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THE POPULAR SCIENCE MONTHLY. 



preserved iu 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 de- 

 scription preserve their properties indefi- 

 nitely if retained under pressure. 



Meeting of the Frcufh Association for 

 the Advaucement of Science. The Presi- 

 dent of the French Association for the Ad- 

 vancement of Science, M. d'Eichthal, deliv- 

 ered an address at the opening of the Nantes 

 meeting, on the connection between pure 

 science and tJie 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 Natare. It would be 

 almost impossible, he said, to enumerate all 

 the branches of human activity which owe 

 their success to the researches of pure sci- 

 ence hygiene, medicine, surgery, the fine 

 arts, mechanics, industry in all its branches, 

 mining, metallurgy, textile industries, light- 

 ing, warming, ventilation, water-supply, etc. 

 He then referred in detail to several exam- 

 ples 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 re- 

 searches 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, Am- 

 pere, 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 re- 

 search, is being made in its construction 

 and its uses, and of the great services which 

 this powerful application of a scientific dis- 



covery renders to man. M. d'Eichthal advo- 

 cated 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 put- 

 ting, 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." 



Thernio-diiTasion. In the Physical Sec- 

 tion, M. Merget stated the results of his 

 researches on the thermo-diffiision of po- 

 rous and pulverulent bodies in the moist 

 state. A " thermo-dififuser " 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 pas- 

 sage of gas is stopped. These facts the au- 

 thor 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-diifuser. M. 

 Merget also offered some observations on 

 the Respiration of Plants. He said : If un- 

 der the influence of light, however feeble, we 

 plunge into water containing carbonic acid, 

 an aerial, or, better, an aquatico-aerial 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. 



