214 LORD RAYLEIGH AND PROFESSOR W. RAMSAY ON ARGON, 
of gas collected from. the system of tubes was not re-admitted to the gas-holder B, but 
was separately stored. 
The crude argon was collected in two operations. First, the quantity made by 
absorption by magnesium in glass tubes with the water-pump circulator was purified. 
Later, after a second supply had been prepared by absorption in iron tubes, the mixture 
of argon and nitrogen was united with the first quantity and circulated by means of the 
mercury circulator, in the gas-holder B. Attention will be drawn to the particular 
sample of gas employed in describing further experiments made with the argon. 
By means of magnesium, about 7 litres of nitrogen can be absorbed in an hour. 
The changing of the tubes of magnesium, however, takes some time; consequently, 
the largest amount absorbed in one day was nearly 30 litres. 
At a later date a quantitative experiment was carried out on a large scale, the 
amount of argon from 100 litres of “atmospheric” 
been absorbed by magnesium, and the resulting argon measured at 12°. During the 
nitrogen, measured at 20°, having 
process of absorbing nitrogen in the combustion-furnace, however, one tube cracked, 
and it is estimated that about 4 litres of nitrogen escaped before the crack was 
noticed. With this deduction, and assuming that the nitrogen had been measured at 
12°, 93°4 litres of atmospheric nitrogen were taken. The magnesium required for 
absorption weighed 409 germs. The amount required by theory should have been 
285 orms. ; but it must be remembered that in many cases the magnesium was by no 
means wholly converted into nitride. The first operation yielded about 3 litres of a 
mixture of nitrogen and argon, which was purified in the circulating apparatus. The 
total residue, after absorption of the nitrogen, amounted to 921 cub. centims. The 
yield is therefore 0°986 per cent. 
At first no doubt the nitrogen gains a little argon from the water over which it 
stands. But, later, when the argon forms the greater portion of the gaseous mixture, 
its solubility in water must materially decrease its volume. It is difficult to estimate 
the loss from this cause. The gas-holder, from which the final circulation took ‘place, 
held three litres of water. Taking the solubility of argon as 4 per cent., this would 
mean a loss of about 120 cub. centims. If this is not an over-estimate, the yield of 
argon would be increased to 1040 cub. centims., or 1°11 per cent. The truth probably 
lies between these two estimates. 
It may be concluded, with probability, that the argon forms approximately 1 per 
cent. of the “atmospheric” nitrogen. 
The principal objection to the oxygen method of isolating argon, as hitherto 
described, is the extreme slowness of the operation. An absorption of 30 cub. 
centims. of mixed gas means the removal of but 12 cub. centims. of nitrogen. At 
this rate 8 hours are required for the isolation of 1 cub. centim. of argon, supposed 
to be present in the proportion of 1 per cent. 
In extending the scale of operations we had the great advantage of the advice of 
