March 1, 1895.] 



KNOWLEDGE. 



49 



AN ILLUSTRATED 



MAGAZINE OF SCIENCE 



SIMPLY WORDED— EXACTLY DESCRIBED 



LONDON: MARCH 1, 1895. 



CONTENTS. 



PAGE 



Argon ; the Newly-Discovered Constituent of the Air. 



By Gkobge MrCxOWAN, Ph.]) 49 



A Myth of Old Babylon. By TnEO. G. Pinches, M.R.A.S. 



{Illuntrated) 52 



The " Eye " of Mars. By E. Waltee Matjndek, F.E.A.S. 



{Illustrated) ... ... ... ... ... ... ... iio 



Letters : — Thomas Henchman; .H. Deslandresu Thomas 



JIoT .59 



The Intelligence of Insects in relation to Flowers, 



By the Rev. Alex. S. Wilson, M.A., B Sc. {Illustrated) 60 



Science Notes 6.3 



Notices of Books 63 



The Cause of the Movement of Glaciers. By P. L. 



Addison, F.G.S., A.-^soc. M. Iii,«t.. C.E. {Illustrated) ... 65 

 New Animals from Madagascar. By R. Ltdekkeb, 



B.A.Cantab., F.R.S 68 



The Face of the Sky for March. By Heebeki 



Sadlee, F.E.A.S 70 



Chess Column. Bt C. D. Locock, B.A.Oxon 71 



ARGON; THE NEWLY-DISCOVERED CON- 

 STITUENT OF THE AIR. 



By Geoege McGowan, Ph.D. 



THOSE votaries of science and others who were 

 privileged to take part in the meeting of the Royal 

 Society, which was held in the theatre of the 

 University of London on January 31st, will look 

 back upon the day as a red-letter one in their lives. 

 As another writer has already remarked, the scene at the 

 meeting — crowded as that was with so many who have 

 made a name for themselves in the scientific world — was 

 in many respects unique, and it will certainly be historical. 

 This meeting, as it fitly happened, was the first to be held 

 under a new rule of the Society, passed by the Council last 

 session, whereby not more than four meetings in any one 

 year are to be devoted to the hearing and consideration or 

 to the discussion of some one important topic, and it was 

 the first to which the general public and reporters were 

 admitted. On that day Prof. William Ramsay read to 

 the Society the paper by Lord Rayleigh and himself upon 

 " Argon," the newly-discovered constituent of air, a com- 

 munication which had been looked forward to with intense 

 interest ever since the meeting of the British Association 



at Oxford last August, when Lord Rayleigh made a verbal 

 statement about the new gas on behalf of his colleague and 

 himself. The effect of that statement upon the audience 

 at Oxford may be better imagined than described. It 

 seemed incredible that we should be hearing to-day for the 

 first time of a gas which constitutes something like one 

 per cent, by volume of the air we breathe, and that its 

 presence should have been overlooked by chemists and 

 physicists all these years. But no one can now have a 

 shadow of doubt that such has really been the case, and 

 that a new constituent of the atmosphere — whether 

 elementary or a mixture of two or more elements remains 

 to be decided — has been brought to light. Hitherto it has 

 lain hidden among the nitrogen of the air, and has been 

 reckoned as part of that nitrogen. 



It may not be without interest to the readers of 

 Knowledge to turn back for a few minutes to the history 

 of the discovery of the two main constituents of air, 

 nitrogen and oxygen (leaving out of account the water 

 vapour, carbonic acid, and the small quantities of other 

 substances found in normal air), before proceeding to the 

 consideration of the new gas. The first observation which 

 aided in overthrowing the old assumption that the air was 

 a simple substance was the noting of the efiect upon an 

 enclosed volume of air of burning a combustible substance, 

 or of heating certain metals in it. This led Robert Boyle, 

 so long ago as the latter half of the seventeenth century, 

 to the conclusion that one ingredient of the air was 

 necessary to respiration and combustion, and to the calcina- 

 tion of the metals, although neither he nor his contem- 

 porary Mayow (who came pretty near to the true 

 interpretation of combustion) was able to isolate it. The 

 disputed question as to whether atmospheric air was a 

 simple substance or a mixture was finally solved experi- 

 mentally by the chemists of the phlogistic era, more 

 especially by Scheele and Priestley, but it was left to 

 Lavoisier to put the proper interpretation upon the results 

 which they had obtained. Nitrogen was first isolated by 

 Scheele, although Rutherford, Professor of Botany in the 

 University of Edinburgh, working independently, obtained 

 it from the air in 1772, and published the record of his 

 experiments before Scheele did. Again, with regard to 

 oxygen, we now know from papers which have quite 

 recently come to light," that Scheele succeeded in isolating 

 oxygen in 1771-1773 from several different compounds 

 (peroxide of manganese, nitrates, red oxide of mercury and 

 oxide of silver), and characterized it thoroughly ; while 

 Priestley, also working independently, first isolated it for 

 certain (from red oxide of mercury) in 1774. The latter, 

 having published his results prior to Scheele, has hitherto 

 been regarded as the discoverer of oxygen. By this im- 

 portant discovery both of those chemists were in a position 

 to recognize air as a mixture of gases. In 1785 Cavendish 

 read a paper entitled "Experiments on Air "t before the 

 Royal Society, in which he proved the identity of " phlo- 

 gisticated air" (nitrogen) with the constituent of nitric 

 acid ; this last he showed to be formed when a series of 

 electric sparks was passed through a mixture of nitrogen 

 and oxygen contained in a tube closed at one end, soap lees 

 (('.('. caustic potash) being used to absorb the acid vapours 

 as they were produced. In those experiments, which 

 extended over many days and which were of necessity made 

 with a very small quantity of material. Cavendish observed 

 that, after all the oxygen and nitrogen m the tube had 

 been used up, a slight residue of gas (not exceeding the 



E. TOn Meyer's History of Chemistry, Second German 



also repiib- 



• See 

 Edition. 



t I'hilosophical Transactions for 1785, Vol. LXXV 

 lished in the Alemhic Club Reprints, No. 3. 



