|Reference : Sur la diminution de densité qu'éprouvent certains corps à la suite d'une forte compr...|
|Scientific journals : Article|
|Physical, chemical, mathematical & earth Sciences : Chemistry|
|Sur la diminution de densité qu'éprouvent certains corps à la suite d'une forte compression et sur la raison probable de ce phénomène|
|[en] Diminution of the Density of Certain Substances Induced by Compression and the Cause of the Phenomenon|
|Spring, Walthère [Université de Liège - ULg]|
|Bulletin de la Classe des Sciences. Académie Royale de Belgique|
|Académie Royale de Belgique|
|[en] Pressure ; Diffusion in Solids ; Density|
|[fr] Pression ; Diffusion dans les solides ; Densité|
|[en] Spring, W. Bulletin de la Classe des Sciences, Academie Royale de Belgique (1904), 1903, 1066-82; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010).
At an amount of metals, as well as other materials, very strong pressure causes, (over 10000 atmospheres, instead of a density increase a decrease [with (NH4)2SO4 for example: 1.773 to 1.750). For these by the author, as well as feature examined more near by KAHLBAUM is tried an explanation, by being brought in compound/connection with the variation in volume with melting. It assumed that perfectly spherical bodies under the influence of an all-sided working strong pressure partly do not arrive at "flowing", thus a change of their molecular structure in the sense of a reduction that is experienced viscosity (pseudo fusion). If this view applies, then bodies, which expand when melting, must experience a volume increase with strong pressure also and in reverse. This consequence is confirmed by the experience. Examples of the first type are tin, lead, cadmium, silver, during bismuth when melting pull together and accordingly also with strong pressure at density increase. Author made wires of different metals, by being pressed by close openings, and observed the fact that Bi-wire was first completely flexible and returned only to some bends to the brittle condition whereby the acceptance by high pressure caused one flowing is supported. The obtained wires were divided ever into 2 parts, and heats one half up to near the melting point, whereby S.c. returned to the normal condition. If one dipped now the "started" and the "fluent" wire together into a salt solution of the same metal, then a weak current could be proven by means of a sensitive galvanometer. The voltage/tension amounts to the following: with tin 0.11, lead 0.12, cadmium 0.20, silver 0.98, bismuth 0.385 milivolts. With the four first, lower volume increase melting metals the "fluent" wire cathode was, with bismuth anode. Similar results were obtained with polished metal bars and rolled out volumes. Over the density variations of some metals with 16° the following table gives information. Metal, Density of the, Fluent, Rolled Metals, Started metals. Lead..., 11.3351, 11.3348, 11.3410. Tin..., 7.3011, 7.3016, 7.3137. Cadmium..., 8.6558, 8.6603, 8.6633. Silver..., 10.2485, 10.2531, 10.2696. Bismuth..., 9.8522, -, 9.8354. One must "protect" from this between firm, in which a metal cannot experience noticeable deformation, and which "apparent" firm differentiates, which by the loss of crystalline structure and the ability of flowing is characterized. Certain materials go possessing easily into this condition over (plastic metals), during different this ability in very small measure or at all; materials of the latter type (coal, sand) cannot be combined also through still so high pressure to a uniform mass.
Reprinted with the permission of the American Chemical Society. Copyright © 2010. American Chemical Society (ACS). All Rights Reserved.
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|Voir aussi : http://hdl.handle.net/2268/68022|
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