450 J. W. Gibbs— Equilibrium of Heterogeneous Substances. 
gas at constant volume, a denotes the constant value of pu~mt, 
end upon the zeros of energy and entropy. The 
found convenient to give the law the following form: 
€ pressure in a mixture of different gases is equal to the sum 
of the pressures of the different gases as existing each by itself at the 
same temperature and with the same value of its potential. 
A mixture of ideal gases which satisfies this law is called an 
ideal gas-mixture. Its fundamental equation in p, t, #4, #2, ete. 
is evidently of the form ; 
unig et SENN. ree, 
Peete me (20) 
where 2’, denotes summation with respect to the different com- 
nents of the mixture. From this may be deduced other 
fundamental equations for ideal gas-mixtures. That in ¢, ¢, v, 
M,.,M™,, etc. is 
~= >,(Eym, +m,t (e.— H,—-c, logi+a, log s))- (21) 
Phases of dissipated energy of ideal gas-:nixtures.—When the 
t 
proximate components of a gas-mixture are so related that 
reduce any other phase of the gas-mixture to a phase of dissi- 
ted energy Th ont wl 3 
ees 
SSRORREE SNe re eee ie ee ee 
