THE ALUMNI JOURNAL 



191 



Cavendish's apparatus for the preparation 

 of argon on the large scale. By this pro- 

 cess, which he had adopted at Mr. 

 Crooke's suggestion, alternating currents 

 from the main of the Electric Supply 

 Company — in connection with the Royal 

 Institution — are passed through a Ruhm- 

 korff s coil, high potential transformers 

 being used, and thence through bent 

 glass tubes, filled with mercury and fitted 

 with platinum points, into a large glass 

 globe in which are the mixed gases. Ar- 

 rangements are made by which absorp- 

 tion by strong caustic alkali takes place 

 after sparking, until the residue resists 

 the prolonged action of the current ; and 

 the top of the globe is cooled by encir- 

 cling it with a jacket of sheet lead through 

 which a continuous current of cold water 

 passes, thus forming an efficient con- 

 denser. It is essential that the platinum 

 terminals should be very massive, so as 

 to resist the enormous heat generated, 

 and the collecting vessel must be made of 

 glass. With this improved apparatus, 

 seven litres of the mixed gases can be ab- 

 sorbed per hour when present in about 

 equal proportions, and passed in auto- 

 matically. The other process for making 

 large quantities of argon has been per- 

 fected by Professor Ramsav, and consists 

 in passing " atmospheric " nitrogen over 

 red hot magnesium turnings contained in 

 a combustion tube, when magnesium 

 nitride is formed, the residue from the 

 ' ' atmospheric ' ' nitrogen consisting of 

 argon. The apparatus is necessarily 

 rather complicated, but by its means 

 argon can be obtained much more rapidly 

 than by sparking ; however, Lord Ray- 

 leigh rather prefers the latter method, as 

 it does not entail such constant attention 

 as the first. The gas prepared by either 

 process is an exceedingly inert body, and 

 it is supposed that the two products are 

 identical. It has been found impossible 

 as yet to produce argon free from nitro- 



gen. It always contains at least 1^2 per 

 cent, of nitrogen, which can readily be 

 detected by the spectroscope. 



Since the reading of the communica- 

 tion before the Royal Society, several at- 

 tempts have been made to induce argon 

 to combine. Thus, no compound had 

 been formed when exposed to the action 

 of titanium at a red heat, although an 

 inert body like nitrogen does. But dur- 

 ing the last few weeks, Berthelot has 

 stated that by the action of the silent 

 electric discharge it can be absorbed bv 

 the vapor of benzine; and so recently as 

 the last few days Lord Rayleigh's son 

 and Professor Meldola had tried to form 

 a compound by sparking argon and 

 acetylene together, when it was noticed 

 that the volume of gas increased, although 

 when acetylene alone was sparked no in- 

 crease was observed. 



Determinations of the solubility of ar- 

 gon in water show it to be the same as 

 oxygen and about two and a half times 

 as much as nitrogen. These are of spe- 

 cial importance as affording indications 

 of good sources of argon on a large scale, 

 owing to the much greater solubility of 

 argon in water than nitrogen. In fact, 

 Lord Rayleigh had recently received 

 from Manchester argon which had been 

 obtained from the condensing water of 

 steam engines. Turning to the spectrum 

 of argon, allusion was made to the in- 

 debtedness of the speaker to Mr. Crookes 

 for his work on the subject, and tubes of 

 rarefied argon were shown, which, when 

 illuminated by an electric discbarge, were 

 red or blue, according to the character of 

 the current employed. Spectroscopic 

 examination had also been utilized in an 

 attempt to distinguish between argon 

 prepared by the alternating current 

 method and that by the magnesium 

 method, although no difference had been 

 detected. A radiometer that Mr. Crookes 

 had charged with argon during the last 



