Whenever any corporation, joint-stock association, limited partnership, or company, subject to tax upon its capital stock imposed by and under the laws of this Commonwealth, owns assets which are exempted or relieved from the capital stock tax under the laws of this Commonwealth, the proportion of the capital stock exempted or relieved from the capital stock tax, by reason of the ownership of such assets, shall be the proportion which the value of such assets bears to the value of the total assets owned by such corporation, joint-stock association, limited partnership, or company.
72 P.S. § 1896