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248 preserved in this way for a month, and found them only a little stale in flavor. After being exposed to air at this pressure, allowing an escape so that only normal pressure remained, the meat suffered no damage, provided the bottle was well corked, so that no external germs could enter. Thus it appears that the micro-ferments which cause fermentation can be killed, when they are moist, by a sufficient tension of oxygen. Fermentations of milk and wine are arrested by high pressure, and fruits keep sound. Diastase continues to act as a ferment, and bodies of this description preserve their properties indefinitely if retained under pressure.

Meeting of the French Association for the Advancement of Science.—The President of the French Association for the Advancement of Science, M. d'Eichthal, delivered an address at the opening of the Nantes meeting, on the connection between pure science and the various methods employed to satisfy the wants of humanity. The text of this address has not yet come to hand, but we give herewith the summary of it, which is published in Nature. It would be almost impossible, he said, to enumerate all the branches of human activity which owe their success to the researches of pure science—hygiene, medicine, surgery, the fine arts, mechanics, industry in all its branches, mining, metallurgy, textile industries, lighting, warming, ventilation, water-supply, etc. He then referred in detail to several examples of the influence which the results of science have had upon progress in the arts, with the motive forces of water, air, and steam, mentioning a multitude of names of men eminent in pure science, from Pascal and Boyle down to Faraday and Sir William Thomson, upon the results of whose researches the great advances which have been made in machinery of all kinds have depended. He then spoke of electricity in connection with the names of Oerstedt, Ampere, Faraday, Becquerel, and Ruhmkorff; passing on to speak, at some length, of the steam-engine in its various forms, of the progress which, by means of scientific research, is being made in its construction and its uses, and of the great services which this powerful application of a scientific discovery renders to man. M. d'Eichthal advocated the establishment of local centres of culture as the best counterpoise to that over-centralization to which France owes so many of its social misfortunes. "In our time," said he, "science, history, and literature, have great wants. Libraries, lecture-halls, laboratories, costly materials, instruments numerous and expensive, are indispensable to pupils for learning, and to teachers for carrying on their researches; it is by putting, on a large scale, these resources at their disposal, that we can attract and fix in our midst men eminent in all branches of human knowledge."

Thermo-diffusion.—In the Physical Section, M. Merget stated the results of his researches on the thermo-diffusion of porous and pulverulent bodies in the moist state. A "thermo-diffuser" is any vessel of porous material, filled with an inert powder, into which is plunged a glass or metal tube pierced with holes. On heating this apparatus, after it has been wetted, water-vapor is given off copiously, passing through the porous substance, while dry air passes through the apparatus in the contrary direction, escaping through the tube. If we stop the mouth of the tube, there is produced a pressure amounting to three atmospheres at the temperature of a dull-red heat. If the pulverulent mass or the porous body ceases to be moist, all passage of gas is stopped. These facts the author does not explain, but he shows that De la Rive's explanation cannot be accepted. M. Merget is satisfied that he has here to do with a thermo-dynamic phenomenon. Thermo-diffusion must play an important part in the gaseous exchanges of vegetal life, as the author showed by taking a leaf of Nelumbium as a thermo-diffuser. M. Merget also offered some observations on the Respiration of Plants. He said: If under the influence of light, however feeble, we plunge into water containing carbonic acid, an aerial, or, better, an aquatico-aërial leaf, passing the extremity of the petiole into a test-tube, where the pressure will be a little less than that of the atmosphere, then there will form around the stomata of the leaf an atmosphere of carbonic acid, and oxygen will be discharged from the end of the petiole.