“ The testimony of Williamson made it reasonably certain that in the event of conviction for murder in the first degree he would render no other verdict than one which required capital punishment. Granting that this challenge for cause should have been sustained, and that this ruling required the plaintiff in error to use one of his peremptory challenges to remove the juror from the panel, we held that the refusal to sustain the challenge was not prejudicial error, as the record disclosed that the defendant was allowed 22 peremptory challenges, when the law allowed but 20. ”