Page:Popular Science Monthly Volume 25.djvu/547

Rh It is stated that the superior strength of the Warsaw brine makes it possible for one ton of coal to produce more salt, by sixty-four cents' worth, than can be produced from the Syracuse brine. This fact, together with the falling off in the Syracuse output, has called marked attention to the Warsaw wells.

The product of salt from the Michigan wells is over 15,000,000 bushels annually, on which the profit is large because the fuel consists of slabs and sawdust, a mere nothing. An eminent authority—Dr. Mitchell—states that there are three sources of the salt-supply in Michigan: 1. In the coal-measures and in the white and porous Parma sandstone, which serves as a reservoir. 2. The "Michigan Salt-Group," which lies between the carboniferous limestone and the sandstones at the base of the carboniferous system. This group consists of various shales, magnesian limestone, and beds of pure gypsum. The material of the reservoir is Napoleon limestone. The depth of boring is 600 to 700 feet, and the total area of the territory is about 17,000 square miles. 3. The "Onondaga" or Salina Salt-Group, which lies 500 feet below the Michigan Salt-Group, and in which alone are found the beds of rock-salt. The most important well is that at Marine City, on the St. Clair River, the total depth being 1,633 feet, and the thickness of the salt-beds 115 feet. The well at Muskegon, on Lake Michigan, is 2,000 feet deep, and the thickness of the salt-beds is 50 feet. Other important wells are operated at Bay City and at Manistee.

Similar beds are found in the Province of Ontario, at Goderich, Huron County. They are in the Salina formation also, the depth averaging about 1,000 feet, and the thickness of the salt about 30 feet. Exceptionally deep wells have been driven to a depth of 1,600 feet through six layers of salt aggregating 125 feet in thickness. The salt area of Canada is estimated at 2,000 square miles, and the probable quantity of salt still in the beds is called 200,000,000,000 tons. The Canadian salt is superior to the Michigan salt in regard to the absence of the earthy chlorides, as the following analysis will show:

The salt-beds of Michigan underlie each other like a nest of saucers—the oldest being in the old dolomite limestones in the ancient