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USEFUL INFORMATION FOR AUTO REPAIRMEN.
Anti-Freezing Cooling Solutions–Substances Usually Combined with Water
Advantages of Different Solutions—Electrolytic Action Not Desirable The Best Mixture—Extinguishing Fires in Volatile Liquids—First Aid to the Injured—Schaefer Method of Artificial Respiration—The Repair Shop Medicine Chest-Remedy for Burns, Cuts and Abrasions-Wounds and Painful Injuries-Home-made Aseptic Gauze.
Anti-Freezing Cooling Mediums.-To lower the freezing point of water it is possible to add various substances and the proportions added determine the point at which the solution will congeal. Among the materials commonly used may be mentioned commen salt, alcohol, glycerine and calcium chloride. The alkaline solutions produce a distinct electrical action wherever two dissimilar metals are used together in the cooling system, such as the brass tubing of a radiator and the solder used at the joints; the cast iron water jacket and the aluminum or brass plates used to close the core print holes; the aluminum pump casing and steel or bronze impeller, and at many other points which will vary with the design of the car and the materials of the components. The alcohol solutions evaporate very quickly, the glycerine solution affects the rubber hose, and the salt solutions leave an incrustation as the water evaporates. It is reasonable to expect electrolytic action when metals of different potential are used together in any alkaline solution, which are electrolytes of high value. Taking it all in all, the selection of the best solution involves a consideration of many facts and various requirements must be considered in the selection of that most suitable. Considering the qualities of such a compound it will be seen that no one will combine all the desirable features, so in selecting the solutions the following should be kept in mind: To begin with, and it is a highly important consideration, the solution used should have no corrosive action, nor should its use prove deleterious on the metals or rubber used in the circulating system. It must be easily dissolved in or combined with water, must be reasonably cheap and not subject to rapid waste by evaporation, and should not be of such character that it will deposit sediment or foreign matter in the jackets, pipes or radiator water spaces. Its boiling point should be as high, if not higher than, that of water, and it should not congeal at temperatures ordinarily met with where it is used.
Substances Usually combined with Water.-Alcohol is prepared by destructive distillation of various vegetable substances which contain starch or sugar, such as potatoes, beets and numerous grains and fruits. Any starchy material will serve for the production of alcohol and the real question is one of cost, which varies with the locality in which the manufacture is carried on. It mixes readily with water, and does not congeal at any known temperature, though its boiling point is about 175 degrees Fahrenheit, and above this point evaporation is rapid. It is a very volatile liquid and will evaporate at very moderate temperatures. The alcohol generally used is denatured by the addition of a substance which renders it unfit for drinking purposes and because of the recent removal of the government tax it may be obtained for about 60 cents a gallon.
Glycerine is obtained as a by-product in the saponification of fats in soap and candle making, and is an oily substance which will vary in color from reddish brown when crude to a colorless liquid when pure. Crude glycerine sometimes contains free acids in small quantities though it may be purified and the color removed when it is to be used for certain purposes. This substance has a much higher boiling point than water, ebullition taking place at a temperature of 554 degrees Fahrenheit. Glycerine when pure is a sweet, colorless liquid and is mixable with water and alcohol in any proportion. It is most largely used in the manufacture of nitroglycerine, though utilized to some extent in pharmacy, soapmaking, filling instruments which require a liquid seal and which are exposed to low temperatures, and sweetening wine. It can be obtained in single gallon lots at a cost about $1.50.
Calcium chloride is a by-product of the Weldon process of obtaining chlorine which is to be incorporated into bleaching powder, from manganese re and hydrochloric acid. It is a salt and is produced in the form of crystals, the crude material being yellowish white in color, though after purification it is clear white. It may be obtained directly from marble or chalk by dissolving these materials in hydrochloric acid. It is comparatively cheap and may be obtained in 10 pound sheet iron drums at nine cents per pound. Chemically pure its cost will vary from 30 to 60 cents per pound. It is very soluble in water, and while it is in solution it will lower the freezing point. It may contain free acid in the crude form, though this may be neutralized by the addition of a little slaked lime. Water will be evaporated rapidly at temperatures in excess of 185 degrees and salt will remain in the form of crystals. While calcium chloride solutions have been very popular they are not so well thought of at the present time because of a certain electrical action which is set up when the water circulation system is composed of dissimilar metals, as is commonly the case in motor car construction and corrosion at the points of juncture is unavoidable. As hydrochloric acid is used when this salt is obtained, there may be some free acid in combination with the cruder grades, and corrosive action will be noted. The corrosive action of chemically pure salt is very slight, though electrical action will be noted if dissimilar metals are employed, regardless of the purity of the salt in the solution.
