752 LIQUEFACTION OF NITROGEN, HYDROGEN AND AIR. 



of an experiment which was performed for the fourth time on Thursday, 

 December 27th, in the presence of ten scientific men — among others Prof. 

 Hagenbach, of Eale, who came expressly to assist at this important 

 experiment. 



At 10 o'clock in the evening the manometer, which had risen to 560 at- 

 mospheres, sank in a few minutes to 505, and remained stationary at this 

 figure for more than half an hour, showing by this diminution in the pres- 

 sure that part of the gas had assumed the liquid form under the influence of 

 the 140 degrees of cold to which it was exposed. The tap closing the orifice 

 of the tube was then opened, and a jet of oxygen spirted out with extraor- 

 dinary violence. 



A ray of electric light being thrown on the escaping jet showed that it 

 was chiefly composed of two parts ; — one central, and some centimetres long, 

 the whiteness of which showed that the element was liquid, or even solid ; 

 the other exterior, the blue tint of which indicated the presence of oxygen 

 compressed and frozen in the gaseous state. 



The success of this remarkable and conclusive experiment called forth 

 the applause of all present. 



"We understand that Messrs. Pictet & Co., of 22, Eue de Grammont, Paris, 

 are fitting up apparatus with the intention of having these experiments 

 repeated at their Freezing-Machine Works, at Clichy, in Paris. — London 

 Chemical News. 



LIQUEFACTION OF NITROGEN, HYDROGEN AND ATMOS- 

 PHERIC AIR. 



M. Cailletet has comunicated to the Academie des Sciences some further 

 particulars on the liquefaction of gases, and at the meeting of the Slst of 

 December a paper was read, from which we translate the following : 



^'Nitrogen. — Pure and dry nitrogen compressed to about 200 atmos- 

 pheres, at a temperature of +13°, then allowed to expand suddenly, con- 

 denses in the most perfect manner; it first produces an appearance like 

 that of a pulverized liquid in small drops of appreciable volume ; this liquid 

 then gradually disappears from the sides to the centre of the tube, at last 

 forming a sort of vertical column following the axis of the tube. The du- 

 ration of these phenomena is about 3 seconds. 



" These appearances leave no doubt as to the true character of the phe- 

 nomena. I first tried the experiment at home at a temperature of — 29°, 

 and I repeated it yesterday, the 30th of December, several times at the 

 Laboratory of the Ecole Normale, in the presence of many savants and 

 members of the Academy, among whom I am happy to name, with his 

 assent, the venerable M. Boussingault. 



'^Hydrogen. — Hydrogen has a'lways been considered the most incondens- 

 able gas, on account of its low density, and the almost complete agreement 

 of its mechanical properties with those of perfect gases. Thus it was only 



