How can I get past Unspeakable Horror?

Hint 1 of 9:

This is really a neat puzzle.

Hint 2 of 9:

Pick up and use whatever you can in the two neighboring rooms.

Hint 3 of 9:

Try to walk in the dark then.

Hint 4 of 9:

First, get a tapestry at the wall in the corridor.

Hint 5 of 9:

In the room with the running goblin, let the tapestry soak with his sweat.
Use the wet tapestry on the chemical sprayer.