io6 Notes and News, 



to any considerable extent, and that is iridium, which is valued at $1,000 

 per pound. It is sometimes, but very sparingly, used in electrical experi- 

 ments. 



A MAN who lived in the swamp daily prayed to Jupiter for health. 

 'Pray from the hill-top, and your prayer will be granted,' answered Ju- 

 piter. — H. C. Fulton, in Random Notes on Natural History. 



During his expedition to Mount Kilimanjaro, Mr. H. H. Johnson no- 

 ticed a singular resemblance or 'mimicry' between the appearance of 

 the tall red-brown antelope and the mounds built by the white ant. The 

 color being the same and the long grass hiding the animal's legs, it was 

 really dithcult to distinguish an antelope from an ant-hill. A more ludi- 

 crous exactness was sometimes given to the mimicry by the sharply 

 pointed leaves of a kind of squill, which suggested the horns of an ante- 

 lope. 



Balloons as an adjunct of warfare are attracting much attention in 

 European military circles, and their possible value in times of peace are 

 •not entirely overlooked. An English writer remarks that the recent suc- 

 cessful attempts at balloon-steerage in France have led many thoughtful 

 persons to believe the day not to be far distant when we shall see bal- 

 loons plying in well-paying passenger traffic between England and the 

 Continent. Another writer adds that such a result would be no more 

 wonderful in its way than the discovery and development of the tele- 

 phone, which, though scarcely a decade old, is already so familiar to us 

 that it no longer seems strange. 



Since the scientific world was surprised, in 1877, by Cailletet's and 

 Pictet's announcements of the production of liquefied oxygen, several ex- 

 perimenters — especially Wroblewski and Olzewski — have successfully at- 

 tacked the problem of liquefying the so-called permanent gases. It was 

 at first thought necessary to employ great pressure in addition to great cold, 

 but in the later researches both oxygen and nitrogen, as well as atmos- 

 pheric air, have been made liquid by intense cold at very moderate pres- 

 sures. Among the interesting results obtained are the following : At 152 

 degrees below zero, Fahrenheit, chlorine forms orange colored crystals; 

 at 175 below hydrochloric acid is a solid ; at 200 below ether solidifies ; at 

 202 below absolute alcohol freezes ; at 299 below oxygen boils ; at 312 be- 

 low air boils; and at 337 below air boils in a vacuum. These extraordi- 

 nary temperatures were measured by means of a hydrogen thermometer 

 and by a thermopile. The lowest temperature yet measured is 373 de- 

 grees below zero, which was produced by the evaporation of solid nitro- 

 gen on suddenly reducing the pressure. From these results it appears 

 probable that every known substance within the reach of man will be 

 eventually obtained in solid form by the mere withdrawal of heat. 



