Phantom of Blood Alley (Barnaby Grimes #4) by Paul Stewart

Barnaby Grimes is a tick-tock lad, high-stacking his way across the rooftops of his city in search of adventure and mystery. In each tale, he encounters a supernatural force and must battle the horrors that await him.

In the fiercely competitive world of early photography, the rewards are immense but so are the risks. After an experiment goes disastrously wrong, Barnaby finds himself on the trail of a mad chemist with a talent for disappearing into thin air . . .

Dog Gone Note: This is a series but can be read as a stand alone.