The Laws of Radiation and Absorption: Memoirs by Prévost, Stewart, Kirchhoff, and Kirchhoff and Bunsen

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American Book Company, 1901 - 131 pages
 

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Page 40 - Considering, therefore, the heat of any temperature to consist of heterogeneous rays, we may state the law thus: The absorption of a plate equals its radiation, and that for every description of heat.
Page 41 - C, than was absorbed of the equally intense ray at A, in its passage between A and B. The amount of heat absorbed by the particles between B and C would therefore be different from that absorbed by the particles between A and B. But this cannot be ; for, on the hypothesis of an equal and independent radiation of each particle, the radiation of the particles between B and C is equal to that of the particles between A and B, and their absorption equals their radiation. Hence the radiation impinging...
Page 23 - ... only 15 per cent. The second group of experiments was designed to compare together the quantities of heat radiated at the same temperature from polished plates of the same substance, but of different thicknesses. The result of this group was, that while the difference between the radiating power of thick and thin glass is so small as not to be capable of being directly observed, there is a perceptible difference between the radiation from thick and thin mica, and a still more marked difference...
Page 122 - What, however, gives to the spectral analytical method a peculiar importance, is the fact that it almost infinitely exceeds the limits to which chemical analysis of matter has heretofore reached. It predicts for us the most valuable conclusions on the distribution and arrangement of geological substances in their formation. Already the few investigations, which this memoir contains, lead to the unexpected conclusion that not only potassium and sodium but also lithium and strontium must be counted...
Page 48 - That the flow of heat from the interior upon the surface of a substance of indefinite thickness, is proportional caeteris paribus to its index of refraction, and that for every description of heat.
Page 68 - ... we may imagine that part of the heat from the interior particles is allowed to pass, thereby swelling up the total radiation to that which it is by DULONG and PETIT'S law.
Page 104 - This axis carries on its lower end the mirror 0 and above it the arm // which serves as the handle to rotate the prism and the mirror. A small telescope is adjusted before the mirror which gives an image of a horizontal scale placed at a short distance. By rotating the prism we can cause to pass before the vertical thread of the telescope C the entire spectrum of the flame and bring every portion of the spectrum into coincidence with this thread. To every reading made on the scale there corresponds...
Page 41 - B with the same intensity as it had at A. But the quality of the ray at B will also be the same as its quality at A. For, if it were different, then either a greater or less proportion would be absorbed in its passage from B to C, than was absorbed of the equally intense ray at A, in its passage between A and B. The amount of heat absorbed by the particles between B and C would therefore be different from that absorbed by the particles between A and B. But this cannot be ; for, on the hypothesis...

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