2. In general, a party may discredit a witness called by the opposite party, who testifies against him, by proving that his character is such as not to entitle him to credit or confidence, or any other fact which shows he is not, entitled to belief. It is clearly settled, also, that the party voluntarily calling a witness, cannot afterwards impeach his character for truth and veracity. 1 Moo. & Rob. 414; 3 B. & Cress. 746; S. C. 10 Eng. Com. Law R. 220. But if a party calls a witness, who turns out unfavorable, he may call another to prove the same point. 2 Campb. R. 556 2 Stark. R. 334; S. C. 3 E. C. L. R. 371 1 Nev & Man. 34; 4 B. & Adolph. 193; S. C. 24 E. C. L. R. 47; 1 Phil. Ev. 229; Rosc. Civ. Ev. 96.