1895.] The Expansion of Argon and of Helium. 



65 



indication of anything extraordinary happening to these gases at 

 high temperatures. When argon thermometer I was heated in the 

 vapour of quinoline a remarkable expansion of the gas was observed, 

 continuing for two hours uutil a maximum value was reached; this 

 gave an apparent temperature of 243*5° for the boiling point of 

 quinoline. On cooling the thermometer, however, it was found to be 

 cracked,' and some drops of quinoline were noticed inside the bulb. 

 The measurements made in this case were therefore rejected, and a 

 new series was begun with argon thermometer II, which gave a value 

 about normal. How the quinoline could have found its way into the 

 bulb while an interior pressure of about 970 mm. existed within it, 

 without the argon escaping rapidly at the same time, is not quite 

 clear. It may be the vapour passed through the crack when the 

 temperature was rather low, and that the opening was closed by the 

 later expansion of the glass. 



For completeness' sake, we give in the table the boiling-points of 

 the same substances determined with a mercury thermometer, as 

 calculated from Ramsay and Young's tables. But the irregularities 

 of the thermometers prevent our giving any definite numbers for the 

 reduction of those tables to accord with any of the gas thermometer 

 scales. A direct comparison, such as was executed by Wiebe and 

 Bottcher with a mercury thermometer of known constitution, like 

 the Jena glass thermometer, would have been desirable. Differences 

 of boiling-point resulting from impurities would have affected both 

 thermometers in the same way, and would have enabled us to ascer- 

 tain how much of the differences found resulted from that source of 

 error. But here also want of time prevented our extending our pro- 

 gramme beyond the limits fixed beforehand. 



Notwithstanding the incompleteness and want of perfection of our 

 work, we do not hesitate to publish our results : the difficulties to be 

 overcome in experiments of this kind are serious, and we did not 

 make it our object to obtain results of remarkable accuracy. The 

 real motive of the work was to discover whether argon and helium 

 show extraordinary behaviour at high temperatures, or not — and our 

 results apparently establish the fact that they do not. Their beha- 

 viour, so far as expansion is concerned and within the limits of 

 temperature which we used, is apparently the same as that of so- 

 called perfect gases or mixtures of them. 



Finally, it is a great pleasure to record our hearty appreciation of 

 the kindly assistance of Professor Ramsay, at whose suggestion, and 

 under whose supervision, these experiments have been conducted. 



VOL. lix. 



F 



