The chairman of the board shall receive a salary in an amount to be determined by the director of the department of labor and industrial relations and within the limits of the appropriations for the purpose. Each of the other members of the state board of mediation shall receive as compensation for their services an amount to be determined by the director of the department of labor and industrial relations, but not to exceed fifty dollars per day; and in addition thereto shall receive all necessary travel and other expenses incurred while actually engaged in the performance of their duties as such members.