A NEW CONSTITUENT OF THE ATMOSPHERE. PANTS. 
The final treatment of the residual 700 cub. centims. of gas was on the model of 
the small scale operations already described (§ 4). By means of a pipette the gas was 
gradually transferred to a large test-tube standing over alkali. Under the influence 
of sparks (from battery and coil) passing all the while, the superfluous oxygen was 
consumed with hydrogen fed in slowly from a voltameter. If the nitrogen had been 
completely removed, and if there were no unknown ingredient in the atmosphere, the 
volume under this treatment should have diminished without limit. But the con- 
traction stopped at a volume of 65 cub. centims., and the volume was taken back- 
wards and forwards through this as a minimum by alternate treatment with oxygen 
and hydrogen added in small quantities, with prolonged intervals of sparking. 
Whether the oxygen or the hydrogen were in excess could be determined at any 
moment bya glance at the spectrum. At the minimum volume the gas was certainly 
not hydrogen or oxygen. Was it nitrogen? On this point the testimony of the 
spectroscope was equally decisive. No trace of the yellow nitrogen line could be seen 
even with a wide slit and under the most favourable conditions. 
When the gas stood for some days over water the nitrogen line again asserted 
itself, and many hours of sparking with a little oxygen were required again to get rid of 
it. As it was important to know what proportions of nitrogen could be made visible 
in this way, a little air was added to gas that had been sparked for some time subse- 
quently to the disappearance of nitrogen in its spectrum. It was found that about 
14 per cent. was clearly, and about 3 per cent. was conspicuously, visible. About the 
same numbers apply to the visibility of nitrogen in oxygen when sparked under these 
conditions, that is, at atmospheric pressure, and with a jar in connection with the 
secondary terminals. 
When we attempt to increase the rate of absorption by the use of a more powerful 
electric arc, further experimental difficulties present themselves. In the arrangement 
already described, giving an absorption of 700 cub. centims. per hour, the upper part ~ 
of the flask becomes very hot. With a more powerful are the heat rises to such a 
point that the flask is filled with steam and the operation comes to a standstill. 
It is necessary to keep the vessel cool by either the external or internal application 
of liquid to the upper surface upon which the hot gases from the are impinge. One 
way of effecting this is to cause a small fountain of alkali to impinge on the top of 
the flask, so as to wash the whole of the upper surface. This plan is very effective, 
but it is open to the objection that a break-down would be disastrous, and it would 
involve special arrangements to avoid losing the argon by solution in the large 
quantity of alkali required. It is simpler in many respects to keep the vessel cool by 
immersing it in a large body of water, and the inverted flask arrangement (fig. 6) has 
been applied in this manner. But, on the whole, it appears to be preferable to limit 
the application of the cooling water to the upper part of the external surface, building 
up for this purpose a suitable wall of sheet lead cemented round the glass, The most 
MDCCCXCV.—A. ZF 
