28 ARGON, A NEW CONSTITUENT OF THE ATMOSPHERE. 



ami, after three hours' woi'k, became very 8h)w. The progress towards leiiioval of 

 nitroireii was examiiiei] from time to time with the spectroscope, the points being 

 approximated and connected with a small Leyden jar. At this stage the yeUow 

 nitrot^en line was faint, but phiinlv visible. After about four hours' more work the 

 yellow line had disappeared, an<l for two hotiis tliere had been no visible contrac- 

 tion. It will be seen that the removal of the last part of the nitrogen was very 

 sloNV, mainly on account of the iai-ge excess of oxygen present. 



The final treatment of the residual 700 c. c. of gas was on the model of the 

 small scale operations alieady described. 



By means of a pipette the gas wa.s gradually transferred to a large test tube 

 standing over alkali. Under the influence of sparks (from battery and coil) pass- 

 inf all the while, the superfluous oxygen was consumed with hydrogen fed in 

 slowly from a vcdtameter. If the nitrogen had been completely removed, and if 

 there were no unknown ingredient in the atmosphere, the volume under this treat- 

 ment should have diminished without limit. P>ut the contraction stopped at a 

 volume of 65 c. c, and the volume was taken backwaids 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 

 hxdidgcn were in excess could Ije determined at any moment by a glance at the 

 spectrum. At the minimum volume the gas was certainly not hydrogen or oxygen. 

 Was it niti'ogen ? On this point the testimony of the speclioscope was equally 

 decisive. No trace of the yellow nitrogen line could be seen even with a wide slit 

 and under the most favorable conditions. 



When the gas stood for some d;iys over water the nitrogen line .ngain asserted 

 itself, ami many hours' sparking with a little oxygen were ivcpiired again to get rid 

 of it. As it was important to know w hat proportions of nitrogen cmdd be made 

 visible in this way, a little air was added to gas that had been sparked for some 

 time subsequently to the disappearance of nitrogen in its spectrum. It was found 

 that about li per cent was clearly, and al)out .". ]ier cent was conspicuously, 

 visible. About the same nund)eis apply to the visil)ility of nitrogen in oxygen 

 when sparked under these conditions, that is, at atmospheric pressure, and with a 

 jar in coiniection with the secondary terminals. 



When we atteuqit to increa.se 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 al)sor])tion of 700 c. c. per hour, the upper 

 part of the flask becomes very hot. With .-i iiion- powerful arc the he;it ri.ses to 

 such a point that the flask is filled with steam and the operation comes to a standstill. 

 The remedy is to be found in the use of a largei vessel subnu-rged, at any rate as 



