HELIUM ABBOT. 125 



Here, then, we have read two new chapters of the wonderful his- 

 tory of helium, its relation to the dreams of the alchemists, and its 

 approach to the extreme limit of the realm of cold. The last chap- 

 ter of the story deals with the great war. 



For two decades previous to the invasion of Belgium the Germans 

 had been constructing their Zeppelins, and the possibilities of this 

 new war weapon were variously estimated. Their employment of it, 

 however, to scatter destruction over undefended towns had not been 

 dreamed of, and the horror which their earlier raids across the 

 Channel into England roused will not soon be forgotten. However, 

 this diabolical engine of destruction proved not to be invulnerable. 

 The hydrogen gas with which these great ships were filled in order 

 to make them lighter than air was in the highest degree inflammable, 

 and when the airplanes reached their high degree of efficiency the avi- 

 ators were able to destroy the Zeppelins by means of inflammatory 

 bullets. Experiments made in the United States have shown that 

 about one in four of the inflammatory projectiles which pierce a 

 hydrogen filled balloon is apt to set it on fire. In this way the Ger- 

 mans lost several Zeppelins, and recognizing the danger of their em- 

 ployment and the comparatively meager results achieved, they at 

 length discontinued the employment of them. But they continued 

 their devilish raids by the use of airplanes, which had reached such 

 large dimensions and such degrees of adaptability for maneuvering 

 that long trips could be made with them to scatter death and destruc- 

 tion over civilian populations. 



At length the Allies retaliated. They also sent their airplanes 

 to give the Germans some realization of that kind of warfare. Their 

 aerial fleets outnumbered the Germans, and with the entrance of the 

 United States into the war probabilities of still further aerial attacks 

 upon Germany became far stronger. But it occurred to allied officers 

 that if a noninflammable gas could be used, then the Zeppelins them- 

 selves, which were far more capable of carrying great weights of 

 guns and bombs, and were capable of making long flights into enemy 

 territory, would be even more suitable for this kind of warfare. 

 Ammonia and hot air were suggested and tested for such purposes, 

 but owing to their comparatively considerable weight as compared 

 with hydrogen they were not altogether satisfactory. But some 

 enthusiast suggested that if helium, which is next lightest to hydrogen 

 of all the gases, could be used the problem would be solved. Noth- 

 ing apparently was more absurd. Kamerlingh Onnes had spent an 

 enormous amount of time to collect for his experiments on liquefac- 

 tion of helium so little as 2 cubic meters of gas. A terrible misfor- 

 tune occurred to him, for an accidental leakage in his apparatus 

 caused the loss of much of this precious store 



