Rensselaer Republican, Volume 21, Number 25, Rensselaer, Jasper County, 21 February 1889 — LIGHT AND HEAT. [ARTICLE]

LIGHT AND HEAT.

Paca!lattlea nf t <rlr Rays , Passing Through VaHoua The rays of beat and of light are quite independent of each other in their ability to make their way through different substances. For example, glass allows the sun's heat rays to pass as readily as the rays of light If the gloss be coated with lamp black, it will let the beat pass through as before, but the light will be arrested. Moreover, heat and light go through water with little loss to either. But if alum be dissolved in the water until the liquid is saturated, the light will pass, but the heat will be detained, and the water will become warm. Ice transmits both heat and light with equal facility; that is, it allows them to go through in proportion to its purity and clearness. An observation made by Dr. Sutherland upon an iceberg in Baffin’s Bay snows very plainly this property of ice. “About half way to the top," says the doctor, “several pieces of granite were found, some of which were deeply imbedded in solid ice, without any communication with the external air. and these, as well as the exposed pieces, were surrounded by what m y lie termed an atmosphere of water.’’ The explanation of this is that the heat of the suit’s rays passes through the ice and falls upon the stone with the same power it would if the same was lying on, the surface. The heat absorbed by the stone raises its tern erature until it is warm enough to meft the ice about it. It is a well known fact that in the latter part nt winter, when the ground is covered deeply with snow and ice, the frost all leaves the soil, and the lower pait of the covering is melted away, while the temperature above is freezing cold. This tqawing is ascrilied to the warmth of tlie ground below, where it is affected by the changes of the s; asons. The internal warmth is supposed to be conducted to the surface as soon as there is a covering of snow and ice to protect the surface from the cold of winter. It would of interest to find out by observation or experiment whether some part of Ibis thawing may not be due to the sun’s heat penetrating through the protecting covering.