hat the fuel required to impart a given
amount of heat to a boiler is practically independent of the steam
pressure, since the temperature of the fire is so high as compared with
the steam temperature that a variation in the steam temperature does not
produce an appreciable effect.

The formulae for the algebraic expression of the relation between
saturated steam pressures, temperatures and steam volumes have been up
to the present time empirical. These relations have, however, been
determined by experiment and, from the experimental data, tables have
been computed which render unnecessary the use of empirical formulae.
Such formulae may be found in any standard work of thermo-dynamics. The
following tables cover all practical cases.

Table 22 gives the heat units contained in water above 32 degrees
Fahrenheit at different temperatures.

Table 23 gives the properties of saturated steam for various pressures.

Table 24 gives the properties of superheated steam at various pressures
and temperatures.

These tables are based on those computed by Lionel S. Marks and Harvey
N. Davis, these being generally accepted as being the most correct.

TABLE 23

PROPERTIES OF SATURATED STEAM

REPRODUCED BY PERMISSION FROM
MARKS AND DAVIS "STEAM TABLES AND DIAGRAMS"
(Copyright, 1909, by Longmans, Green & Co.)
____________________________________________________________________
|Pressure,| Temper- |Specific Vol-|Heat of |Latent Heat|Total Heat|
| Pounds |ature De-| ume Cu. Ft. |the Liquid,| of Evap., |of Steam, |
|Absolute |grees F. | per Pound | B. t. u. | B. t. u. | B. t. u. |
|_________|_________|_____________|___________|___________|__________|
| 1 | 101.83 | 333.0 | 69.8 | 1034.6 | 1104.4 |
| 2 | 126.15 | 173.5 | 94.0 | 1021.0 | 1115.0 |
| 3 | 141.52 | 118.5 | 109.4 | 1012.3 | 1121.6 |
| 4 | 153.01 | 90.5 | 120.9 | 1005.7 | 1126.5 |
| 5 | 162.28 | 73.33 | 130.1 | 1000.3 | 1130.5 |
| 6 | 170.06 | 61.89 | 137.9 | 995.8 | 1133.7 |
| 7 | 176.85 | 53.56 | 144.7 | 991.8 | 1136.5 |
| 8 | 182.86 | 47.27 | 150.8 | 988.2 | 1139.0 |
| 9 | 188.27 | 42.36 | 156.2 | 985.0 | 1141.1 |
| 10 | 193.22 | 38.38 | 161.1 | 9