J. W. Gibbs — Vapor- Densities, 289 
action between the vapor and the mercury diminished the vol- 
ume of the vapor, and thus increased the numbers obtained for 
the density. : 
TasLEe II.—PrroxipE or NITROGEN. 
Experiments at less than Atmospheric Pressure. 
PLAYFAIR and WANKLYN,—TROOST,.—NAUMANN, 
Tempera- Présbia: tec ped Density observed. | Excess of obs. density. 
: byeq.0)-Ipew. T NN. (Pew. N 
7°5 (301) 1631 | 1-783 +°152 
7 35 1:90 16 ~.*§ 
7 1°77 1°59 —'18 
(323) 2°524 | 2°52 ie 
22°5 1365 2°34 2°35 +701 
25 101 2-26 2-28 +°02 
15 1 9-41 2°38 —°03 i 
0°8 153°5 2-41 2-46 +°05 
301 2°59 2°70 +11 
18-5 136 2-43 2°45 +°02 
18 279 2°61 2°71 +10 
15 172 2°51 2°52 +01 
6°8 172 2°53 2" + 
65 224 59 2°66 +07 
16 228-5 2°61 2°62 +01 
} 175 5 2°63 +°05 
11°3 (159) 2°620 | 2°645 +°025 
ll 190 2-76 +:10 
105 163 2°64 2°73 +09 
42 (129) 2-710 | 2°588 —"122 
4 | 1725 2-77 2 +°08 
25 145 2-76 [2°85] +09 
1 138 2-78 2° +06 
—1 153 2°83 2°87 +°04 
3 84 26 2°92 +16 
—5 123 2°85 2°98 +°13 t 
=6 1255 | 2-87 [2-94] +07 
The same table includes two experiments of Troost,* by 
Dumas’ method, but at the very low pressures of and 
16™". Insuch experiments we cannot expect a close agree- 
ment with the formula, for the same error in the determination 
of the weight of the vapor, which would make a difference of 
* Com: Rendus, t. lxxxvi (1878), p. 1395. 
Am. Jour. bd hae Scie: Vou. XVIIL—No. 106, Ocr., 1879, 
19 
