Arizona silver belt., 1900-05-17
THE ABSOLUTE ZERO.
A Temperature 500 Degrees Colder
 than a Summer Day.

k.owledge k of conditions which had en matters of mathematical demon ,.ration rather than of experience. The measurement of these conditions N iS very dilhcult, The properties of bStances in this extreme cold were ulknowu and great field of research vas at once opened.
 As heat consists in the energy of notion of the molecules of body, the tea at once presents itself that the point might be reached, theoretically 3r least. where the molecules, having st their energy of motion little by little as the temperature was reduced, nad been brought to rest. Such point would mark the limit of cold and body at that temperature would possess no heat at all, This point, for onyiuus reasons, is known as the ''ab- >,Iute zero.' It's value is determined, Uy means of the relation between eX- llllNlbl VI SdNtN diIh ,p lie between 2730 and 240o below the zero of the centigrade scale. Logical ly. all temperatures should be reckoned from that point, as, indeed, for many practical purposes, they are.
 Now. with all known gases liqueted, We are getting wonderfully near to this point. Just how near is as yet somewhat a matter of inference. All ordinary thermometers fail. Even the air thermometer is frozen solid and the hydrogen thermometer is of little use Electrical methods are doubtful because nobody knows just how the electrical properties Of substances vary at such temperatures. Dewar, with liquid hydrogen, has obtained d temperature within about 2l0 of the absolute serO-some 2S0' centigrade or more than 5000 fahrenheit colder than the temperature of an ordinary summer day; and solid hydrogen is about 50 ceatigrade colder yet. It will be interesting to relate, 50 far as they are yet known, some of the properties of substances at these low tempera- lures.
 The beautiful experiments which it tS possible to perform before an audi ence with liquid air in quantity have become we'll known. All ordinary liquids are frozen. Alcohol becomes ice, mercury a solid 50 hard that it will drive nails. A jet of carbon diox- idle gas falls as snow: and to make the liquid air boil violently it is only necessary to set a kettle of 1t upon a cake of ice. In spite of this, liquid air Is kept for hours in unsealed cans, m which evaporation is comparatively slow. For the rarer liquetied gases, in small quantities, Dewar has de yiSed the vacuum flask. The liquid oxygen or hydrogen, or whatever 1t may be, is in the inner vessel, and the space between that and the outer flask is exhausted, the two tasks being sealed together at the neck. It IS found that the evaporation is only about One-tfth as rapid as when this space is filled with air.
 Under such conditions air may be seen as clear, colorleSs liquid when very cold. The solid air at higher temperature is characterized as a nitrogen jelly, from which strong magnet will draw the oxygen.
 oxygen as liquid in considerable quantity shows pale blue color, a' does the solid oxygen. It is highly magnetic and good insulator. LiquiC ozOne is indigo blue and very explo Siye. Nitrogen forms an opaque solid Hydrogen as liquid is colorless ant transparent, and as solid Is trans parent ice with frOthy surface, due probably to very rapid evaporation. II iS said to be distinctly non-metallic FluOrine, very ditficult to liquefy, IS clear yellow liquid, very mobile. l
 lS said to be distinctly non-neldllic
 Fluorine, very ditliclut to liquefy, IS clear yellow liquid, very mobile. l
 does not attack glass at these low tenn
 peratureS. ArgOn forms colorles
 liquid. and at very low temperature
 an opaque solid The liquids are gen
 erally colOrless and transparent, eN
 cept lluorine and chlorine, which ar
 both yellOw.-Detroit Journal.
 The Smithsonian Institution, whic
 is one of Washington's famous publl
 buildings. was founded by an Engiisf
 man who had never been in Americ
 aud so far as is known, had no friend
 Or acquaintances in this countr.
 Through some strange caprice he Tel