The expression of opinions by the court as to the materiality of evidence in ruling upon offers of testimony, are not usually proper objects of exception, but declarations or statements may be assumed by the court, in the presence of the jury, with respect to its weight and materiality, as to be prejudicial and ground of exception by the aggrieved party. Haug v. Hangan, 51 Minn. 558, 53 N. W. 874. An agent's authority can not be proved by his declarations, nor by his acts done without the knowledge or authority of his principal. Whitney v. Lake, 91 Pa. St. 349; Eastland v. Maney, 36 Tex. Civ. App. 147, 81 S. W. 574; Ehrenworth v. Putnam (Tex. Civ. App. 1900), 55 S. W. 190. A person, not in actual possession but authorized to sell, is a mere broker, and his declarations can not be admitted to affect the title of his principal. Pier v. Duff, 63 Pa. St. 59. In an action for deceit arising out of an exchange of properties through a broker acting for defendant, evidence that defendant stated that his broker had made a mean trade for him, and that he had made a poor trade, warrants a finding that such broker was acting for defendant in effecting the exchange. Arnold v. Teal, 182 Mass. 1, 64 N. E. 413.

The question of whether a broker employed to procure a purchaser was the efficient cause of the sale, or whether the means employed by him and his efforts resulted in a sale, must be deduced from the facts relating to the transaction, and not from the conclusion of a witness. Geiger v. Riser (Colo. Sup. '10), 107 P. 267.