LONDON. Royal Society, November 9.— Sir Archibald Geikie K.C.B., president, in the chair.—Sir William Ci-ookes: The spectrum of boron. The physical properties of the element boron are almost unknown, notwithstanding the efforts of many chemists who have worked on the subject. Moissan, who came nearest to obtaining the pure element, only succeeded in getting it in the form of an amorphous powder. He said it was not possible to melt or volatilise it in a carbon crucible or arc as it was changed into carbon boride, and concluded that boron passed from the solid to the gaseous state without becoming liquid. Recently Dr. Weintraub, of the General Electric Company, U.S.A., has not only obtained boron in a state of purity, but has prepared it in a fused homogeneous state. His process consists in running an alternating-current arc between water-cooled copper electrodes in a mixture of boron chloride vapour with a large excess of hydrogen. The boron agglomerates on the ends of the electrodes, where it grows in the form of small rods. After a while the arc runs between two boron electrodes; and if the current is of proper value the rods melt down to boron beads, which eventually fall off, whereupon the same process repeats itself. The first specimens received from Dr. Weintraub were deposited from a vaporous state from boron chloride and hydrogen in the manner described. Subsequently he kindly sent the author some lumps of fused boron which had been prepared from magnesium boride. This boride dissociates at a relatively low temperature (12000), especially in vacuo, and with rapidity at 15000. The fusion is effected between copper electrodes, the affinity of copper for boron being so slight that it can be directly fused on to the electrode without being contaminated with copper. Another way of fusing boron is in what Dr. Weintraub calls a mercury arc furnace, based on the fact that most refractory bodies, such as tungsten, tantalum, boron, &c., have no affinity whatever for mercury. The result of the author's work on boron is to show its photographed spectrum consists essentially of three lines, the wave-lengths of which, according to accurate measurements, are 3451-50, 2497-83, and 2496-89. For more easy comparison the wavelengths of these lines measured by different observers are given below in a tabular form:—