From and after the passage of this act, any individual, partnership or corporation, who or which requires from persons in his or its employ, under penalty of forfeiture of part of wages earned by them, a notice of intention to leave such employ shall be liable to pay to the party injured a sum equal to the amount of said forfeiture, if he or it discharges, without similar notice, a person in such employ, except for incapacity or misconduct, unless in case of a general suspension of labor in his or its mine, shop or factory, or a suspension of work ordered by the employes of such individual, partnership or corporation.