Bulldog Martin gains no more personality or background than he did in his earlier stories, but to my great surprise, he does gains powers, of a sort. The series did not run very long, there are only five installments in this era, which is likely why he has been neglected by later writers. Well, that and the embarrassingly racist portrayal of his sidekick, Jonah.
In More Fun Comics 52 Bulldog receives a package from a recently deceased friend, inventor Professor Livix, which contains pills that render one invisible. Bulldog takes to carrying these around and popping them whenever he comes across a crime, enabling him to recover the stolen Romanof Ruby, bust up a protection scam and prevent an innocent man from being arrested for the murder of his uncle.
But, distressingly, the first thing he does, in issue 52, is bust up a union meeting. In this tale, all the union bosses are corrupt, and unions exist only to rob both the worker and employer. The writer must have been a Republican.
Bulldog invisibly walks out of a house at the end of issue 55, his final story, and is never seen again. Perhaps taking too many of the pills had that effect.
Bulldog Martin: More Fun Comics 51 – 55 (Jan – May 40)