Burns' Anno. Stat. 1901, Sec. 6629a, declares that no contract for the payment of any sum as commissions for finding a purchaser for the real estate of another, shall be valid unless the same shall be in writing, signed by the owners of the real estate or his legally appointed and duly qualified representative. Held, that such section did not invalidate a written contract between real estate brokers by which one of them agreed to pay the other one dollar per acre for finding a purchaser for land which the first broker had for sale. Provident T. Co. v. Darraugh, 168 Ind. 29, 78 N. E. 1030. And that letters qualifying the original authority to pay plaintiff $1 per acre for finding a purchaser did not constitute a revocation of the authority. Id.