Democratic Sentinel, Volume 15, Number 23, Rensselaer, Jasper County, 26 June 1891 — ICE BY MACHINERY. [ARTICLE+ILLUSTRATION]

ICE BY MACHINERY.

A NEW AND WONDERFUL INDUSTRY. di*w Artificial Ice Is Vatic by the Aid of Steam—the i ifi'ereutMethods Employed Manufacturing It—lnteresting Facts.

0 make ice by steam; to reduce the temperature by the combustion of coal; to convert heat into cold, is a problem which modern science has solved, and that, too, in a practical way. Paradoxical as this statement appears. the most skeptical may be convinced of its

absolute truth by Inspecting any one of tbe three large manufactories in Chicago where ice making and refrigerating machinery is constructed. Aft ii r viewing the enormous engines there, possessed of the strength of an hydraulicram and the n'ccty of a chronometer, any remaining doubt as to their practicability will be dispelled by visiting tbe new ice making p ant at Throop and Van Buren streets, or any large pack-ing-house or brewery, where acres of ■apace are kept, summer and winter, at a constant temperature but Utt e abote the freezing joint, by the use of these very engines, and without consuming a ■single pound of ice. In this century of unpa’a'leled progress, wonders have trod so clo ; ely upon the heels of wonders, that the ordinary

layman in the world of science has been •unable to keep pace with them, or fully comprehend the principles underlying •many of the great inventions which have revolutionized economics, and largely contributed to the comforts of his own •life. Very few have a comprehensive -idea of ice-making machinery, though ’the matter is one susceptible of lucid ‘demonstration. At a temperature of 32 degrees Fahrenheit water congeals and becomes ice. To the schoolboy, yearning to try his cherished skates, and the iceman eager to begin the harvest of his crop, this process appears a very slow one. It ■would seem, indeed, that water, reduced to a temperature below the freezing ■point, ought almost instantly to take on .a crystalline form, and cbanec en masse from a fluid to a solid. For lack of better terms we speak of nature as possessed of likes and dislikes; loving this and abhorring that. In this sense matter seems both to change its state and taae on another and different condition. Were it not for this change would be the rule; nothing would be stable; .chaos would reign. That water does not freeze more rapidly is due to the presence in it of latent heat, which must be expelled before the change can take place. Latent heat is as mysterious an affair as •electricity. In no way can. it affect the •senses; the most delicate thermometer •will not indicate its presence, yet it is -none the less certain that, it exists and in never varying quantities. To illustrate this, place a block of ice at a temperature of 32 degrees in a kettle over a fire. When it is entirely melted the resulting water will be but little /raised in temperature from that of the ice. Faraday dete.rmined that to melt a •cubic yard of ice, about 1,500 pounds, •without raising the temperature, requires seventy pounds of coal. It was known to the people of ancient fßome that wet clothing becomes rapidly ••and powerfully chilled, yet not one of alf jM» philosophers saw in the circumstance a suggestion for manufacturing Ice to cool the wine and sherbet of royalty, in lieu of the snow brought from Jthe tops of mountains. This was left to Dr. Joseph Black, the Scotch-Irish •chemist of Edinburgh, who, about 1760, who formulated and made public his famous theory of latent heat. He found -that to convert one pound of water at 212 degrees into steam, at the same temperature, requires six and one half times ’the heat necessary to raise the same .amount of water from 61 to 212 degrees. In other words, if one pound of steam at 212 degrees is mixed with six and onehalf pounds of water at 62 degrees, •there will result seven and one-half *<x?unds of boiling water. It was at •once evident that if, of six and one-half pounds of water at 62 degrees, one-half . pound could be suddenly converted into eteam, the remaining six pounds would be frozen. The problem was, how to effect this. If any elastic fluid, ntmospheric air, ."•for instance, is compressed, it becomes heated, and if cooled down to its original temperature, the same heat must be .restored in the process of expansion to Its normal condition. This heat is with•drawn from the atmosphere or other surrounding substance, thus reducing the temperature. By the expansion of liquid sulphuric acid or solidified carbonic acid, water can be frozen in a red■bot dish, and a small quantity added to •a glass of boiling water will almost instantly convert it into solid ice. It is •upon this principle of latent heat that dee-making machinery depends. The original or “ground” patents for Towering the temperature by machinery ■expired some years ago, and are now common property. In consequence of •this, vast numbers of ice machinery •manufactories have sprung up all over Kthe civilized world, more than fifty bestaf located in the United States alone, letory has its own special the number of different 'Mines on the market is rge. They may, however,, to two distinct varieties—jonia mac lunes. bines.' include all those produced by the evaporaiie liquid. They include

I the apparatus which employ sulphuric I etherj gasoline, chymogene and-other derivatives of petroleum. The liquid is evaporated in a partial vacuum, by ■means of which the process is greatly facilitated. Having absorbed r heat in the process the gas is condensed and used over and over. Ammonia machines differ from those using ether principally in this: that no