Advantages of Different Solutions. The substances previously discussed all have advantages, some as relates to first cost. others to freedom from trouble. Alcohol is without doubt the best material to use from the viewpoint of action on metal or rubber, as it does not form deposits of foreign matter, will not freeze at known temperatures, and has no electrical effect. It is extremely volatile, however, and because of its low boiling point will evaporate at temperatures much less than that of the boiling point of water, and the solution in the water circulation system of the modern motor car often heated to this point, especially when the natural system of water circulation is employed. Combinations of water, alcohol and glycerine have been tried, and have given excellent results. The addition of the glycerine to a water-alcohol solution reduces liability of evaporation to a large extent and increases the boiling point. Glycerine and water solutions were formerly considered favorably, but of late have been abandoned because of certain strong disadvantages. Crude glycerine often contains free acid, and in many cases, if no free acid is found, it may break down when exposed to heat, and liberate fatty acids, which are found combined with other elements in all fats and oils of animal or vegetable origin. While this acid may not attack metals to any appreciable extent, still its presence in the cooling system is not desirable. Glycerine, as is true of most oils, has a destructive effect on rubber hose and gaskets, and should not be used in large proportions on any car where much of the piping system is of rubber hose. Glycerine is expensive and is liable to decompose under the influence of heat, and as the proportions used with water are larger than is necessary with other substances, these solutions are being replaced with alcohol, water and glycerine compounds, which are most satisfactory in ordinary practice.
Positive Proof of Electrical Action. To demonstrate that with saline solutions a certain amount of electrical action was unavoidable, the writer made a series of tests in which a number of pairs of dissimilar metals were placed in calcium chloride solution and a low reading voltmeter interposed in the circuit showed voltage ranging from one-fifth to one-half volt, depending upon the metals used, the strength of the solution and the temperature. The electrical action in every case was greater as the temperature was increased. Extreme care was taken in making these tests, and the results obtained were carefully checked by another series of tests with the same metals and fresh solutions. The solution used was the weakest of the calcium chloride and water combinations, and was made of two pounds of salt to a gallon of liquid. This solution has a freezing point of 18 degrees F., only a few degrees lower than plain water. With zinc and copper the current indication was two-fifths of a volt, just half as much energy as obtained with salammoniac, a recognized electrolyte, in previous test. The temperature was about 68 degrees Fahrenheit. Copper and cast iron showed more energy than when the same elements were immersed in standard electrolyte, namely, three-tenths of a volt. Copper and solder showed the same as when sal-ammoniac was used, the indication being one-fifth volt. When aluminum and cast iron were tested the indication was less than one-tenth volt. Aluminum and brass produced one-fifth volt, brass and solder one-tenth volt and brass and cast iron one-tenth volt. This electrolyte is the weakest of the calcium chloride solutions which have been advised by men who know, for use in the circulation system. Its suitability for the purpose is left to the reader's judgment.
The results with the stronger solution were about the same, the only difference noted being that the needle moved over further with each stronger solution, though it settled to about the same reading as with the weaker solution for the same elements. All the elements were tested in four different mixtures and results carefully noted. To test the effect of increased temperature on current production, four ounces of the strong solution, that of five pounds calcium chloride to the gallon of water, was heated to 180 degrees Fahrenheit, a temperature slightly less than its boiling point, and the zinc and copper elements placed in the jar and a reading taken. While the reading at 70 degrees Fahrenheit was two-fifths volt, at the higher temperature the indication of the needle was threefifths volt, almost as much as obtained with the regular sal-ammoniac solution at normal temperatures.
Electrolytic Action Not Desirable.- Where there is electrical action there is also corrosion and deterioration of the metal which acts as the negative element. While it is true that the current produced between the metals falls off in pressure because of polarization of the positive element, it must be considered that the constant circulation of the solution through the jacket and piping must to a certain extent act as a depolarizer because of agitation of the liquid, which has a tendency to keep the surface of the positive element free from gas bubbles. It is reasonable to assume that there will be a continued electrical action all the time that the solution is in a cooling system, though at times this may be very slight. To be sure that the action was caused by the calcium chloride alone