340 Canadian Record of Science. 



Describing his attempts to cause a complete union of atmospheric 

 nitrogen with oxygen by means of the electric spark, he says : "If 

 there is any part of the phlogisticated air (nitrogen) of our atmosphere 

 which differs from the rest and cannot be reduced to nitrous acid, we 

 may safely conclude that it is not more than 1- 120th part of the 

 whole." Cavendish, however, laid no emphasis on this residual 1 -120th, 

 except as indicating by its minuteness the great purity of the nitrogen 

 from air. But in these days science no longer neglects "residual 

 phenomena," and has found, in many cases before this, abundant 

 evidence of the valuable results to be obtained by a study of them. 



In the first attempts to isolate the suspected gas, Cavendish's 

 method was employed. Electric sparks were passed through air 

 confined over weak alkali, and oxygen gradually added till in excess. 

 The products of the union of nitrogen and oxygen caused by the spark 

 were absorbed by the alkali, and finally, when no further absorption 

 took place, the excess of oxygen was removed by alkaline pyrogallate. 

 A residue was obtained which was in all instances proportional to the 

 amount of air operated upon. 



Another method of isolating argon, and which also serves for 

 preparing it in considerable quantities, is as follows : Air from which 

 moisture and carbon dioxide have been removed is freed from oxygen 

 by passing it over red-hot copper, and from nitrogen by magnesium 

 turnings heated to a bright redness. The removal of the last portions 

 of nitrogen is a tedious operation, requiring some two days, when the 

 residual gas is found to be pure argon. 



The gas obtained by either of these methods has a density one-fourth 

 greater than oxygen (16.20), and dissolves in water about two and 

 a-half times as freely as nitrogen. On account of its solubility, it is 

 present in larger proportion in the gases dissolved in rain-water than 

 in the air, as is indicated by the fact that "nitrogen" prepared from 

 the gases expelled from water has a higher density than that from air, 



The spectrum of argon has been examined by Professor Crookes. 

 who finds that " No other spectrum-giving gas or vapor yields spectra 

 at all like those of argon," and says further, " As far, therefore, as 

 spectrum work can decide, the verdict must be that Lord Rayleigh and 

 Professor Ramsay have added one if not two members to the family of 

 elementary bodies." 



Professor Olszewski of the University of Cracow, well known for his 

 researches on the liquefaction of air and other gases, was furnished 

 with 300 cc. of argon for the determination of its behaviour at low 

 temperatures and high pressures. He reports that it can be liquefied 

 only when its temperature is reduced (by liquid ethylene) to — 121° C, 

 and that the necessary pressure at that temperature is 50.6 atmos- 

 pheres ; or, in other words, that its "critical temperature and 

 pressure " are — 121° and 50.6 at. respectively. Its boiling-point is 



