SCIENCE, INVENTION, DISCOVERY. 



333 



Liquid Air. Popular attention has been 

 attracted to this subject recently in America by 

 the experiments of Mr. Charles E. Tripler, 

 although the liquefaction of gases is by no 

 means new. It was first accomplished by 

 Northmore in 1806, who succeeded in obtaining 

 liquid chlorine by pressure. Faraday followed. 

 Two factors are necessary to liquefy a gas, 

 pressure and cold. Every gas, so far as now 

 known, will liqttefy under a given pressure, 

 provided it is cooled to a certain temperature 

 known as its " critical temperature." In 1877 

 two French experimenters, Pictet, Cailletet, 

 working separately, and along different lines, 

 succeeded in liquefying oxygen. This was fol- 

 lowed in 1883 by successful experiments by two 

 Russian physicists, Wrobleski and Olszewski. 

 Among other surprising results they succeeded 

 in freezing alcohol. It was not until 1890 

 that liquid air and oxygen were produced in 

 any quantity. This was first done by Prof. 

 Dewar, of the Royal Institution, London. 

 About this time Mr. Tripler, of New York, 

 developed a form of apparatus which may be 

 said to be a practical machine. The capacity 

 of his plant is about 40 gallons per day. The 

 process claimed by this physicist is also claimed 

 by Mr. Thompson in England, and Dr. Carl 

 Linde of Munich, Germany. 



The effects of the intense cold which can be 

 produced by evaporating liquid air, oxygen, or 

 hydrogen are almost beyond comprehension ; 

 practically all plastic or soft materials when 

 immersed in it become hard and brittle, leather 

 being an exception; some metals become brittle, 

 and can be broken or crumbled ; alcohol may be 

 frozen, and air and oxygen themselves solidify 

 if placed in liquid hydrogen. The possibili- 

 ties of liquid air are many. It can be used 

 for refrigeration ; motor vehicles and launches 

 can be operated by it ; surgeons can use it in 

 operations, and for ventilating and cooling 

 rooms it is invaluable. 



Magnet. The iron ore which possesses 

 the property of attraction was given the name 

 of magnet by the Greeks, because it was first 

 found in Magnesia in Asia Minor, or accord- \ 

 ing to another account because it was first dis- 

 covered by a shepherd named Magnes, who 

 had iron tips on his shoes, and "while walking 

 over some rocks found that his feet stuck to 

 them in a mysterious way. The ore is now 

 called magnetite, and is an oxide of iron con- 

 taining about seventy-three per cent, of iron 

 when pure. It is a very valuable ore, and 

 supplies a large amount of the finest iron and 

 steel of commerce. Large deposits occur in 

 Norway and Sweden, Finland and the Ural ; 

 in the Adirondack region in northern New 

 York ; in northern New Jersey; in eastern 



Pennsylvania, the most noted locality being 

 Cornwall, Lebanon County, where the mines 

 have been worked for over a hundred years ; 

 in North Carolina, California, and Oregon, 

 and several places in Canada. It is also found 

 in the form of sand in some places in North 

 America, India, and New Zealand. One of the 

 largest occurrences of magnetic sand is on the 

 south shore of Long Island, near Quogue, 

 where a furnace was built and an attempt made 

 to work it ; but the enterprise proved unsuccess- 

 ful and was abandoned. 



Mariner's Compass. The Chinese as- 

 cribed the invention of the compass to their 

 Emperor Hong-Ti, who they say was a grand- 

 son of Noah ; some of their historians refer 

 the invention of it to a later date, 1115 B. C. 

 The honor of its discovery, however, though 

 much disputed, is generally given to Flavio 

 Gioja, a native of Amalfi, an ancient com- 

 mercial city of Naples, A. D. 1302. The com- 

 pass is also said to have been known to the 

 Swedes in the time of King Jarl Birger, 1250. 

 The variation of the needle was first discov- 

 ered by Columbus in his voyage of discovery, 

 1492. The compass box and hanging compass, 

 used by navigators, were invented by William 

 Barlowe, an English divine and natural philos- 

 opher, in 1608. The measuring compass was 

 invented by Jost Bing, of Hesse, in 1602. 

 The dipping needle was invented by Robert 

 Norman, a compass maker of Ratcliffe, Eng- 

 land, in 1580. 



Matches, Invention of. Previous to 

 1829 the matches in use consisted of a slender 

 stick with a pointed end, which had been 

 dipped in sulphur ; and they were lighted by 

 touching them to a spark struck into tinder by 

 flint and steel. In that year, however, what 

 was known as the " Instantaneous Light-Box" 

 was invented. It consisted of a small tin box 

 containing a bottle, in which was placed some 

 sulphuric acid, with sufficient fibrous asbestos 

 to soak it up and prevent its spilling out of the 

 bottle, and a supply of properly prepared 

 matches. These consisted of small splints of 

 wood about two inches long, one end of 

 which was coated with a chemical mixture 

 prepared by mixing chlorate of potash, pow- 

 dered loaf-sugar and powdered gum arabic, 

 the whole colored with a little vermilion, and 

 made into a thin paste with water. The splints 

 were readily inflamed by dipping the prepared 

 ends into the sulphuric acid. These were suc- 

 ceeded by the lucifer, or loco-foco match, 

 which was ignited by friction ; and that, in 

 turn by the Congreve, which was similar to 

 the sulphur matches now in use ; and this, 

 shortly afterward, by the present parlor match. 



Maxim Self- Acting Gun was invented 



