In addition to all other taxes of every kind imposed by this title, there is hereby levied a license or privilege tax upon each person engaged in the business of operating an express company in the State of Alabama for the privilege of engaging in such business; said license or privilege tax shall be due and payable to the Department of Revenue by check made payable to the Treasurer annually in advance, on or before October 1 of each year, and shall be in a sum equal to two and one-half percent of the gross receipts of such express company from all the intrastate business within the State of Alabama during the preceding calendar year.