SCIENCE-GOSSIP. 



ARGON, THE NEW ELEMENT. 



'PHE year 1894 w1 ^ 8° down to posterity as 

 marked by one of the greatest of scientific 

 discoveries. During several years past the Right 

 Hon. Lord Rayleigh, F.R.S., has been occupied 

 with a series of intricate investigations of various 

 gases and their physical measurements. For 

 some time he has been puzzled by the varying 

 weights of nitrogen under different chemical condi- 

 tions. This led him to suspect that associated with 

 this gas was some matter as yet uninvestigated. It 

 came about by finding that nitrogen obtained from 

 the atmosphere was one half per cent, heavier than 

 when extracted from chemical compounds. This 

 was mentioned at the last meeting of the British 

 Association, at Oxford, and caused Mr. William 

 Ramsay, F.R.S., Professor of Chemistry at Univer- 

 sity College, London, in conjunction with Lord 



Mr. Crookes said: "Through the kindness of 

 Lord Rayleigh and Professor Ramsay I have been 

 enabled to examine the spectrum of this gas in 

 a very accurate spectroscope and also to take 

 photographs of its spectra in a spectrograph fitted 

 with a complete quartz train. The results are 

 both interesting and important, and entirely corro- 

 borate the conclusions arrived at by the discoverers 

 of argon. 



"Argon resembles nitrogen in that it gives two 

 distinct spectra according to the strength of the 

 induction current employed. But while the two 

 spectra of nitrogen are different in character, one 

 showed fluted bands and the other sharp lines, the 

 argon spectra both consist of sharp lines. It is, 

 however, very difficult to get argon so free from 

 nitrogen that it will not show the nitrogen flutings 

 superposed on its own special system of lines. I 

 have used argon prepared by Lord Rayleigh, Pro- 

 fessor Ramsay and myself, and, however free it 

 was supposed to be from nitrogen, I could always 



Spectra of (a) Argon and (hi Nitrogen. 

 (From Photographs,: by Mr. W. Crookes, F.R.S.) 



Rayleigh, to pursue these investigations, the result 

 being the discovery of one, if not two, new elements. 



These facts were placed unreservedly before the 

 world by these gentlemen at a special meeting of 

 the Royal Society held on the 31st of January last, 

 in the theatre of the University of London, before 

 an audience, perhaps never more brilliant in this 

 country. Three papers were then read on the new 

 gas, which proved the splendid results still to be ob- 

 tained by patient and well-directed original research. 



The new gas is named Argon, and has been obtained 

 from the air by atomolysis, by red-hot magnesium 

 and by sparking with an electrical current. Critical 

 examination shows that Argon is absolutely distinct 

 not only from nitrogen, but from all other matter. 

 An exceedingly interesting paper upon its spectro- 

 scopic analysis was read by Mr. William Crookes, 

 F.R.S., as one of the three above referred to. We 

 select from an abstract of Mr. Crookes' statements, 

 the following extracts to show how the gas behaved 

 under his treatment. The spectra illustrating his 

 paper, so far as refer to the comparison of Argon 

 and nitrogen, are herein reproduced from photo- 

 graphs taken by this eminent physicist. 



detect the nitrogen bands in its spectrum. These, 

 however, soon disappear when the induction spark 

 is passed through the tube for some time, varying 

 from a few minutes to a few hours. 



"The pressure of argon giving the greatest 

 luminosity and most brilliant spectrum is 3 mm. 

 The best pressure for nitrogen is 75 or 80 mm. At 

 this point the colour of the discharge is an orange- 

 red, and the spectrum is rich in red rays, two being 

 especially prominent at wave-lengths 69656 and 

 705-64. On passing the current the traces of 

 nitrogen bands soon disappear, and the argon 

 spectrum is seen in a state of purity. 



" If the pressure is further reduced, and a Leydeu 

 jar intercalated in the circuit, the colour of the 

 luminous discharge changes from red to a rich 

 steel-blue, and the spectrum shows an almost 

 entirely different set of lines. It is not easy to 

 obtain the blue colour and spectrum entirely free 

 from the red. It appears that a low electromotive 

 force (3 cm. spark, or 27,600 volts) is required to 

 bring out the red, and a high E.M.F. and a very 

 hot spark for the blue. The red glow is produced 

 by the positive spark, and the blue by the negative 

 spark. 



" I have taken photographs of the two spectra of 

 argon partly superposed. In this way their dis- 

 similarity is readily seen. In the spectrum of the 

 blue glow I have counted 119 lines, and in that of 

 the red glow 80 lines, making 199 in all. Of these 



