238 ANNUAL OP SCIENTIFIC DISCOVERY. 



this respect it was the most powerful oxidizer that was known. A tube 

 containing several rings of metallic arsenic had been placed for a short 

 time in a bottle of ozone. The metal had entirely disappeared, and 

 had become transformed into arsenic acid. Paper wet with a solu- 

 tion of proto-sulphate of manganese was introduced into a bottle of 

 freshly prepared ozone, and, in the course of a short time, black spots 

 appeared over the surface, proving that the manganese had" passed 

 to a higher degree of oxidation. Nitrogen and sulphur are easily 

 oxidized by it. Schonbein succeeded in procuring a quantity of 

 nitre by the agency of ozone in contact with nitrogen and potassa. 

 Sulphur was also converted to sulphuric acid. Paper stained with 

 sulphuret of lead was immediately bleached when exposed to an ozonic 

 atmosphere. Some curious experiments of Schonbein's were shown, in 

 which portraits and inscriptions were seen in white letters on a dark 



f round, as a result of placing stencilled metallic plates on papers which 

 ad been exposed to light and air, or insulated. The result was that 

 in these spots the sulphuret of lead had entirely disappeared, having 

 been converted to colorless sulphate of lead by the oxodizing action of 

 ozone. The alleged bleaching properties of solar light on colored arti- 

 cles are thus probably due to the agency of ozone in other words, to 

 a process of oxidation and alteration of color. Sulphuretted hydrogen 

 and all foul effluvia are speedily oxidized and destroyed by ozone. It 

 is, therefore, the great purifier of the air ; and owing to its continued 

 exhaustion by oxidating processes, it is difficult to discover the pres- 

 ence of ozone in large and populous places or in close and crowded 

 dwellings. In the open air of the country, and on the sea, it constantly 

 exists in a proportion which is probably subject to great variations, al- 

 though ruled by laws which are at present unknown. Schonbein has 

 contrived an Ozonometcr for testing the amount contained in air. It 

 is prepared by immersing paper in a solution made of one grain of 

 iodide of potassium, ten grains of starch, and two hundred grains of 

 water. The paper is dried, and, when intended for use, is exposed 

 for some time to the air. There is no change until it is wet with 

 water, when, if ozone was present in air to which it had been exposed, a 

 blue color will appear, the intensity of which varies according to the 

 quantity of ozone present and the length of exposure. The ozonometer 

 consists of a series of papers thus colored in different degrees, and bears 

 some analogy to the cyanometer long since proposed by Humboldt. 



Prof. Faraday stated that he had detected ozone in the currents of 

 air coining over the sea near Brighton. When he examined the cur- 

 rents of air coming over the town, no ozone could be detected, but 

 when he again returned to the windward side, and received the air 

 before it reached the town, ozone was distinctly manifested. It was 

 thus established that in populous places there was a constant con- 

 sumption of this principle. As the working of the electrical machine 

 produces ozone, so does the current generated from a galvanic battery. 

 It is also evolved in numerous chemical processes. If pure ether, 

 mixed with water, be introduced into a wide-mouthed bottle, and the 

 vapor allowed to become diffused, it will afford none of the reactions 

 for ozone. But if a glass rod be made hot in the flame of a spirit 



