A balloon of similar capacity to the one above mentioned was charged as strongly as possible with ozone, and afterwards washed with water. The same piece of flesh was suspended within it; and the opening being carefully closed, it was left inside for nine hours before the air of the balloon presented the least odour of putrefaction. The air was tested every thirty minutes by an ozonometer, and the proportion of ozone found to be gradually diminishing; but as long as the paper of the instrument exhibited the slightest trace of blue, there was no smell, which only came on as the last signs of ozone disappeared. Thus, all the miasm given off by the piece of flesh during nine hours was completely neutralised by the ozone with which the balloon had been impregnated, so small in quantity as to be but the 6000th part of a gramme. One balloon filled with ozonified air, would suffice to disinfect 540 balloons filled with miasmatic air. 'These considerations,' says M. Schoenbein, 'shew us how little the miasma of the air are to be appreciated by weight, even when they exist therein in a quantity very sensible to the smell, and how small is the proportion of ozone necessary to destroy the miasm produced by the putrefaction of organic substances, and diffused through the atmosphere.' The presence of ozone in any vessel or in the atmosphere, may be detected by a test-paper which has been moistened with a solution composed of 1 part of pure iodide of potassium, 10 parts of starch, and 100 parts of water, boiled together for a few moments. Paper so prepared turns immediately blue when exposed to the action of ozone, the tint being lighter or darker according to the quantity. Schoenbein's ozonometer consists of 750 slips of dry bibulous paper prepared in the manner described; and with a scale of tints and instructions, sufficient to make observations on the ozone of the atmosphere twice a day for a year. After exposure to the ozone, they require to be moistened to bring out the colour. M. Schoenbein continues: 'We must admit that the electric discharges which take place incessantly in different parts of the atmosphere, and causing therein a formation of ozone, purify the air by this means of organic, or, more generally, oxidizable miasma; and that they have thus the important office of maintaining it in a state of purity suitable to animal life. By means of atmospheric electricity, and, indirectly, nature thus attains on a great scale the object that we sometimes seek to accomplish in a limited space by fumigations with chlorine.