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See detailSur l'illumination de quelques verres
Spring, Walthère ULiege

in Recueil des Travaux Chimiques des Pays-Bas et de la Belgique (1900), XIX

Spring, W. Recueil des Travaux Chimiques des Pays-Bas (1900), 19, 339-49; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010). Ruby-glass is made by the ... [more ▼]

Spring, W. Recueil des Travaux Chimiques des Pays-Bas (1900), 19, 339-49; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010). Ruby-glass is made by the addition of traces of gold chloride to an ordinary fused glass; the glass so obtained is at first colourless and only assumes a ruby colour during subsequent prolonged heating. When an intensely luminous electric beam is passed tangentially through a small cylinder of the colourless gold-glass, practically no internal illumination is visible; in the case of the ruby-glass, however, a yellowish-brown, luminous trace is produced, probably due to reflection from minute particles of metallic gold. The intensity of colour of the ruby-glass depends on the time of its reheating, and determines the intensity of illumination necessary to produce a visible trace; the deeper the colour of the glass the less illumination is required. In the colourless glass, the gold probably exists in a state of extreme subdivision, and the reheating which produces the ruby colour brings about a coarser colloidal aggregation, similar to that which takes place in gelatino-bromide plates during maturation (de Bruyn, Rec. Trav. Chim., 1900, 19, 236). Red glass coloured by copper, and yellow glass coloured by silver, show respectively dull brown and greyish luminous traces, due to the finely divided metals. Glasses coloured by silicates of iron, chromium, manganese, and cobalt show only a faint luminous trace, and, allowing for the presence of small air bubbles, are optically "void" (vide). Glasses which are colourless of themselves show a faint bluish trace and are yellow when viewed through a great length; they thus resemble media containing an extremely minute turbidity (compare Abstr., 1899, ii, 537, 585). Glass decolorised by manganese compounds shows an intensely green fluorescence, the luminous trace being green when the incident light is either violet or blue, but suppressed when it is green, yellow, or red. Glasses containing iron alone or manganese alone are not fluorescent. Reprinted with the permission of the American Chemical Society. Copyright © 2010. American Chemical Society (ACS). All Rights Reserved. [less ▲]

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See detailRecherches biologiques sur une chytridinée parasite du lin
Marchal, Émile ULiege

in Bulletin de l'Agriculture (1900), XVI

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See detailLes comtes d'Auvergne au VIe siècle
Kurth, Godefroid ULiege

in Bulletin de la Classe des Lettres et des Sciences Morales et Politiques (1899), 11

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See detailThéodore Watts
Hamélius, Paul ULiege

in Revue de Belgique (1899), Deuxième série. T. XXVI

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See detailWas dachte Shakespeare über Poesie?
Hamélius, Paul ULiege

Book published by Société belge de librairie (1899)

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See detailSur la diffusion de la lumière par les solutions
Spring, Walthère ULiege

in Recueil des Travaux Chimiques des Pays-Bas et de la Belgique (1899), XVIII

Spring, W. Chemiker-Zeitung (1899), 23, 375-77; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed Jully 15, 2010). Following its studies over the color water(see p ... [more ▼]

