When you are in the Greenhouse (research lab aka production zone), you can use a herbicide to reach the closet with the Living Quarters key. However, taking the key sets off an alarm, and a fire hose prevents you from leaving the way you came in. Instead, climb to the ceiling and go to the upper left inside the glass dome. The glass is cracked there and you can use the Rubber mallet to break it and escape.
(If you don't have the mallet, replace the key to shut off the alarm, then go get the mallet from the trash at Sully's and come back for the key.)
its in the museum on mainstreet of steamworks island :)
There is a very old Dirty Beaker in the Steamworks Museum (far upper right). Use the machines and climb the vines to reach the beaker. You need this at the Greenhouse in the Laboratory (Production zone, right side of the island).
It's Steamworks Island #14th Island
(The solution is at the related question "How do you beat Steamworks Island")
the crab on steamworks island is next to the living quarters
You go to Steamworks and head to the museum and there is the Deogen
steamworks island
There is a video walkthrough at the related link below. There are written WikiAnswers solutions at the related questions, as there are for all Poptropica islands. (How do you beat Steamworks Island) (What is the walkthrough for Steamworks Island)
Steamworks island
how to do the bridge terminal on poptropica's steamworks island
you can get it on the far left of steamworks island, past the living headquarters.
jump