“ Assuming that the allegations of the bill concerning the nature and validity of the plaintiffs' title and the existence, invalidity, and recording of the defendants' certificates of location constitute a part of the plaintiffs' cause of action, it is plain that a controversy respecting the construction and effect of the mining laws is involved and is sufficiently real and substantial to bring the case within the jurisdiction of the district court. ”

“ A case does so arise where an appropriate statement of the plaintiff's cause of action, unaided by any anticipation or avoidance of defenses, discloses that it really and substantially involves a dispute or controversy respecting the validity, construction, or effect of a law of Congress. ”

“ With considerable detail the bill alleges that the plaintiffs are the owners of a placer mining claim in Montana for which a United States patent was issued to their predecessors in interest in 1895; that they and their predecessors have been the owners and in actual possession for more than twenty years; that at the time of the application for the patent no mineral-bearing vein or lode was known to exist within the boundaries of this placer claim ”