near Saint Louis. No. 2 and No. 3 are the celebrated Stourbridge clays of England:

Analyses of Cheltenham and Stourbridge clays.

Fire-clay has been mined in Jefferson County, Colorado, since 1865, and the manufacture of firebrick and furnace material has kept pace with the growth of the smelting industry in the West. No statistics of the production of firebrick, muffles, etc., are available, and the consump tion of fire-clay by the works at Denver and Golden could not be secured for the years previous to 1880, except in one case. The following table gives the amount of clay used by years, in tons of 2,000 pounds. Previous to 1880, the Denver Fire-Clay Company, of Denver, used 1,500 tons of clay in manufactures:

The number of fire-bricks made in 1882 in Golden, is estimated at 2,500,000, and the total value of all the products of the industry at the same place at $167,000.

Cornish clay miners are paid $2.50 per day of 10 hours, and in the works the wages paid vary from $1 for boys to $2.25 for men, per day of 10 hours.

Pottery clay.-Pottery clay is found quite abundantly in many parts of the Rocky Mountain region, occasionally, as at some points along the line of the Union Pacific railroad in Wyoming, and at Golden and Morrison in Jefferson county, Colorado, in a state of great purity and excellence. Two establishments in Colorado, the Cambria Brick and Tile Works at Golden, and the Terra Cotta Works at Denver, owned by Mr. Thomas Moulton, are engaged in the manufacture of the best quality of drain tiles, and pavement tiles, making also large quantities of sewer piping of unsurpassed durability. Both works also manufacture flowerpots, hanging-baskets, jars, jugs, and many other forms of earthenware.

These wares are sold at prices said to be as low as those of the eastern works, and are of excellent quality. The entire local market and the demand in the adjoining towns is supplied by the works at Golden and Denver.

The Denver Terra Cotta Works used during 1882 one carload of pottery clay per week, and 550 tons during the year.

CLAYS OF THE PACIFIC COAST.

While most of the discoveries of fire and fine potter's clays so fre quently announced have proved disappointments, the deposits found consisting of infusorial or other nearly worthless earths, material suitable for making firebrick and fine earthenware really exists in many places on the Pacific coast, the following being the California localities most distinguished for these natural products: Steatite, saponite, or soapstone, a good fire-clay, reported as occurring near Mokelumne Hill, Calaveras county; at the town of Antioch, and in the clay seams of the Black Diamond coal mines, Contra Costa county; in the Cerro Grande mine, Inyo county; and at various places in El Dorado, Mendocino, Santa Barbara, and Los Angeles counties. Clay from some, if not all, of these localities has been made into firebrick, crucibles, etc., and is found to answer well for these purposes.

While some of the trials made of the California fire-clays have, through a careless selection of material, turned out badly, others have proved entirely successful, and there is little doubt but the greater portion of the firebrick hereafter used in that State will be made at home. The price of the imported article, Scotch and English, ranges in San Francisco from $35 to $43 per thousand, that of domestic manufacture selling for about one-fourth less.

A clay found in Bingham cañon, and at other various points about Salt Lake City, Utah, has been used extensively and with satisfactory results at the large smelters operating in the vicinity of that city. A species of sandstone quarried in Red Butte cañon, three miles east of Great Salt Lake, has also been employed for building furnaces at these establishments, and found to stand about as well as the best English firebrick.

Deposits of kaolin, some of them very extensive, have been found in many parts of the Far West. Though not of the finest quality, some very handsome porcelain ware has been made from this material. Clays suitable for the manufacture of stoneware and the more common kinds of earthenware so abound that potteries are numerous in California, Oregon, and Utah. Sands of the several kinds required in manufacturing glass are found everywhere. There is in Monterey county, California, plenty of the white sand used in making the finer varieties of glass, that for coarser wares being obtained from the sand hills and dunes about San Francisco.

ABRASIVE MATERIALS.

CORUNDUM AND EMERY.

BY HENRY GANNETT.

Definition. These substances, so nearly allied mineralogically, are sharply distinguished in the trade. Mineralogically, the former is a nearly pure alumina, while the latter contains a large proportion, from 20 to 33 per cent., of iron oxide. The trade distinctions are somewhat as follows: Emery is always black, while corundum is of various colors, though more frequently gray, and is never black. It is much harder than emery, and sharper, cuts deeper and more rapidly, but is on the other hand more brittle and consequently less durable.

Imports of emery.-Almost all our supply of true emery is imported. Many supposed discoveries of emery of good quality have been made, but all have failed to stand the commercial test. Magnetite, ilmenite, and massive garnet are often mistaken for emery, and indeed attempts have been made to replace true emery by these substances. For some time emery was produced at the well known mine at Chester, Massachusetts, but the material was found to be too soft and the mine is now abandoned. It comes from Turkey, near Smyrna, and the island of Naxos. Other foreign localities are reported, but their product does not appear to be of importance, and none is imported from them to the United States. The importations in the fiscal year 1882 are reported at 45,560 cwts., valued at $58,428, of the crude emery ore, which is ground here, and $28,975 worth of ground emery, prepared in England. The average price of Turkish emery, ground in this country, is reported as follows: grain, 33 to 6 cents per pound. That of the best English ground is: grain, 10 cents per pound; flour, 8 cents per pound.

