Lillian Eichler Watson,
Book of Etiquette, Volume I
“ RECEIVING THE CHANCE CALLER It is not always very convenient to entertain chance callers, especially if one has some important business or appointment to attend to. But when the servant at the door has admitted that her mistress is at home, the hostess should exert every effort to make good the servant's assurance. She must not keep the caller waiting, nor must she ask to be excused after the caller has been admitted. If important business claims her time, she may come to the drawing-room and after welcoming the visitor, explain the situation and ask to be excused. ”
