=Illuminating Gas.=--Many persons die every year by inhaling illuminating gas. People unacquainted with the use of gas fixtures often blow out the light instead of turning the key. A prevailing custom in some families is to keep the light burning low during the night. A variation of pressure in the pipes, or a sudden draught of air, extinguishes the slender flame, and gas escapes into the room, often with fatal results. Leaky pipes or faulty fixtures may have the same effect. If the key be loose, tighten the screw that holds it in place. If there is a leak in the pipe or joint, which may be determined by applying a match, a gas-fitter should at once be summoned. Delay is dangerous and may prove fatal. If a room be heavily charged with gas, get the windows and doors open as soon as possible. Do not go near with a light, lest an explosion follow. Naphtha and benzine are also highly explosive. When either is used to clean clothing, the work should be done in the open air, and never where the fumes may come in contact with the fire of stove or range, or with the flame of candle or lamp. Gas burners, oil lamps, sperm candles, all forms of illuminants, consume the oxygen of a room and increase the carbonic acid. An oil lamp of ordinary dimensions gives off as much carbonic acid as an adult person. A man, seated in a room of moderate dimensions and using a good oil lamp, will require 6,000 cubic feet of fresh air every hour in order to keep the air from becoming vitiated beyond the point of wholesomeness. Gas from coal, coke, or charcoal fires is as dangerous as illuminating gas. Heaters, ranges, stoves, and furnaces should be kept in complete order, so that no gas shall escape. Its entrance into a bedroom is often so stealthy as to stupefy the unconscious sleeper and destroy life without awakening him. =Sewer Gas.=--Of all forms of vitiated air in cities, none is responsible for such serious derangement of health as that which is polluted by the air or gas from sewers and waste pipes. Some physicians and sanitarians hold that sewer air is often the direct cause of typhoid fever, scarlet fever, diphtheria, and cholera. Others maintain that the sewers and pipes furnish favorable breeding places for the germs of these diseases, which germs are carried through the air and produce their effects. The important matter is to keep the waste pipes flushed and well trapped. Some precautions against sewer gas are treated in the chapter on Dwellings. =Influence of Climate and Temperature.=--Diarrhœal diseases, both of adults and children, are most frequent during hot weather. In July, August, and September there are from ten to twelve times as many cases as at other seasons of the year. Proper diet and suitable clothing will go far toward protecting the individual from the ill effects of climate and season.