Schonbein, the discoverer of ozone, found that when strips of paper previously saturated with starch and iodide of potassium and dried were exposed freely to the air but protected from rain and the direct action of the sun, they underwent a peculiar discoloration (when immersed in water) after an exposure of 24 hours. A scale of tints numbered from one to ten afforded the means of comparative observation, and thus the Ozonometer was constructed, and a means established of registering the amount of ozone in the air of various localities from day to day.
Schonbein also observed that the proportion of ozone was largely augmented after heavy falls of snow. For the exposure of the ozone papers, an ozone cage is employed, as shown at Fig. 67.
67.
Ozone Cage.
Scale about 1/6.
Ozone may be prepared artificially as a disinfectant by cautiously mixing without friction or concussion equal parts of peroxide of manganese, permanganate of potash, and oxalic acid. For a room containing 1,000 cubic feet, two teaspoonfuls of the powder, placed in a dish and moistened with water occasionally, will develop the ozone and disinfect the surrounding air without producing cough.
The most important and interesting series of facts, however, connected with ozone are those established by the researches of M. Houzeau, who states:—
1. That country air contains an odorous oxidizing substance, with the power of bleaching blue litmus, without previously reddening it, of destroying bad smells, and of bluing iodized red litmus.
2. That this substance is ozone.
3. That the amount of ozone in the air at different times and places is variable, but this is at most 1/700,000 of its volume, or 1 volume of ozone in 700,000 of air.
4. That ozone is found much more frequently in the country than in towns.