2(5 ARGON, A NEW CONSTITUENT OF THE ATMOSPHFRE. 



The ar-'on was collected in two operations. First the quantity made by 

 absorption by magnesium in glass tubes with the water-pump ciiculator was 

 pui-itied. Later, after a second supply had been prepai'ed by absorption in iron 

 tubes, the mixture of argon and nitrogen wjis united with tlie first (quantity and 

 circulated, by means of the mercury circulator, in the gasholder B. Attention 

 will be drawn to the pailicular sample of gas employed in describing further 

 experiments made with the argon. 



By means of magnesium, about seven litres of nitrogen can be absorbed in an 

 hour ; the changing of the tul>es of magnesium, however, takes some time ; conse- 

 quently the largest amount absorbed in one day was nearly thirty litres. 



The pi-incipal objection to the oxygen method of isolating argon, as hitherto 

 desci-ibed, is the extreme slowness of the operation. An absorption of 30 c. c. of 

 mixed gas means the removal of but 12 c. c. of nitrogen. At this rate eight hours 

 are lequiied for the isolation of 1 c. c. of argon, supposed to be present in the pro- 

 portion of 1 per cent. 



In extending the scale of operations we had the great advantage of the advice 

 of Mr. Crookes, who a short time ago called attention to the flame rising from pla- 

 tinum terminals which convey a high-tension alternating electric discharge, and 

 pointed out its dependence upon c-..iiil.ustion of the nitrogen and oxygen of the air.' 

 Mr. Crookes was kind enough to arrange a demonstration at his own house w'ith a 

 small alternating cuirent plant, in which it appeared that the absorption of mixed 

 gas was at the rate of 500 c. c. per hour, or nearly twenty times as fast as with the 

 battery. The arrangement is similar to that first described by Spottiswoode.'^ The 

 primary of a Ruhmkoi-fl" coil is connected directly with the alternator, no l)reak or 

 condenser being required, so that in fact the coil acts simply as a high-potential 

 transformer. When the arc is established the platinum terminals may be separated 

 beyond the initial striking distance. 



Tlie plant with which the large scale operations have been made consists of a 

 De Meritens alternator, kindly lent by Professor J. J. TIk.iusoii, and a gas-engine. As 

 transformer, one of Swinburne's hedgehog pattern has l)een employed with success, 

 but the ratio of transformation (-'4:1) is scarcely sufiicient. A higher potential, 

 although perhaps not more efficient, is more convenient. The striking distance is 

 <'reater, and the arc is not so liable to go out. Accordingly most of the work to 

 be described has been peiformed with transformei-s of the Ruhmkorff type. 



The apparatus has been vaiied greatly, and it cannot be regaiiled as having 

 even yet assumed a completely satisfactory and final form. But it will give a sufR- 



' Chemical News, vol. LXV, p. 301, 1892. 



' A mode of exciting aa induction-coil. Philadclpliia Magazine, vol. VIII, p. 390, 1829. 



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