"Onetap" wrote in message
...
On 1 Apr, 21:07, "Rick Hughes"
wrote:

People used to call at houses once a week to collect it ............ I
seem
to recall it was boiled down to make saltpeter


I think the process was more like composting, there's details on
wikipedia;
http://en.wikipedia.org/wiki/Potassi..._of_production

The saltpetre men could dig up any stable or outbuilding floor for
material and often dug up the earth floors in houses.


OK ... agree just read
"Urine has also been used in the manufacture of saltpetre for gunpowder. In
this process, stale urine placed in a container of straw hay is allowed to
sour for many months, after which water is used to wash the resulting
chemical salts from the straw."

So I was right about collection, but not about boiling it :-) ..........