body for disease germs, and in addition because they lay bare nerve tissue which thereby becomes irritated and causes a shock to the entire system.
In mild burns, where the skin is not broken but is merely reddened, an application of moist baking soda brings immediate relief. If this substance is not available, flour paste, lard, sweet oil, or vaseline may be used.
In more severe burns, where blisters are formed, the blisters should be punctured with a sharp, sterilized needle and allowed to discharge their watery contents before the above remedies are applied.
In burns severe enough to destroy the skin, disinfection of the open wound with weak carbolic acid or hydrogen peroxide is very necessary. After this has been done, a soft cloth soaked in a solution of linseed oil and limewater should be applied and the whole bandaged. In such a case, it is important not to use cotton batting, since this sticks to the rough surface and causes pain when removed.
45. Carbon Dioxide. A Product of Burning. When any fuel, such as coal, gas, oil, or wood, burns, it sends forth gases into the surrounding atmosphere. These gases, like air, are invisible, and were unknown to us for a long time. The chief gas formed by a burning substance is called carbon dioxide (CO2) because it is composed of one part of carbon and two parts of oxygen. This gas has the distinction of being the most widely distributed gaseous compound of the entire world; it is found in the ocean depths and on the mountain heights, in brilliantly lighted rooms, and most abundantly in manufacturing towns where factory chimneys constantly pour forth hot gases and smoke.
Wood and coal, and in fact all animal and vegetable matter, contain carbon, and when these substances burn or decay, the carbon in them unites with oxygen and forms carbon dioxide.
The food which we eat is either animal or vegetable, and it is made ready for bodily use by a slow process of burning within the body; carbon dioxide accompanies this bodily burning of food just as it accompanies the fires with which we are more familiar. The carbon dioxide thus produced within the body escapes into the atmosphere with the breath.
We see that the source of carbon dioxide is practically inexhaustible, coming as it does from every stove, furnace, and candle, and further with every breath of a living organism.
46. Danger of Carbon Dioxide. When carbon dioxide occurs in large quantities, it is dangerous to health, because it interferes with normal breathing, lessening the escape of waste matter through the breath and preventing the access to the lungs of the oxygen necessary for life. Carbon dioxide is not poisonous, but it cuts off the supply of oxygen, just as water cuts it off from a drowning man.
Since every man, woman, and child constantly breathes forth carbon dioxide, the danger in overcrowded rooms is great, and proper ventilation is of vital importance.
47. Ventilation. In estimating the quantity of air necessary to keep a room well aired, we must take into account the number of lights (electric lights do not count) to be used, and the number of people to occupy the room. The average house should provide at the minimum 600 cubic feet of space for each person, and in addition, arrangements for allowing at least 300 cubic feet of fresh air per person to enter every hour.
In houses which have not a ventilating system, the air should be kept fresh by intelligent action in the opening of doors and windows; and since relatively few houses are equipped with a satisfactory system, the following suggestions relative to intelligent ventilation are offered.
1. Avoid drafts in ventilation.
2. Ventilate on the sheltered side of the house. If the wind is blowing from the north, open south windows.
48. What Becomes of the Carbon Dioxide. When we reflect that carbon dioxide is constantly being supplied to the atmosphere and that it is injurious to health, the question naturally arises as to how the air remains free enough of the gas to support life. This is largely because carbon dioxide is an essential food of plants. Through their leaves plants absorb it from the atmosphere, and by a wonderful process break it up into its component parts, oxygen and carbon. They reject the oxygen, which passes back to the air, but they retain the carbon, which becomes a part of the plant structure. Plants thus serve to keep the atmosphere free from an excess of carbon dioxide and, in addition, furnish oxygen to the atmosphere.
49. How to Obtain Carbon Dioxide. There are several ways in which carbon dioxide can be produced commercially, but for laboratory use the simplest is to mix in a test tube powdered marble, or chalk, and hydrochloric acid, and to collect the effervescing gas as shown in Figure 24. The substance which remains in the test tube after the gas has passed off is a solution of a salt and water. From a mixture of hydrochloric acid (HCl) and marble are obtained a salt, water, and carbon dioxide, the desired gas.
50. A Commercial Use of Carbon Dioxide. If a lighted splinter is thrust into a test tube containing carbon dioxide, it is promptly extinguished, because carbon dioxide cannot support combustion; if a stream of carbon dioxide and water falls upon a fire, it acts like a blanket, covering the flames and extinguishing them. The value of a fire extinguisher depends upon the amount of carbon dioxide and water which it can furnish. A fire extinguisher is a metal case containing a solution of bicarbonate of soda, and a glass vessel full of strong sulphuric acid. As long as the extinguisher is in an upright position, these substances are kept separate, but when the extinguisher is inverted, the acid escapes from the bottle, and mixes with the soda solution. The mingling liquids interact and liberate carbon dioxide. A part of the gas thus liberated dissolves in the water of the soda solution and escapes from the tube with the outflowing liquid, while a portion remains undissolved and escapes as a stream of gas. The fire extinguisher is therefore the source of a liquid containing the fire-extinguishing substance and further the source of a stream of carbon dioxide gas.
51. Carbon. Although carbon dioxide is very injurious to health, both of the substances of which it is composed are necessary to life. We ourselves, our bones and flesh in particular, are partly carbon, and every animal, no matter how small or insignificant, contains some carbon; while the plants around us, the trees, the grass, the flowers, contain a by no means meager quantity of carbon.
Carbon plays an important and varied role in our life, and, in some one of its many forms, enters into the composition of most of the substances which are of service and value to man. The food we eat, the clothes we wear, the wood and coal we burn, the marble we employ in building, the indispensable soap, and the ornamental diamond, all contain carbon in some form.
52. Charcoal. One of the most valuable forms of carbon is charcoal; valuable not in the sense that it costs hundreds of dollars, but in the more vital sense, that its use adds to the cleanliness, comfort, and health of man.
The foul, bad-smelling gases which arise from sewers can be prevented from escaping and passing to streets and buildings by placing charcoal filters at the sewer exits. Charcoal is porous and absorbs foul gases, and thus keeps the region surrounding sewers sweet and clean and free of odor. Good housekeepers drop small bits of charcoal into vases of flowers to prevent discoloration of the water and the odor of decaying stems.
If impure water filters through charcoal, it emerges pure, having left its impurities in the pores of the charcoal.
