1. Material facts or questions which wbre in issue in a former suit and were there judicially determined by a court of competent jurisdiction are conclusively settled by the judgment therein so far as concerns the parties to that action and persons in privity with them and cannot be again litigated in any future action between the same parties or privies, and this rule also applies not only to what was determined but also as to every other question which might properly have been litigated in the ease. (Hixon v. Ogg, 53 Ohio St., 361, and Strangward v. American Brass Bedstead Co., 82 Ohio St., 121, followed and approved.)

2. Privity of contract is the relationship that exists between two or more contracting parties and where the legality of a contract is determined in a suit brought by a tax payer, the parties to such contract with knowledge of such suit are in privity and bound thereby although only one of them is made party to such suit.

3. Where the legality of a public contract has once been determined in a proceeding- in a court of competent jurisdiction, between a taxpayer and the public officials who were parties to such contract and other officials whose official action is necessary to the process of payment of money due under said contract, all parties and their privies to such record are bound by such judgment; in an action in mandamus to compel payment of the amount due under such contract afterwards brought by one in privity with one of the parties to the prior suit, such officials will not be allowed to avail themselves of the same defenses that were passed upon and determined in such prior suit, such judgment constituting res adjudicata.