July 17, 1885.1 



SCIENCE. 



61 



bore the concomitant privations and physical exer- 

 tion it required. 



The first general assembly for 1885, of the Geo- 

 graphical society of Paris, took place on the 24th of 

 April. The president, Mr. de Lesseps, gave a brief 

 address, in which he touched upon the much greater 

 sensitiveness to occurrences in little-known lands, 

 which the extension of telegraphs and means of trans- 

 portation has brought about among the more civi- 

 lized nations ; and the growing importance, from all 

 points of view, of geographical instruction in schools, 

 universities, and even in the reading-matter fur- 

 nished the general public by the daily and periodical 

 press. 



Dr. Ballay, in an address on the new possessions 

 of France in Africa, sums up by saying, that while 

 the Ogowe can never be rendered navigable, it can 

 at least be made useful for bateaux. Its basin is natu- 

 rally fertile, and rich in resources. On the other 

 hand, the country extending from this basin to the 

 Kongo is generally sterile. Ivory is about the only 

 product. There is little to hope for from this region ; 

 but it is the beginning of the practicable route for 

 reaching the trade of the upper river, which has in- 

 habitants of intelligence and thrift. The natural 

 products of all this region, such as rubber, ivory, etc., 

 may be expected to become rapidly exhausted. It 

 should therefore be provided that artificial cultiva- 

 tion, new industries and crops, should be introduced 

 and directed by the whites. In this way a perma- 

 nent trade will arise, and commerce be permanently 

 benefited. 



From Iceland, under date of March 21, we learn 

 that the shocks of earthquake which had devastated 

 the vicinity of Husavik, North province, began Nov. 

 2, 1884, and continued at short intervals, but less 

 energetically, until the 25th of last January. On this 

 day stables were thrown down, springs burst from 

 the ground in new places, and small elevations 

 were visible in a formerly level sandy plain. It is 

 singular that on every historical occasion when 

 earthquakes have been felt in Spain, Iceland has 

 simultaneously suffered : this may be due, however, 

 to the prevalence of earthquakes in Iceland at all 

 times. 



The Corwin has returned from Bering Sea to San 

 Francisco for some repairs. She reports the sea 

 ice unusually far south in April and May in that 

 sea. No whales had yet been taken. 



THE LIQUEFACTION OF OXYGEN.^ 



Liquid ethylene, the use of which I have already ex- 

 plained to the Academic des sciences, furnishes, when 

 boiled in the open air, a cold suflBcient to cause oxy- 

 gen, if compressed and reduced to this temperature, 

 to present, when the pressure is diminished, a hard 

 boiling appearance, which continues for an apprecia- 

 ble time. By evaporating the ethylene by the air- 

 pump, the temperature is sufficiently lowered to 



^ Condensed from La Nature, May 16. 



reduce the oxygen to a liquid state. I have endeav- 

 ored to avoid the inconvenience and complication 

 which result from working in a vacuum, and to this 

 end have already suggested the use of liquid methane, 

 by means of which the liquefaction of oxygen and 

 nitrogen may be easily brought about. 



I thought, however, that, notwithstanding these 

 advantages, ethylene, which is so easily prepared and 

 handled, ought to be preferred to methane; and, by 

 means of ethylene boiled in open jars, I have succeeded 



cailletet's apparatus for the liquefactiox op 



OXYGEN. 



in reducing the temperature sufficiently to cause the 

 complete liquefaction of oxygen. The process I use is 

 very simple, and consists in evaporating the ethylene 

 by forcing into it a current of air or of hydrogen at a 

 very low temperature. In my apparatus, the steel 

 receiver B, which contains the liquid ethylene, is at- 

 tached to a copper worm three or four millimetres 

 in diameter, closed by a screw-tap arranged in a glass 

 jar, S. On turning into this jar some chloride of 

 methyl, the temperature falls to — 25° ; but if we 

 blow into this air which we have dried by passing it 

 through a flask, C, containing chloride of calcium, we 

 soon have .a cold of — 70°. The ethylene thus cooled 

 condenses, and fills the worm. When the tap is 

 opened at the base of the jar S, the ethylene flows 



