Abstract
Annales de Chimie et de Physique, July and August, 1871. This number contains the second portion of a very lengthy memoir by M. Berthelot on explosive agents in general; this half of the communication deals with dynamite, gun cotton, picric acid and potassic picrate. At the end of the memoir a general table is given which shows the amount of heat generated and the volume of gas formed by one kilogram of substance; the product of these two numbers will of course give the relative effects produced by each compound; the numbers given show that if nitroglycerine produces an amount of force equal to 94, picric acid equals 54, gun cotton 50, potassic picrate 34, whilst gunpowder has only an explosive force equal to 14. M. Janssen contributes a very valuable paper on the atmospheric lines in the solar spectrum. He finds that the bands observed by Brewster and Gladstone can be resolved into fine lines comparable to the solar lines properly so called, and that the atmospheric lines are more numerous than the solar lines in the red, orange, and yellow portions of the spectrum. The atmospheric lines are always visible in the solar spectrum, some lines it is true almost disappear when the sun is very high, but they are those which are never very intense; the author finds that the intensity of the atmospheric lines observed at the horizon is about fifteen times as great as when observed in the meridian. M. Janssen has also examined the spectrum of the moon and stars, and more particularly of Sirius and α in Orion; he has not succeeded in observing any new lines whatever in the spectrum of the moon, proving that our satellite cannot have any appreciable atmosphere. M. Raoult has found that a solution of cane sugar sealed up in vacuo and exposed to light for five months is partially changed into glucose. Amongst the other original memoirs there is a very long one by Dr. de Coppet on the temperature of congelation, in saline solutions. There are also a considerable number of abstracts of papers from foreign journals, making up altogether a very bulky number.
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Scientific Serials . Nature 5, 512–513 (1872). https://doi.org/10.1038/005512b0
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DOI: https://doi.org/10.1038/005512b0