A Pennsylvania statute imposed a tax on the shares of trust companies, the companies to be primarily liable therefor and the value of the shares to be ascertained by adding together so much of the amount of capital stock paid in, surplus, and undivided profits as was not invested in the stock of corporations liable to pay to the Commonwealth a capital stock tax or tax on shares, or relieved from the payment of capital stock tax or tax on shares, and dividing the sum by the number of outstanding shares. The corporations so relieved were those exclusively engaged in laundering, curing meats and manufacturing, except breweries and ones with the right of eminent domain. On appeal by a trust company from so much of an assessment under this statute as was based on United States bonds and national bank stock among its assets, the Supreme Court of Pennsylvania affirmed a decision sustaining the assessment in toto. The Supreme Court of the United States, in an opinion by Justice Roberts, reversed the decision as a whole on the ground the exemption of certain stock holdings from the calculation of the value of the shares indicated that the tax, despite the words of the statute, was on corporate assets rather than on the shares as such and, also because of the exemption, operated to discriminate against United States bonds and national bank stock. Justice Cardozo, in an opinion concurred in by Justices Brandeis and Stone, dissented as to that part of the decision relating to United States bonds on the ground the tax was truly one on shares and the exemption of stock in a narrow class of domestic corporations relieved of taxation for reasons of public policy was not discriminatory. Schuylkill Trust Co. v. Pennsylvania, 296 U. S. 113, 56 S. Ct. 31.(1935).