That which is mined. Though frequently applied to substances containing metals, in its proper sense includes all fossil bodies or matters dug out of mines.3 A fossil, or what is dug out of the earth. In its enlarged sense, comprises all the substances which form, or have formed, part of the solid body of the earth, both external and internal, and which are now destitute of, and incapable of supporting, animal or vegetable life.4 Petroleum is a mineral, and as much a part of the realty as timber or coal. A right to experiment for oil, and to sever and remove it upon giving a portion to the lessor, is a license to work land for minerals; and so coupled with an interest as not to be revocable at the pleasure of the licensor. Where the grantor in a deed conveying realty reserved certain timber and "all minerals," and the grantee claimed the mineral oil, the court said: "It is true that petroleum is a mineral; but so are salt and other waters, impregnated or combined with mineral substances; so are rocks, clays, and sand: anything dug from mines or quarries; in fine, all inorganic substances are classed under the general name of 'minerals.' If the reservation embraced all these things, it is as extensive as the grant. That something may be retained for the vendor, 'minerals' inust then be limited in its meaning. The parties doubtless thought and wrote, not as scientists, but as business men using the language of every-day life; and in popular estimation petroleum is not regarded as a mineral substance any more than is animal or vegetable oil, and it can, indeed, be so classified only in the most general or scientific sense." Minerals beneath the surface may be conveyed by a deed, distinct from the right to the surface. They constitute a corporeal hereditament, and pass by apt words, with delivery of the deed and registration. 1 Kahn v. Smelting Co., 102 U. S. 645 (1880); Bissell v. Foss, 114 id. 260 (1885), cases; 42 Cal. 370; 79 Va. 160; 50 E. C. L. 685. 2 Higgins v. Armstrong, 9 Col. 46 (1885); 5 id. 111. 3 Rosse v. Wainman, 14 M. & W. *872 (1845), Parke, B. [Bainbridge, Mines, &c., 1, cases. Appeal of Stoughton, 88 Pa. 198 (1878). Fur. v. Halderman, 53 Pa. 229 (1866). Dunam v. Kirkpatrick, 101 Pa. 43-44 (1882), Gordon, J. See also Hartwell v. Camman, 10 N. J. E. 128, 132-36 (1854). • Caldwell v. Fulton, 31 Pa. 475 (1858). But each proprietor must so use his own property as not to injure another proprietor.2 A tenant for life cannot open and operate a new mine: it would injure the inheritance; but his right to operate previously opened mines, and work them. even to exhaustion, cannot be questioned. What is termed a mineral lease is frequently found to be an actual sale of a portion of the land. It differs from an ordinary lease in this, that, although both convey an interest in land, the latter merely conveys the right to its temporary use and occupation, while the former conveys absolutely a portion of the land itself. If the entire interest of the lessor is conveyed, in the whole or a portion of his land, the conveyance cannot properly be regarded as a "demise," but as an "assignment." 4 See MINE; AQUA, Currit, etc.; LAND, Public; QUARRY; VEIN; WASTE, 1.