Fbbeuaey 24, 1899.] 



SCIENCE. 



277 



It seemed to me a pity to boil away all the 

 air without collectiug the last residue ; for, 

 though it seemed improbable that the looked- 

 for element could be here, yet it was, indeed, 

 possible that a heavier gas might accom- 

 pany the argon. This suspicion was con- 

 firmed. The residue from the liquid air 

 consisted chiefly of oxygen and argon, and, 

 after removing the oxygen and nitrogen, be- 

 side the spectrum of argon were two bril- 

 liant lines, one in the yellow, which was not 

 identical with Dj of helium, and one in the 

 green. This gas was decidedly heavier than 

 argon ; its density was 22.5 instead of the 

 20 of argon. We had, therefore, discovered 

 a new body, which was an element, for the 

 ratio between the specific heats was 1.66. 

 To this element we gave the name ' kryp- 

 ton.' Up to this time we have not followed 

 further the study of this element ; we have, 

 however, collected and preserved many resi- 

 dues which are rich in krypton. It was, 

 however, our first intention to examine the 

 lightest part of the argon. In many, how- 

 ever, we remai'ked, in passing, that the 

 wave-length of the green line of krypton 

 is exceedingly close to that of the northern 

 lights, being 5,570, while the latter is 5,571. 



Our whole supply of argon was now lique- 

 fied in the following manner. The gaso- 

 meter containing the argon was connected 

 with a series of tubes in which the gas 

 passed over respectively hot copper oxid, 

 concentrated sulphuric acid and phos- 

 phorus pentoxid ; it then passed by a two- 

 way cock into a small flask, holding about 

 30 cubic centimeters, which was enclosed in 

 a Dewar tube. By means of the other open- 

 ing of the cock, the flask was connected 

 with a mercury gasometer. By means of a 

 U-shaped capillary and mercury trough, it 

 was also possible, through a three-way cock, 

 to collect the gas at will in glass tubes. 

 About 50 cubic centimeters of liquid air were 

 poured into the double-walled tube, and, by 

 means of a Fleuss air pump kept constantly 



in action, the liquid air boiled at 10 to 15 

 millimeters pressure. The argon liquefied 

 rapidly as soon as subjected to this low tem- 

 perature, and in the course of half an hour 

 it was completely condensed. Altogether 

 there were about 25 cubic centimeters of a 

 clear, limpid, colorless liquid, in which 

 floated white flakes of a solid substance. 

 By stopping the pump, the pressure over the 

 liquid air was now increased, and the argon 

 boiled quietly, the first portions of the gas 

 being collected in the mercury gasometer. 

 Changing now the three-way cock, the 

 largest portion of the argon passed back 

 into the iron gasometer ; after nearly all the 

 liquid had boiled away and only the solid 

 substance was left in the flask, the last por- 

 tions of the gas were collected separately. 

 The solid substance remained persistently 

 in the flask ; it was slowly volatilized by 

 means of a Topler pump, which stood in 

 connection with the apparatus. 



We first directed our attention to the 

 lighter fractions, for these had for us the 

 greatest interest. The density of this gas 

 was found to be 14.67 ; the ratio between 

 the specific heats was as usual 1.66, and the 

 spectrum showed, beside the well-known 

 groupings of argon, a large number of red, 

 orange and yellow lines of varying intensify. 

 Evidentlj% we had before us a new element, 

 which was contaminated with argon. 



This gas was then liquefied in a similar 

 apparatus to that first used, but constructed 

 on a smaller scale ; a portion, however, re- 

 mained uncondeused. Even by i-aising the 

 reservoir of the mercury gasometer until 

 an overpressure of an atmosphere was 

 reached, it was impossible to convert all 

 the gas into a liquid, although the temper- 

 ature of the boiling air was reduced as low 

 as possible by rapid pumping. By repeated 

 raising and lowering of the reservoir, we 

 finally passed all the gas through the cooled 

 space, in order to free it, as far as possible, 

 from argon. The uncondensible gas was 



