[ 467 ] 

 LX. Intelligence and Miscellaneous Articles. 



ON THE LIQUEFACTION OF OZONE. 

 BY P. HAUTEFEUILLE AXD J. CHAPPUIS. 



]V I CAILLETET having placed at our disposal the apparatus 

 -^-*- • he has set up at the Ecole Xonnale for the liquefaction of 

 ethylene, as well as the whole arrangement which he employs 

 in order to study the changes of state of what are called the per- 

 manent gases, we hare been able to complete our first experiments 

 upon the liquefaction of ozone. 



The study of the conditions under which a sudden expansion 

 determines the formation of a mist in a mixture of oxygen and 

 ozone has permitted us to establish that pure ozone is less easily 

 liquefied than carbonic acid ; the addition of carbonic acid to that 

 mixture furnishes by compression a liquid of a pale blue colour, 

 which coloration we attributed to ozone liquefied at the same time 

 as the carbonic acid. From all these facts we concluded that it was 

 possible to obtain ozone in a liquid form, and that that liquid would 

 be strongly coloured. 



Those deductions have just been fully confirmed by experiment ; 

 for we have obtained ozone in liquid drops of a deep indigo-blue 

 colour. This liquid has been preserved nearly thirty minutes under 

 a pressure of 75 atmospheres ; its vaporization is not very rapid, 

 even under the atmospheric pressure. 



The liquefaction was attained by compressing with about 125 

 atmospheres a mixture of oxygen and ozone contained in the test- 

 tube of M. Cailletet's apparatus, which is terminated by a capillary 

 tube recurved at its upper portion, permitting the descending 

 branch to be immersed in a jet of liquid ethylene, lowering its tem- 

 perature probably below —100°. When the gas operated on con- 

 tains not more than 10 per cent, by weight of ozone, the gas 

 compressed with 125 atmospheres is not perceptibly coloured in 

 the ascending branch, while the blue coloration is very distinct in 

 all the refrigerated portion of the capillary tube.' 



Does this coloration depend on the presence of a mixed liquid 

 formed of ozone and oxygen, or on that of a thin film of liquid 

 ozone lining the interior of the capillary tube ? The absence of a 

 distinct meniscus leaves this question undecided ; but, in favour of 

 the first of these hypotheses, we have noticed that the coloration 

 was not more intense in the lower than in the upper part of the 

 refrigerated tube, and that a sudden expansion does not determine 

 the formation of a mist, which so well indicates, in M. Cailletet's 

 experiments, the passage from the gaseous to the liquid state. 



The tube becomes instantaneously colourless in consequence of 

 the expansion, and contains in the thin part which terminates it a 

 liquid drop of a deep indigo-blue ; the ozone contained in the mix- 

 ture is almost all condensed in the sloping part ; for a fresh com- 

 pression with 125 atmospheres does not communicate to the tube 

 any appreciable coloration. 



