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acetobutyl action alcoholic solution alkaline alumina ammonia ammonium analysis anhydride arsenious oxide atomic weight bands benzene berberine Boisbaudran bromine bulb Calculated carbon cent Chem chemical chloride cold colour colourless compound containing cooling crystallisation crystals decomposed decomposition dehydrothiotoluidine determined dextrin diazotised didymium dilute dissolved distilled dried earths erbia ether ethyl evaporated experiments fibre following results formation formed formula fractionation gave the following gives gram gram gave gram H₂O gram substance gave heated hydrochloric acid hydrogen chloride hydrogen fluoride insoluble iodide liquid manganic melting point mercury metal method mixed mixture molecular weight molecule mols needles nitrate nitric acid nitrogen obtained oxide oxygen peroxide phosphorescence phosphorus platinum potash potassium precipitate prepared pressure pure reaction readily residue salt samarium separated silver small quantity sodium soluble spectra spectrum sulphate sulphuric acid tellurium temperature thiophosphoryl fluoride tion Trans tube vapour volume washed yellow yttria yttrium
Page 637 - Ba = 68-5 the consecutiveness of change in atomic weight, which with the true values is so evident, completely disappears. Secondly, it had become evident during the period 1860-70, and even during the preceding decade, that the relations between the atomic weights of analogous elements were governed by some general and simple laws. Cooke, Cremers, Gladstone, Gmelin, Lenssen, Pettenkofer, and especially Dumas, had already established many facts bearing on that view. Thus...
Page 636 - The atomic weight of an element may sometimes be amended by a knowledge of those of the contiguous elements. Thus, the atomic weight of tellurium must lie between 123 and 126, and cannot be 128. 8. Certain characteristic properties of the elements can be foretold from their atomic weights. The aim of this communication will be fully attained if I succeed in drawing the attention of investigators to those relations which exist between the atomic weights of dissimilar elements, which, as far as I know,...
Page 635 - ... 4. The elements which are the most widely diffused have small atomic weights. " 5. The magnitude of the atomic weight determines the character of the element just as the magnitude of the molecule determines the character of a compound body.
Page 641 - The periods of the elements have thus a character very different from those which are so simply represented by geometers. They correspond to points, to numbers, to sudden changes of the masses, and not to a continuous evolution. In these sudden changes destitute of intermediate steps or positions, in the absence of elements intermediate between, say, silver and cadmium, or aluminium and silicon, we must recognise a problem to which no direct application of the analysis of the infinitely small can...
Page 649 - I will confine myself to simple substances and to oxides. Before the periodic law was formulated the atomic weights of the elements were purely empirical numbers, so that the magnitude of the equivalent, and the atomicity, or the value in substitution possessed by an atom, could only be tested by critically examining the methods of determination, but never directly by considering the numerical values themselves ; in short, we were compelled to move in the dark, to submit to the facts, instead of...
Page 636 - ... periodic law could not have been discovered, and which rendered its appearance natural and intelligible. In the first place, it was at that time that the numerical value of atomic weights became definitely known. Ten years earlier such knowledge did not exist, as may be gathered from the fact that in 1860 chemists from all parts of the world met at Karlsruhe in order to come to some agreement, if not with respect to views relating to atoms, at any rate as regards their definite representation....
Page 648 - When, in 1871, I described to the Russian Chemical Society the properties, clearly defined by the periodic law, which such elements ought to possess, I never hoped that I should live to mention their discovery to the Chemical Society of Great Britain as a confirmation of the exactitude and the generality of the periodic law.
Page 640 - atom," nevertheless history and custom have drawn a sharp distinction between the two words, and the present chemical conception of atoms is nearer to that defined by the Latin word than by the Greek, although this latter also has acquired a special meaning which was unknown to the classics. The periodic law has shown that our chemical individuals display a harmonic periodicity of properties dependent on their masses. Now natural science has long been accustomed to deal with periodicities observed...
Page 272 - Our notions of a chemical element have expanded. Hitherto the molecule has been regarded as an aggregate of two or more atoms, and no account has been taken of the architectural design on which these atoms have been joined. We may consider that the structure of a chemical element is more complicated than has hitherto been supposed. Between the molecules we are accustomed to deal with in chemical reactions and ultimate atoms...
Page 635 - Without entering into details, I will give the conclusions I then arrived at in the very words I used: — '1. The elements, if arranged according to their atomic weights, exhibit an evident periodicity of properties. '2. Elements which are similar as regards their chemical properties have atomic weights which are either of nearly the same value (eg platinum, iridium, osmium) or which increase regularly (eg potassium, rubidium, caesium). '3. The arrangement of the elements, or of groups of elements,...