Popular Science Monthly
��919
��amount of mercury vapor is left between the walls, it will be solidihed and deposited upon the walls of liie vessel upon the entrance of a liquid gas. In this manner it acts as a mirror and reflects heat wa\-e3 that impinge upon the outer surface of the container. Thus was the familiar commer- cial vacuum bottle created.
Now that the methods for producing low temperatures have been explained, we will briefly review some of the more wonderful phenomena that occur when matter is sub- jected to such severe low temperatures.
Strange Things That Happen When Gases Are Liquefied
If a piece of silver forming part of an electrical circuit is immersed in liquid air and held there, it undergoes a physical modification that reduces its electrical re- sistivity to an almost unnoticeable amount. It was predicted by physicists that at abso- lute zero a metallic substance would offer no resistance to an electrical current.
Professor Dewar discov- ered that if a magnet was re- peatedly im- mersed in liq- uid air, its magnetic influ- ence was not only intensified but perma- nently increas- ed. Also, curi- ously enough, oxygen ma>' be separated from the nitrogen in liquid air by magnetic means.
A student of physics would naturally ask:
��tures red things become yellow and yellow tilings white and so on.
It has been found that if a bell con- structed of pure lead is subjected to such a low temperature, it has a pure metallic ring when struck a sharp blow. Bits of vegetable matter immersed in liquid air become so hard and brittle that they may be powdered in a mortar. In the labora- tory of the British Royal Societv, it was found that the bacteria cculd not be de- stroyed even by the lowest temperatures.
The "absolute zero" has been set by physicists as being 273° Centigrade below zero (459.4° Fahrenheit below zero). In this condition matter will have absolutely no heat. The nearest approach to this has been in the liquefaction of hydrogen or ^254° Centigrade ( — 425.2° Fahrenheit).
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��an upstairs and a guestroom in this improvised home
��Will a liquid gas alter the color or light-absorption of a substance? The answer is, yes. Understanding, as we do, that the color of a substance depends upon the wavelength of the ether waves of the spectrum it absorbs, it would be natural and tempting for one to conclude that it was the great contraction of the mole- cules that affected its wave absorption at this temperature. We must be more cau- tious than positive in making this pretty assertion as final at this time. It has been found, however, that at these low tempera-
��Transforming a Railroad Water -Tank into a Home for Two X OLD water -tank in a Western town stood idle until an enterprising citizen came along and rec- ognized in it the making of a home for himself and his wife.
He set to wcrk with car- penter's tools, and in a week he had the in- terior fitted up comfortabK-. He cut win- dows where he wanted them and made a door large enough for the champion tall man in the through without
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To disguise the tank-home as far as pos- sible and also to add an element of archi- tectural beauty^ to the whole, he fitted the roof with extensions, placing windows in the extremities.
This gave him the happy thought of building an upper room to the structure. Now he has plenty of room for guests, since he has finished off and furnished the ad- dition as a spare chamber. A chimney was also added and stoves were installed.
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