Whenever any controversy or difference arises relating to the conditions of employment or rates of wages between any employer, whether resident or non-resident, and his employees, such controversy involving the interest of not less than 10 employees in the same general line of business in this state, the commissioner shall, upon application as hereinafter provided, visit the locality and make careful inquiry into all the conditions and circumstances of the situation, hear all persons interested therein who may come before him, advise the respective parties what, if anything, ought to be conceded by either or both, and adjust such controversy or difference and, within 5 days after such inquiry, make a written decision thereon, a copy of which shall be furnished the parties and a copy kept on file in the department of labor.