The ultra-violet rays are said to have a very beneficial effect upon the teeth. Experiments carried out in Paris, using a mercury vapour lamp as the source of light, show that discoloured teeth are whitened and given a pearly lustre by these rays, at the same time being sterilized so that they do not easily decay. The Röntgen rays are used for the treatment of lupus, and more particularly for deeper growths, such as tumours and cancers, for which the Finsen rays are useless, owing to their lack of penetrating power. The action of these two kinds of rays appears to be similar, but the X-rays are much the more active of the two.
Electricity is often applied to the body through water, in the form of the hydro-electric bath, and such baths are used in the treatment of different kinds of paralysis. Electric currents are used too for conveying drugs into the tissues of the body. This is done when it is desired to concentrate the drug at some particular point, and it has been found that chemicals can be forced into the tissues for a considerable distance.
Dr. Nagelschmidt, a great authority on medical electricity, has suggested the use of electricity for weight reducing. In the ordinary way superfluous flesh is got rid of by a starvation diet coupled with exercise, but in many cases excessively stout people are troubled with heart disorders and asthma, so that it is almost impossible for them to undergo the necessary muscular exertion. By the application of electric currents, however, the beneficial effects of the gentle exercise may be produced without any exertion on the part of the patient, and an hour’s treatment is said to result in a decrease in weight of from 200 to 800 grammes, or roughly 7 to 27 ounces.
CHAPTER XXVI
OZONE
The great difference between the atmospheric conditions before and after a thunderstorm must have been noticed by everybody. Before the storm the air feels lifeless. It does not satisfy us as we draw it into our lungs, and however deeply we breathe, we feel that something is lacking. After the storm the air is delightful to inhale, and it refreshes us with every breath. This remarkable transformation is brought about to a very large extent by ozone produced by the lightning discharges.
As far back as 1785 it was noticed that oxygen became changed in some way when an electric spark was passed through it, and that it acquired a peculiar odour. No particular attention was paid to the matter however until about 1840, when Schönbein, a famous German chemist, and the discoverer of gun-cotton and collodion, became interested in it. He gave this strange smelling substance the name of “ozone,” and he published the results of his experiments with it in a treatise entitled, “On the Generation of Ozone.” Schönbein showed that ozone could be produced by various methods, chemical as well as electrical. For instance, if a piece of phosphorus is suspended in a jar of air containing also a little water, in such a manner that it is partly in the water and partly out of it, the air acquires the characteristic smell of ozone, and it is found to have gained increased chemical energy, so that it is a more powerful oxidizing agent. For a long time the exact chemical nature of ozone could not be determined, mainly because it was impossible to obtain the substance in quantities sufficiently large for extensive experimental research, but also on account of its extremely energetic properties, which made it very troublesome to examine. These difficulties were so great that investigators were in doubt as to whether ozone was an element or a compound of two or more elements; but finally it was proved that it was simply oxygen in a condensed or concentrated state.
Apparently ozone is formed by the contraction of oxygen, so that from three volumes of oxygen two volumes of ozone are produced. In other words, ozone has one and a half times the density of oxygen. Ozone has far greater oxidizing power than oxygen itself; in fact it is probably the most powerful of all oxidizing agents, and herein lies its great value. It acts as nature’s disinfectant or sterilizer, and plays a very important part in keeping the air pure, by destroying injurious organic matter. Bacteria apparently have a most decided objection to dying; at any rate they take an extraordinary amount of killing. Ozone is more than a match for them however, and under its influence they have a short life and probably not a merry one.
Ozone exists naturally in the atmosphere in the open country, and more especially at the seaside. It is produced by lightning discharges, by silent electrical discharges in the atmosphere, by the evaporation of water, particularly salt water, by the action of sunlight, and also by the action of certain vegetable products upon the air. The quantity of ozone in the air is always small, and even pure country or sea air contains only one volume of ozone in about 700,000 volumes of air. No ozone can be detected in the air of large towns, or over unhealthy swamps or marshes. The exhilarating effects of country and sea air, and the depressing effects of town air, are due to a very large extent to the presence or absence of ozone.
A great proportion of our common ailments are caused directly or indirectly by a sort of slow poisoning, produced by the impure air in which we live and work. It is popularly supposed that the tainting of the air of rooms in which large numbers of people are crowded together is due to an excessive amount of carbonic acid gas. This is a mistake, for besides being tasteless and odourless, carbonic acid gas is practically harmless, except in quantities far greater than ever exist even in the worst ventilated rooms. The real source of the tainted air is the great amount of animal matter thrown off as waste products from the skin and lungs, and this tainting is further intensified by the absence of motion in the air. Even in an over-crowded room the conditions are made much more bearable if the air is kept in motion, and in a close room ladies obtain relief by the use of their fans. What we require, therefore, in order to maintain an agreeable atmosphere under all conditions, is some means of keeping the air in gentle motion, and at the same time destroying as much as possible of the animal matter contained in it. Perhaps the most interesting and at the same time the most scientific method of doing this is by ozone ventilation.
In the well-known “Ozonair” system of ventilation, ozone is generated by high-tension current. Low-tension current is taken from the public mains or from accumulators, and raised to a very high voltage by passing it through a step-up transformer. The secondary terminals of the transformer are connected to a special form of condenser, consisting of layers of fine metal gauze separated by an insulating substance called “micanite.” The high tension between the gauze layers produces a silent electrical discharge or glow. A small fan worked by an electric motor draws the air over the condenser plates, and so a certain proportion of the oxygen is ozonized, and is driven out of the other side of the apparatus into the room. The amount of ozone generated and the amount of air drawn over the condenser are regulated carefully, so that the ozonized air contains rather less than one volume of ozone in one million volumes of air, experiment having shown that this is the most suitable strength for breathing. Ozone diluted to this degree has a slight odour which is very refreshing, and besides diminishing the number of organic germs in the air, it neutralizes unpleasant smells, such as arise from cooking or stale tobacco smoke. Ozone ventilation is now employed successfully in many hotels, steamships, theatres and other places of entertainment, municipal and public buildings, and factories.