Spring, W. Chemiker-Zeitung (1899), 23, 375-77; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed Jully 15, 2010). Following its studies over the color water(see p. 1011) reports authors over experiments concerning so-called shining of the liquids was examined particularly to solutions, D. hot liquids, those from molecules with different forces of attraction combined law. The used solutions disintegrate after their behavior into three groups: asymmetrical those of the alkali metal salts, education those of the ground compound/connection and heavy metal salts and C. those of the actual colloidal solutions only the solutions of the group of asymmetrical - were examined chlorides,bromides, chlorates and nitrates of sodium, potassium, ammonium, calcium and barium - can be represented without special difficulty optically empty(Tyndall), by distillation to one with usual water solution of these salts some drops of a colloidal iron, zinc or a cadmium oxide hydrate solution prepared add, the well jelly precipitation tear then all for portion cups with itself and leave an optically empty liquid. A similar clarifying of the solutions from the second group could not be accomplished because of the chemical reactions occurring thereby and the formation of basic salts. Author was content to compare a shining of the filtered solutions with that distilled water also filtered solutions the zinc, cadmium, manganese, cobalt, nickel old person behaved completely like distilled water, on the other hand solutions of aluminum, chrome, a, copper, mercury and lead salts made the electrical light bundle strongly visible. In by the dissociated effect water is formed for the latter trap on the salts a metal oxide hydrate, which, equal the colloids, which reflects light laterally. Addition decreased from HCl to the solutions(lead solution except for) corresponding shining, with the help of a strong light bundle one can recognize therefore the character of a solution. Clear one aqueous solutions of really colloidal substances such as gelatin, rubber arabicum, dextrine, alcoholic of colophony, sandarac, mastic, lacquer, furthermore stagnant Selfen solutions, diluted Solutions of alkali silicates, of different coloring materials as citizen of Berlin blue, Phenyl blue etc. show a constant strong light cone in each concentration. The past experiments could not decide the question, whether this light diffusion depends dissolved substances on the imperfect type of the solution or however on the molecular size, yet. From its observations author concludes that the clear can be separated solutions, which appear alike with usual lighting in intensive light into such asymmetrical, which behave as optically empty, and in education such, which reflects the light laterally. Only the first are chemically completely homogeneous, in them are an intimate mutual compound gel to assume with the solvent. That light-ether is closer in such a solution than everywhere in the empty area, but from same condensation. Those optically empty solutions are all also Electrolyte, the ions cause therefore no unequal condensation of light ether. In that it already cause the electrostatic forces before the light of a stream a regular distribution of the ions, so that these probably affect the refractive indexes, but the continuous light in its straight-line run cannot disturb. Although solutions that To group of education as electrolytes seem, steps the diffusion of the light only after suitable Diluted the solution up. Furthermore the salts of the metals concerned do not suffer an hydrolytic Dissociation, absolute homogeneity can any more exist, and consequently the hydrolysis is to be differentiated from the electrolytic Dissociation with respect to the light bundle. Finally come the solutions as really not electrolytic, i.e. as colloidal forwards, then they cause the diffusion of the light in each degrees of the Diluted u.7 can be never regarded as true transparent liquids. Substances with complicated molecules behave in an intensive light beam, similarly a molecular complex, therefore the majority of the organic bodies causes a light diffusion similarly colloidal solutions, but becomes shining organic liquids still more complicated by the occurrence of fluorescence features. Reprinted with the permission of the American Chemical Society. Copyright © 2010. American Chemical Society (ACS). All Rights Reserved. [less ▲]

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See detailProgramme du cours pratique de chimie générale
Spring, Walthère ULiege

Learning material (1899)

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See detailLes maladies microbiennes (suite)
Masius, Voltaire ULiege

Speech/Talk (1899)

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See detailEtude d'un cas particulier très important du mouvement de rotation d'un corps solide
Folie, François ULiege

in Bulletin de la Classe des Sciences. Académie Royale de Belgique (1899), 3

The author searches if the Eulerian nutation is insignificant and if the hour remains uniform when we take for reference point the instantaneous pole by restricting to the case of solid earth and where ... [more ▼]

The author searches if the Eulerian nutation is insignificant and if the hour remains uniform when we take for reference point the instantaneous pole by restricting to the case of solid earth and where there are no disruptive forces. [less ▲]

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See detailSur un procédé de détermination de la méridienne
Folie, François ULiege

in Bulletin de la Classe des Sciences. Académie Royale de Belgique (1899), 5

The author establishes the foundations of his determination process of the meridian line and recommends the use.

