Each person, firm or corporation which shall do the business of an express company, upon railroads or otherwise, in this State, by the carrying of any kind of property, money, papers, packages or other things, are hereby declared to be common carriers, and shall receive, safely carry and promptly deliver at the express office nearest destination every such article as may be tendered to them, and in the carriage of which they are engaged. No such company shall be compelled to carry any gunpowder, dynamite, kerosene, naptha, gasoline, matches or other dangerous or inflammable oils, acids or materials, except under such regulations as may be prescribed by the Railroad Commission. No person, firm or corporation so engaged shall demand or receive for such services other than reasonable compensation.