The Social Gangster (Craig Kennedy, Scientific Detective)

"The fifth volume in the chronicles of Craig Kennedy, Scientific Detective, takes up the familiar and successful formula for a new round of adventures. Kennedy deals with the usual sorts of crimes--jewel theft, missing persons, wrongly accused suspects, fixed horse races, arson, murder, and blackmail--but he uses scientific procedures to analyze the evidence, sometimes involving fantastical devices. In this volume, for example, we have a new form of lie detector, a primitive sound recorder, a device that detects eavesdropping, rays that cause explosives to spontaneously ignite, a perpetual motion machine which is debunked but which conceals a device that dissolves walls, mysterious drugs, and murder by means of germs. There's also a mystery involving voodoo, although there's no supernatural content. For fans of the Sherlock Holmes genre in particular, although SF readers should be entertained by Kennedy's methods." -- Don D'Ammassa, Science Fiction Chronicle