Lignite is more compact than peat, and is found buried to some depth under layers of clay or sandstone. It is dark brown to black in color, and still retains pretty clear traces of the plants from which it was derived. It also usually contains a considerable amount of moisture, and when this is dried out, it tends to crumble badly, so that it is undesirable to handle it much, or to ship it far, before using. It has a fair fuel value and is fairly widely used; but it is very desirable that some method be found, by which lignite could be treated to obtain its by-products, and at the same time make it more compact, so it would not crumble with the handling incident to using it in furnaces. There are extensive lignite deposits in this country in North and South Dakota, Montana, Wyoming, Colorado, New Mexico, Texas, Louisiana, and Mississippi. Bituminous Coal _soft coal_ This type of coal is compact, black in color, and breaks readily, but does not crumble as badly as lignite. It contains considerable water, and still has some hydrogen and oxygen compounds in it. Bituminous coal is the product of plant remains which have been preserved for long periods, (millions of years), sealed from the air by the overlying beds of rock. The pressure has made it compact, and nearly all traces of the original plants have disappeared. Bituminous coal is our most abundant fuel, occurring the world over in seams from less than an inch in thickness to some over fifteen feet thick. The United States is peculiarly fortunate in the abundant and easily accessible deposits of this type of coal, in Pennsylvania, West Virginia, Ohio, Kentucky, Tennessee, Indiana, Illinois, Michigan, Iowa, Missouri, Kansas, Nebraska, Texas, Utah, and Colorado.