Id. at 738, 242 P.2d 732. In Triangle Royalty Corp. v. Graves, 206 Okla. 409, 242 P.2d 740 (1952), a case brought by plaintiffs to quiet title to a certain mineral interest, we also applied the doctrine after a previous foreclosure judgment. The plaintiffs or their predecessors in Graves were defendants in the foreclosure action and had actual or constructive notice thereof.

The law applied there is applicable and controlling in this appeal. This Court stated in Lucus v. Cowan, supra, that it is settled law in Oklahoma that where a grantor conveys a mineral interest in land under warranty of title when the property is subject to a mortgage the grantor is obligated to satisfy, and thereafter permits the property to be sold at a mortgage foreclosure, the grantors subsequent reacquisition of the property operates to revest the after-acquired property in his grantee. See also, Singer-Fleischaker Royalty Co. v. Whisenhunt, 402 P.2d 886 (Okla. 1965), Grisham v. Southland Royalty Co., 332 P.2d 1099 (Okla. 1958), Equitable Royalty Corp. v. Hullet, 206 Okla. 233, 243 P.2d 986 (1952), Hanlon v. McLain, 206 Okla. 227, 242 P.2d 732 (1952), Bliss v. Wilcox Oil Co., 206 Okla. 232, 242 P.2d 739 (1952), Triangle Royalty Corp. v. Graves, 206 Okla. 409, 242 P.2d 740 (1952), and Born v. Bentley, 207 Okla. 21, 246 P.2d 738 (1952). In Lucus v. Cowan, supra, it is also held that the after-acquired estate passes to the grantee on his grantor's re-entry into the chain of title by operation of law, and without the intervention of any court. These precepts are controlling in this action.

"It is settled law in Oklahoma that a grantor who conveys a mineral interest in land under warranty of title, which land is subject to a mortgage and which the grantor is obligated to satisfy, but thereafter permits the property to be sold at a mortgage foreclosure, subsequent reacquisition of such property by said grantor operates to revest immediately the after-acquired title in grantee and will inure to his benefit. Grisham v. Southland Royalty Company, supra ( 332 P.2d 1099); Marx v. Beard, supra ( 302 P.2d 132); Equitable Royalty Corp. v. Hullet, supra ( 206 Okla. 233, 243 P.2d 986); Hanlon v. McClain, 206 Okla. 227, 242 P.2d 732; Bliss v. Wilcox Oil Co., 206 Okla. 232, 242 P.2d 739; Triangle Royalty Corp. v. Graves, supra ( 206 Okla. 409, 242 P.2d 740); Born v. Bentley, 207 Okla. 21, 246 P.2d 738."

31 C.J.S. Estoppel § 51, p. 229. In Triangle Royalty Corp. et al. v. Graves, 206 Okla. 409, 242 P.2d 740, estoppel was held available to the grantee of mineral interest as against subsequent purchasers from the grantor, who, like Porter, had reacquired title from the mortgage holder. Plaintiffs obviously misconstrued the rule.

In addition to what we have pointed out about the nature of plaintiff's cause of action in demonstrating that it could not have accrued before defendants' reacquisition of the land, this court has already held that this type of action is not one for the recovery of real property. See Triangle Royalty Corp. v. Graves, 206 Okla. 409, 242 P.2d 740. Thus defendants' contention that the 5-year limitation period made applicable to execution and judicial sales of real estate by sec. 93(1), supra, applies to a cause of action like plaintiff's has already been determined adversely to them. As defendants have failed to demonstrate any error in the judgment of the trial court, said judgment is hereby affirmed.

The controlling rule here applicable which protects mineral rights from tax resale when the land owner re-acquires title, in legal philosophy and in resulting protection of mineral right holders, is somewhat akin to the rule applied in four cases decided by this court last year where mineral right holders were protected from loss by foreclosure of mortgage liens when the landowner re-acquired title. See Equitable Royalty Corp. v. Hullet, 206 Okla. 233, 243 P.2d 986; Hanlon v. McClain, 206 Okla. 227, 242 P.2d 732; Bliss v. Wilcox Oil Co., 206 Okla. 232, 242 P.2d 739, and Triangle Royalty Corp. v. Graves, 206 Okla. 409, 242 P.2d 740. In Warner v. Day, supra, protection was afforded both to a mortgage holder and to a mineral rights holder when the land owner re-acquired his land title after tax resale.

While this case was pending appeal, this court, on April 1, 1952, handed down four decisions which apply the doctrine of estoppel by deed to the assertion of after-acquired title by grantor as against the grantee in a mineral deed containing unconditional covenants of warranty. We refer to Equitable Royalty Corporation et al. v. Hullet et al., 206 Okla. 233, 243 P.2d 986; Hanlon et al. v. McLain et al., 206 Okla. 227, 242 P.2d 732; Bliss et al. v. Wilcox Oil Co., 206 Okla. 232, 242 P.2d 739; and Triangle Oil Corp. et al. v. Graves et al., 206 Okla. 409, 242 P.2d 740. The facts in Equitable Royalty Corporation et al. v. Hullet et al., above cited, would be on all fours with the facts in the instant case, except that the habendum and warranty clause there made no mention of the outstanding mortgage of record, while in the instant case the mortgage to the Exchange Trust Company is expressly excepted from the covenants in the mineral deed against encumbrances. It is contended by the plaintiff that the estoppel by deed and after-acquired title doctrine are not applicable because of this exception.