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See detailL'Actinonema du tilleul ("Actinonema tiliae")
Marchal, Émile ULiege

in Bulletin de l'Agriculture (1899), XV

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See detailNotice sur Notger
Kurth, Godefroid ULiege

in Académie royale des sciences, des lettres et des beaux-arts de Belgique (Ed.) Biographie nationale (1899)

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See detailDiscours prononcé à la distribution des prix de l'École Saint-Luc
Kurth, Godefroid ULiege

Speech/Talk (1899)

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See detailRapport sur le mémoire de MM. V. Chauvin et A. Roersch : Etude sur Nicolas Cleynaert
Kurth, Godefroid ULiege

in Bulletin de la Classe des Lettres et des Sciences Morales et Politiques (1899)

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See detailAvant-projet d'un programme de travaux lu à la Commission royale d'Histoire
Kurth, Godefroid ULiege

in Compte rendu des séances de la commission royale d'histoire (1899), IX(5e série), -

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See detailL'Actinonema du tilleul ("Actinonema tiliae")
Marchal, Émile ULiege

in Bulletin de la Société centrale forestière de Belgique (1899), 6

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See detailLa nécrose du tilleul et du marronnier d'Inde ("Nectria cinnabarina")
Marchal, Émile ULiege

in Bulletin de la Société centrale forestière de Belgique (1899), 6

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See detailSur la réalisation d'un liquide optiquement vide
Spring, Walthère ULiege

in Recueil des Travaux Chimiques des Pays-Bas et de la Belgique. 2e série (1899), XVIII

Spring, W. Recueil des Travaux Chimiques des Pays-Bas (1899), 18, 153-68; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010). Tyndall has assumed that ... [more ▼]

Spring, W. Recueil des Travaux Chimiques des Pays-Bas (1899), 18, 153-68; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010). Tyndall has assumed that when a beam of light passes through a gas its path is made evident by the illumination of minute solid or liquid particles present as impurities. Lallemand, however, from experiments with carefully distilled liquids, concluded that the illumination of a fluid medium by light is a specific property of the medium, and that each medium has a certain "coefficient of illumination", dependent on its nature. The author now shows that, although it is impossible to obtain a truly transparent liquid (that is, one which is not rendered luminous by the passage of a beam of light) by distillation or filtration, liquids can be rendered optically pure by means of a current of electricity; on passing, for example, a current through water containing a small quantity of silica or ferric hydroxide in suspension, the suspended matter is deposited at the cathode, and carries with it the minute particles which render the water capable of being illuminated. The same result is also obtained by adding clear lime water to a solution of silicic acid, and leaving the precipitate to subside in a stoppered vessel; on examining the liquid in a beam of light, care being taken that the vessel is not opened, it is found to be perfectly transparent. The subsidence of other gelatinous precipitates, such as the hydroxides of iron, aluminium, and zinc, from water renders the latter non-illuminable; the subsidence of crystalline precipitates, however, such as barium sulphate or calcium oxalate, gives no such result. It thus appears probable that the minute suspended particles can only be removed by being surrounded, during the precipitation, with a heavy, gelatinous envelope. The filtration of water through a layer of a gelatinous precipitate, out of contact with the air, renders it transparent; but if filtered in contact with air, this result is not obtained. The reason why distillation fails to yield transparent liquids is thus made evident. In the case of organic liquids, the author has not obtained such definite results; the subsidence of gelatinous precipitates from organic liquids is, as a rule, very incomplete, so that optical transparency cannot generally be obtained. It appears probable also, that many organic liquids become luminous on the passage of a beam of light, owing to fluorescence. The particles which are rendered luminous in water by a beam of light appear to consist largely of organic matter, but luminescence is also due to minute bubbles of gas; this is made clear by the increased illumination which occurs when the pressure in the space above the water is diminished, and by the fact that optically transparent water is rendered luminescent by passing air through it. Reprinted with the permission of the American Chemical Society. Copyright © 2010. American Chemical Society (ACS). All Rights Reserved. [less ▲]

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See detailSur la plasticité des corps solides et ses rapports avec la formation des roches
Spring, Walthère ULiege

in Annales de la Société Géologique de Belgique (1899), XIV

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