THE GASES OF THE ATMOSPHEEE 139 



years fruitless and that the liquefaction was accom- 

 plished in 1908 by Professor Kamerlingh-Onnes of 

 Leiden. The boiling point of the liquid is the lowest 

 known, as it is approximately 4*5 absolute or 268 

 to 269 below zero Centigrade. 



Immediately after the meeting of the Chemical 

 Society in London Ramsay and his wife went to Paris 

 in fulfilment of an engagement to lecture on argon to 

 the Societe Chimique de Paris. Before leaving home 

 he received through M. le Chatelier an urgent request 

 that he would give a demonstration on the same sub- 

 ject to the 500 students of the feole Poly technique. 

 This he consented to do, and in a letter to his children, 

 dated ; Paris 31st March, 1895, he gave them an account 

 of the proceedings on both occasions. Needless to say, 

 the lectures were received with enthusiastic applause. 



This period, so full of interest and excitement, must 

 have been very exhausting to Ramsay, for it must not 

 be forgotten that the teaching at University College 

 made considerable demands on his time and energy. 

 At the end of the session he wisely sought a holiday 

 under conditions which would make him secure of 

 uninterrupted relief, and in company with his colleague, 

 Professor W. P. Ker, he started in August for Iceland. 

 Some account of this excursion will be found later on. 

 Some bottles of gas were collected at the hot springs 

 near Reykjavik, but they appear to have contained no 

 helium but only a notable quantity of argon. (Kellas 

 and Ramsay, Proc. Roy. Soc., Nov. 1895.) 



