In American Sugar Refining Co. v. Louisiana, 179 U.S. 89 (1900), the Supreme Court held that a statute of Louisiana exempting from its operation planters and farmers grinding and refining their own sugar and molasses, but which imposed a license tax upon persons and corporations carrying on the business of refining sugar and molasses, did not deny the equal protection of the laws to such persons and corporations as were thus taxed. It was as if the statute had imposed a tax upon the business of refining sugar and molasses, and had declared, as reasonably it might have done, that those who only refined their own sugar and molasses should not be regarded as belonging to that class. The Supreme Court said in that case: "The power of taxation under this provision was fully considered in Bell's Gap Railroad Co. v. Pennsylvania, 134 U.S. 232, in which it was said not to have been intended to prevent a State from changing its system of taxation in all proper and reasonable ways. It may, if it chooses, exempt certain classes of property altogether; may impose different specific taxes upon different trades or professions; may vary the rates of excise upon various products; may tax real and personal estate in a different manner; may tax visible property only and not securities; may allow or not allow deductions for indebtedness. `All such regulations, and those of like character, so long as they proceed within reasonable limits and general usage, are within the discretion of the state legislature or the people of the State in framing their constitution.'" Again: "The discrimination is obviously intended as an encouragement to agriculture, and does not deny to persons and corporations engaged in a general refining business the equal protection of the laws."