SALT

1667

SALTPETER

Vienna by rail. It has a fine appearance from the sea, as it is surrounded by white walls five miles long, and its houses and mosques are shaded by dark-leaved trees, while a citadel, the old Acropolis, looks down from the rocky heights above it. The main buildings are the mosques, most of them now Christian churches; among them are St. Sophia, St. George and St. Demetrius. The old mosque once was a temple of Venus. Here is the court of the hippodrome where Theodosius ordered the massacre of 7,000 citizens. Via Equatia, the highroad from Rome to Byzantium, passes through the city. Trade is steadily growing, especially since the opening of the railroad to Servia. Cotton, flour, soap, bricks, leather, silk and carpets are among its manufactures. Salonica is the Thessa-lonica of the Christians, to whom St. Paul wrote Thessalonians I and II. The town was founded by Cassander in 315 B. C, who named it after his wife, sister of Alexander the Great. Population about 150,000; of whom nearly 61,000 are Jews of Spanish descent, 25,000 are Turks and 14,000 Greeks. Salonica also is a vilayet in Turkey; area 13,510 square miles; population 1,130,800.

Salt. Common salt is chloride of sodium (NaCl). It occurs in nature both m beds or strata, when it is called rock-salt, and in solution in water. Aside from the sea and from salt lakes, the underground waters of many regions contain salt. The salt of commerce is partly mined from the beds of rock-salt, partly extracted frrm salt waters. In the latter case the brine may be natural, as in the case of the sea, salt lakes and salt wells; or artificial. In the case of artificial brines fresh water is allowed to flow over beds of salt, and from the resulting solution salt is extracted. In the extraction of salt from salt water two general processes are in vogue. In one the water is allowed to evaporate in the open air under the influence of the sun; and in the other evaporation is hastened by means of artificial heat. By the former process the coarse salt and by the latter the fine salt of commerce are obtained. Beds of rock-salt represent, deposits from solution on the bottoms of salt lakes, lagoons etc. In some lakes, as Great Salt Lake, such deposits are being made at the present time. Similar deposits have been made in the past, and subsequently buried bv -vther sediments, as sand, mud etc. Some of these beds of salt were made millions of years ago. Some are hundreds of feet thick. The salt in solution in underground waters may have been derived from salt-beds over which the waters seeping in from the surface have passed, and some of the natural brines may represent sea-water with which the sediment was originally filled and which has never been drained "out. The thickest salt-beds of this country, so far as now known, are on the coast of Louisiana, on Avery's Island

(Petite Anse). Other salt-beds occur in New York, Pennsylvania, Ohio, Michigan and Ontario, Canada. The output of salt in the United States in 1906 was 28,172,38c? barrels (280 lbs. perbbl.), value $6,658,350. The United States produce more salt than any other country. Great Britain, Russia, Germany, France, India, Spain and Italy are great producers in the' order named. The total product for the world in 1901 was more than 12,000,000 short tons.

Salt Lake City, capital of Utah, is on Jordan River, twelve miles from Great Salt Lake and 4,265 feet above the sea. It covers twelve square miles. Its streets are 132 feet wide, shaded by fine trees, many of them freshened by streams of running water from the neighboring mountains, and lighted by electricity. The finest public buildings are the Mormon temple, which cost $4,000,-000, with walls built of dressed granite, twenty feet thick at the bottom, tapering to six feet at the top ; the tabernacle, a huge building in the shape of an ellipse, with a dome-shaped roof resting on sandstone pillars, and seating 7,000; and the city and county building. Though Mormon influence is strong, there are Roman Catholic, Episcopalian, Presbyterian, Congregational and Methodist churches. St. Mark's cathedral (Episcopalian) the cathedral (Roman Catholic) and the First Presbyterian Church are the finest Gentile churches. The city is the center of large mining-industries, and has smelting-works, flour and paper mills, foundries, machine-shops, breweries and tanneries. It has good free public schools, supported at an annual cost of $500,000, and an enrollment of 15,500. Here is the University of Utah, a coeducational institution supported by the state, having 53 instructors and 957 students, including the preparatory department. There also are denominational schools. Salt Lake City was founded in 1847 by Brigham Young who, with a company of Mormon pioneers, left Council Bluffs in the spring to find a site for the future Mormon capital. For years the growth of the city depended upon the inflow of Mormon immigrants, but later the mines in its vicinity attracted Gentiles or non-Mormons. The population of the city is 92,777.

Salt'peter or Ni'ter is potassium nitrate (KNOs). It generally is in long, colorless, six-sided prisms. Its taste is cooling and very salty. It dissolves in water but not in alcohol. Mixtures of niter and carbon or of niter and sulphur or of all three explode with great energy on applying heat. If saltpeter be thrown on glowing coals, it flashes briskly. Niter is found in India and Persia as a natural product, on the soil or scattered through the upper rocks. But most saltpeter is now made from the Chilean sodium nitrate. Niter is used in making sulphuric acid, nitric acid, fireworks and, especially gunpowder. It also is a medicine. Sodium