624 REGNAULT’S HYGROMETRICAL RESEARCHES, 
TABLE continued. 
Barometer | Final tem- | Tempera- 
Number | at the end] perature |ture of the| Weight of the vapour. 
ofthe | of theex-| inthe {| saturated Difference. 
aspirator. | periment. | aspirator. { space. | Observed. |Calculated. 
Hos 6. 2 P. P’, 
mm 4 5 * . ; 
43 1 76482 20°85 20°43 1031 1-0374 ~ 0-006 
44 1 76410 20°83 20°75 1:058 | 1:0586 | —0-001 
45 2 757°80 21:60 | 21-40 1:072 | 10752 | —0:003 
46 2 756°35 21°57 21°55 1-083 | 10855 | —0-002 
47 1 752:05 24:80 24:93 1-342 | 13456 | —0:004 
48 1 752-07 24°50 24:17 1-280 | 1:2880 | —0-008 
49 1 752°38 24:18 23°42 1:227 | 1:2380 | —0-011 
50 1 752.13 24°10 23°37 1-220 | 1:2338 | —0:013 
51 1 758°20 27°27 26°94 1-486 | 147380 | +0-013 
52 1 758-20 26°89 26°74 1-442 | 14500 | —0-:008 
53 1 761°91 25°63 25°11 1315 | 13279 | —0-013 
54 1 76-21 25°91 25°91 1-382 | 13919 | —0:010 
55 1 750-12 26°74 26:28 1-407 | 14179 | —0-011 
56 1 749-06 24-61 24-05 1-239 | 1:2489 | —0:010 
57 1 749:97 24:99 24:31 1-257 | 1:2673 | —0-010 
58 1 750°46 24:84 24:77 1:292 | 13066 | —0-014 
59 1 753°98 24:14 23:11 1:167 | 11801 | —0:013 
60 1 75352 24:19 24-49 1:247 | 1:2602 | —0-013 
61 1 752-91 24°61 24:83 1:296 | 13117 | —0-015 
62 1 753°12 24°46 24-82 1-296 | 13122 | —0-016 
63 1 755°81 23°23 22-59 1139 | 1:1487 | —0-011 
64 1 755°68 23°50 23°34 1191 | 1:2022 | —0-011 
65 1 755°15 23°72 23°80 1:225 | 1:2358 | —0-011 
66 1 75732 24°16 24°18 1:248 | 1:2625 | —0014 
67 1 757-62 23°86 23°85 1:223 | 12383 | —0-015 
68 1 761°96 22°65 22-44 1:130 | 11414 | —0011 
It will be seen in this table that all the numbers calculated 
are a little greater than those which have been found by direct 
experiment, and that by the same fraction of the total weight. 
This fraction is very small; it amounts to about one-hundredth. 
We may thence conclude that the densities of aqueous vapour 
in a state of saturation in the air at low temperatures may be 
calculated from the law of Mariotte, and that the relation of the 
weight of a volume of this vapour to that of a similar volume of 
air taken under the same circumstances of temperature and pres- 
sure, is rather weaker than the theoretical density of vapour. It 
is true that the difference which exists between the calculated 
weights of the vapour and those found by experiment may be 
explained in another manner. We may admit that the density 
of vapour in a state of saturation in the air is the same as that 
which we have found in vacuo =0°622, but that the elastic forces 
of the vapour which J have taken in my table of the tensions of 
vapour in vacuo are too high by a small quantity; this would 
agree with what we have found above (page 610) by direct ex- 
ee i 
