Radioactivity Science Before Curie

It was Robert Boyle, in his ” Skeptical Chymist,” who first controverted these ancient and medieval notions, and who gave to the word “element” the meaning that it now possesses.

Continuing Early Science of Radioactivity,
Today we begin the third part of the series with our selection from a special aticle to The Great Event Evemts by Famous Historians, Volume 20 by Sir Oliver Lodge published in 1914. The selection is presented in 2 easy 5 minute installments. For works benefiting from the latest research see the “More information” section at the bottom of these pages.

Sir Oliver Lodge (1851-1940) discovered electromagnetic radiation which led to the invention of radio.

Previously in Early Science of Radioactivity.

Time: 1903
Place: Paris

In the days of the early Greeks the word “element” was applied rather to denote a property of matter than one of its constituents. Thus, when a substance was said to contain fire, air, water, and earth (of which terms a childish game doubtless once played by all of us is a relic), it probably meant that they partook of the nature of the so-called elements. In flammability showed the presence of concealed fire; the escape of “airs” when some substances are heated or when vegetable or animal matter is distilled no doubt led to the idea that those airs were imprisoned in the matters from which they escaped; hardness and permanence were ascribed to the presence of earth, while liquidity and fusibility were properties conveyed by the presence of concealed water. At a later date the “Spagyrics” added three ” hypostatical principles ” to the quadrilateral; these were “salt,” “sulphur,” and “mercury.” The first conveyed solubility and fixedness in fire; the second, in flammability; and the third, the power which some substances manifest of producing a liquid, generally termed “phlegm,” on application of heat, or of themselves being converted into the liquid state by fusion.

It was Robert Boyle, in his ” Skeptical Chymist,” who first controverted these ancient and medieval notions, and who gave to the word “element” the meaning that it now possesses — the constituent of a compound. But in the middle of the seven teenth century chemistry had not advanced far enough to make his definition useful, for he was unable to suggest any particular substance as elementary.

The modern conception of the elements was much strengthened by Dalton’s revival of the Greek hypothesis of the atomic constitution of matter, and the assigning to each atom a definite weight. This momentous step for the progress of chemistry was taken in 1803 ; the first account of the theory was given to the public, with Dalton’s consent, in the third edition of Thomas Thomson’s “System of Chemistry” in 1807; it was subsequently elaborated in the first volume of Dalton’s own “System of Chemical Philosophy,” published in 1808. The notion that compounds consisted of aggregations of atoms of elements united in definite or multiple proportions familiarized the world with the conception of elements as the bricks of which the universe is built. *Yet the more daring spirits of that day were not without hope that the elements themselves might prove decomposable. Davy, indeed, went so far as to write in 1811: “It is the duty of the chemist to be bold in pursuit; he must recollect how contrary knowledge is to what appears to be experience. … To inquire whether the elements be capable of being composed and decomposed is a grand object of true philosophy.” And Faraday, his great pupil and successor, at a later date, 1815, was not behind Davy in his aspirations when he wrote: “To decompose the metals, to re-form them, and to realize the once absurd notion of transformation — these are the problems now given to the chemist for solution.”

Indeed, the ancient idea of the unitary nature of matter was in those days held to be highly probable. For attempts were soon made to demonstrate that the atomic weights were themselves multiples of that of one of the elements. At first the suggestion was that oxygen was the common basis; and later, when this supposition turned out to be untenable, the claims of hydrogen were brought forward by Prout. The hypothesis was revived in 1842, when Liebig and Redtenbacher, and subsequently Dumas, carried out a revision of the atomic weights of some of the commoner elements, and showed that Berzelius was in error in attributing to carbon the atomic weight 12.25 instead of 12.00. Of recent years a great advance in the accuracy of the determinations of atomic weights has been made, chiefly owing to the work of Richards and his pupils, of Gray, and of Guye and his collaborators, and every year an international committee publishes a table in which the most probable numbers are given on the basis of the atomic weight of oxygen being taken as sixteen. In the table for 191 1, of eighty- one elements, no fewer than forty-three have recorded atomic weights within one-tenth of a unit above or below an integral number. My mathematical colleague, Karl Pearson, assures me that the probability against such a condition being fortuitous is 20,000 millions to one.

The relation between the elements has, however, been approached from another point of view. After preliminary suggestions by Dobereiner, Dumas, and others, John Newlands in 1862 and the following years arranged the elements in the numerical order of their atomic weights, and published in The Chemical News of 1863 what he termed his law of octaves — that every eighth element, like the octave of a musical note, is in some measure a repetition of its forerunner. Thus, just as C on the third space is the octave of C below the line, so potassium, in 1863 the eighth known element numerically above sodium, repeats the characters of sodium, not only in its physical properties — color, softness, ductility, malleability, etc. — but also in the properties of its compounds, which, indeed, resemble each other very closely. The same fundamental notion was reproduced at a later date, and independently, by Lothar Meyer and Dmitri Mendeleeff; and to accentuate the recurrence of such similar elements in periods, the expression ” the periodic system of arranging the elements” was applied to Newlands’ arrange- j ment in octaves. As every one knows, by help of this arrangement Mendeleeff predicted the existence of then unknown elements, under the names of eka-boron, eka-aluminum and eka-silicon, since named scandium, gallium, and germanium by their discoverers, Cleve, Lecoq de Boisbaudran, and Winckler. It might have been supposed that our knowledge of the elements was practically complete; that perhaps a few more might be discovered to fill the outstanding gaps in the periodic table.

But we are confronted by an embarras de richesse. The discovery of radioactivity by Henri Becquerel, of radium by the Curies, and the theory of the disintegration of the radioactive elements, which we owe to Rutherford and Soddy, have indicated the existence of no fewer than twenty-six elements hitherto unknown. To what places in the periodic table can they be assigned?

Beginning with radium, its salts were first studied by Ma dame Curie; they closely resemble those of barium. The atomic weight, too, falls into its place; as determined by Madame Curie and by Thorpe, it is 89.5 units higher than that of barium; in short, there can be no doubt that radium fits the periodic table, with an atomic weight of about 226.5. It is an undoubted element.

Mme. Marie Curie begins here. Sir William Ramsay begins here. Sir Oliver Lodge begins here.

More information here and here, and below.

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