362 Scientific Intelligence. 



and dropping readily from one vessel to another, a density not 

 unlike that of marsh gas would be suggested; this being 0-41 at 

 its boiling point in air. By allowing 10 co of liquid hydrogen to 

 evaporate, collecting the gas and measuring its volume, the ap- 

 proximate density, however, was found to be rather less than 0*07. 

 The liquid therefore is about one-fourteenth the density of water; 

 i. e., it bears to water the same relation that gaseous hydrogen 

 does to air. Hence the atomic volume of liquid hydrogen is 

 about 14, that of liquid oxygen being about 13*7 ; the atomic 

 volumes at their respective boiling points being very near each 

 other. The density of hydrogen vapor at its boiling point is 

 about one-half that of air ; approaching that of marsh gas. The 

 ratio of hydrogen vapor to the liquid is as 1 : 100, whereas this 

 ratio in the case of oxygen is 1 : 255. " Liquid hydrogen is in all 

 respects the most extraordinary fluid chemists have ever had to 

 deal with. No chemist could have anticipated that a liquid 

 with a density of one-fourteenth that of water could have been 

 capable of collection and manipulation in vacuum vessels with 

 the same ease practically as manipulation with liquid air was car- 

 ried on ten years ago and that by its means we shall approach 

 within 20° or 25° of the absolute zero." — Chem. News, lxxvii, 

 261, June, 1898. g. f. b. 



4. On the Boiling Point of Liquid Ozone. — Ozone was 

 obtained as a liquid, indigo-blue in color, by Hautefeuille and 

 Chappuis in 1882. In 1887 Oslzewski roughly fixed its boiling 

 point at — 106°. Troost has now repeated the experiment and has 

 determined the boiling point with greater accuracy. The ozone 

 was obtained by means of a Berthelot ozonizer, kept at —79° by a 

 mixture of solid carbon dioxide and methyl chloride. The lique- 

 faction was effected in a vertical tube, the lower portion of which 

 was immersed in a bath of liquid oxygen contained in a Dewar 

 double bulb. The ozone liquefies before reaching the part of the 

 tube thus immersed, and collects in small drops having an oily 

 appearance and not wetting the glass. An iron-constantin 

 couple was employed to fix the temperature, used in connection 

 with a Deprez-d'Arsonval galvanometer. A curve was obtained 

 for the apparatus using the temperatures of melting ice, of boil- 

 ing methyl chloride, of mixtures of solid carbon dioxide and 

 methyl chloride (controlled by the hydrogen thermometer), of 

 boiling nitrous oxide, of liquid ethylene, of melting solid ethylene 

 and of the boiling point of oxygen. In this way the temperature 

 could be read to within half a degree. One of the junctions of 

 the thermo-couple was placed in the liquid ozone, the other was 

 placed in melting ice. The bath of liquid oxygen was thus 

 lowered until its free surface was about 3 cm below the lower end 

 of the tube containing the ozone, and the galvanometer deflec- 

 tions were noted. At first they decreased, • but finally became 

 steady, remaining so during the time that the ozone was in ebulli- 

 tion, when they fell again rapidly. Transferred to the curve, 

 the stationary point corresponds to a temperature of— 119°. 



