DR. ANDREWS ON THE GASEOUS STATE OE MATTER. 
447 
From these tables it is evident that the value of g(l — P ) is constant so long as the 
carbonic acid is in the gaseous state, but that it rapidly diminishes when the gas passes 
into the intermediate conditions, till at high pressures it falls nearly as low as if the 
liquid had actually been formed. This will at once appear from the following short 
table, calculated from my former experiments at 13°T, showing the values of s(l — p) 
in the gaseous and liquid states : — 
Table XXV.- — Values of g(l —p) at 13°T. 
P- 
£. 
t'. 
1-P. 
s(i-P)- 
47-50 
l 
76-16 
13-1 
0-3763 
0-00494 
48-76 
1 
80-43 
13-1 
0-3938 
0-00490 
48-89 
1 
80-90 
13-1 
0-3957 
0-00489 
54-56 
1 
480-4 
13-1 
0-8864 
0-00184 
75-61 
500^7 
13-1 
0-8490 
0-00169 
90-43 
1 
510-7 
13-1 
0-8229 
0-00161 
From this investigation it follows that the relations of pressure and volume at a con- 
stant temperature for a body in the gaseous state is given by the equation 
v(l —pv)=c 
(C) 
where p is the external pressure, v the volume of the gas, and c a constant. 
From this equation the properties of homologous points already given in equations 
(A) and (B) follow as a direct consequence. For if 
and 
v(l—pv)=c 
v'( 1 — p'v') = c' 
be the equations of any two iso thermals ; then, since at homologous pointsj??; =pV, we 
shall have 
v' d 
If the values of g(l —p) in Tables XXII., XXIII., XXIV. are carefully examined, it 
will be seen that they have a slight tendency to diminish, particularly at the lower tem- 
peratures; and a similar observation applies to the values of jp in former tables. It 
must be remembered that the pressures recorded in these tables are those of the air- 
manometer, and would require a small correction to reduce them to true pressures. The 
data for making this correction are so imperfect, and for the higher pressures so uncer- 
