34 On the Electrical Properties of Pure Substances. 



occur at low temperatures. For this purpose I prepared 



Tube 7, which is figured in the Plate in the position 

 it occupied before it was sealed oft'. This tube was prepared 

 with even more than the usual care. Thus, the cleaning 

 of the tube occupied two days and the final rinsing was 

 accomplished by means of some thrice- distilled water from 

 the platinum and gold still. This water ran into the tube direct 

 from the still. The electrodes were prepared by sparking 

 during five hours with a discharge sufficient to make them red- 

 hot, during which time the tube was thrice filled and exhausted. 

 The next day the tube was heated twice, and on each occasion 

 about 500 cub. eentim. of gas were passed through it ; after 

 which it was exhausted as far as possible (in an hour), and 

 then the final charge was allowed to enter. The tube was 

 sealed ofT at 8" 7 millim. pressure, and then put in salt and 

 pounded ice and kept at —14° C. by means of frequent stirring 

 and the addition of fresh ice and salt. Sparked 2 hours with 

 effective sparks : no effect. (The effect was looked for the 

 next day, when the temperatures were equalized, but was not 

 observed.) 



Jan. 2. Sparked for 2 hours at about —10° C, all kinds of 

 sparks, No effect. 



The filamentary tube was then replaced by a wider one, as 

 it was observed that the gauge only acted very slowly owino' 

 to the extreme fineness of the filamentary tube. The spark- 

 tube then required to be pumped out and prepared afresh, 

 except for the heating of the electrodes, which, however, inci- 

 dentally took place. 



Jan. 4. Sparked 1£ hours at -10° G. No effect. 



Jan. 6. Sparked 7 hours at a mean temperature of — 8° C; 

 various sparks. No effect. 



Jan. 7. Observed again, at very uniform temperatures. 

 Still no effect, 



Jan. 12. Ditto. 



The conclusion is that no effect is produced on nitrogen, so 

 far as condensation goes, by sparking it at a temperature of 

 about — 10°C. and at a pressure of 8*2 millim. 



Summary of Results, 



1. Nitrogen can be prepared by a continuous process in a 

 state of great purity. 



2. Nitrogen so prepared cannot be caused to condense by 

 any available kind of spark down to a temperature of —10° 0. 

 and a pressure of about 8 millim. 



3. "When mercury is present, a compound of mercury and 



