At Mineral Point, Tuscarawas County, Ohio, and at New Lisbon, Ohio, a clay nearly similar to the Mt. Savage clay is found ; its appearances and properties are about the same ; it is non-plastic, and is treated in the same manner.
For all these clays the " cement" is coarsely ground, mixed with from one-sixth to one-tenth plastic clay, gradually dried and tempered, and then hard-burned.
The fire-brick made from the clay from the coal-measures of Kentucky, Pennsylvania, Ohio, Illinois and Missouri. are also held in high esteem.
The following is an analysis of Farrandsville, Pa., fire-clay, by J. Blodget Britton, Iron-Master's Laboratory, Philadelphia, December, 1878:— Silica 45.26 Alumina 37.85 Sesquioxide of iron 2.03 Lime .08 Magnesia .02 Potash 1.26 Water and organic matter [3.30 Oxide of manganese and loss .20 100.00 Mount Savage Clay. In the year 1841 the Mount Savage Fire-Brick and Iron Company of Mount Savage, Md., was or ganized, which name was changed in 1870 to the Union Min ing Company of Allegany County, Md.
Mount Savage, Md., is located at the foot of Savage moun tain, nine miles north of Cumberland, Md., on the line of the Cumberland and Pennsylvania railroad. The Mount Savage fire-brick have achieved a national reputation for their excellent qualities for use in blast furnaces, rolling-mills, steel plants and gas furnaces. Analysis of Mass. Inst. of Technology : Silica 50.457 Alumina 35.904 Protoxide Iron Lime .133 Magnesia .018 Potash trace Water and Organic Matter 12.774 Another analysis : • Silica Alumina . 35.33 Protoxide Iron 1.44 Lime .34 Magnesia .07 Potash trace Water A great many analyses of this clay have been made at vari ous times and by different chemists, but it would not be safe to take any one of the results as a test, for the difference in them is probably due as much to the chemists as to the samples. The following is an average of several results, which will prob ably give as accurate an analysis as one could obtain : Silica 55.75 Alumina 33.23 Impurities 2.06 Water 50.37 The bed of clay lies at the very bottom of the coal-measures of this basin. On top of the clay lies an 8-inch bed of coal ; beneath it lies from 3 to 4 inches of shale ; and then comes the conglomerate rock which marks the baundary of this basin.
The bed of clay varies from 8 to 20 feet in thickness.
The clay is divided into two varieties, the hard and the soft ; and these are distinguished by their physicial properties. One of these varieties is of a medium gray color, shading almost to black. This clay is very hard, and rattles like crockery when thrown into the chutes. It has a distinct, though not regular, conchoidal fracture ; it is non-plastic unless ground to an impalpable powder, and does not crumble much when ex posed to the weather in heaps, being affected for only about 3 or 4 inches from the surface, though exposed for years. In parts of the mine this clay, when finally broken, is sharp enough to cut one's hands.
The other variety is a very plastic clay, of much lighter color, weathering very rapidly, and in one season's exposure crumbling to powder.
The peculiarity of this deposit is, that the two clays are so intermixed in the same bed, and in such a way, that in the present development of the mine there is no accounting for the difference in structure of the clay. In one place the bed will be full from roof to floor of hard clay, and in another place, within a few feet of the former, the clay will all be soft. These sudden changes cannot be accounted fora Usually, the soft clay lies on top of the hard, and acts as a sort of protector for it, keeping off the coal water. In some places, again, there is a gradual change from one to the other, from hard to soft and back again ; and often the hard clay lies between layers of the soft. This is what causes the difficulty in the mining work and makes it seem irregular ; for where the hard clay is struck small pillars and large chambers are made, and vice versa.
The impurities in this clay are much the same as in all other clays, except that they are fewer and smaller in amount. There are some balls of iron ore found in the bottom of the bed, but these can readily be seen. The most objectionable impur ity is iron pyrites, which is found in the slips of the soft clay, and particularly in the casts of roots in that variety. The de tection of these iron pyrites is impracticable until after the brick have been subjected to the intense heat of the kiln, when discoloration is shown in spots on their surfaces.