FLUIDITY AND VAPOR PRESSURE

157

the iuidity vapor-pressure curve of the class. Not only do all
the members of this class fall together in a single parabolic curve,
shown in Fig. 58, but substances of other classes give a curve of
similar form, as will now be demonstrated.

If we take a single substance, such as heptane, as our standard

TABLE XL.— FLUIDITIES AND VAPOR PRESSURES CORRESPONDING TO THE
STANDARD FLUIDITY VAPOE-PRESSFEE CURVE

fluidity reduced
Vapor pressure in mm
Fluidity reduced
Vapor pressure in mm
Fluidity reduced
Vapor pressure in mm

100
0.5
310
111.1
420
396.7

110
0.7
315
119.0
425
415.7

120
1.0
320
127.8
430
434.9

130
1.7
325
136.5
435
455.5

140
2.2
330
146.1
440
476.1

150
3.0
335
155.4
445
497.3

160
4.3
340
165.2
450
520.0

170
6.1
345
175.5
455
542.2

180
8.2
350
186.2
460
566.8

190
11.0
355
197.6
465
589.5

200
14.2
360
210.4
470
614.7

210
17.7
365
223.2
475
635.9

220
22.3
370
236.6
480
660.1

230
27.7
375
251.0
485
683.7

240
34.1
i 380
266.0
490
711.7

250
41.2
385
281.1
495
736.3

260
49.3
390
296.2
500
760.0

270
58.8
395
311.4
505
783.8

2SO
69.1
400
328.3
510
810.0

290
81.8
405
344.7
515
838. 8

300
95.9
410
360.7
520
869.5

305
103.2
415
378.4
525
902.0

substance with a, fluidity of approximately 500 at the boiling-
point, we can compare other substances with this one. Since
other substances do not have the same fluidity at the boiling-
point, we multiply the fluidity at the boiling-point by a factor
so that the product or the reduced fluidity will "be 500. The
fluidities for other temperatures are also reduced by similarly