American corundum localities.-Corundum has been discovered at a large number of points in the United States, particularly in the Appalachian region, and the material from some of these localities has gone extensively into the trade, where it is supplanting emery to a certain extent, although its higher price, produced by the greater expense involved in crushing and grinding it, tends to reduce the demand for it. The following localities are reported:

Chester, Hampden county, Massachusetts. This locality was worked originally for emery, as above stated.

Westchester county, New York. It may be that this is an emery. It is reported as being too soft for most purposes.

Chester and Delaware counties, and near Allentown, Pennsylvania. A large part of the production at present comes from Chester county, Pennsylvania.

Delaware, but in small amount.

Cullakenee mine, western North Carolina. This mine has been worked, but its product is not known.

Corundum Hill, Macon county, North Carolina. This locality is reported as having produced 200 tons. Various precious stones are found here, as emeralds, rubies, sapphires, topazes, and amethysts. Corundum also occurs at the Hogback mine, Jackson county; Paisley mine, Heywood county, and in Madison county, in the same State.

In Fannin county, Georgia, where recent discoveries have been made. It is also reported as occurring at other points in Georgia, in South Carolina, Alabama, and Arkansas.

The principal sources of supply appear to be Chester and Delaware counties, Pennsylvania, and North Carolina.

Figures of production are difficult to obtain. Estimates for the year 1882 range from 400 to 1,000 tons, although it appears that 500 tons is probably near the truth. The crude rock sells for $10 to $15 per ton, while the ground corundum brings from 12 cents to 15 cents per pound. The demand appears to be as yet comparatively light.

BUHRSTONES.

Most of the buhrstones used in this country are imported. The sources of supply are France, Belgium, and Germany, whence the material is brought, partially dressed, by steamer, at low rates of freight. The French and Belgian stones are a subaqueous deposit of silica mixed with shell. The stone is both hard and porous. The German stone is a basaltic lava.

The principal localities from which buhrstones are obtained in the United States are:

Ulster county, New York, where a rock known as the millstone grit is quarried, which in the form of dressed stones is preferred for grinding minerals, etc.

Peninsula, Ohio, where the white variety of the formation known as the Berea grit (described by Professor Read in the following section) is quarried for the purposes of grinding oatmeal and pearling barley, for which it is said to be especially well adapted.

In the Southern States, for grinding corn, a great variety of stones is employed, as almost any sharp siliceous rock will answer the purpose.

In the larger mills metallic rollers have to a large extent supplanted buhrstones. It is estimated that of the larger flouring mills from onehalf to two-thirds are now using rollers.

BEREA GRIT.

BY M. C. READ.

The Berea sandstone, Berea grit, Amherst stone, or Ohio stone, as it is variously called, is a characteristic member of the sub-Carboniferous rocks of Ohio, found about 300 feet below the Coal-Measure rocks, with its outcrop extending from the Ohio river northward through the central part of the State into Huron county, and passing thence eastwardly, in an undulating line, to near the northeast corner of Trumbull county. It is ordinarily a rather fine-grained sandstone, with a sharp grit, but differing greatly in its character in different localities. Amherst has furnished from it the best building stone, Berea the best grindstones; but other localities in the region described are capable of furnishing equally good material for both of these uses.

In places the rock is massive, in others it is in regular layers, of a thickness varying from several feet to a few inches; much of the latter is evenly bedded, making an excellent flagging stone. In some of the quarries, especially in Huron county, these thin strata furnish the finest examples of ripple-marking to be found in the State.

Its exposure in Summit county is confined to the valley of the Cuya. hoga river and the bluffs bordering it. It appears at the bottom of the valley near the south line of Borton township, and from thence rises in the bluffs to the north line of the county. It is in this county a hard, evenly-bedded, compact rock varying in color from nearly white to a dark brown, but in places so irregularly colored as to detract somewhat from its value as a building stone.

The quarry most extensively worked is a little south of the village of Peninsula, in Borton township. The upper part has here been removed by glacial action, leaving about 40 feet undisturbed, which can be quarried with a slight stripping of earth, while the product is carried by a gravity road to the canal and railroad below.

Some years ago a diligent search was made in the State for a stone especially fitted for the construction of a safe vault, and after thorough tests the white rock from this quarry was selected as the best that could be found. The preference was given to it on account of its strength and hardness and because of the facility with which blocks of any required size could be obtained. It is largely used for buildings, for abutments of bridges, and other similar purposes. But there is a special use to which it has been applied which is worthy of mention.

Mr. Fred. Shumacher, of Akron, is the founder of the oatmeal industry in this country, and has also been extensively engaged in the work of pearling barley. He found considerable difficulty in obtaining millstones suitable for his work, and after protracted tests of all available material, selected the white variety of this Peninsula stone as the best that he could find. Its great hardness and very sharp grit especially