Can mustard seeds burn skin?

[Slaign]

I remember hearing a story when I was younger, about how court "wizards" would use science that both the peasants and their leaders were ignorant of to appear magical.

 

The story went as follows:

 

A crime is committed in a village under a lord's protection, and there are 3 suspects. The lord calls his court wizard and demands he find out which is guilty. The wizard takes his leave to prepare, and chooses 3 similar rocks of a porous nature. He takes one of the rocks and grinds mustard seeds with it until it is coated in mustard powder. Returning to the lord, he summons the three suspects and tells them they will be subjected to a test. They must each hold onto a stone, and the stones will burn the one who is guilty. The wizard then passes out the stones, giving the mustard covered stone to the person he believes is guilty. The suspects squeeze the stones, and sure enough, in time the man holding the mustard stone must drop it from the pain, and has evidence of a burn on his hand.

 

So, my question is whether or not this sounds plausible? Would the trick work?

 

In my search of the internet, I haven't found a trace of the story itself. Searches about mustard being able to cause burns turns up pages claiming yellow mustard can be used to actually treat burns. I thought perhaps it's a matter of concentration, and searched for information about mustard seeds and powder, and found this page: http://homecooking.about.com/od/cookingfaqs/f/faqhotmustard.htm

 

This is the bit I found relevant: "It is the chemical reaction between two compounds, myrosin and sinigrin, that combines to turn up the heat when the cells of the seeds are broken and mixed with cold water. This combination results in mustard oil that can actually cause burning or blistering when it comes in contact with the skin, so be careful when making your own mustard."

 

This makes it seem like you need cold water to initiate the reaction, which is absent in the story. Perhaps our wizard may have wet the mixture before applying it to the stone, but the website seems to indicate that the reaction doesn't last long. Maybe the sweat from our accused's hand would cause the reaction, but it wouldn't be cold. Or, maybe it's all bunk and it wouldn't work.

 

Thoughts?

[Endy0816]

Plausible

 

Phytocontact Dermatitis due to Mustard Seed Mimicking Burn Injury: Report of a Case

 

My guess is they would need to hold the stone for awhile or the wizard would need to increase the reaction rate though.

[John Cuthber]

Yes

http://en.wikipedia.org/wiki/Mustard_plaster#Side_effects

[Slaign]

Thanks!