A NEW CONSTITUENT OF THE ATMOSPHERE. 199 
Although it seemed almost impossible that these residues could be either nitrogen 
or hydrogen, some anxiety was not unnatural, seeing that the final sparking took 
place under somewhat abnormal conditions. The space was very restricted, and the 
temperature (and with it the proportion of aqueous vapour) was unduly high. But 
any doubts that were felt upon this score were removed by comparison experiments 
in which the whole quantity of air operated on was very small. Thus, when a 
mixture of 5 cub. centuns. of air with 7 cub. centims. of oxygen was sparked for one 
hour and a quarter, the residue was 47 cub. centim., and, after removal of oxygen, 
06 cub. centim. Several repetitions having given similar results, it became clear 
that the final residue did not depend upon anything that might happen when sparks 
passed through a greatly reduced volume, but was in proportion to the amount of air 
operated upon. 
No satisfactory examination of the residue which refused to be oxidised could be 
made without the accumulation of a larger quantity. This, however, was difficult of 
attainment at the time in question. The gas seemed to rebel against the law of 
addition. It was thought that the cause probably lay in the solubility of the gas in 
water, a suspicion since confirmed. At length, however, a sufficiency was collected 
to allow of sparking in a specially constructed tube, when a comparison with the air 
spectrum taken under similar conditions proved that, at any rate, the gas was not 
nitrogen. At first scarcely a trace of the principal nitrogen lines could be seen, but 
after standing over water for an hour or two these lines became apparent. 
[The apparatus shown in fig. 1 has proved to be convenient for the purification of 
small quantities of argon, and for determinations of the amount of argon present in 
various samples of gas, e.g., in the gases expelled from solution in water. To set it 
in action an alternating current is much to be preferred to a battery and break. At 
the Royal Institution the primary of a small RunMKorFrF was fed from the 100-volt 
alternating current supply, controlled by two large incandescent lamps in series with 
the coil. With this arrangement the voltage at the terminals of the secondary, 
available for starting the sparks, was about 2000, and could be raised to 4000 by 
plugging out one of the lamps. With both lamps in use the rate of absorption of 
mixed gases was 80 cub. centims. per hour, and this was about as much as could well 
be carried out in a test-tube. Even with this amount of power it was found better 
to abandon the sealings at D. No inconvenience arises from the open ends, if the 
tubes are wide enough to ensure the liberation of any gas included over the mercury 
when they are sunk below the liquid. 
The power actually expended upon the coil is very small. When the apparatus is 
at work the current taken is only 2°4 amperes. As regards the voltage, by far the 
greater part is consumed in the lamps. ‘The efficient voltage at the terminals of the 
primary coil is best found indirectly. Thus, if A be the current in amperes, V the 
total voltage, V, the voltage at the terminals of the coil, V, that at the terminals of 
the lamps, the watts used are* 
* Ayrton and Sumpner, ‘ Proc. Roy. Soc.,’ vol. 49, p. 427, 1891. 
