GAS 



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GAS 



pils working at desks which are not only read- 

 ily adjustable but. also as readily convertible 

 into work-benches. You may find a large 

 group of pupils in the auditorium equipped 

 with a stage, stereopticon, motion picture ap- 

 paratus, player piano, organ, phonograph and 

 such other furnishings as are helpful in mass 

 instruction. Some pupils will be found in cor- 

 ridors where pictures, maps and specimens are 

 on exhibition. Some are in laboratories, work- 

 ing, watching, "showing" or engaged in a reg- 

 ular class exercise. Some are engaged in drill- 

 ing upon the "essentials," some are occupied 

 with the arts and crafts, some are in the gym- 

 nasium and swimming pool, and so on. 



Economic Use of School Buildings. The sys- 

 tem provides for the more economic use of 

 school buildings, especially where buildings 

 are such as are necessary in the "complete 

 unit school plant." When used in the manner 

 described, such a building will accommodate 

 about 2,400 pupils, instead of 1,200 when the 

 school is conducted in the traditional way. It 

 is obvious that a school system made up of 

 such "complete" centers would cost less be- 

 cause of no duplication of expenses for sites, 

 buildings, equipment, janitors, principals and 

 instruction, the cost of the last-named item 

 being materially reduced by departmentalizing 

 the work and thus eliminating all overhead 

 charges for special supervisors. The system 

 also gives a better division of time between 

 the old and new studies, the possibility of bet- 

 ter teaching and adaptation of studies to 

 individual pupils by reason of departmental 

 teaching and a better use of time which pupils 

 oftentimes, under other conditions, spend in 

 a variety of harmful ways. The system, more- 

 over, provides an escape from the "lock-step" 

 system of graduation and promotion, making 

 it possible to promote pupils by subjects in- 

 stead of grades. 



Such are some of the more important fea- 

 tures of a school system in process of devel- 

 opment in harmony with the two principles 

 stated above a system which seeks to bring 

 together in a unitary way, with economy and 

 efficiency in management, all the recreational 

 and educational agencies of a city. W.P.B. 



GAS. In some of the old books on chem- 

 istry we find the following story of the origin 

 of the term gas. 



The philosophers of the Middle Ages, who 

 are now known as alchemists, were troubled by 

 explosions caused by fire coming in contact 

 with invisible contents of the vessels used in 



their experiments. Not understanding the 

 cause of these explosions, they attributed them 

 to the presence of evil spirits; in the seven- 

 teenth century a Flemish chemist applied the 

 term gecst, meaning ghost or spirit, to those 

 invisible vapors, and from this we derive the 

 word gas. 



All matter exists under one of three forms 

 solid, liquid or gaseous, the most elusive of 

 all. Many gases, as oxygen, hydrogen, nitro- 

 gen and carbon dioxide, possess neither color 

 nor odor, and we .can detect them only by 

 their effect upon us or upon some substance 

 placed in them. For instance, if a lighted 

 candle is placed in a jar containing carbon 

 dioxide the flame will be extinguished. On 

 the other hand, if we fasten a lighted match to 

 the end of a fine steel wire or the mainspring 

 of a watch and place them in a jar containing 

 oxygen, the wire or the watch spring will burn 

 and throw off brilliant sparks. For these and 

 other reasons the chemist feels as sure that 

 these and other gases exist as that wood and 

 stone exist, and by observations and experi- 

 ments he has learned a great deal about these 

 unseen substances. 



Air is the gag with which people are most 

 familiar. It was by studying air that learned 

 men obtained many hints as to the habits of 

 other gases. They discovered that gas shares 

 certain properties with other kinds of matter. 

 Although it is often invisible, tasteless and 

 without smell, gas can easily be shown to 

 have weight. It is the pressure of the air, for 

 example, that sustains the column of mercury 

 in the tube of a barometer. Everybody has 

 experienced the push of the atmosphere when 

 the wind blows; it often exerts a force so 

 enormous as to level forests and sweep the 

 masts from ships upon the sea. As compared 

 with liquid or solid substances, the weight of 

 a gas is, of course, quite small; water, for ex- 

 ample, weighs nearly 800 times as much as air; 

 and air, again, is about fourteen and a half 

 times as heavy as hydrogen, the lightest known 

 gas. 



Early scientists thought of gas as a substance 

 that never lost its airlike quality; it remained 

 for Faraday, in the years 1823 to 1845, to show 

 that this is not true. By applying cold and 

 pressure he reduced most of the common gases 

 to a liquid state. In 1869 Andrews showed 

 that carbonic-acid gas cannot be liquefied if 

 its temperature is above 88 F. (31 C.), but 

 that only a moderate pressure is necessary to 

 liquefy it at or below that temperature. It 



