The Secretary of Agriculture shall provide, if practicable, any interested persons with duplicates of the official naval stores standards of the United States upon request accompanied by tender of satisfactory security for the return thereof, under such regulations as he may prescribe. The Secretary of Agriculture shall examine, if practicable, upon request of any interested person, any naval stores and shall analyze, classify, or grade the same under such regulations as he may prescribe. He shall furnish a certificate showing the analysis, classification, or grade of such naval stores, which certificate shall be prima facie evidence of the analysis, classification, or grade of such naval stores and of the contents of any package from which the same may have been taken, as well as of the correctness of such analysis, classification, or grade and shall be admissible as such in any court.