CHEMICAL SCIENCE. 223 



OZONE AND TUE ATMOSPHERE. 



An important contribution to our knowledge of ozone, and its relations 

 to the atmosphere and to electrical phenomena, has recently been made 

 by Dr. G. Meissner of Gottingen. From an abstract of these researches, 

 given in S Hitman's Journal, (May and July numbers, 1864,) by Prof. 

 S. W. Johnson, and to which we would refer our readers, we derive the 

 following curious information respecting the formation of clouds and mists. 

 Meissner's researches confirm the theory of the vesicular nature of mist. 

 He has also discovered, by experiment, that while it is easy to condense 

 moisture from any moist gas or gaseous mixture by cold or rarefaction, 

 it is impossible to produce, a mist unless the gas is oxyyen, or contains 

 this element. The water condensed by artificial means from pure oxygen 

 or from the atmospheric air always exhibits the character of a cloud; 

 that, separated from other gases or mixtures free of oxygen, always as- 

 sumes directly the form of rain. Where oxygen is present, the water 

 condenses in vesicles; in other cases, in solid drops. Meissner states, 

 further, that air saturated with moisture gives a cloud on sudden rare- 

 faction until the pressure is reduced to about eight inches of barometric 

 pressure. At this levity the cloud is, however, extremely delicate and 

 transitory, and under a less pressure no cloud could be produced. This 

 stand of the barometer corresponds to a hight in the atmosphere, above 

 tide-level, of 27,000 feet. According to Ivar.it z, the lightest and highest 

 clouds, cirrhi, are formed at an average altitude of 20,000, and a greatest al- 

 titude of 24,000 feet. The densest artificial cloud is formed in the densest 

 air, and the heaviest cumuli are formed within o,000 feet from the sea-level. 



THE INFLUENCE OF OZONE ON VEGETATION. 



The influence of ozone on vegetation has been studied by Mr. Carey 

 Lea, of Philadelphia, and the results reported in the American Journal 

 of Science. Two sets of experiments were made. In the first, the 

 water with which the seeds came in contact was made to contain those 

 Solid substances which are most essential to vegetation. In the second, 

 very pure river water was used. For the first, phosphate of soda, silicate of 

 potash, sulphate of magnesia, nitrate of lime, and sesquichloride of iron 

 were added to water in a proportion such as to be equivalent to -fa of 

 one per cent of solid matter. In order to afford a just term of compar- 

 ison, two vessels every way similar were filled with this prepared water, 

 were covered with gauze, so that the gauze should rest on the surface of 

 the water, and were placed under bell-glasses resting on glass plates. 

 Wheat and maize grains were placed on this gauze, and beneith one bell- 

 glass was introduced the ozone generating mixture. On the 12th day 

 the experiment was terminated. The average hight of the wheat plants 

 not exposed to the ozone was 10 inches, of those exposed 4 inches. 

 The effect of ozone in checking the growth of the roots was very re- 

 markable, especially with the wheat plants. In those not exposed to 

 ozone the roots attained a length equal to about ^ of tiie hight of the 

 stem. In those exposed to it the roots, after starting, almost imme- 

 diately ceased to grow. The strongest plant attained a hight of 6 inches, 

 and developed 6 rootlets, averaging only ^ of an inch in length; while 

 those not exposed to ozone had many roots exceeding 2 inches. As 



