The daily morning journal and courier., 1899-06-19

pendlture of about seven horSe-poWerS. Tripler'S apparatus is on much larger scale and furnishes from thirty to forty gallons of liquid air in day of ten hours at cost, as he estimates, of twenty cents a gallon.
 As 1t runs from the liquefer, the air is a mobile clear liquid, which, owing to it's oxygen constituent, has slight tinge of blue. It is slightly lighter than water, upon which 1t at first floats, giving off dense white fumes of Soltditied moisture. But since its nitrogen eVaporates more rapidly than the oxygen, the liquid grad ually becomes heavier and then sinks into the water in the form of spheroids, which go lower and loWer until finally they reach the bottom of the vessel. It has been recently shown that one-half of the liquid air, when fresh from the lique- fer, is oxygen; while the last portions which remain on evaporation contain 90 per cent of this constituent. Unless the air is purified before liquefying the carbonic acid and moisture which it con- tains are solidified at the same time, and the product is milky. It may be ob- tained clear, however by filtration. In the later forms of liquef1er the filtration is effected in the apparatus, so that the issuing liquid is perfectly clear.
 Since as has been estimated, one cu- bic inch of liquid air yields eight hum dred cubic inches of common air, 1t fol- lows from the laws of gaseous pressure that if this substance obeys these laws, one volume of liquid air, when raised just above it's critical temperature, and occupying the same volume, would exert a pressure practically of 800 atmos- pheres, or 12,000 pounds per square inch. Evidently, by making the space greater into which the liquids expands, any pressure less than this can be obtained. Clearly, therefore. the great thickness of the vessels required to contain liquid air at anything like its maximum pressure is prohbitory so far as it's transporta- l ton is concerned. But it is quite obvi- ous that there cannot be any difference between one pressure produced by di- rect compression and another of equal value generated by the evaporation of | liquid air at the same temperature. The great pressure generated by liquid air in evaporating may be shown by placing some of this material in a heavy metal
 tube closed at one end, and then driving into the tube a wooden plug. In few seconds the accumulated pressure will force out the plug with loud report, and if the experiment. is performed in the open air the plug will rise to the night of a hundred feet or more.
 Since liquid air, as it comes from the liquetier, is actively boiling and has g temperature not far from minus 191 de- | Co iey pO16ar than any surrounding substance. | Poured into a glass tumbler, or even upon ice, it abstracts heat from these bodies and boils more furiously than be- fore. Gradually, however as it cools the | tumbler and the ice to temperature nearer its own, the activity of the boil ing is greatly diminished To preserve liquid air, therefore it must be protected from all access of heat. In transporting l it, is is placed in an open tin can, en- closed in a second and larger one, and sometimes in third, the spaces between them being packed with on-conduct- ing material, such as hair felt, Protect ed in this way it may be carried with loss of not move than or 10 per cent per hour. But is is to Dewar that we owe the best device for protecting liquid gases against external heat The we'll known Dewar bulbs or tubes consist of an inner vessel to contain the material, surrounded by a second, and sometimes even by third, globe or tube, the spaces between them being exhausted to the highest attanable vacuum. By this re- moval of the air the transference of heat by conduction and convection is prevent d A,,I i,,r, J,o Gi1vprp1 on it's exterior radiation is also cut off. So that in such vessels liquid air may be preserved for thirty-sx and even for forty eight hours.
 | One of the most novel and striking properties of liquid air is it's intense &C., tion on combustible substances. Since, even when fresh, it is ona-half oxygen, this amount gradually increasing by evaporation to nine-tenths, the liquid contains one of the clements of conlbus- ton in it's most concentrated form. And. although by itself the liquid is en- tirely harmless yet when mixed with the other combustible element it becomes an explosive of intense power. It is we'll known fact that gunpowder, guncotton and even nitroglycerin, contains less en- ergy for an equal mass than ordinary coal. Hence their intense activity is due to the great rapidity with which their energy Is set free. A piece of newspaper, a bit of cotton waste or of cotton wool, soaked with liquid air and fred burns with fierce rapidity. So suddenly is this tremendous energy set free that by enclosing a bit of cotton waste as big as ones thumb, upon which a drop or two of oil has been placed, and which is moistened with liquid air, in a two-inch gas pipe of a second four-lnch pipe of equal thickness, the ends of both being open, the violent explosion when the waste is fired is sufficient to burst both these pipes and tear them to shreds.
 The intense activity of liquid air on combustibes leads to interesting experl- ments A piece of steel tape or watch spring to the end of which a bit of match is attached and ignited, burns with brilliant scintillations when inn mersed in liquid air. By taking an elec- tric light carbon, heating it's end to bright redness and plunging it into li- quid air. contained if you please in an ice tumbler, the carbon burns brilliant ly in the condensed oxygen, giving a light as brilliant as the electric arc, at taining a temperature of nearly three thousand degrees above zero in the m,ds | of n r,,aJiI1no ml,io1, at q tpmnpTat1lre