LIQUID AIR

New Zealand Mail, Issue 1508, 24 January 1901, Page 54

LIQUID AIR

THE NEW REFRIGERANT. 'Liquid air is annoqnced as the latest refrigerating agent, for purposes of dairy aiid factory work, having passed the experimental stage- and reduced to* practice. A contract made- by the Standard Butter Company of Owego, New York, with the Tripler Liciuid Air Company, originators of the process of making liquid air commercially, gives them the exclusive right to sell, use and dispose of for power and refrigeration in dairying, the plan of use including the combination of the energy of motive power and refrigeration, the motive power to be used to operate the separators, pumps, churns, etc., and use it as a refrigerant for the cooling of cream and for the storage rooms. It is also to be used in the transport of milk and cream, its small bulk as compared with ice required for same refrigerating power adapting itself where transportation of perishable products in well preserved condition and at a lower cost of freight are items of importance. What liquid air is is tliiijs explained : To the average person the term liquid air means that which is weird and intangible, and so many vague answers have been given that it seems as if it belonged to the occult, and that some great mystery surrounded it. Liquid air, however, is simply air reduced to so low a temperature as to assume a. liquid state. Following out the rules of the conversion of liquids into* gases and the increase therein in volume, we arrive at the converse, that the conversion of gases into liquids involves the compression or reduction in volume. In liquid air this is in the ratio of 800 to X. or 800 cubic inches of air are compressed to 1 cubic inch of. liquid air. The discovery o-f Tripler is that lie has. succeeded in liquefying air by purely mechanical means, using no cooling medium, to reach the- critical point, outside of a self-intefnsive system. His apparatus consists of a boiler, with its steam connections directly connecting with a straight line air compressor. The air is compressed three stages, the first at 551 b to 651 b pressure to the square inch the second 3001 b to 4001 b, and third and last at 20001 b to 250<Jlb to the square inch. The law of lowering temperature, resulting from the expansion of gas, is invdrse as to compression, and the air is cooled between the first and second and second and third compression. Liquid air, when filtered, is a clear bluish liquid, weighing about 71b to the gallon, But, as ordinarily seen, is of a milky 1 appeiarance, due to the presence of ;minute particles of carbon dioxide in the frozen state, giving the same appearance to the liquid air as finely divided portions of casein are said to' give colour to milk. Thei temperature is approximately 312 deg below zero, a statement that conveys but little, as the average mind fails to realise that degree of cold. An India rubber ball allowed to remain for a few seconds in liquid air becomes so brittle that it can. be broken by pressure from the hand, and a tin dipper allowed to remain in it for a moment can be crusheid as could a very fine glass tumbler. Absolute alcohol can be frozen solid with

it by simply immersing the vessel containing the alcohol in the- liquid air, and a, test tube filled with liquid air put in a tumbler of whisky will freeze the whisky solid, and it can be taken out as so much ice. 'ln a. few seconds the test tube can be removed from the block of whisky, leaving what is practically a tumbler made of alcohol, a medium used in most cases to prevent freezing. By putting mercury into a mould and a handle in it, it can be frozen with liquid air in the shape of a hammer, so that nails can be driven with it.

Liquid air can be used exactly the same as steam ; the holder or tank representing the boiler, the liquid air the water, and the outside atmosphere the furnace fire. The result of the action of the low atmospheric heat is exactly the same as in the case of the furnace fire 1 , the liouid being converted into a gas, creating a pressure as in steam, with the one exception that we may develop any power pressure, even beyond a practical point, and it is so absolutely under control that, in one minute the pressure has been varied from 2501 b to the square inch to 151 b to the square inch, held at the latter point for 15 minutes, then run up to 1501 b to the square inch pressure and allowed to remain there, being at all times perfectly under control of the operator, and requiring no more knowledge of mechanics than does the mere operation of a soda water fountain. If we are to sift out strictly the theories of the laws of energy, we arrive at the point that in liquid air is stored the original energy transmitted by the coal consumed plus the low heat energy from the atmosphere.

Comments having been made on the ger of explosion, it is stated that there question of the danger of handling liquid air, by reason of the supposed dancannot be imagined a condition under which liquid air in itself will explode. There can be no spontaneous combustion nor spontaneous increase in pressure, and the only effect of a rise in temperature of the surrounding atmosphere to an abnormal degree would be that the pressure of the vapourised air would act exactly as a hydraulic press, gradually rending apart the tank in which the air was stored, and allowing the air to escape. It becomes then, by reason of being- uucciifined, just as harmless as ordinary air, gradually vapourising- and assuming its natural state.