“ By its order of October 11, 1937, this Court noted probable jurisdiction and directed the attention of counsel to the questions as to (1) the existence of the required jurisdictional amount and (2) the adequacy of the remedy at law. Appellants concede that in view of the terms of the statute prohibiting any action to recover the tax, if paid, except as therein provided, Laws of Washington, 1935, chapter 180, title 18, p. 837, § 199, there would be no remedy available at law in the federal court and hence that federal equity jurisdiction would not be outsted. ”

“ This suit was brought to restrain the enforcement against the Northern Pacific Railway Company of the 'compensating tax' imposed by title 4, of chapter 180, page 726, of the Laws of Washington of 1935. The act levies a tax of 2 per cent. ”