Spirits of Mercap

Words fail to adequately describe the sheer odourousness.

  The Spirits of Mercap are a group of oily and volatile liquids that, when extremely dilute, have an unpleasant smell that resembles a rotting garlic or onion. When concentrated and pure, Spirits of Mercap become horrifically and dangerously noxious.   They are named after the (possibly apocryphal) ancient Alchemist known as Mercap the Smelly, who according to legend was banished to the middle of a remote bog as punishment for unleashing such a vile pollution upon the unfortunate populace.   Spirits of Mercap are most commonly derived by curious but ignorant, or particularly unwise, Alchemists from foul sludges that can be found in the dark, unpleasant depths of the equally foul Undercess. This sludge must be treated first with Red Aqua of Fortis, and then with Aqua of Muria under a gentle heat in an alembic until a pale oily liquid trickles out of the spout. Spirits of Mercap are easy to identify, aside from the extreme stench, from their readiness to burn with a bright blue flame, and from their immediate and spontaneous ignition in the presence of Hydra's Fortis. Phials of Spirits of Mercap that have been left alone for too long may grow tiny crystals of sulphur. Such phials should be treated with care, as they have a distressing tendency to detonate when subjected to shock.   For any Alchemist foolish enough to work with Spirits of Mercap, it is often recommended only to do so whilst wearing a beaked mask meshed with copper and stuffed with fragrant rosemary, lavender, and resin, or alternatively with Treacle of Althaea, or with a perfume soaked rag. All clothing worn is to be put to the flame immediately after work ceases, the destruction of any trace of Spirit of Mercap is more important than the monetary and material cost of replacing these articles.    

Mercap Ooze

  Much to the distress of any unfortunate soul who has to adventure down into the already unpleasant confines of the Undercess, a new strain of Noxious Ooze has been discovered that is full of vacuoles containing Spirits of Mercap. It is recommended that they are not to be pierced no matter what, and are to instead to be dealt with using a liberal application of cleansing fire.