880 J. W. Gibbs — Vapor- Densities. 
evidently represented by ae The numbers of the fifth 
L 
column, which are represented in the same way by ed 
R 
where p, denotes the pressure as determined by Regnault’s 
experiments, have been calculated by the present writer by 
eee : P- 
multiplying the numbers of the third column by Pit =P =) 
Pr(P—Px) 
TaspLte VII.—AceEtic Acip. 
Determinations of Vapor-density by Distillation. 
Density Density Densit 
|| Pressure | observed, || Pressure | calc, from ¥ Excess of 
"MOF || dae | miotta||bgeant,| NOEARUIN | opnimant | observed dents 
Landolt. by eq. (12). = hemes I Il. 
25-0 235 2°42 15°13 3°86 3°80 —-06 
23°8 22°4 2°23 14°19 3°86 3°56 —*30 
22°6 21-6 2°29 13°31 3°87 3°16 Ba & | 
21°5 20°4 2°24 12°54 3:87 3°68 —19 
20°4 19°2 2-05 11°81 3°88 3°37 — "51 
20-2 19:0 2-28 11°68 3°88 3°75 pS 
20°0 18°9 213 11°56 3°88 3°52 —"36 
17-4 16°8 2°09 9°95 3°89 3°56 45 
15°6 15°6 1-98 8°96 390 3°48 —42 
15°3 153 1:95 8°81 3°90 3°42 — "48 
15°3 15°3 1°85 8°8 3°90 3°24 —"66 
14:7 1571 1-78 8°54 3-91 3°18 — 13 
12°7 137 1:96 7-60 3°91 3°56 —'35 
12-4 13°5 1:89 7-46 3°92 3°45 — het 
As the height of the barometer in Horstmann’s experiments is 
not given, it has been necessary to assume P=760. The imac: 
curacy due to this circumstance is evidently trifling. The last 
obtained from Horstmann’s and Regnault’s experiments above 
the values calculated from equation (12) with the use of Re 
The densities obtained by experiment are without exception 
less than those obtained from equation (12). At the highest 
temperatures, where the liability to error is the least, both 1 
respect to the measurement of the pressure of saturatec vapo 
and in respect to the analysis of the product of distillation, the 
results of experiment are most uniform, and most nearly 
approach the numbers required by the formula. At the lowest 
temperatures, the greatest observed density is about one 
_ eleventh less than that required by the formula, the differ- 
ence being about the same as between the highest and lowest 
observed values for the same temperature. 
si 
mae 
7 EEEE——z—-—S—:srt tr rt 
a 
