Sur la densité et l'état allotropique de certaines variétés de soufre : Remarque sur la détermination de la densité des corps en poudre fine

in Bulletin de la Classe des Sciences. Académie Royale de Belgique (1907), (6), 684-708

Sur la détermination des périodes d'étoiles varaibles

in Astronomy and Astrophysics (1980), 92

It is maintained that the periods announced for 11 Ori and 137 Tau by Winzer (1974) are not the true ones, but related periods. It is emphasized that in order to find the correct period of a star, it is ... [more ▼]

It is maintained that the periods announced for 11 Ori and 137 Tau by Winzer (1974) are not the true ones, but related periods. It is emphasized that in order to find the correct period of a star, it is necessary not only to use a good method of period determination (e.g., Renson 1978), but also to have a good series of measurements, especially concerning the time distribution of the measurements. Otherwise, the true period cannot be distinguished from the related ones. [less ▲]

Sur la diffusion de la lumière par les solutions

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 ▲]

Sur la digestion des albuminoïdes chez quelques invertébrés

in Bulletin de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique. Sciences (1878), XLIV(8), 213

Sur la dilatation des aluns

in Bulletin de l'Académie Royale des Sciences, des Lettres et des Beaux-arts de Belgique. Sciences. 3e série (1882), III(4), 331-349

Sur la dilatation, la chaleur spécifique des alliages fusibles et leurs rapports avec la loi de la capacité des atomes des corps simples et composés pour la chaleur

in Annales de Chimie et de Physique. 5e série (1876), VII

Sur la diminution de densité qu'éprouvent certains corps à la suite d'une forte compression et sur la raison probable de ce phénomène

in Bulletin de la Classe des Sciences. Académie Royale de Belgique (1903), (12), 1066-1082

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 ... [more ▼]

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. [less ▲]

Sur la discordance entre les variations respiratoires des pressions intracarotidiennes et intrathoraciques

in Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences (1882), XCIV

Sur la discrétisation totale des problèmes paraboliques

in Bulletin de la Société Royale des Sciences de Liège (1992), 61(6), 441-455

We set an algorithm for the numerical resolution of parabolic problems combining the finite element method for the space variables x and the discontinuous Galerkin method for the time t. By using the ... [more ▼]

We set an algorithm for the numerical resolution of parabolic problems combining the finite element method for the space variables x and the discontinuous Galerkin method for the time t. By using the Legendre's polynomials in t, we reduce the resolution of the system of qN linear equations, where N is the amount of finite element degrees of freedom and q-1 is the degree of the approximations with respect to t, to two inversions of NxN matrices and one evaluation of a NxN matrix polynomial of degree q by a technic of Horner's type. The systematic character of the coefficients allows an algorithm with q as a parameter. [less ▲]

Sur la floculation des milieux troubles

in Recueil des Travaux Chimiques des Pays-Bas et de la Belgique. 2e série (1900), XIX

Spring, W. Recueil des Travaux Chimiques des Pays-Bas (1900), 19, 204-35 ; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010). This paper commences ... [more ▼]

Spring, W. Recueil des Travaux Chimiques des Pays-Bas (1900), 19, 204-35 ; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010). This paper commences with an historical summary of the researches of previous observers on liquids rendered turbid by the presence of solid substances in a minute state of division (pseudo-solutions), and a bibliography of the subject is given in an appendix. Details are then given of the author's own experiments, the results of which are summarised as follows. Solutions of salts which, which like those of polyvalent metals, cannot be obtained in an optically transparent condition (Abstr., 1899, ii, 537) bring about the flocculation of turbid liquids much more readily than solutions of any other salts. This result is due partly to the agglutinative power of the metallic hydroxides formed by the hydrolysing action of the water, and partly to the flocculating action of the acids simultaneously produced. The extent of the flocculation caused by hydroxides is closely connected with their chemical and physical character as well as with the nature of the turbidity. The behaviour of the turbidity towards salt solutions somewhat resembles that of a membrane, the acid formed by the hydrolysis of the salt traversing the liquid by diffusion whilst the metallic hydroxide is precipitated with the substance causing the turbidity. The persistence of very fine turbidities bears a relation to the Brownian motion. In consequence of this motion, particles suspended in pure water frequently collide with one another without coming into actual contact, but if an electrolyte is present the particles agglutinate, the Brownian motion ceases, and the flocks formed are deposited. The flocculation of liquids is not brought about by electrical action at a distance, as by Rontgen rays or the electricity developed by a statical machine or an induction coil, and cannot therefore be compared with the precipitation of dust particles in air. The feeblest electric current is, however, sufficient to induce clarification, which in the majority of cases commences at the cathode. Electrolytes of the same conductivity but having different anions and cations influence the flocculation very unequally. Electrolytes having the same cation induce flocculation in equal times, whilst the nature of the anion plays only a secondary part. The rate of flocculation in different electrolytes having the same anion is exactly in the order of the velocities of the cations in electrolysis. It therefore appears that the primary cause of the flocculation brought about by electrolytes is to be sought in the velocities of the ions. Reprinted with the permission of the American Chemical Society. Copyright © 2010. American Chemical Society (ACS). All Rights Reserved. [less ▲]