Open main menu

Page:Popular Science Monthly Volume 19.djvu/590

This page has been proofread, but needs to be validated.
574
THE POPULAR SCIENCE MONTHLY.

The New Eddystone Lighthouse.—The last coping-stone of the new Eddystone Lighthouse was laid on the 1st of June by the Duke of Edinburgh. The foundation stone was laid by the same prince as Master of the Trinity Board on August 19, 1879. It is expected that the tower will be ready for the exhibition of the light next March. The new tower is double the height of the old one, and is made of uniform granite. The light, instead of being fixed as at present, will be oscillating, and will consist of a powerful white, double-flashing half-minute light, showing two successive flashes of about two and a half seconds' duration, divided by an eclipse of about four seconds, the second flash being followed by an eclipse of about twenty-one seconds. The light will be visible all around the horizon, for seventeen and a half miles, and will overlap the light of the Lizard, where there are now eight miles of darkness. A subsidiary white light is to be mounted in an upper room, to cover the reef of rocks known as the Hand Deeps, which will be adjusted so as to be seen only within the area of danger occasioned by those rocks.

 

Sulphur Formation in the Soil of Paris.—M. Daubrée has called attention to a formation of native sulphur which is now going on in the soil of Paris. The mineral has been found in considerable quantities among the rubbish dug up from the Place de la République, presenting a crystalline appearance to the naked eye, and showing under the glass the octahedral forms which arc most characteristic of the natural crystals. The origin of this substance, which is found in situations that preclude the supposition of emanations of illuminating gas having anything to do with it, is evidently to be ascribed to the presence of sulphate of lime, old plaster, and various organic matters which have been brought together during the last two centuries in the filling up of the ditch that formerly encircled the city. The sulphur occurs at a depth of from eight or ten inches to ten feet below the surface, and over an area of one hundred and sixty by fifty or sixty feet, forming in reality a kind of bed or deposit of the mineral. Specimens have been obtained from it of workable sulphur, analogous to that of Sicily and other countries, consisting of a breccia of small fragments incrusted with crystals of sulphur, cementing them one to another.

 

A Vegetable Digestive Agent.—M.Wurtz, in a paper read before the French Academy of Sciences, has drawn general attention to the great chemical and therapeutical value of papaine, a vegetable substance which excites the digestive faculty, as opium produces sleep. Both these substances are obtained in the same manner, by cutting into the epidermis of plants whose lactiferous vessels are charged with medical juices. The Carica papaya, or common papaw-tree, belongs to the family of the Cucurbitaceæ, or gourds; its straight, cylindrical trunk, from ten to sixteen feet high, is terminated at the top by a cluster of large palmate leaves, which give it the appearance of a palm tree. The fruits, hanging in clusters under the leaves, have the shape of roundish cucumbers, and are much esteemed when ripe. The papaw appears to have originated in the Moluccas, but has been acclimated in India, Mauritius, the Island of Réunion, the Antilles, and a considerable part of South America. The milky juice which contains the papaine is white, slightly bitter, and styptic, free from tartness, has an acid reaction, and is so highly charged with albumen that Vauquelin compared it to blood deprived of its coloring-matter. It flows from incisions made in the bark and the green fruits, and is immediately bottled and sent to market either pure or with the addition of ten or twelve per cent, of alcohol to prevent fermentation. If pure, it comes coagulated; if mixed with alcohol, it remains liquid, and, after standing, separates into a clear liquid and a white precipitate, composed in great part of albumen, tibrine, and a considerable quantity of precipitated papaine. Alcohol precipitates from it crude papaine; this, after being washed in alcohol and ether, to remove fatty matters, is again dissolved in water. The precipitate from this solution is pure papaine, which, when purified by dyalise, has the composition of an albuminoid substance. Papaine, refined with the sub-acetate of lead, offers several distinctive characteristics, among which are: 1. It is very soluble in water, dissolving like a gum; 2. The solution makes a lather