DE. ANDREWS ON THE GASEOUS STATE OF MATTEE. 
437 
Table XII. — Values of a! at different temperatures. — Constant Volume. 
p. 
0°— 6°‘5. 
0°— 64°. 
64° -100°. 
16-42 
0-004754 
0-004607 
21-48 
0-00537 
0-005237 
0-004966 
25-87 
0-00588 
0-005728 
0-005406 
30-37 
0-006357 
0-005861 
33-53 
0-00734 
0-006973 
0-006334 
It follows from this investigation that the value of a! is greater at high than at low 
pressures ; it changes also with the temperature, the pressure remaining constant, being 
less at high than at low temperatures. The values are, for this reason, average values 
for each range of temperature. The law of Gay-Lussac, therefore, fails both in the case 
of a and of a! ; that is to say, the dilatation by heat of a body in the ordinary gaseous state , 
whether measured by its expansion under constant pressure or by the increase of elastic 
force under constant volume , is not a simple function of the initial volume or initial 
elastic force, but a complex function changing with the temperature *. 
In the next Table will be found the change in the value of a' between 64° and 100° 
under a large range of pressure and referred to the pressure at 64° as unit. 
Table XIII. — Values of a' from 64° to 100°. — Constant Volume. Pressure at 64°=1. 
p. 
1 *' 
I C0 2- 
a'. 
21-42 
24-19 
61-00 
100-67 
0-04968 
0-04969 
0-003526 
28-65 
32-60 
63-80 
100-67 
0-03624 
0-03622 
0-003718 
35-29 
40-44 
63-74 
100-67 
0-02869 
0-02870 
0-003956 
42-74 
49-25 
63-98 
100-54 
0-02303 
0-02303 
0-004166 
48-40 
56-16 
63-94 
100-48 
0-01986 
0-01986 
0-004387 
67-65 
80-99 
63-80 
100-50 
0-01288 
0-01289 
0-005392 
94-27 
118-60 
63-78 
100-50 
0-00778 
0-00778 
0-007018 
* The statement of Eegnattlt that the air and carbonic acid thermometers march sensibly together appears 
to he at variance with this conclusion. But Eegxault’s own experiments, which were made at pressures dif- 
fering little from that of- the atmosphere, indicate an unequivocal although small difference, and in the right 
direction, between the two thermometers. With a sulphurous acid thermometer the difference was considerable, 
and in conformity with the result stated in the text (Me'm. de l’Acad. des Sciences, vol. xxi. pp. 187-88). 
3 p 
MDCCCLXXYI. 
