| 260 | 18.135 | .055142 | | 270 | 18.387 | .054386 | | 280 | 18.639 | .053651 | | 290 | 18.891 | .052935 | | 300 | 19.143 | .052238 | | 320 | 19.647 | .050898 | | 340 | 20.151 | .049625 | | 360 | 20.655 | .048414 | | 380 | 21.159 | .047261 | | 400 | 21.663 | .046162 | | 425 | 22.293 | .044857 | | 450 | 22.923 | .043624 | | 475 | 23.554 | .042456 | | 500 | 24.184 | .041350 | | 525 | 24.814 | .040300 | | 550 | 25.444 | .039302 | | 575 | 26.074 | .038352 | | 600 | 26.704 | .037448 | | 650 | 27.964 | .035760 | | 700 | 29.224 | .034219 | | 750 | 30.484 | .032804 | | 800 | 31.744 | .031502 | | 850 | 33.004 | .030299 | |_____________|____________|____________| Example: Required the volume of air in cubic feet under 60.3 pounds gauge pressure per square inch at 115 degrees Fahrenheit. P = 144 (14.7 + 60.3) = 10,800. T = 115 + 460 = 575 degrees. 53.33 × 575 Hence v = ----------- = 2.84 cubic feet, and 10,800 1 1 Weight per cubic foot = - = ---- = 0.352 pounds. v 2.84 Table 27 gives the weights and volumes of air under atmospheric pressure at varying temperatures. Formula (9) holds good for other gases with the change in the value of the constant as follows: For oxygen 48.24, nitrogen 54.97, hydrogen 765.71. The specific heat of air at constant pressure varies with its temperature. A number of determinations of this value have been made and certain of those ordinarily accepted as most authentic are given in Table 28. TABLE 28