The authorities which establish this proposition are too numerous and the principle is now too well settled to require any extended argument or reasoning to support it. Edwards v. R. R., 129 N.C. 78; Lindsay v. R. R., 132 N.C. 59. Before the Court can be required to give an instruction, it must be so framed as to be complete in itself, and it must not only be justified by the evidence, but it must not exclude from the consideration of the jury any testimony which is proper to be taken into account and weighed by them in arriving at a conclusion upon the issues involved, and, above all things, it must not require the jury to treat as a conclusion of law, even under the instruction of the Court, that which is in its very nature a mixed question of law and fact.