§ 13. Cancellation of consent. When a consent to the plan shall have
been filed in the office of the county clerk as herein provided, it
shall be binding upon both parties thereto as long as the relation of
employer and employee exists between the parties, and expire at the end
of such employment, but it may at any time be canceled on sixty days'
notice in writing from either party to the other. Such notice of
cancellation shall be effective only if served personally or sent by
registered letter to the last known post-office address of the party to
whom it is addressed, but no notice of cancellation shall be effective
as to a claim for injury occurring previous thereto.