The owner of two parcels of land listed them for sale with a real estate broker. After some months the broker wrote the owner, referring to one tract, while the owner had, in fact, sold this tract some time before, but did not notice that the description referred to it, and allowed the broker to secure a purchaser; held, that his mistake was not such a mistake as would prevent the broker from recovering his stipulated commission. Luce v. Ash, 132 N. W. 708, 28 S. D. 109.