A NEW CONSTITUENT OF THE ATMOSPHERE. 225 
discharge has been passed for four hours, the spectrum of nitrogen disappears, and 
the argon spectrum manifests itself in full purity. A specially constructed tube, with 
magnesium electrodes, which we hoped would yield good results, removed all traces 
of nitrogen it is true, but hydrogen was evolved from the magnesium, and showed its 
characteristic lines very strongly. However, these are easily identified. The gas 
evolved on heating magnesium in vacuo, as proved by a separate experiment, consists 
entirely of hydrogen. 
Mr. Crookes has proved the identity of the chief lines of the spectrum of gas 
separated from air-nitrogen by aid of magnesium with that remaining after sparking 
air-nitrogen with oxygen, in presence of caustic soda solution. 
Professor ScousteR has also found the principal lines identical in the spectra of 
the two gases, when taken from the jar discharge at atmospheric pressure. 
12. Solubility of Argon in Water. 
The tendency of the gas to disappear when manipulated over water in small 
quantities having suggested that it might be more than usually soluble in that liquid, 
special experiments were tried to determine the degree of solubility. 
The most satisfactory measures relating to the gas isolated by means of oxygen 
were those of September 28. The sample contained a trace of oxygen, and (as 
judged by the spectrum) a residue of about 2 per cent. of nitrogen. The procedure 
and the calculations followed pretty closely the course marked out by BunsEn,* and 
it is scarcely necessary to record the details. The quantity of gas operated upon was 
about 4 cub. centims., of which about 14 cub. centims. were absorbed. The final 
result for the solubility was 3°94 per 100 of water at 12° C., about 24 times that of 
nitrogen. Similar results have been obtained with argon prepared by means of 
magnesium. Ata temperature of 13°9°, 131 arbitrary measures of water absorbed 
5°3 of argon. This corresponds to a solubility in distilled water, previously freed 
from dissolved gas by boiling 7m vacuo for a quarter of an hour, and admitted to the 
tube containing argon without contact with air, of 4:05 cub. centims. of argon per 
100 of water. 
The fact that the gas is more soluble than nitrogen would lead us to expect it in 
increased proportion in the dissolved gases of rain water. Experiment has confirmed 
this anticipation. Some difficulty was at first experienced in collecting a sufficiency 
for the weighings in the large globe of nearly 2 litres capacity. Attempts at 
extraction by means of a Topler pump without heat were not very successful. It was 
necessary to operate upon large quantities of water, and then the pressure of the 
liquid itself acted as an obstacle to the liberation of gas from all except the upper 
layers, Tapping the vessel with a stick of wood promotes the liberation of gas in a 
* “Gasometry,’ p. 141. 
MDCCOXCV.—A. hE 
