CHEMICAL SCIENCE. 237 



which the atmosphere containing it possessed. When electricity is 

 produced from a powerful machine, and allowed to be discharged by a 

 point, there is a feeling of a current or aura as of vapor escaping, and 

 at the same time a remarkable odor. If, during the passage of the 

 electricity, a piece of paper, moistened with a solution of iodide of 

 potassium and starch, be brought near, the discharge causes the pro- 

 duction of blue iodide of farina. The blue color thus produced is the 

 result of the oxidation of the potassium by the ozone, and the setting 

 free of the iodine. This is one of the best tests of the presence of ozone. 

 It was formerly supposed that nitric acid was produced by the dis- 

 charge of the spark, and that the decomposition of the iodide was 

 occasioned by this acid as a result of the union of oxygen with 

 nitrogen in the air ; but this theory will not account for the smell 

 and other properties of this extraordinary agent. Schonbein produces 

 ozone in very large quantities by introducing into capacious bottles, 

 with glass stoppers, pieces of cut and cleanly scraped phosphorus, 

 with a small quantity of water, so that the phosphorus may be partly 

 in and partly out of the liquid. A vapor slowly rises in a current. 

 After ten or twelve minutes the ozone is produced, and may be procured 

 in a mixture with oxygen and nitrogen by removing the phosphorus 

 at a water-bath, and thoroughly washing the interior of the bottle with 

 water, in which ozone is insoluble. This body is thus separated from 

 the vapor of phosphorus and phosphorus acid. 



A remarkable property possessed by ozone is its bleaching power. 

 Some ounces of a solution of indigo being poured into a bottle contain- 

 ing ozone, and shaken, the color is as completely destroyed as if chlo- 

 rine was present. A very small quantity of ozone would thus entirely 

 discharge the color of a very large quantity of sulphate of indigo. It 

 has already been stated to be so little soluble in water, that a bottle 

 containing it may be repeatedly rinsed with water without losing its 

 ozone contents. If, however, the stopper be removed, and it is exposed 

 to the air, it soon passes off. Ozone appears to be entirely destroyed 

 by heat ; or, at any rate, its production by electricity ceases when 

 sparks are received from a red-hot metallic point. This fact was in- 

 geniously illustrated by insulating a small galvanic battery, capable 

 of raising at pleasure a platina ball to full redness ; the battery was 

 made part of the machine, and the platina ball the terminal point from 

 which the discharges of electricity were received. The machine was 

 set to work, and it was clearly and distinctly proved by Prof. Faraday 

 that the discharges from the red-hot platina ball produced neither the 

 aura, the smell, nor the decomposing effects on iodide of potassium and 

 starch, which were immediately manifested when the ball was allowed 

 to cool, and the electric fluid was then passed through it. The oxidiz- 

 ing properties of ozone are indicated upon metals which in practice it 

 is rather difficult to convert to oxides namely, silver. A piece of pol- 

 ished silver had been placed in a bottle of ozone for several hours, and 

 had acquired a distinctly brown tarnish, not from sulphur, but from a 

 process of ozonation, or, in other words, oxidation. Polished lead simi- 

 larly treated was also oxidized. Ozone had always a tendency to bring 

 metals and metallic oxides to their highest degree of oxidation. la 



