Powder of Algaroth

Powder of Algaroth was made by pouring butter of antimony, antimony trichloride, into a substantial quantity of water, whereupon a fine white powder immediately precipitates out of the clear liquid, a dramatic and easily repeated demonstration that made the preparation a popular one to describe and discuss across seventeenth century chymical literature. Vittorio Algarotti, the Veronese physician credited with first describing the method in the mid sixteenth century, gave his name to the resulting powder, and the preparation became closely associated with the broader wave of intense seventeenth century interest in antimony's medicinal chemistry connected to the Basil Valentine literature and to the wider contemporary antimony controversy over whether antimony compounds were legitimate, valuable medicines or dangerous, unpredictable poisons unfit for use.

Powder of algaroth was used, at real and well documented risk, as a powerful purgative, prescribed in carefully measured doses to induce vomiting and bowel evacuation, a therapeutic use that walked a genuinely narrow line given antimony's real toxicity in anything beyond a carefully controlled small dose, and the substance's alternate name, mercurius vitae, the mercury of life, is chemically inaccurate and misleading, since the preparation contains no mercury whatsoever, its properties deriving entirely from antimony chemistry, a naming confusion this entry deliberately notes rather than lets pass silently, since taking the historical name at face value would misidentify the compound's actual composition.

Powder of Algaroth is identified as antimony oxychloride, SbOCl, an identification well confirmed and essentially uncontested, its formation from butter of antimony explained cleanly by modern chemistry as a hydrolysis reaction: antimony trichloride reacts with water, replacing some of its chlorine with oxygen from the water molecules and releasing hydrochloric acid, precipitating the far less soluble oxychloride as a solid white powder in the process.

The compound's misleading historical name, mercurius vitae, is a documented naming error worth flagging explicitly rather than repeating uncritically, since it attributes the preparation's properties to mercury when the underlying chemistry is entirely a matter of antimony reacting with water, a clear example of how an alchemical name could mislead about a substance's actual elemental composition even when the preparation method itself, as recorded, is perfectly clear and reproducible. The seventeenth century antimony controversy that surrounded preparations like this one, real physicians on both sides arguing in earnest over whether antimony compounds belonged in medicine at all, is itself well documented and offers useful context for why a compound this hazardous was nonetheless in genuine, sustained therapeutic use.