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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

and not acid in solution the various solutions were carefully tested with litmus paper for acid without detecting the minutest trace. Then for the purpose of testing the litmus paper a single drop of hydrochloric acid placed in the solution turned the blue litmus to a light pink, proving conclusively that the test paper was of proper strength. Then consider that all the time the engine is in operation the temperature is nearly to the boiling point of the solutions, in some cases more, and it will be seen that the degree of electrical activity is considerably increased.

The cellular cooler is composed of innumerable soldered joints and at every one of these there will be a certain amount of electrical action, which in the aggregate will amount to a considerable current. At various other points of the cooling system, wherever there is two unlike metals in combination, we have other small currents, which decompose their quota of metal and assist in filling the system with sediment and foreign matter, not to mention the salt crystals which will be formed as the solution evaporates. The writer does not claim that the test showed absolute results, but they demonstrated that without doubt electrical action does exist when solutions of calcium chloride or any other salt are used to prevent freezing.

The Best Mixture.—Plain water and alcohol solutions would be the best were it not for the ease with which such compounds boil and the rapidity with which they evaporate. We have seen that the objections advanced against calcium chloride solution have ample foundation and that such compounds are not suitable for use, the chief advantage, that of cheapness, having been eliminated by the reduction in the price of denatured alcohol. The addition of a little glycerine to an alcohol and water solution reduces liability of evaporation, and when used in such quantities it has no injurious effect to speak of on rubber hose. The tables show the combinations and their freezing points and the proper proportions of the mixtures used must, of course, be governed by conditions of locality, but it is better to be safe than sorry, and make the solutions strong enough for the extremes that may be expected. The writer has used both alcohol and water, and glycerine, alcohol and water solutions, with good results, though considerable trouble

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has already been expe. rienced when saline solutions were employed.

Oils of various kinds have been recommended, these being of the character often used in lubricating icemaking machinery, and ma de especially to withstand low temperatures. Such oils will not absorb heat as well as water and should be used only where exceptionally good meth. ods of cooling are provided, such as a large radiator, all metal piping and positive pump. This oil will attack rubber hose, however, and it would seem, all things considered, alcohol solutions are preferable to all others.

The following tabulaFig. 465.—Special Testing Hydrometer for De- tions give the relative

termining Density of Alcohol-Water Cooling values of solutions comSolutions, Giving Freezing Points.

monly employed :

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CALCIUM CHLORIDE SOLUTIONS

2 pounds salt, 1 gallon water....
3 pounds salt, 1 gallon water.
4 pounds salt, 1 gallon water..
5 pounds salt, 1 gallon water.

.Freezing point, 18° F.
.Freezing point, 1.5° F.
..Freezing point, -17° F.
..Freezing point, -39° F.

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