scribed no method, and those who followed him did not accept his answer to the question, What is the beginning of all things? But the special claim of Thales to notice lies in the fact that he was the first to ask the question, and the first to attempt to establish a physical beginning.
IONIC ORDER, one of the three orders of architecture, the distinguishing characteristic of which is the volute of the capital. Its main features are the same as in the Doric style; their forms, however, are different. The Ionic order has more moldings, its forms are richer and more elegant, and, as a style, it is lighter and more graceful than the Doric. As regards the proportions of the Ionic order, no such remarkable difference as in the Doric is perceptible in the monuments which have been preserved to us. The height of the column is from 8½ to 9 times the lower diameter; the distance between the columns averages about twice the diameter, while the height of the entablature is not quite one-fourth that of the column. The most perfect specimens of the Ionic order are the temples of Minerva Pallas and of Erectheus in the Acropolis at Athens, and of Fortuna Virilis and the Coliseum at Rome.
IONS, the components into which an electrolyte is broken up on electrolysis. The one, the anion (the electro-negative component—e. g., chlorine), travels “against” the current (in its conventional direction in the circuit), and is deposited on or chemically attacks the anode or positive electrode; the other, the cation (the electro-positive component—e. g., copper), travels "with" the current to the cathode—e. g., to the spoons in the plating bath. See Electricity.
IOS (ī′os), an island in the Ægean Sea, one of the traditional birth-places of Homer. His mother was born here, according to the ancients, and the poet's grave was likewise assigned to the island.
IOWA, a State in the North Central Division of the North American Union; bounded by Wisconsin, Illinois, Missouri, Nebraska, South Dakota, and Minnesota; admitted to the Union, Dec. 28, 1846; number of counties, 99; capital, Des Moines; area, 56,025 square miles; pop. (1890) 1,911,896; (1900) 2,231,853; (1910) 2,224,771: (1920) 2,404,021.
Topography.—The surface of the State is generally level, with a gentle rise toward the N. The highest elevation is near Spirit Lake, in Dickinson co., 1,694 feet. The center of the State forms a watershed between the Mississippi and the Missouri. There are no hills of consequence, the entire surface being a plateau, and whenever irregularities occur, they are depressions below the general level. There are steep bluffs along the river banks, caused by the wearing away of the drift and rocks by the water. The State is covered with prairie land, with no swamps or natural forests. The water system is divided into two parts, those rivers flowing into the Mississippi in the E., and those flowing into the Missouri in the W. Among the former are the Upper Iowa, Turkey, Maquoketa, Wapsipinicon, Cedar, Iowa, Skunk, Des Moines, and Boone, while the Missouri system includes the Chariton, Grand Platte, Nodaway, Nishnabotna, Boyer, Maple, Little Sioux, Rock, and Floyd rivers. The Big Sioux river forms most of the W. boundary. There are many small and beautiful lakes, the largest being Spirit Lake, and the Okoboji Lakes, in Dickinson co.
Geology.—The State presents 20 distinct geological formations. The N. part belongs to the drift deposits of Minnesota. Lower down the Lower Silurian is prominent, with Potsdam sandstone, lower magnesium limestone, and St. Peter's sandstone. The Upper Silurian is represented by the Niagara and Le Clair limestone, and the Devonian by the Hamilton and Chemung carboniferous limestones.
Mineralogy.—The Illinois coal field extends over an area of 20,000 square miles in this State, and lead is found in Galena limestone near Dubuque. The coal production of the State in 1918 was 8,240,000 tons, which was 725,000 tons less than the production of 1917. The other mineral products are mineral waters, cement, gypsum, sand and gravel. The value of the cement produced in 1916 was $6,870,863. The total value of the mineral production in that year was $39,336,372.
Soil.—The soil generally is a soft black loam, formed directly through deposits of the Quaternary age, and varies from 1 to 100 feet in depth. The soil is easily worked, free from stones and stumps, and of almost inexhaustible fertility. The soil of the prairies is a diluvial drift, while the river beds furnish a light alluvial deposit. The principal natural trees are several varieties of oak, hickory, elm, black walnut, linden, cottonwood, maple, cedar, slippery elm, butternut, sycamore, ash, pine, and box-elder.
Agriculture.—The fertility of the soil and the ease with which it may be worked present special advantages for agricultural pursuits. Among native fruits
