288 J. W. Gibbs — Vapor- Densities, 
the first number being obtained immediately from equation 
(10) by differentiation, and the second by differentiation after 
substitution of =D for p. The ratio of these numbers evi- 
after the opening. The errors due to this source may evidently 
be diminished by diminishing the intervals of temperature ’ 
[2°85], [2:94], Naumann’s paper has 2:57, 2°65, 2°84, 30! 
respectively. In some cases the temperatures and pressures of 
two experiments are so nearly the same that it would be allow- 
able to average the results, at least in the column of excess of 
ferences are almost uniformly positive and increase as the tem 
fae diminishes, it is evident that they might be consider 
imin 
(10), without seriously impairing the agreement of that eq!* 
