The fact that on certain occasions the defendant did not sell intoxicating liquor to persons who wished to buy it, had no tendency to contradict or control the evidence that at other times he had made sales of such liquor as testified to by the government witnesses. Proof that a man has violated the law in particular instances cannot be rebutted by proof that he did not violate it in other instances when he had the opportunity and was tempted to do so. Exceptions overruled.