VP = 1700 × 14·706 × {1 + 0·002083 (T − 32)}
1 + 0·002083 × 180
= 18183{1 + 0·002083 (T − 32)}.(9.)

If, by means of this formula (9.), and any of the formulæ (1.), (2.), (3.), (4.), (5.), T were eliminated, we should obtain a formula between V and P, which would enable us to compute the enlargement of volume which water undergoes in passing into steam under any proposed pressure. But such a formula would not be suitable for practical computations. By the formulæ (1.) to (5.), a table of pressures and corresponding temperatures may be computed; and these being known, the formula (9.) will be sufficient for the computation of the corresponding values of V, or the enlargement of volume which water undergoes in passing into steam.

In the following table, the temperatures corresponding to pressures from 1 to 240 lbs. per square inch are given by computation from the formulæ (2.) to (5.), and the volumes of steam produced by an unit of volume of water as computed from the formula (9.).

The mechanical effect is obtained by multiplying the pressure in pounds by the expansion of a cubic inch of water in passing into steam expressed in feet, and is therefore the number of pounds which would be raised one foot by the evaporation of a cubic inch of water under the given pressure. [Pg509]

Total pressure in Pounds per Square Inch.Corresponding Temperature. Volume of the Steam compared to the Volume of the Water that has produced it.Mechanical Effect of a Cubic Inch of Water evaporated in Pounds raised One Foot.
1102·9208681739
2126·1108741812
3141·074371859
4152·356851895
5161·446171924
6169·238971948
7175·933761969
8182·029831989
9187·426742006
10192·424262022
11197·022212036
12201·320502050
13205·319042063
14209·117782074
15212·816692086
16216·315732097
17219·614882107
18222·714112117
19225·613432126
20228·512812135
21231·212252144
22233·811742152
23236·311272160
24238·710842168
25241·010442175
26243·310072182
27245·59732189
28247·69412196
29249·69112202
30251·68832209
31253·68572215
32255·58332221
33257·38102226
34259·17882232
35260·97672238
36262·67482243
37264·37292248
38265·97122253
39267·56952259
40269·16792264
41270·66642268
42272·16492273
43273·66352278
44275·06222282
45276·46102287
46277·85982291
47279·25862296
48280·55752300
49281·95642304
50283·25542308
51284·45442312
52285·75342316
53286·95252320
54288·15162324
55289·35082327
56290·55002331
57291·74922335
58292·94842339
59294·24772343
60295·64702347
61296·94632351
62298·14562355
63299·24492359
64300·34432362
65301·34372365
66302·44312369
67303·44252372
68304·44192375
69305·44142378
70306·44082382
71307·44032385
72308·43982388
73309·33932391
74310·33882394
75311·23832397
76312·23792400
77313·13742403
78314·03702405
79314·93662408
80315·83622411
81316·73582414
82317·63542417
83318·43502419
84319·33462422
85320·13422425
86321·03392427
87321·83352430
88322·63322432
89323·53282435
90324·33252438
91325·13222440
92325·93192443
93326·73162445
94327·53132448
95328·23102450
96329·03072453
97329·83042455
98330·53012457
99331·32982460
100332·02952462
110339·22712486
120345·82512507
130352·12332527
140357·92182545
150363·42052561
160368·71932577
170373·61832593
180378·41742608
190382·91662622
200387·31582636
210391·51512650
220395·51452663
230399·41402675
240403·11342687

[Pg511]

In the absence of any direct method of determining the general relation between the pressure and volume of common steam, empirical formulæ expressing it have been proposed by different mathematicians.

The late Professor Navier proposed the following:—Let S express the volume of steam into which an unit of volume of water is converted under the pressure P, this pressure being expressed in kilogrammes per square mètre. Then the relation between S and P will be

S = a,
b + mP

where a = 1000, b = 0·09, and m = 0·0000484.