OF GASES AND VAPOURS. 201 
: 1 
In this equation the two constants B and are to be deduced 
from observations. 
16. From some of the experiments of Magnus there accord- 
ingly results vases 
Pp "2555: ; 
logs = 33602 +6 Le ey ee (3.) 
The following table shows how far the values calculated ac- 
cording to this formula coincide with those observed by Mag- 
nus, and then gives a comparison of the results of this formula 
with those which Arago and Dulong obtained from their expe- 
riments :-— 
p. | t. 
According Difference. 
In Millimetres. | Calculated. to 
Magnus. 
9°43 —89-49 — 88-66 +0°83 
9-88 —88-79 — 88-02 +0:°77 
22-24 —75°95 —7615 —0°20 
71:20 —55°03 — 55°10 —0:07 
73°74 —5434 | —54:30 | +0-04 
114-65 —45°45 —45°26 +019 
284-97 — 25:20 —25:17 +0:03 
387715 —17:72 —17°75 — 0-03 
42°54 — 9-09 — 9:20 —O11 
565°50 — 8-09 — 819 — 0:10 
p- t. 
According to| Difference. 
In Atmospheres.| Calculated. Arago 
and Dulong. 
2°14 +2256 22°42 —0:14 
28705 32-09 31°77 — 0°32 
45735 48-31 48:37 +0:06 
64977 61:51 61:30 —0-21 
73755 66°50 66°54 +0-04 
11-632 85°52 85°78 +0-26 
17°185 103°3 103-2 —O1 
17°285 103°6 103-9 +0°3 
18-504 106°8 107-2 +0°4 
21:555 1143 114-7 +04 
23:934 119°6 1201 +0°5 
The temperatures enumerated as observed in the experiments 
of Arago and Dulong are corrected for the air thermometer from 
the indications of the smaller thermometer exposed to the steam, 
according to the formula given by August*. 
For the freezing-point, therefore, ¢ = — 100°, the formula 
* Poggendorff’s Annalen, xxii. p. 119. 
