OZONE.
The Greek language has again been selected by the discoverer, Schönbein, of Basle, for the title or name of this curious modification of oxygen, and it is so termed from οξειν, to smell. The name at once suggests a marked difference between ozone and oxygen, because the latter is perfectly free from odour, whilst the former has that peculiar smell which is called electric, and is distinguishable whenever an electrical machine is at work, or if a Leyden jar is charged by the powerful Rhumkoff, or Hearder coil; it is also apparent when water is decomposed by a current of electricity and resolved into its elements, oxygen and hydrogen. When highly concentrated it smells like chlorine; and the author recollects seeing the first experiments by Schönbein, in England, at Mr. Cooper's laboratory in the Blackfriars-road. Ozone is prepared by taking a clean empty bottle, and pouring therein a very little distilled water, into which a piece of clean scraped phosphorus is introduced, so as to expose about one-half of its diameter to the air in the bottle, whilst the other is in contact with the water. (Fig. 104.)
For the sake of precaution, the bottle may stand in a basin or soup plate, so that if the phosphorus should take fire, it may be instantly extinguished by pouring cold water into the bottle, and should this crack and break, the phosphorus is received into the plate.
Fig. 104.
a. A quart bottle, with the stopper loosely placed therein. b. The stick of clean phosphorus. c. The water level just to half the thickness of the phosphorus. d d. A soup-plate.
When the ozone is formed the phosphorus can be withdrawn, and the phosphorous-acid smoke washed out by shaking the bottle; it is distinguishable by its smell, and also by its action on test paper, prepared by painting with starch containing iodide of potassium on some Bath post paper; when this is placed in the bottle containing ozone, it changes the test blue, or rather a purplish blue.
Ozone is a most energetic body, and a powerful bleaching agent; if a point is attached to the prime conductor of an electrical machine, and the electrified air is received into a bottle, it will be found to smell, and has the power of bleaching a very dilute solution of indigo. Ozone is not a mere creation of fancy, as it can not only be produced by certain methods, but may be destroyed by a red heat. If a point is prepared with a loop of platinum wire, and this latter, after being connected with a voltaic battery, made red hot, and the whole placed on an insulating stool, and connected with the prime conductor of an electrical machine, it is found that the electrified air no longer smells, the ozone is destroyed; on the other hand, if the voltaic battery is disconnected, and the electrified air again allowed to pass from the cold platinum wire, the smell is again apparent, the air will bleach, and if caused to impinge at once upon the iodide of starch test, changes it in the manner already described. (Fig. 105.)
Fig. 105.