125. Validity and extent of implied grant.

The implied grant is valid only to the extent that the grantor is able to grant it, so that, in the case of subjacent support, the doctrine of implied grant is confined to the case of the person who is the owner of both surface and subjacent mines1 at the time of the severance. If the surface owner has no right to support, or has it for the land in its natural state only, a purchaser of the surface does not by implication purchase also the right to support for any burden he may place on the surface2