Page:The American Cyclopædia (1879) Volume XVI.djvu/514

 494 WATAUGA WATER mon paper-making wasp is the polistes fuscata (Fabr.), of a general brown color. The com- mon mud wasp (E. fraterna, Say) makes its cells of clay, plastering it against the outer or inner walls of houses ; each cell contains a sin- gle egg, and a supply of living spiders for the young ; other species use flies for the same pur- pose. These ferocious and predatory insects are remarkable for the very slight stalk which unites the thoracic and abdominal regions. As they not only destroy bees and steal honey, but injure fruit by their gnawings, farmers are gen- erally glad to destroy them when an opportu- nity offers. This may be effected by hot water, sulphurous vapors, or common smoke ; or the vapor of ether or chloroform may be intro- duced, when the nest may be dug up or stripped from the trees, and be handled with impunity. WATAUGA, a N. W. county of North Caro- lina, bordering on Tennessee, and drained by the New and Watauga rivers; area, 550 sq. m. ; pop. in 1870, 6,287, of whom 226 were colored. The surface is generally mountain- ous; the Alleghanies form the E. boundary, Iron mountain extends along the W. border, and Yellowstone mountain occupies the 8. part. The soil of the valleys is very fertile. Iron ore is found. The chief productions in 1870 were 6,160 bushels of wheat, 17,317 of rye, 75,944 of Indian corn, 18,724 of oats, 11,381 of potatoes, 50,598 Ibs. of butter, 13,- 850 of wool, and 1,538 tons of hay. There were 812 horses, 5,038 cattle, 7,039 sheep, and 6,607 swine. Capital, Boone. WATCH. See CLOCKS AND WATCHES. WATEE, a liquid composed of oxygen and hydrogen. The earlier chemists supposed it to be an element, and it was only about a century ago that the researches of Cavendish and Lavoisier established its compound nature, which has since been abundantly verified both by analysis and by synthesis. By the action of an intense heat or by the electric current it is resolved into its constituents and yields one volume of oxygen gas and two volumes of hydrogen gas; or, as the former has 16 times the density of the latter, eight parts by weight of oxygen to one of hydrogen. These two gases when mingled in these proportions unite with explosive violence by the contact of flame, and reproduce water, the union being attended with great elevation of tempera- ture. Pure water at ordinary temperatures is a liquid devoid of taste and smell, transparent, and nearly colorless, but when viewed in mass is found to possess a faint blue color. A cubic inch of pure water, at a temperature of 62 F. and a barometric pressure equal to 30 in. of mercury, weighs 252-458 grains troy; and for the purposes of ordinary calculation a cubic foot of water may be reckoned at 1,000 oz. avoirdupois, or 62 i Ibs. In France water at its point of maximum density, or 4 C. (39-2 F.), is taken as the standard, and the weight of a cubic centimetre at this temperature, and under a pressure equal to 760 millimetres of mercnry, is one gramme, which is the unit of weight in the metric system. Its density at this temperature is about 770 times that of atmospheric air, and is taken as the standard of comparison for the density of all liquid and solid bodies. Hence its specific gravity is said to be unity or TOGO. (See GRAVITY, SPECIFIC.) Water is slightly elastic, and by the increased pressure of one atmosphere has its volume diminished to the extent of about 0*000047, its compressibility increasing with the augmenta- tion of temperature. The density of water be- low 89'2 F. is diminished by cooling, it being 0-999877 at 82 (0 C.). One hundred parts of water at 32 expand to 104-29 when heated to 212, and to 110-16 at 314-24. At the tem- perature of 32 liquid water under the ordi- nary conditions of pressure becomes changed into ice, with a considerable augmentation of volume. The specific gravity of ice is -920, water at its greatest density (at 39-2) being 1 '000. The expansion of nearly -^ wh ich takes place in the freezing of water suffices to break very strong vessels ; but when so confined that its expansion is prevented, it can be cooled to very low temperatures without losing its liquid form. Pressure thus reduces the freezing point and prevents the congelation of water, and in like manner lowers the melting point of ice. Ice is a crystalline solid which as- sumes the forms of the hexagonal system of crystallization, as is well seen in snow flakes. Its color when in large masses is like that of liquid water, slightly blue. Much heat is lib- erated in the formation of ice, so that water cooled to 82 requires a prolonged exposure to a temperature below this point for its solidifi- cation ; and conversely the melting of ice is at- tended with a great absorption of heat. When a pound of water at 174-56 F. is mixed with a pound of ice at 32, the latter in melting reduces the temperature of the whole to 32. Water is volatile at all temperatures, a portion of watery vapor being given off from ice be- low the freezing point. As the temperature is raised, the tension of the vapor disengaged from the surface of the liquid augments, until it equals the atmospheric pressure, beyond which the liquid enters into ebullition. The boiling point of water in metallic vessels is 212 when the barometric column is 29-922 in., but va- ries with the pressure, so that on mountains, where the weight of the barometric column is reduced, the boiling point is proportionally lowered, while under increased pressure it is augmented. Thus, with a pressure equal to two atmospheres water boils at 260-52 ; with four atmospheres, at 293-72 ; with ten atmos- pheres, at 858-88 ; and with 30 atmospheres, at 457'2, a temperature above the melting point of tin. The nature of the inner surface of the containing vessel affects somewhat the point of ebullition, so that in smooth glass or porcelain it is one or two degrees above that in a rough metallic vessel. The evaporation of water at temperatures below boiling takes place only