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Page:Popular Science Monthly Volume 65.djvu/192

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188
THE POPULAR SCIENCE MONTHLY.

THORIUM, CAROLINIUM AND BERZELIUM.

In a paper entitled 'Thorium, Carolinium, Berzelium,' presented at the Chemists' Club, New York, the evening of April 8, by Dr. Charles Baskerville, professor of chemistry at the University of North Carolina, the following interesting and important facts were brought out. As the result of a number of years' study of the element thorium, Dr. Baskerville has succeeded in extracting from it two novel chemical elements. The work indicated an agreement with the conclusions of Hofmann and Zerban in opposition to those of Schmidt, Curie and Rutherford, namely, that thorium is a primary radio-active body. Although no thorium preparations had yet been prepared absolutely free from any activity, numerous reasons were given which pointed toward the correctness of the conclusion that thorium is not a primary radio-active element. An extremely interesting observation touching this may be noted, namely, a preparation was obtained from a large amount of the wash waters used in the I manufacture of the Welsbach mantles which was very much more radio-active than the original thorium and yet showed no thorium by chemical methods, and the merest trace was found in the spectrum made with a large Rowland grating. Whether it be primarily radio-active or not, the speaker maintained would not interfere with the other conclusions obtained from the investigations of himself and a number of his students.

Pure thorium was fractioned by phenyl hydrazine and the fractions obtained varied in their atomic weights from 214 to 252, the original thorium showing 232.6. That method was abandoned as time-robbing, and an effort was made to separate the constituents by fractional distillation of the chlorides as they were made by passing chlorine over a mixture of pure carbon and thorium dioxide. Very elaborate apparatus was devised I for this purpose, the mixture being placed within a carbon boat and the distillation carried out within quartz tubes. A white vapor was given off at a comparatively low temperature which 1 condensed in the cooler portion of the tube and was readily collected by solution in alcohol. The thorium was distilled away from the boat and collected as fern-like crystals of the tetrachloride within the quartz tube. A ; residue remained in the boat. These three materials were more or less purified and atomic weight determinations made of them. That which remained : in the boat after different methods of purification showed an atomic weight of 255.6. Its oxide gave a specific gravity of 11.26, the original thorium having an atomic weight of 232.6 and | specific gravity of 10.5. The original thorium oxide was pure white, whereas this residue possessed a pinkish tinge. This is the carolinium of the new element reported by Dr. Baskerville in 1900. The volatile body gave an atomic weight of 213, assuming its quadrivalence. The oxide gave a specific gravity of 8.44. It possesses a slight green color. As Berzelius first noted this 'Meisserdampf,' stating that it was not thorium, the author named the element berzelium after the famous Swedish chemist who discovered thorium. The new thorium gives a white oxide and shows an atomic weight of 220. The specific gravity of this oxide is 9.2. Carolinium oxide is soluble in hydrochloric acid. Neither of the other oxides, nor the original thorium oxide, is soluble in this acid. All the oxides show radioactivity. Several chemical differences were also noted. The speaker carefully stated that the materials were not yet in the state of purity that was desired. He stated that none of these substances give absorption spectra. Some slight differences had been noted in the arc spectra, but no definite conclusions could be drawn. Samples of the materials had been sent to Sir William Crookes, by request, who is