on the privilege of engaging in intrastate commerce, a conclusion which obviously ignores the question of the tax's actual impact on interstate commerce, the precise question on which many previous decisions have turned.[714] TAXES ON NET INCOME The leading case under this caption is United States Glue Co. _v._ Oak Creek[715] where it was held that the State of Wisconsin, in laying a general income tax upon the gains and profits of a domestic corporation, was entitled to include in the computation the net income derived from transportations in interstate commerce. Pointing out the difference between such a tax and one on gross receipts, the Court said the latter "affects each transaction in proportion to its magnitude and irrespective of whether it is profitable or otherwise. Conceivably it may be sufficient to make the difference between profit and loss, or to so diminish the profit as to impede or discourage the conduct of the commerce. A tax upon the net profits has not the same deterrent effect, since it does not arise at all unless a gain is shown over and above expenses and losses, and the tax cannot be heavy unless the profits are large." Such a tax "constitutes one of the ordinary and general burdens of government, from which persons and corporations otherwise subject to the jurisdiction of the States are not exempted * * * because they happen to be engaged in commerce among the States."[716] Adhering to this precedent, the Court has held that a tax upon the net income of a nonresident from business carried on by him in the State is not a burden on interstate commerce merely because the products of the business are shipped out of the State;[717] also that a tax which is levied upon the proportion of the net profits of a foreign corporation earned by operations conducted within the taxing State is valid, if the method of allocation employed be not arbitrary or unreasonable.[718] Where, however, the method of allocating the net income of a foreign corporation attributed to the State an amount of income out of all proportion to the business there transacted by the corporation, it was held void.[719]