Responding to the invitation of the appellant, the district court treated the demurrer as a motion to dismiss, and ruled accordingly. Not only that, but the appellant elected to stand upon the demurrer and suffer judgment to be entered against her. Thereby the appellant waived her statutory right to insist that a demurrer, in lieu of a motion to dismiss, cannot be filed against her application to modify the decree for alimony. Heitzman v. Hannah, 206 Iowa 775, loc. cit. 779, 221 N.W. 470; McPherson v. Commercial Building Securities Co. et al., 206 Iowa 562, loc. cit. 566. 218 N.W. 306; Overland Sioux City Co. v. R.J. Clemens, 189 Iowa 1293, loc. cit. 1296, 1297, 179 N.W. 954. The demurrer, so called, was sufficient in form to be a motion to dismiss. So, in view of the fact that the appellant made no attack thereon, but by her conduct induced the district court to treat the demurrer as a motion to dismiss, she cannot now complain of the action of the district court in treating the demurrer as a motion to dismiss.

An acknowledgment which is taken by an officer who is disqualified to take it by reason of his interests or relationship to a party is ordinarily said to be void. Ramsey v. California Packing Corp., 51 Cal.App. 517, 201 P. 481; Knudsen v. Lythman, 33 Idaho 794, 200 P. 130; Ogden Building Loan Ass'n v. Mensch, 196 Ill. 554, 63 N.E. 1049; Myers v. Eby, 33 Idaho 266, 193 P. 77, 12 A.L.R. 535. Where the acknowledgment of an instrument is void, the instrument itself is inadmissible to record, and the attempted recording thereof is a nullity for any purpose. 1 C.J.S., Acknowledgments, § 57, p. 828; Heitzman v. Hannah, 206 Iowa 775, 221 N.W. 470; Cowan v. Dale, 189 N.C. 684, 128 S.E. 155; Gulf Production Co. v. Continental Oil Co., Tex.Civ.App., 61 S.W.2d 185. GIVENS, Justice.

It has been held that a motion to dismiss filed in a law action may be treated as a demurrer. Heitzman v. Hannah, 206 Iowa 775, 221 N.W. 470. It would seem that the converse of such rule should be true. The record leaves no doubt but what the position of counsel was that the motion to dismiss retained its character as such notwithstanding the transfer of the case to the law calendar. They were emphatic in the declaration that no part would be taken in its submission until after five days notice.