If at any time the Secretary of Agriculture finds, upon investigation and after due notice and opportunity for hearing to interested parties, that any class of products of any commodity is of such low value, considering the quantity of the commodity used for their manufacture, that the imposition of the processing tax would prevent in whole or in large part the use of the commodity in the manufacture of such products and thereby substantially reduce consumption and increase the surplus of the commodity, then the Secretary of Agriculture shall so certify to the Secretary of the Treasury, specifying whether such results will in his judgment most effectively be prevented by a suspension of the imposition of the processing tax or a refund of the tax paid, with respect to such amount of the commodity or any product thereof as is used in the manufacture of such products, and thereafter, as shall be specified in such certification, (1) the imposition of the processing tax shall be suspended with respect to such amount of the commodity as is used in the manufacture of such products, and thereafter, as shall be specified in such certification, (2) the imposition of the processing tax shall be suspended with respect to such amount of the commodity as is used in the manufacture of such products until such time as the Secretary of Agriculture, after further investigation and due notice and opportunity for hearing to interested parties, revokes his certification to the Secretary of the Treasury, or (3) the Secretary of the Treasury shall refund (in accordance with the provisions of, to such persons and in such manner as shall be specified in, such certification) the amount of any tax paid (prior to the date of any revocation by the Secretary of Agriculture of his certification to the Secretary of the Treasury, upon further investigation and after due notice and opportunity for hearing to interested parties) under this chapter with respect to such amount of the commodity or any product thereof as is used after the date of such certification in the manufacture of such products, or shall credit against any tax due and payable under this chapter the amount of tax which would be refundable. During the period in which any certificate under this section is effective, the provisions of subsection (e) of this section shall be suspended with respect to all imported articles of the kind described in such certificate; and notwithstanding the provisions of section 623 of this title, any compensating taxes, which have heretofore, during the period in which any certificate under this section has been effective, become due and payable upon imported articles of the kind described in such certificate, shall be refunded by the Secretary of the Treasury if the same have been paid, or, if the same have not been paid the amount thereof shall be abated. Notwithstanding the provisions of section 623 of this title, the Secretary of the Treasury shall refund or credit any processing tax paid on or before June 12, 1934, with respect to such amount of cotton as was used in the manufacture of large cotton bags (as defined in the Certificate of the Secretary of Agriculture, dated June 12, 1934) between June 13, and July 7, 1934, both inclusive.