciated what a useful thing it
would be if man could have the same command of cold as of
heat, and undertook experiments into its possibilities that
terminated in his death. Among his notes there is this:
Heat and cold are Nature's two hands whereby she chiefly
worketh, and heat we have in readiness in respect of the fire,
but for cold we must stay till it cometh or seek it in deep
caves or high mountains, and when all is done we cannot
obtain it in any great degree, for furnaces of fire are far
hotter than a summer's sun, but vaults and hills are not much
colder than a winter's frost.
History is filled with interesting references to the early
use of snow and natural ice, especially by the French, Span-
iards and Italians, devotees of better living. In England, the
sale of natural ice from the wagons of fishmongers was an
early practice that continues to this day. In the United States
•a cargo of natural ice was sent from New York to New
Orleans in 1799, the first delivery of natural ice to an American
home was made in 1802, and Frederick Tudor exported natural
ice from the United States to the West Indies in 1805 to help
stay the ravages of yellow fever.
147.—The Formation, Harvesting and Storing of Natural
Ice.—The formation of ice is a very common phenomenon of
Nature, but the exact process followed in converting water