A mistake as to a quality or characteristic of the adversary party can not be treated as a mistake as to identity, so as to render the contract invalid.1 A mistake as to the race or nationality of the adversary party is not a mistake as to his identity.2 One who has agreed to sell a lot in an addition which is intended for high-class residence property, can not avoid specific performance on the ground that he did not know that the purchaser was a negro, and that if a lot is sold to a negro it will affect the value of the rest of such tract?