Eisner v. Macomber,
252 U.S. 189 (1920)  page 206

•    “As repeatedly held, this [the 16th Amendment] did not extend the taxing power to new subjects,… . Brushaber v. Union Pacific R.R. Co., 240 U.S. 1, 17-19; Stanton v. Baltic Mining Co., 240 U.S. 103, 112 et seq.; Peck & Co. v. Lowe, 247 U.S. 165, 172-173.