Whenever it shall come to the knowledge of the commissioner, either by notice from the mayor of a city, a county commissioner, the president of a board of trade or other representative body, the president of a central labor council or assembly, or of any 5 reputable citizens or otherwise, that a strike or lockout is seriously threatened or has actually occurred in the state, involving an employer and his or its present or past employees, if at the time such employer is employing, or, up to the occurrence of the strike or lockout was employing, not less than 10 persons in the same general line of business in any city or town in this state, and the commissioner shall be satisfied that such information is correct, it shall be his duty, within 3 days thereafter, to put himself in communication with such employer and employees, and endeavor by mediation to effect an amicable settlement between them, or to persuade them to submit the matter to said board of arbitration, and to act as hereinbefore provided in case of disputes and controversies.