The defendant claimed that he only acted as a broker between the plaintiff and the Liverpool firm for the sale of the soda ash in question, and upon the trial offered much testimony, consisting of letters and telegrams which passed between himself and the plaintiff, and which led up to and finally culminated in the written contract of sale which is set forth in the statement of the case. This testimony was offered for the purpose of showing that defendant acted simply as a broker, and that the contract should be construed simply as a broker’s sold note. This testimony was all rejected by the trial court, upon the ground that it tended to vary and contradict the terms of a written contract. This ruling was strictly right. The contract which defendant executed, and under which the goods were delivered, was a plain and unambiguous contract of sale, and upon familiar rules previous negotiations could not change its legal effect. There was nothing to *58prevent the defendant from malting a contract binding himself personally if he chose to do so, notwithstanding his ordinary business may have been simply that of a broker, and notwithstanding also the fact that he may have preliminarily negotiated in the capacity of a broker in this very transaction. Having made such a contract, he cannot now relieve himself from responsibility thereunder by showing that he was acting simply as agent or broker for a principal, whether such principal was disclosed or undisclosed. Weston v. McMillan, 42 Wis. 567.

We shall consider but one other question upon this appeal, and that is the question of the effect upon the rights of the. parties of the use of six tierces of the soda ash by the plaintiff in January or February following the sale, for the purpose of testing its fitness for the manufacture of glass. Assuming that the evidence is sufficient to establish an implied warranty that the soda ash in question was of a quality reasonably fit to be used in the manufacture of glass, the question is, Could the plaintiff, after having decided that the material was wholly unfit, and notified the defendant of its decision and its rejection of the material, proceed to use three quarters of a ton of the material in making a practical test, and still insist on its right of rejection? It seems clear that the plaintiff was entitled to a reasonable time after actual receipt of the material to exercise the right of rejection in case the goods did not conform to the contract. Renj. Sales (6th ed.), § 703. If this fact could only be ascertained by a practical test, the plaintiff also had the right, within such reasonable time, to make such practical test, using only so much of the material as was reasonably necessary for the purpose, without thereby losing the right of rejection. Benj. Sales (6th ed.), § 896; Philadelphia Whiting Co. v. Detroit White Lead Works, 58 Mich. 29. Rut this test is plainly for the purpose only of enabling the purchaser to decide whether the material con*59forms to the contract. If the fact can be determined by-inspection alone, the test is not necessary, and the use of the material, therefore, clearly unjustifiable. Now in this case the plaintiff’s officers determined at once, and upon inspection alone,' that the material was unfit for their purposes, and so notified the defendant, and rejected the entire lot. They did not claim to need any test. They took their position definitely. After that act they could not deal with the property in any way inconsistent with the rejection, if they proposed to insist upon their right to reject. Churchill v. Price, 44 Wis. 540. They must do no act which they would have no right to do unless they were owners of the goods. Benj. Sales (6th ed.), § 703. Under these rules it is evident the plaintiff had no right to use up a quantity of the material several weeks after the rejection. By the .rejection it became defendant’s property, if such rejection was rightful. Plaintiff had no right to use any part of it. It is claimed that the use was simply for the purpose of providing evidence of unfitness for the purposes of the trial of this case; but one has no right to use his opponent’s property for the purpose of making evidence. The act was an unmistakable act of ownership, and entirely inconsistent with the claim that the material had been rejected and was owned by defendant. It follows that the judgment must be reversed.

By the Court.— Judgment reversed, and cause remanded for a new trial.