A NEW CONSTITUENT OF THE ATMOSPHERE. 211 
8. Separation of Argon on a Large Scale. 
To separate nitrogen from “atmospheric nitrogen” on a large scale, by help of 
magnesium, several devices were tried. It is not necessary to describe them all in 
detail. Suffice it to say that an attempt was made to cause a store of “ atmospheric 
nitrogen” to circulate by means of a fan, driven by a water-motor. The difficulty 
encountered here was leakage at the bearing of the fan, and the introduced air 
produced a cake which blocked the tube on coming into contact with the magnesium. 
It might have been possible to remove oxygen by metallic copper; but instead of 
thus complicating the apparatus, a water-injector was made use of to induce circula- 
tion. Here also it is unnecessary to enter into details. For, though the plan worked 
well, and although about 120 litres of “atmospheric nitrogen” were absorbed, the 
yield of argon was not large, about 600 cub. centims. having been collected. This 
loss was subsequently discovered to be due partially, at least, to the relatively high 
solubility of argon in water. In order to propel the gas over magnesium, through a 
long combustion-tube packed with turnings, a considerable water-pressure, involving 
a large flow of water, was necessary. The gas was brought into intimate contact 
with this water, and presuming that several thousand litres of water ran through the 
injector, it is obyious that a not inconsiderable amount of argon must have been 
dissolved. Its proportion was increasing at each circulation, and consequently its 
partial pressure also increased. Hence, towards the end of the operation, at least, 
there is every reason to believe that a serious loss had occurred. 
It was next attempted to pass “atmospheric nitrogen” from a gas-holder first 
through a combustion tube of the usual length packed with metallic copper reduced 
from the oxide; then through a small U-tube containing a little water, which was 
intended as an index of the rate of flow; the gas was then dried by passage through 
tubes filled with soda-lime and phosphoric anhydride ; and it next passed through a 
long iron tube (gas-pipe) packed with magnesium turnings, and heated to bright 
reduess in a second combustion-furnace. 
After the iron tube followed a second small U-tube containing water, intended to 
indicate the rate at which the argon escaped into a small gas-holder placed to receive 
it. The nitrogen was absorbed rapidly, and argon entered the small gas-holder, But 
there was reason to suspect that the iron tube is permeable by argon at a red heat. 
The first tube-full allowed very little argon to pass. After it had been removed and 
replaced by a second, the same thing was noticed. The first tube was difficult to 
clean ; the nitride of magnesium forms a cake on the interior of the tube, and it was 
very difficult to remove it; moreover this rendered the filling of the tube very 
troublesome, inasmuch as its interior was so rough that the magnesium turnings could 
only with difficulty be forced down. However, the permeability to argon, if such be 
the case, appeared to have decreased. The iron tube was coated internally with a 
skin of magnesium nitride, which appeared to diminish its permeability to argon. 
74 19) 
