Ian Adams said:
rhychydwr1 said:
As far as I am aware saltpetre does not exist in UK caves. No idea why. I have explored many bat caves and mines but have never found saltpetre.
Interestingly, "Calcium Nitrate" (as opposed to Potassium Nitrate) is also called Saltpeter(petre) by Wikipedia and that is the stuff we find in caves.
Obviously, Wikipedia is an authority on the matter.
Ian
Saltpetre is a generic term for several "nitrate salts"
As calcium nitrate is very soluble it isn't found in caves that are very wet.
I think most British caves fall into the "wet" category so I don't believe any worthwhile deposits occur here. Certainly I am unaware of any extraction from UK caves so I assume our climate precludes it.
Calcium nitrate is also the Saltpetre that was extracted in the US caves.
Calcium nitrate is very soluble so is only to be found in dry caves.
The calcium nitrate was leached from the cave soil in vats, collected and then taken from the caves to be processed.
The first stage was to concentrate the solution using evaporation, generally using wood fires.
The concentrate was then reacted with potash (potassium carbonate, from the ashes of the wood fires used in the evaporation process). The calcium would be precipitated as calcium carbonate and would be replaced by the potassium in the solution to make potassium nitrate. The subsequent solution would be further "dried" by evaporation and the saltpetre crystals would remain.
The process is well documented and was primarily used to produce saltpetre for gunpowder, when the main source was denied. During the war between America and the UK (1812), the UK controlled the world's supply of Saltpetre, which was produced in one of our colonies (India). The UK blockaded the US ports, so a source of home produced Saltpetre was needed by America. Later during the American Civil War (1861 to 1865) the North blockaded the Confederates and they had to make their own gunpowder in the same way.
There are several good books produced by Angelo I George* as well as specific books about the main Saltpetre caves in the US, predominantly Mammoth Cave (Ky), Great Saltpetre Cave (Ky), Big Bone Cave** (Tn) and Wyandotte Caves (In), although many more caves were used.
*
Mamoth Cave Saltpeter Works, Angelo I. George - ISBN 0971303827
The Saltpeter Empires, Angelo I. George - ISBN 0971303800
**
Big Bone Cave, Larry E. Mathews ISBN 9781879961241