SECTION. 1. All sawmills are under obligation to issue an invoice for every transaction of sale of lumber. There shall be printed at the foot of every page of the invoice a certificate stating that the lumber or lumbers sold to the purchaser are exactly of the same kind or kinds described in the invoice. This invoice may be couched in the following or similar terms:
"We certify that the kind or kinds of lumber or lumbers listed on this invoice are exactly the same as those sold or delivered (or to be delivered) to the purchaser."