air-pumps are required to produce a partial vacuum and draw off the vapor, and that enormous pressure is necessary to condense the ammonia into flnid form. In ether machines the power is principally employed in aiding evaporation; while in ammonia machines it is used only in the compression of the gas. The reason of this is found in the different natures of the two materials employed. Ether is, in its normal condition, an exceedingly volatile liquid, while ammonia is a gas having but little more than half the weight of atmospheric air. Like all gases, ammonia can bo compressed to a liquid, and it is in this form that it is introduced into an ice machine. Ether machines are decidedly passe in this country, though they are still used to some extent in Europe; as likewise are air machines, particularly in England. The latter are fast giving place to ammonia machines, being operated on the same general principle of expansion. A description of the construction and modus operand! of an ammonia machine will convey an intelligent idea of how Ice is made by steam. Every such apparatus consists of three parts: (1) An engine and ammonia pumps, by means of which the gas is p aced under a liquefying pressure; (2) a condenser, in which the compressed gas, heated by the process of compression, is cooled and so changed into a liquid form: (3) a system of evajiorating coils, in which the liquid ammonia is expanded into a gaseous state and then cools the surrounding space, when used as a refrigerator, or brine when employed in making ice. Liquid ammonia is prepared by manufacturing chemists, and is furnished in heavy iron drums to guard against the danger of explosion. It is allowed to enter the evaporating coils, and, having been fully expanded, enters the compression

pumps and is fairly started on its circuit. What the heart is to the human body the compression pumps are to the ammonia machines, and it is here that the greatest strength must be combined with the finest possible finish. The compressor must be able to withstand a pressure of more than three hundred pounds to the s;uare inch, while the piston must fit so tightly and perfectly that not even the subtle gas can find a I eak, and at the same time occasion no great amount of friction. It is in the construction of the apparatus that the greatest amount of ingenuity has been 1 exercised. Another very important matter is the

; coaling apparatus by which the compressed gas is reduced in temperature ufitil it assumes a liquid form. Where water can be cheaply attained, it is generally employed alone, the gas being allowed to circulate through it iu metal coils. Where water is scarce, however, ,or of rather a high temperature, huge piles of coils are erected in the open air, and a large amount of the heat thus disposed of. To facilitate this, water is allowed to drip over the coils, and by its low temperature, ahd the fact that it

.largely evaporates, greatly aids the process. - The method thus described Is called the “direct exnanson” process. ’The “brine system” Is the same, except that the expanding gas is confined to colls which are submerged in brine—L e , a strong solution of salt, which will not congeal unless at a every low temperature. When the brine has become very

cold it is forced in pipes through the rooms to be cooled. Both systems are used and have their advocates. The direct ex pan-ion plan is probably the most economical, but in the very possible event of a leak the contents of the coldstorage or cooling rooms might bo ruined. Besides the anhydrous or liquid form, ammonia is also used in a saturated so-

lution. Water has a powerful affinity for ammonia, appropriating as much as 670 times its own bulk of the gas. Aqua ammonia is introduced and expanded, and the sams results obtained as by the other system. It is, however, an inferior method, rapidly falling into disuse, and need not le described in detail.

An ice machine in operation is a curious spectacle. Liquid ammonia begins to expand at a temperature of forty degrees below zero, and in consequence of this intense cold the large iron pipes in which it takes place are, on the hottest days of summer, covered with solid frost, and appear to be coated with a snowwhite enamel. Some machines leak ammonia badly and thus produce a most disagreeable odor. This waste is quite an Important matter from a financial stand-point, since anhydrous ammonia costs in the neighborhood of fifty cents a pound. In making ice the same machine is used as in refrigerating. The ammonia is allowed to expand in coils which are submerged in brine. The tanks holding the brine are shallow, and present a large surface. Into these are immersed tin molds or cans, containing the water to be frozen. These vary in size according to the ice-producing capacity of the machine. They are usually two feet or more in length and from eight by eight to eleven by twenty-two inches in breadth and depth Slow freezing makes clear ice, and twenty-four hours is usually employed in congealing the contents of the molds. Sometimes these are all emptied at once, but more generally this is done singly, and at such Intervals of time as to complete the circuit every twenty-four hours, the cans being refilled with water as fast as the ice is withdrawn. The better class of machines use distilled water, thus insuring the purest sort of ice. This is obtained by condensing the exhaust steam from the engines. Ice-making machines vary in producing capacity from one to one hundred tons in twenty-four hours. A ton of coal will produce, in machines of large capacity, seven tons of ice. Artificial ice is clear as crystal, and being uniformly frozen and iree from air bubbles, is not only of the most wholesome sort imaginable but has greater lasting properties than the natural product. It is claimed to have been" demonstrated from actual experiments that manufactured ice requires, under the same conditions, 10 per cent more time to melt than does that naturally frozen. Just now the demand for ice machinery largely excels the producing capacity of all the factories in xhe coun-

try. This Is no doubt largely due to the mildness of the past winter and the consequent shortness of the ice crop; but ice-making is largely on the increase, and In time will drive the natural product from the market, except, perhaps, in the extreme northern portion of the country. In Chicago refrigerating machinery has been found not only more convenient, but much cheaper than ice, and is employed by the greater part of the breweries, packing-houses and coldstorage establishments. It is claimed that ice can be made in Chicago for 90 cents a ton, which is doubt ess mu' h less than the cost of the natural article in ordinary seasons, storage, transportation, extra handling and waste being taken into account. If this estimate proves to be correct, steam-made ice will soon be almost universally used in this city. The Germans have gone deeper into the science of making artificial ice than any other nation. They have technically exhausted the subject, but are a long way behind the United States in the character and practical operation of the machines actually in use. Chicago, who counts herself as nothing if not in the lead, is sending cold-produc-ing machinery to all parts of the Union and to South America, where she successfully competes with European machines. The industry is new, but will assume, and that in the near future, vast proportions, enabling people of very moderate circumstances to use ice. and that in the summer as well as winter season. Dwight Baldwin.

REFRIGERATING MACHINES.

PORTION OF ATMOSPHERIC CONDENSERS.

MODEL ICE PLANT.

VIEW OF CHILL-ROOMS.

INVENTIONS MAKE STRANGE COMBINATIONS.