“The Mystic Mullah” has some interesting connections.  This was published in the January issue of Doc Savage Magazine. The first item is a story by Dashiell Hammett titled “The Dain Curse.” It is a hard-boiled detective published in 1929 that features the Continental Op.

Of interest to Doc Savage fans is an incident in the first part of the book.  The Continental Op is staying at a “temple” operated by a religious cult.  The entire operation is a scam and designed to trick people into believing they have been visited by spirits.  The cult utilizes a few simple tricks to sway people.  The illusion of a visiting spirit is created by blowing up a balloon hidden in a pipe located in the room.  The balloon expands into a human-like shape. This is all done while the occupant is sleeping.  At the same time, an anesthetic type gas is pumped into the room so that the victim’s senses are dulled so that the apparition appears real.  Hidden speakers allow the spirit to rouse the victim from his slumber and instruct him on the wonders of the temple.

Here are a few passages from “The Dain Curse” describing the encounter between the Continental Op and the apparition:

“Not more than three feet away, there in the back room, a pale bright thing like a body, but not like flesh, stood writhing before me.

It was tall, yet not so tall as it seemed because it didn’t stand on the floor, but hovered with its feet a foot or more above the floor.   …   The thing was like a man who floated above the floor, with a horrible grimacing greenish face and pale flesh that was not flesh, that was visible in the dark, and that was as fluid and as unresting and as transparent as tidal water.”

Dashiell Hammett

A similar trick is employed in the January 1935 Doc Savage story, “The Mystic Mullah.”  A balloon device is used to create the illusion of a hovering, disembodied head.  The gas in this story is of a poisonous nature rather than a stupefying one.

“It was a fantastic thing, that face. Its color was not human, but a greenish hue, the tint that comes to meat in the first stages of decay. The green countenance shone with a fantastic luminosity . . .

The thing Renny had fallen over must have been blown across the room by the grenade blast. It was such a device as fake spiritualists and magicians sometimes use to make luminous heads appear in thin air – a telescoping tube of some length, to the end of which was fixed a thin-walled rubber balloon face which could be inflated by blowing through the tube; then, by suction, drawn back into the tube, and the telescoping affair collapsed. Manipulation of thin threads caused the appearance of lip motion. “

This cover looks strangely like the description above.  It is the February 28, 1931 issue of Detective Story Magazine.

The similarities between the illusions in the two stories are interesting. The idea of spirits and gas was carried further in “The Majii” from September 1935.  The gas in that story had a hypnotizing effect.  Of course, Hammett and Dent were not the only authors to employ stupefying gases in their stories.  This was also a trademark signature of the notorious Dr. Fu Manchu from the Sax Rohmer stories.