Powder of sympathy was a form of sympathetic medicine, current in the 17th century in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

, whereby a remedy was applied to the

weapon A weapon, arm or armament is any implement or device that can be used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime, law enforcement, s ...

that had caused a

wound A wound is a rapid onset of injury that involves lacerated or punctured skin (an ''open'' wound), or a contusion (a ''closed'' wound) from blunt force trauma or compression. In pathology, a ''wound'' is an acute injury that damages the epider ...

with the aim of healing the injury it had made. Weapon salve was a preparation, again applied to the weapon, but based on material from the wounded

patient A patient is any recipient of health care services that are performed by healthcare professionals. The patient is most often ill or injured and in need of treatment by a physician, nurse, optometrist, dentist, veterinarian, or other heal ...

rather than on any remedy for the wound.

History

The powder is said to have consisted of

green vitriol Iron(II) sulfate (British English: iron(II) sulphate) or ferrous sulfate denotes a range of salts with the formula Fe SO4·''x''H2O. These compounds exist most commonly as the heptahydrate (''x'' = 7) but several values for x are know ...

, first dissolved in water and afterward recrystallized or calcined in the sun. The

Duke of Buckingham Duke of Buckingham held with Duke of Chandos, referring to Buckingham, is a title that has been created several times in the peerages of England, Great Britain, and the United Kingdom. There have also been earls and marquesses of Buckingham. ...

testified that

Kenelm Digby Sir Kenelm Digby (11 July 1603 – 11 June 1665) was an English courtier and diplomat. He was also a highly reputed natural philosopher, astrologer and known as a leading Roman Catholic intellectual and Blackloist. For his versatility, he is d ...

had healed his secretary of a gangrenous wound by simply soaking the bloody bandage in a solution of the powder (possibly due to the

oligodynamic effect The oligodynamic effect (from Greek ''oligos'', "few", and ''dynamis'', "force") is a biocidal effect of metals, especially heavy metals, that occurs even in low concentrations. In modern times, the effect was observed by Carl Nägeli, although ...

). Digby claimed to have got the secret remedy from a Carmelite monk in Florence, and attributed its potency to the fact that the sun's rays extracted the spirits of the blood and the vitriol, while, at the same time, the heat of the wound caused the healing principle thus produced to be attracted to it by means of a current of air — a sort of wireless therapy. The powder was also applied to solve the

longitude problem The history of longitude describes the centuries-long effort by astronomers, cartographers and navigators to discover a means of determining the longitude of any given place on Earth. The measurement of longitude is important to both cartography ...

in the suggestion of an anonymous pamphlet of 1687 entitled "Curious Enquiries". The pamphlet theorised that a wounded dog could be put aboard a ship, with the knife used to injure the dog left in the trust of a timekeeper on shore, who would then dip said knife into the powder at a predetermined time and cause the creature to yelp, thus giving the captain of the ship an accurate knowledge of the time.

References

{{superstition Alchemical substances Magic powders Obsolete medical theories Superstitions