574 
SECOND REPORT — 1832 . 
N.E. and N.W. inclusive, were classed together. The follow¬ 
ing are the general results : 
grs. 
Mean of 47 Observations West.35*7964 
58-East..35*7944 
39-South.35*7941 
51-North.35*7943 
Hence,— 
Difference between West and East ... 
South and North.. 
West and South... 
West and North .. 
g r - 
*0050 "| 
*0005 I 
*0053 f 
*0051J 
West being + 
These differences are too trifling, perhaps, to be much relied 
on either way ; but they appear to show, what might indeed 
have been anticipated, that air from the West contains a very 
small fraction per cent, of oxygen more than air from the East, 
South, or North, which are nearly identical; and in air from 
these quarters, under ordinary circumstances, in London, the 
place of the oxygen is doubtless supplied by carbonic acid gas. 
5. Of the Weight of Atmospheric Air at other Temperatures ; 
and on the haw of its Expansion hy Heat. 
A diagram and tables were exhibited, showing the results of 
nearly a thousand experiments made upon dry and moist air, 
at different temperatures between 35° and 75°. These expe¬ 
riments were commenced in May 1830, and continued daily till 
August 1831. The air on each day was generally introduced into 
the apparatus about 11a. m., where it was permitted to remain 
first in contact with lime-water, and afterwards with sulphuric 
acid and distilled water till the next morning between 7 and 9 
a. m., when its weight in the dry and moist states was carefully 
determined. The results prove beyond a doubt that the mer¬ 
curial and air thermometers do not go on pari passu between 
35° and 515°, as at present generally supposed, but that there 
is a gradually increasing difference from 35° upwards, and 
amounting at 75° to upwards of |ths of a degree, the mercu¬ 
rial thermometer being in advance; (that is to say, 65° on the 
mercurial scale coincides almost exactly with 61 J° on the air 
scale). How far this difference continues to increase, is not at 
present known, but there is reason to believe that it goes on to 
upwards of 100°, and afterwards gradually diminishes till of 
course at 515° it disappears altogether. 
These results show what very little reliance can be placed 
on experiments hitherto made with gases, or rather on calcula¬ 
tions deduced from them. Thus 100 cubic inches of dry atmc- 
