While this topic has wasted too much of our time, and everyone can be forgiven for presuming that this alleged substance is completely baseless, I think I might be able to shed some light on the mystery.
There are several "glow in the dark" substances, known as phospors. In a different chemistry forum, someone discoved that CaO fused in B2O3 strongly glowed for several seconds after being exposed to UV light.
"Calcium sulfide with strontium sulfide with bismuth as activator, (Ca,Sr)S:Bi, yields blue light with glow times up to 12 hours, red and orange are modifications of the zinc sulfide formula. Red color can be obtained from strontium sulfide."
Since arsenic is in the semiconductor family, it would not be surprising if some little known, or even unknown
phosphor composition could have been discovered by these "alchemists".
Here is NickDC's site:
http://www.lost-academy.com/t4-the-glowing-white-philosophical-mercury(It is very frustrating trying to read anything he writes, because of athe alchemist terminology and a very unclear confusing writing style)
Here is a list of alchemical terminology, if anyone wants to waste their time:
http://www.levity.com/alchemy/al_term1.htmlThere ar, however, a few interesting compounds discovered by alchemists:
Cadet's fuming liquid (Cadet's liquid): heavy brown liquid first prepared by the French chemist Louis Claude Cadet de Gassicourt. Cadet's liquid is highly toxic, smells strongly of garlic, and spontaneously bursts into flame when exposed to air. It is mainly cacodyl oxide ([(CH3)2As]2O) with other cacodyl compounds such as dicacodyl ([(CH3)2As]2).
As for the talk about "taking away the poison", this almost certainly refers to antimony, which is found in nature mixed with arsenic. Antimony was frequently used as a medicine, but the arsenic contaminants, which are difficult to separate out, caused unnecessary poisonings.
Here is an relevant quote that I recently found:
"People will only accept facts if they resemble what they already believe to be the truth."--Andy Rooney