Page:Popular Science Monthly Volume 52.djvu/591

Rh elevation of four thousand feet extends approximately over an area of twenty-six thousand five hundred square miles, while another seventy two thousand five hundred square miles may be added which lie between three thousand and four thousand feet. The country has suffered much of recent years, with all South Africa, from rinderpest, locusts, and drought, but more favorable conditions are hoped for, and with them anything can be grown that can be grown in Cape Colony. Wheat and oats, however, will have to be raised in the dry season with irrigation. For markets the farmer must look to the local towns, and their growth will depend upon the development of the gold prospects; and a wider market awaits the stock farmer. Matabeleland has been demonstrated to be a good cattle country. The natives formerly possessed considerable herds of sheep and goats, but these were killed and eaten during the scarcity of food. Sheep, however, seem to thrive well, as do pigs and donkeys. Well-bred fowls are subject to much disease, and the native birds are very small and lay small eggs. Horses do badly in all parts of Rhodesia. The speaker did not look upon the land as a ready-made paradise. Such a spot is hardly to be found in the unoccupied world; but "the earthly paradise of a happy home in a wild land must be created by a man's own labor, patience, intelligence, and perseverance."

Liquefied Fluorine.—The much-sought for alkahest, or universal solvent of the ancient alchemists, is almost realized in fluorine, which was first prepared by Moissan in 1886. The transparent vessels in which it is contained have to be made of some fluoride, its action on ordinary glass being vigorous and destructive. The difficulty of handling the gas, even in the laboratory, has hence been very great, the fluoride vessels being brittle and clumsy as well as expensive. Professors Dewar and Moissan, being desirous of more fully investigating the properties of the gas, recently conducted a series of experiments at the Royal Institution, in which by means of liquid oxygen they succeeded in liquefying fluorine, and in this comparatively inert state could more fully and carefully examine its properties. The apparatus used for liquefying the gas consisted of a small cylinder of thin glass, into the upper part of which was fused a platinum tube surrounding a smaller tube of the same material. The fluorine enters through the larger tube, passes around the glass envelope, and escapes through the smaller tube. The glass cylinder being cooled down to the temperature of boiling liquid oxygen (-183°), the current of fluorine gas was passed through the bulb without becoming liquid; at this low temperature, however, the fluorine did not attack the glass. On still further lowering the temperature of the liquid oxygen, by exhaustion, a yellow liquid was seen collecting in the glass envelope, while gas no longer escaped from the apparatus. At this moment the escape tube was closed to prevent the entrance of air, and the glass bulb soon became full of a clear yellow liquid possessed of great mobility. Fluorine thus liquefies at about -185°. The chemical activity of the gas was found greatly reduced when in the liquid state, but even then benzene or oil of turpentine underwent spontaneous decomposition when brought into contact with it. It would thus seem that the powerful affinity of fluorine for hydrogen is the last to disappear. In a subsequent experiment, in which liquid air was used and a temperature approximating -210° obtained, the liquid fluorine showed no signs of solidification. Experiments to determine its density led to the conclusion that it had about the same specific gravity as amber, 1·14. Different samples of the liquid examined with the spectroscope showed no specific absorption bands in the visible spectrum. It was found to be not magnetic.

Monazite.—Much has been said of late years, in discussions concerning the "rare earths" and the search in them for new metals, about monazite; and the mineral has obtained considerable commercial importance in consequence of its use in the manufacture of the incandescent mantles of the Welsbach light. Monazite, as described by H. B. C. Nitze in the Franklin Institute, is essentially a phosphate of the rare earth metals cerium, lanthanum, and didymium. It also usually contains small variable percentages of thoria in the form of thorite or orangite—a derivative of another rare metal, thorium. It