1895.] on Argon. 529 



very appreciably risen, owing to the union of the nitrogen and the 

 oxygen gases under the influence of the electrical discharge, and 

 subsequent absorption of the resulting compound by the alkaline 

 liquid with which the gas space is enclosed. 



By means of this little apparatus, which ii very convenient for 

 operations upon a moderate scale, such as for analyses of " nitrogen " 

 for the amount of argon that it may contain, we are able to get an 

 absorption of about 80 cubic centimetres per hour, or about 4 inches 

 along this test tube, when all is going well. In order, however, to 

 obtain the isolation of argon on any considerable scale by means of 

 the oxygen method, we must employ an ajiparatus still more enlarged. 

 The isolation of argon requires the removal of nitrogen, and, indeed, 

 of very large quantities of nitrogen, for, as it appears, the proportion 

 of argon contained in atmospheric nitrogen is only about 1 per cent., 

 so that for every litre of argon that you wish to get you must eat up 

 some hundred litres of nitrogen. That, however, can be done upon 

 an adequate scale by calling to our aid the powerful electric discharge 

 now obtainable by means of the alternate current supply and high 

 potential transformers. 



In what I have done upon this subject I have had the advantage 

 of the advice of Mr. Crookes, who some years ago drew special 

 attention to the electric discharge or flame, and showed that many 

 of its properties depended upon the fact that it had the power of 

 causing, upon a very considerable scale, a combination of the nitrogen 

 and the oxygen of the air in which it was made. 



I had first thought of showing in the lecture room the actual 

 apparatus which I have employed for the concentration of argon ; 

 but the difficulty is that, as the ajjparatus has to be used, the working 

 parts are almost invisible, and I came to the conclusion that it would 

 really be more instructive as well as more convenient to show the 

 parts isolated, a very little effort of imagination being then all that 

 is required in order to reconstruct in the mind the actual arrange- 

 ments employed. 



First, as to the electric arc or flame itself. We have here a 

 transformer made by Pike and Harris. It is not the one that I have 

 used in practice ; but it is convenient for certain purposes, and it can 

 be connected by means of a switch with the alternate currents of 

 100 volts furnished by the Supply Company. The platinum terminals 

 that you see here are modelled exactly upon the plan of those which 

 have been employed in practice. 1 may say a word or two on the 

 question of mounting. The terminals require to be very massive on 

 account of the heat evolved. In this case they consist of platinum 

 wire doubled upon itself six times. The platinums are continued by 

 iron wires going through glass tubes, and attached at the ends to the 

 copper leads. For better security, the tubes themselves are stopped 

 at the lower ends with corks and charged with water, the advantage 

 being that, when the whole arrangement is fitted by means of an 

 in H'trnhber stopper into a closed vessel, you have a witness that, as 



