Examination room (spoiler)

[Turtleproof]

Well, how did you get passed it? I'm encountering the exact same bug. I'm certain that all six have been added (I missed the chemical behind the books, sulfur I think) and the substance is in place yet it still says "insufficient chemicals."

EDIT, AND BUG REPORT:

I exhausted every possible option and quit. This morning I started the game again and chemicals I had long ago collected had been returned to the room:

CHLORINE
IODINE

SULFUR was the one chemical I had not found (I found it during my previous attempt). However, when I loaded this morning I found all three chemicals back in the room, not in my inventory. I collected those three chemicals and put them into the machine. The SUBSTANCE was also back in my inventory, and I installed it.

I completed the puzzle with no error messages and continued.

If this issue has been identified and fixed already, I apologize.