Miscellaneous Data

A bbl. of Portland cement=4 bags, and weighs about 380 lbs.

A cu. ft. of loose measured broken trap stone weighs about 90 lbs.

A cu. ft. of broken stone, well shaken down, weighs about 100 lbs.

A cu. ft. of crusher-run stone weighs about 100 lbs.

A cu. ft. of cinder concrete averages 110 lbs. A cu. ft. of conglomerate concrete averages 130 lbs.

A cu. ft. of gravel concrete averages 150 lbs. A cu. ft. of sandstone concrete averages 148 lbs..

A cu. ft. of sandstone concrete averages 143 lbs.

A cu. ft. of trap concrete averages 155 lbs. Loose, unrammed concrete weighs from 5 to 25 per cent less than when well tamped.

One cubic foot of anthracite coal weighs about 58 pounds.

One cubic foot of bituminous coal weighs from 47 to 50 pounds.

Bearing Power of Soils. Table XXIII gives the hearing power of various soils, and will be found of use in calculations for footings, foun dations, etc.

Water. Water is a chemical compound of two gases—hydrogen and oxygen-2 volumes of hydrogen and 1 volume of oxygen, or 2 parts of hydrogen and 16 parts of oxygen by weight. It is never found absolutely pure in nature, be cause it is the best solvent known and absorbs or dissolves impurities from the air and soil. Water boils under atmospheric pressure of 14.7 lbs. per sq. in., at the elevation of Chicago, at 212° F., and passes off as steam. Water expands when heated so that its greatest density is at a temperature of 39.1° F. (4° C.), when it weighs 62.425 lbs. per cubic foot gallons). Below 39.1° F. to freezing point (32° F. or 0° C.) its density remains practically unchanged.

Water has the greatest specific heat (capacity for heat) of any known liquid or substance. It is incompressible by pressure, but expands with heat and decreases in density; that is, the same weight of water will occupy a larger volume with increase of temperature.

One pound of water evaporated to steam at atmospheric pressure, requires 966.1 heat units (B. T. U.).

Water increases 1,646 times its original vol ume on conversion to steam at the same pres sure. It increases suddenly about one-eighth

its volume on freezing, exerting tremendous force.

One gallon (U. S. Standard) of water at 39.1° F. weighs 8 lbs. oz., and contains 231 cu. in.

One foot of water column at 39.1° F.=62.425 lbs. on the sq. ft.; or 0.4335 lb. on the sq. in.; or 0.0295 atmosphere, or 0.8826 in. of mercury at 32° F.

One atmosphere equals the weight of a water column 1 in. square and 33.9 ft. high.

One atmosphere equals the weight of a mer cury column 29.92 in. high.

One inch of mercury column at 32° F. equals 1.133 ft. of water column.

To find the pressure in pounds per square inch of a column of water, multiply the height of the column in feet by .434. Approximately every foot of elevation is equal to one-half pound pressure per inch.

Air. Air consists of a mechanical mixture of gases, principally nitrogen and oxygen, in the ratio of 20.7 volumes of the former to 79.3 volumes of the latter; and by weight, of 23 parts of nitrogen to 77 parts of oxygen. Air in its natural state contains small quantities of other gases—CO. (carbon dioxide or carbonic acid gas), water vapor, ammonia, argon, helium, etc.

Air is compressible, and its volume varies inversely as the pressure applied at uniform temperature. It also increases or expands upon heating a proportional amount, depending upon the temperature to which it is heated.

The weight of dry air at atmospheric pres sure (14.7 lbs. per sq. in.) is 0.0807 lb. per cubic foot.

One cubic foot of air raised 1° F. requires 0.02056 heat snit (B. T. U.).

One cubic foot of air raised from 0° to 70° F. requires 1.4392 heat units (B. T. U.).

Steam.

Under the ordinary atmospheric pressure of 14.7 pounds per square inch, water boils at 212° F., passing off as steam, the tem perature at which it boils varying with a vari ation in the pressure. Steam is perfectly trans parent, colorless, dry, and wholly invisible ex cept when partially condensed, when the spray or mist makes it visible.