Page:Popular Science Monthly Volume 4.djvu/656

638 to be made. The pellet is then laid obliquely and pressed down by the fore-feet and head of the insect, so as to cause it to adhere firmly to the surface on which it is building. As it proceeds, it smoothes the inside of the cylinder by working with its jaws and pushing the front of its flat head against the plastic clay. The first section being thus finished to its satisfaction, it flies off to secure small spiders. It seizes a spider with its fore-feet, stings it in just such a way as to paralyze, without destroying its life, and then deposits it in the bottom of the cylinder.

An egg is then laid beside the spider, and the wasp flies off to secure other spiders. This is continued until the cavity, which holds from twelve to fifteen of the smaller kinds, is' full. The wasp then covers the open end with a cap of the same material as before, after which it adds other sections to the number of three or four, filling each with spiders and depositing one egg in each. The young larva feeds on these paralyzed spiders, and, as it seems, requires from twelve to fifteen of them to nourish it until it is ready to become a pupa. Unlike some other clay-nest builders, this wasp does not nurse its young, but they are securely sealed up in the sections, and feed themselves. When ready to come forth, the wasp gnaws a round hole in the wall of its cell, and issues forth as a perfect insect.

The Uses of Baryta.—Baryta is an alkaline earth of a gray color, not easily fusible, and poisonous. Its various salts are extensively used in the arts, as will be seen from a paper read by Dr. Lewis Feuchtwanger, before the Polytechnic Club, of which we present a synopsis. The sulphate of baryta, 66 per cent, of baryta and 34 of sulphuric acid, is the only baryta-salt that is not poisonous. It is abundant in England, France, Germany, and the United States, where it usually occurs in connection with beds or veins of metallic ores, as gangue, or veinstone. Sometimes, however, it forms distinct veins, in company with the secondary limestone, and very often in fine crystals, along with calcite and celestine. Connecticut and Missouri have long furnished abundant material for the arts. Next come Virginia, New York, New Hampshire, Massachusetts, Pennsylvania, Kentucky, and Tennessee. The variety known as "Bologna spar" is an ornamental stone, of a brown color, and concentric rings, originally found in a bed of clay near Bologna. The sulphate of baryta also often occurs associated with lime, and some silica and alum, and is then called calcareobaryte; when associated with strontia it is called baryto-celestine.

Witherite is a carbonate of baryta, consisting of 78 per cent, baryta and 22 carbonic acid. It is found, in considerable quantities, in England, Silesia, Hungary, Sicily, and Chili, but not much in the United States. It is largely used in plate-glass manufacture in France, as also in the manufacture of beet-root sugar, and permanent white. Latterly, it has come into use for paint, in combination with soluble glass and white oxide of zinc. The metallic base of these salts is barium. It is a white, malleable, and fusible metal, readily oxidizing in air, and decomposing water at common temperature. The pure baryta, oxide of barium, is used for the production of peroxide of hydrogen, which is much recommended as a medicinal reagent, and employed in the arts for bleaching animal tissue, and converting brown into blond hair. The oxide, or caustic baryta, rivals, in caustic properties, potash, soda, and ammonia.

The chloride of barium is got by fusing the sulphate of baryta with chloride of calcium, in a reverberatory furnace, and then extracting with hot water, leaving the sulphate of lime undissolved. Chlorate of baryta, used in pyrotechny, and which burns with a green flame, is prepared by dissolving artificial carbonate of baryta in chloric acid solution. Nitrate of baryta, likewise used in pyrotechny, may be got by dissolving the native carbonate in nitric acid and evaporating the solution, octahedral crystals being deposited. The native sulphate of baryta is used to adulterate white lead, often to the extent of 25 to 50 per cent.

The artificial sulphate, permanent white, is much used in the manufacture of a paper of the purest white, for collars, cards, etc. In copper metallurgical operations, the sulphide of barium has latterly been employed for the purpose of precipitating from an ammoniacal copper solution the copper as a