delivered the opinion of the court.
The plaintiffs instituted this action on a writing obligatory made by the defendants. Ives and McLemore suffered a default, and a discontinuance was entered as to Hadnot. The other defendants filed two special pleas; first, that they were mere sureties in the writing obligatory, and after it became due, the plaintiffs, without 'the knowledge, approbation or consent of the defendants, by contract, agreement and arrangement with Ives, the principal, extended the time of payment ten months, whereby they were discharged. Second, the same as the first, with the additional circumstances that suit had been brought on the writing obligatory which the plaintiffs dismissed, and gave a further time of ten months, and that Ives, the principal, was then solvent, but had since become insolvent. In both pleas it is averred that the time was given “ by contract, agreement and arrangement,” without averring a consideration for the contract. To these pleas the plaintiffs demurred; the demurrer was overruled and respondeat ouster awarded, under which the plaintiffs replied, and a verdict found for the defendants.
There is no other question involved in the case than that *318which arises on the plaintiffs’ demurrer to defendants’ pleas, and it is insisted that this cannot now be examined, because, by-replying, the plaintiffs waived their demurrer. This position would probably be the correct one, if the court had not rendered judgment of respondeat ouster, and there is nothing in the record to show that the plaintiffs asked leave to reply. The court would probably have been justified in rendering final judgment, but it did not do so; and it would be too rigid to say that the plaintiffs waived their right, by complying with the interlocutory judgment of the court, unless it should also appear that the judgment was given at their instance. If the defendants had complained of the judgment of respondeat ouster, we might have reversed on error brought by them, but then we would not have entered a final judgment in their favor, without inquiring whether we could properly do so on the demurrer. If the plaintiffs had failed to reply, then evidently they might have attacked any judgment rendered on the demurrer, and as the court did not give final judgment, we can perceive no reason for holding that the plaintiffs waived their right by conforming to the judgment of respondeat ouster. A waiver must arise from the voluntary act of the parties. The plaintiffs should not be prejudiced by an erroneous judgment of the court, so that, under the circumstances of the case, we cannot'well do otherwise than examine the judgment on the demurrer.
One of the objections to the pleas is, that they do not aver a consideration for the contract to give time. Certainly by averring the consideration on which the agreement was formed, the pleas would have been more in conformity to the correct standard of special pleading. Such a contract was not binding without a consideration, and it is a general rule that, wherever a contract or instrument does not of itself import a consideration, then the consideration on which it was founded must be averred in pleading.
But the case presents a difficulty still more formidable. These pleas were interposed to an action on a sealed instrument, which, by the common law cannot, we apprehend, be sustained. *319To sealed instruments all parties are principals, unless it appear on the face of the instrument that some are sureties, and tíiey cannot by plea be allowed to change their character; they are estopped by their seals. The case of Sprigg v. The Bank of Mount Pleasant, 10 Peters, 257, was in every essential particular like the present. In that case the parties had acknowledged themselves bound as principals, but this circumstance made no difference • it was only a reiteration of what the law had already declared, unless the contrary appeared on .the instrument. And the court laid down the rule expressly, as well settled, that when principal and surety bind themselves jointly and severally in a bond, although there is no admission in the instrument that all are principals, yet the surety,cannot aver by pleading that he is only a surety. This is no doubt the correct rule, and must prevail unless the statute will let in such a defence. It provides that the defendant, in an action on a sealed instrument, may, by plea, impeach or go into the consideration of the same as if it had been a promissory note. This provision seems to have been designed to enable the party to reach the consideration by plea, but the plea here sets up matter subsequent and in discharge of the defendants, and we are not prepared to carry the statute so far as to embrace the defence assumed in this plea.
It has been common for sureties, in forthcoming bonds, to avail themselves of such a discharge on motion, but the reason for this is obvious. Such bonds show, on their face, the character of the respective obligors. In the case of The People v. Jansen, 7 Johns. Rep. 337, the court held that such a defence could be let in at law, but the reason was, that the suretyship appeared on the face of the bond. When this is not the case, this defence can oply be set up in a court of chancery.
It is insisted that the plaintiffs should have replied the estoppel instead of demurring, but this was not necessary, inasmuch as the declaration averred the signing and sealing of the instrument. Nor was it. necessary to set out the instrument before demurring. If it showed on its face that the defendants were *320only sureties, it was for them to crave oyer and set out the bond, and then their plea might have been good. It is intimated, in the case referred to in 10 Peters, as above, that the proper course is for the plaintiffs to demur to the plea. The court then erred in overruling the demurrer, for which reason the judgment is reversed and cause remanded.