Chemical Weapons Lab

Overview
The Chemical Weapons Lab is required to build chemical-based units, including the Chem Trooper, Bio Grenadier, Light Chemical Tank, and Heavy Chemical Tank. It also provides 10 storage for Chemical Vials. Contrary to what you may expect, this building does not actually produce Vials - they must be acquired through missions, occupying Chemical buildings, battling certain Rebel Army forces or through the Chemical Reservoir.

Unlike other buildings whose primary purpose is to unlock units, it appears that, like the Chemical Storage Facility, it is possible to build multiple Chemical Weapons Labs in a single outpost because this counts as a warehouse. It is better, however, to build the Chemical Storage Facility for storage of Chemical Vials.

As of Patch 2.2, players can raid or occupy the Chemical Weapons Lab and the Chemical Storage Facility (But not the Chemical Sprinkler) to obtain Chemical Vials.