December 2, 1898.] 



SCIENCE. 



775 



detected. It appeared, therefore, vain to 

 attempt to discover a new gas in minerals ; 

 and the justice of Dr. Stoney's hypothesis 

 was next tested. It was, of course, not out 

 of the question that the souglit-for gas 

 might exhibit some powers of combination, 

 and that it might have been absorbed, along 

 with the nitrogen of the air, by tlie magne- 

 sium over which the gas had been sent at a 

 red heat in order to absorb and remove the 

 nitrogen. The compound of magnesium 

 with nitrogen is very readily decomposed 

 by water ; the products are ammonia and 

 hydroxide of magnesium. A large quantity 

 of this magnesium nitride was accordingly 

 treated with water, and the resulting am- 

 monia absorbed by means of weak sulphuric 

 acid. There was merely a trace of gas 

 which refused to be absorbed, and, on ex- 

 amination, it turned out to be the familiar 

 hydrogen, which was formed by the action 

 of the water on some metallic magnesium 

 which had escaped combination with nitro- 

 gen. This experiment was interesting, in- 

 asmuch as it proved that magnesium refuses 

 to combine with even the smallest trace of 

 argon. The ammonia resulting from this 

 treatment, it is true, might have conceiva- 

 bly contained a compound of the new gas ; 

 but a similar sample had previously been 

 decomposed, so as to obtain from it its nit- 

 rogen, and that sample of nitrogen had 

 been found by Lord Eayleigh to possess the 

 same density as a sample of nitrogen of 

 which the source could not be traced to the 

 atmosphere. Lastly, it was conceivable 

 that the hydroxide of magnesium might 

 have contained some compound of the new 

 element. It was, therefore, treated with 

 water, and the soluble portion separated 

 from the insoluble. The soluble portion, 

 on examination, proved to contain nothing 

 but the carbonate of magnesium. The in- 

 soluble portion was not further dealt with, 

 but was kept in reserve. 



The argon of the atmosphere was next 



examined. A large quantity having been 

 prepared, it was purified, and by passing it 

 into a vessel immersed in liquid air, made 

 to boil at an even lower temperature than 

 usual by pumping away the air-gases as 

 they boiled off; the argon, too, was com- 

 pletely changed into liquid. Liquid argon 

 is clear and colorless, whereas liquid air 

 has a faint blue tint, owing to the blue 

 color of the oxygen it contains. The argon 

 was next made to boil, by allowing the tem- 

 perature of the liquid air to rise a few de- 

 grees, and the first portions of argon-gas 

 were collected separately, the remainder 

 going back into the gas-holder in which it 

 had originally been stored. The gas thus 

 obtained was lighter than argon, and more 

 difiicult to liquefy ; this was shown by the 

 necessity of compressing it into the bulb 

 in which liquefaction took place. The most 

 volatile portions of this liquid were next 

 collected separately, and the gas proved to 

 be still less dense than the former sample. 

 It was not possible to liquefy more than a 

 small fraction of this last specimen of gas, 

 to however low a point the temperature of 

 the boiling air was reduced ; and after 

 another repetition of the same process the 

 gas appeared to be as light as the process 

 could make it. Its density was 9.75 times 

 that of hydrogen, and, making allowance 

 for a small quantity of argon which it must 

 necessarily have contained, this number 

 becomes reduced to 9.6.* The weight of a 

 molecule, compared with the weight of an 

 atom of hydrogen, as previously explained, 

 must therefore be 19.2 ; and 19.2 lies be- 

 tween the atomic weights of fluorine, 19, 

 and of sodium, 23, falling therefore into the 

 predicted place in the Periodic Table. The 

 specific heat ratio of this new gas, to which 



* This gas has since heen found to contain a trace 

 of helium, the presence ot which would lower the 

 above density. The actual density will, therefore, 

 be somewhat higher than 9.6, but it will probably 

 not exceed 10. It has not yet been determined. 



