A NEW CONSTITUENT OF THE ATMOSPHERE. 201 
In beginning an experiment, the tubes were heated with long-flame burners, and 
pumped empty ; a little hydrogen was formed by the action of the moisture on the 
metallic magnesium; it was oxidised by the copper oxide and absorbed by the 
phosphoric pentoxide. A gauge attached to the SPRENGEL’s pump, connected with 
the apparatus, showed when a vacuum had been reached. A quantity of nitrogen 
was then measured in E, and admitted into contact with the red-hot magnesium. 
Absorption took place, rapidly at first and then slowly, as shown by the gauge on the 
SPRENGEL’s pump. A fresh quantity was then measured and admitted, and these 
operations were repeated until no more could be absorbed. The system of tubes was 
then pumped empty by means of the SPRENGEL’S pump, and the gas was collected. 
The magnesium tube was then detached and replaced by another. The unabsorbed 
gas was returned to the measuring-tube by a device shown in the figure (G) and the 
absorption recommenced. After 1094 cub. centims. of gas had been thus treated, 
there was left about 50 cub. centims. of gas, which resisted rapid absorption. It still 
contained nitrogen, however, judging by the diminution of volume which it 
experienced when allowed to stand in contact with red-hot magnesium. Its density 
was, nevertheless, determined by weighing a small bulb of about 40 cub. centims. 
capacity, first with air, and afterwards with the gas. The data are these :— 


grm. 
(a.) Weight of bulb and air — that of glass counterpoise . . 0°8094 
- ,, alone — that of glass counterpoise. . . 0€°7588 
m bi Aer eile Woe, sw OU auld gt ete 00506 
(b.) Weight of bulb and gas — that of glass counterpoise . .. 0°8108 
e » alone — that of glass counterpoise. . . 0°7588 
a GSI | Mad tig ge IG owe aor ee ON coo) Om (an boa gees om OAA0) 
Taking as the weight of a litre of air, 1°29347 grms., the mean of the latest 
results, and of oxygen (= 16) 1°42961 grms.,* the density of the residual gas 
is 14°88. 
* The results on which this and the subsequent calculations are based are as follows (the weights 
are those of 1 litre) :— 

Air. Oxygen. Nitrogen. Hydrogen. | 
PiBeenauor = 225, 1:29349 1438011 | 1:25647 0:08988 
Won Jonny a cs 129383 142971 1:25819 
TED UCL Mirra etnie| 1:29330 142910 1:25709 0:08985 
IVAYERIGH); 5°. 5 1:29327 1:42952 1:25718 0:09001 




REGNAULT’s numbers have an approximate correction applied to them by Crarrs. The mean of these 
MUCCCXCV.— A. 2D 
