Where a contract between an owner of land and his agent for sale contained specific authority to the agent to sell a certain acreage, evidence was inadmissible, in an action by the agent for commissions, to show that the tract contained a greater acreage than stated, to defeat the claim, where there was no proof that the defendant asserted any claim to a greater acreage prior to the time plaintiff made the sale. Denton v. Howell (Tex. Civ. App. '05), 87 S. W. 221.