\'2 ARGON, A NEW CONSTITUENT OF THE ATMOSPHERE. 



ilejitli of liquid ill urdei' to render possible the witlidrawal of the tubes, but it has 

 the great advantage of dispensing with sealing electrodes into the principal vessel, 

 which might give way and cause the loss of the experiment at the most incon- 

 venient moment. With the given battery and coil a somewhat short spark, or aic, 

 of about 5 mm. was found to be more favorable than a lari'er one. When the 

 mixed gases were in the right proportion, the rate of absorption was about 30 c. c. 

 per hour, or 30 times as fast as Cavendish could wnik with the electrical machine 

 of his day. 



To take an example, one experiment of this kind started with 50 c. c. of air. 

 To this, oxygen was gradually added until, oxygen being in excess, theie wjis no 

 perceptible contraction during an hour's spaiking. The remaining gas was then 

 transferred at tlie pneumatic trough to a small measuring vessel, sealed by mercurv, 

 in which the volume was found to be 1.0 c. c. On treatment w itli alkaline pyro- 

 gallate, the gas shiank to .32 c. c. That this small residue could not be nitrogen 

 was argued from the fact that it had withstood the prolonged action of the spark, 

 although mixed with oxygen in nearly the most favoi-able propoitiou. 



The residue was then transferred to the test tube with an addition of another 

 50 c. c. of air and the whole worked up with oxygen as before. The residue was 

 now 2.2 c. c, and after removal of oxygen .76 c. c. 



Although it seemed almost impossible that these residues couhl be either 

 nitrogen or hydrogen, some anxiety was not unnatural, seeing that the final spark- 

 ing took [)lace under somewhat abnormal conditions. The space was veiy I'e- 

 stricted, and the temperature (and with it the i)roportion of a(pieous vapor) was 

 unduly high. But any doubts that wei-e felt upon this scoiv were lemoved by 

 comparison experiments in ^vhi(•ll the whole quantity of air operated on was veiy 

 small. Thus when a mixture of 5 c. c. of air with 7 c c. of oxygen was sparked 

 for \^ houi-s, the residue was 0.47 c. c. and after removal of oxvireu 0.06 c. c. 

 Several repetitions having given similar results, it became clear that the final resi- 

 due did not depend upon anything that might happen when sparks psussed through 

 a greatly reduced volume, ht/t was in. proportion to the amount of air operated upon. 



No satisfactory examination of the residue which i-efu.sed to lie oxidized could 

 be madi* witiioiit the accumulation of a larger quantity. This, however, was difii- 

 cnlt of attainment at the time in (luestion. The mis seemed to rebel acainst the 

 law of addition. It was thougliL that the cause probably lay in the solubility of 

 the gas in water, a suspicion since coiifiinied. At length, however, a sufficiency 

 was Collected to allow of sparking in a s[)ecially constructed tube, when a conq)ari- 

 son with the air spectrum taken under similar conditions [iroved that at any rate 

 the gas was not nitrogen. At first scarcely a trace of the principal nitrogen lines 



