ยง 2218. Trial of issue raised on motion. The court may order that an issue of fact raised on a motion shall be separately tried by the court or a referee. If the issue is triable of right by jury, the court shall give the parties an opportunity to demand a jury trial of such issue. Failure to make such demand within the time limited by the court, or, if no such time is limited, before trial begins, shall be deemed a waiver of the right to trial by jury. An order under this rule shall specify the issue to be tried.