378 J. W. Gibbs — Vapor- Densities. 
cooled to any desired temperature, with deposition of the excess 
of acid, by passing upward through a spiral tube in a suitable 
bath. The acid is then separated from the air, and the quantity 
of each determined. It is assumed that the air is exactly satu- 
find a very marked disagreement, as may be seen by the ol- 
lowing numbers, which relate to the highest temperatures of 
Temperature ________ 631 629 599 Sil 490 487 446 414 
ure (Land.)..-..110°0 1092 97:0 690 634 63°0 531 466 
Density calc. eq. (12). 367 367 369 375 377 37% 379 3 Ps 
Density obs.____._.__ 319 311 312 316 2:89 298 275 26 
It will be observed that while the values obtained from equation 
(12) pling with diminishing temperatures, the values ob- 
ne i 5 
Dear every mark of a very exceptional precision. (Compare 
Tables VII and IV.) The explanation of this disagreement © 
in the calculations, and it will be interesting to see how the 
its may be modified by the adoption of different pressures: 
_ In determinations of the pressure of saturated vapors, 
great values are so much more easily accounted for than errors 
direction, especially when the pressures #° 
especial interest attaches to the lowest figures which 
* Lieb. Ann., Suppl. vi (1868), p. 157. 
