BMCKELL, C. J.—

The bill substantially alleges, that the appellee is proceeding to execute a power of sale, con*266tained in a mortgage executed to him by the appellant. The execution of the power it is alleged is inequitable, because the appellant, for damages resulting from a breach of an agreement, by which the appellee was to advance the appellant moneys to carry on his mercantile business, and to purchase cotton during the cotton season of 1873 and 1874; and was liable also for damages, for making sales contrary to instructions, of cotton shipped him for sale ; and these damages, it is averred, exceed the amount of the mortgage debt. On final hearing, the temporary, injunction was dissolved, and the bill dismissed.

We concur with the chancellor, that the bill is without equity. If we assume, that it is shown by the evidence, that the appellee agreed to advance the appellant moneys to carry on his mercantile business, and to buy cotton, during the cotton season of 1873-4, it would be difficult to ascertain any consideration for the agreement, or its extent, or how far the parties intended that it should extend, with any degree of' certainty. It was not agreed that any particular sum should be advanced, nor are there facts stated, from which the sum may be ascertained. Agreements are sometimes so indefinite and uncertain, as to be wholly void. Thus, in the case of Erwin & Williams v. Erwin, 25 Ala. 236, an agreement that in consideration, of plaintiffs purchasing of the defendants, a store-house, and a stock of dry goods, the defendant would assist them, by indorsing their paper, and advancing them money to carry on the business, was held void. And in Adams v. Adams, 26 Ala. 272, a promise by a father on valuable consideration, that he would give a daughter, “ a full share of his property, which was then and there worth twenty-five thousand dollars,” was declared void for uncertainty. The agreement now insisted on, if made, falls within the principle of these authorities.

Independent of this consideration, the damages resulting from its breach, are unliquidated. There is no legal standard by which they can be measured accurately and ascertained. A court of equity will not set-off against a clear and certain debt, damages which are strictly unliquidated, springing out. of transactions not connected with the debt.—Livingston v. Livingston, 4 Johns. Ch. 293; Pulliam v. Owen, 25 Ala. 492; Jennings v. Webster, 8 Paige, 502; Jordan v. Jordan 12 Geo. 77.

A mortgagor may, if the mortgagee is seeking a foreclosure in equity, set-off any debt, or demand, he may hold against the mortgagee, which would be the proper subject of set-off,, *267if the mortgagee was suing at law for the recovery of the mortgage debt.— Chapman v. Robertson, 6 Paige, 627; Irving v. DeKay, 10 Paige, 319. But if it becomes necessary for the mortgagor, to resort to equity for relief upon the ground, that he has a proper set-off, against the mortgagee, or the mortgage debt, he must show some other fact, than the mere existence of a demand which is the proper subject of set-off. T. C. & D. R. R. Co. v. Rhodes, 8 Ala. 206; Cave v. Webb, 22 Ala. 583. The damages the complainant may have sustained from the defendant’s violation of his instructions to postpone the sale of his cotton, under our statute are the subject of set-off. The difference between the sum realized on the unauthorized sale, and the sum which would have been realized, if the instructions had been obeyed, is the measure of damage. No ground of equitable relief in respect to this demand is shown. The remedy at law is adequate, the party liable is solvent, and there has been no agreement thax it should be discounted from the mortgage-debt.

The suggestion that the law would apply these set-offs to the payment of the mortgage debt, can not be supported. There is a very broad distinction between a payment, and a-set-off, and distinct demands are never in the absence of an agreement between the parties applied as payments of each, other.— Green v. Storm, 3 Sandf. Ch. 305.

The decree of the chancellor is affirmed.