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Page:Popular Science Monthly Volume 46.djvu/883

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choice. Of such animals only a small fraction are night feeders by nature or choice. The real night feeders—bats, lemurs, lorises, etc.—are mostly insect-eaters, and their day sleep is sound, almost to lethargy—so that it is extemely difficult to disturb their slumber. Between these two kinds of sleep is the form enjoyed by the large carnivora and the domestic animals. Tigers and lions have no reason to be afraid of anything but man, and sleep soundly and carelessly. Yet they possess the power of vigilance in sleep, which they can use, if required. Domestic animals, under man's protection, sleep well, and usually wake deliberately. Dogs are drowsy or wakeful, and, according to their state of mind and circumstances, seem to sleep lightly or heavily at will. "Nothing can be more slow, reluctant, and leisurely than the enforced waking of a petted housedog when it does not wish to be disturbed. It will remain deaf to a call, twitch its feet if tickled, but not unclose its eyes, and stretch and yawn like a sleepy child. But mention something interesting to the same dog when sleeping, such as the word 'walk,' or click the lock of a gun, and it is on its feet in an instant, and ready for enterprise." Even human sleep, this writer adds, "can be made vigilant by solicitude or previous resolve. It is a common experience that persons who are heavy sleepers can awaken at a certain hour by resolving to do so, or if roused by a sound previously agreed on recognize it as a call to awaken and do awaken instantly."

 

The Tanning School of Freiburg.—What is probably the only tanning school in the world—as distinguished from schools in which the chemistry of tanning is taught—was opened in 1889 at Freiburg, Saxony. Instruction is given in it in the theory and practice of the preparation of leather, in tanning, and in finishing. It is supported conjointly by the state, the city of Freiburg, and friends. It is attended by pupils from all parts of the world. It is completely fitted up with all the machinery and apparatus for tanning, and has rooms and machines for the unworked skins, lime baths, vats, cutting, rolling, and pressing. The machinery is all from the United States, and the director of the institution is an American tanner. Besides him, the teaching force includes a body of chemists, teachers, and a corps of practical tanners. The students give two hours a day—ten hours a week—in assisting at the operations of the tanners. Hides from all parts of the world are experimented upon every year, with all kinds of tanning processes, barks, and materials. The processes of the old and new schools are shown and compared; and it is said that the former give good and expensive, and the latter quick and cheap results. Lectures are given in the winter on subjects related to tanning; and excursions to tanneries, to the woods where the bark is collected, and to the yards where the bark is stored, are a part of the instruction.

 


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The process of manufacturing calcium carbide by heating in an electric furnace a mixture of coal dust and lime is now well known. The appearance of this material, in masses, is like that of the mineral serpentine, it being greenish gray in color, with a luster like that of feldspar. If a few drops of water are thrown on this seeming rock, gas is given off, which, if ignited, burns with a brilliant flame, and will continue to blaze, if supplied with water, till the mineral is exhausted. It is proposed to use acetylene gas thus produced for local gas engines. A charge of the mineral is placed in a closed vessel in which a regulated supply of water is admitted. A little water entering evolves a quantity of gas, whose pressure shuts off the water, and, as the gas is exhausted, more water is admitted to renew the supply.

The fiftieth anniversary of the discovery of anæsthesia by Horace Wells was celebrated in Hartford, Conn., December 10th, by a meeting and banquet of about fifty dentists of the State. It was claimed by some of the speakers that there w as now no question as to Dr. Wells's priority in the discovery; and the story of the early experiments was told by Dr. G. Q. Colton, whose administration of laughing gas fifty years ago suggested to Dr. Wells the idea of using it as an anæsthetic. Mr. J. Gray read a paper in the British Association on the Distribution of the Picts in Britain, as indicated by Place Names. The Picti of North Britain and the Pictones or Pictavi of South Gaul are both mentioned by Roman writers. The evidence of place names shows that probably the whole intervening country was at an earlier date occupied by the same race. The language of the Picts was Basque. The name Pict is derived