Abstract
PARIS Academy of Sciences, September 20.—M. Wurtz in the chair.—The following papers were read:—On the odours of Paris, by M. Sainte-Claire Deville. He analysed some of the moist black earth exposed in a trench in the Rue St. Jacques. The amount of salts in the impregnating liquid indicates considerable concentration (which can be easily explained). The dust from horses' shoes and from wheels of vehicles is thought to be the origin of sulphides and protoxide of iron, and of the dark coloration. The escape of gas, estimated at about a tenth of the gas circulating in the pipes, furnishes part of the sulphur, the carbonated hydrogen and the coal-tar which abounds. Through this escape the sub-soil is rendered wholesome (in the author's opinion), and cannot exhale any dangerous odour. There is a slight smell of sulphuretted hydrogen (not worse than that from sulphurous mineral waters), and a smell of healthy empyreumatic products.—M. de Tchihatchef presented a work of his on Spain, Algeria, and Tunis, but treating chiefly of Algeria. Such questions as the material and moral results of the annexation to France, the mode of action of the new administrative and social institutions, the assimilation of the Arab and the Christian elements, &c., are treated; the author has also studied the geology and botany of the country.—Observations of the new planet Coggia (287) at the Paris Observatory (equatorial of the western tower), by M. Bigourdan.— On a new experiment for showing the direction of the rotation communicated by bodies to polarised light, by M. Govi. A pure spectrum is produced with rectilinearly polarised light, and a plate of rock crystal is interposed, giving a dark band; also an analyser. The spectrum and analyser have a joint movement of rotation (one end of the spectrum being at the centre of the circle of which the spectrum represents the radius). The dark band moves along the spectrum (during rotation) one way or the other according to the nature of the quartz plate (dextrogyrous or laevogyrous). If the motion be sufficiently rapid for the impression on the eye to be continuous, one may trace out in space, or on a screen, opposite spirals. Curious variations are obtained by interposing plates of mica, gypsum, &c.—Study of telluric lines of the solar spectrum (Nice Observatory), by M. Thollon. With his powerful spectroscope, he has resolved the telluric groups B, D, and a of Ångström into their simple elements, separating these elements from each other, and from the other metallic lines.—On the liquefaction of ozone and on its colour in the gaseous state, by MM. Hautefeuille and Chappuis. They passed some highly ozonised oxygen (prepared by their new process) into a Cailletet apparatus. From the first strokes of the piston the capillary tube appeared azure blue. With several atmospheres' pressure the gas became of an indigo blue, the mercury meniscus looking steel blue through it. Sudden liberation from 75 atm. produced a mist, indicating liquefaction (300 atm. were necessary in the case of oxygen). Ozone is a little less easy to liquefy than carbonic acid. If the ozonised oxygen be not compressed slowly and in cold, the ozone is dsecomposed, giving a strong detonation and a yellowish flash. Thus the mixture contains an explosive gas.—On Brunton's tunnelling machine, by M. Biver. This gives an account of results with the machine as used in the lignite pits in the Fuveau Valley. It appears, inter alia, that of 51 horse-power of the motor only 12.4 was transmitted to the machine, 38.6 being lost.—Telescope with double action for pointing long-range guns, by M. de Broca.—On losses in manufacture of vinegar, by M. Garcia.
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Societies and Academies . Nature 22, 528 (1880). https://doi.org/10.1038/022528b0
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DOI: https://doi.org/10.1038/022528b0