THE MAKING OF OZONE AS A LABORATORY EXERCISE The purpose of this article is to describe the construction of an ozonizer that can be made by the student in the laboratory thus enabling him to make ozone, and a t the same time supplement the time-honored sulfur exercise to illustrate allotropism. The accompanying figures are selfexplanatory. The bottle B is filled with oxygen collected in the usual way over water, using sodium peroxide. (Potassium chlorate will not serve the purpose on account of impurities in the gas generated.) Cork A is inserted, and the wires C,C' brought in contact with wires from an induction coil for from 5 to 10 seconds. The presence of ozone can be proved by the odor, by the starch-iodide test, and by the blackening effect on a silver coin. The material needed by the student for these ozonizers is readily available in the laboFromi 1 Frouna 2 ratory except possibly the two A-2-hole rubbe cork straight pieces of copper wire. B-Wide-mouthed bottle The coustruction of the ozoC,C'-No. 16 bare copper wire T-Glass tube nizer, the setting up of the -lass tube, closed at lower end. (In the sodium peroxide oxygen gen- jimplified form, Figure 2. G is left open, and wires shortened to prevent sparking.) erator, the making of t h e theR,R'-Rubber bands, cut from rubber tubing starch-iodide solution. etc.. afford a pleasing and a profitable laboratory exercise. One induction coil (a Ford coil works nicely) placed on a side-shelf with the secondary wires arranged so the wires C,Cf may be easily placed in contact will serve an ordinary laboratory section. The presence of moisture does not interfere when the bottleis filled with pure oxygen, but when air is used the bottle should be dry and the current passed for 15 to 20 seconds for best results. Figure 2 illustrates a simplified form of apparatus which may be thrust through a hole in a cardboard placed over a bottle of oxygen or air.
