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The Busy Man's Hand-Book (Percussion or friction It)

percussion or friction. It is simply motion applied to any atoms, directly, or by transfer.

No heat is ever created. It is always a transfer of the motions of gases as in fires, and of the motions of gases in the interstices of other bodies. No heat is ever lost. In all cases it is only a transfer. In winter, more is transferred than received, and in summer more received than parted with. If one hemisphere is cold, the other is so much hotter.

COMBUSTION. Combustion is the destruction of a body by the union of its hydrogen with oxygen, and the simultaneous dispersion of its carbon in smoke and flame. The three elements are necessary, and always present. The heat arises from the fixation of the oxygen gas, or its condensation from its gaseous to a condensed fluid or solid form. We create a flame, or light a candle, by exciting its hydrogen by another flame. Oxygen in the air then combines with heat; this excites more hydrogen, and the flame continues as long as hydrogen and oxygen are present. In combustion, 1 lb. hydrogen consumes 6 lbs. of oxygen; 1 lb. of carburetted hydrogen 4 lbs. of oxygen; 1 lb. of olifiant gas, of olive-oil, of wax, and of tallow, 3.5 lbs. of oxygen; I lb. of phosphorus, 1.5; of charcoal, 2.8; and of sulphur, 1.36 of oxygen.

One lb. of hydrogen and 6 of oxygen melt about 350 lbs. of ice; 1 lb. of rapeoil and 3.5 oxygen, 124 of ice; 1 lb. of carburetted hydrogen and 4 of oxygen, 85 of ice; 1 lb. of charcoal and 2.8 of oxygen, 50 of ice; and 1 lb. of caoutchouc, 42 lbs. of ice.

Lamps were used by the ancients, and candles were an invention of the middle ages. At first, wicks were made of hemp, papyrus, and the pith of rushes. The latest wick is porous stone.

The safety-lamp is founded on the principle that flame, in passing through iron-wire meshes, loses so much of its heat, as not to be capable of igniting inflammable substances around (flame alone igniting gas). There ought to be above 625 apertures to the square inch. A pin stuck in a rush-light extinguishes it on the same principle of conveying heat from the wick.

CALOFIRIC POWER OF VARIOUS FUELS.-The unit of heat is the amount of heat required to raise 1 lb. of water through 1° F. The mechanical equivalent of heat is the amount of heat generated by a body weighing I lb. when suddenly arrested after falling from a height of 772 feet. The calorific power of a fuel (or its heat units) represents the number of pounds of water which can be raised through 1° F. by the combustion of 1 lb. of that fuel. The following is the calorific power of some fuels: 62,031 Heat units. Coal tar Hydrogen..

Marsh gas. 14,225 Heat units. 23,513 " Sulphur.. 3,996 " Olefiant gas " - 21,344 Carbon " 14,544 Carbonic oxide 4,325 " Coke. 12,800 " Alcohol ،، - 12,330 Drywood " 7,353 One lb. of carbon burning to CO generates 4451 units of heat, while the CO from 1 lb. of carbon burning to CO₂ generates 10,092 units of heat. SPECIFIC HEAT OF VARIOUS BODIES.-The specific heat of a body is the ratio of the quantity of heat required to raise that body 1º to the quantity required to raise an equal weight of water 1º. Example: Water is the standard=1. The specific heat of mercury is 03332, therefore the quantity of heat required to heat 1 lb. of mercury 1º F. would heat 1 lb. of water .03332° F., or the quantity of heat required short table: to heat I lb. of water I° F. would heat 30 lbs. of mercury 1° F. The following is a Water=1.

Iron (wrought) Iron (cast)..

Copper Lead.

Mercury Sulphur Carbon Wood charcoal. ....

METALS.

Water=1. .11379 Silver. .12983 Gold .09215 Platinum .0314 LIQUIDS. 03332 Alcohol SOLIDS. .20259 Coal. .024111 Ice .24111