Potassium Nitrate

Note: There really are much easier ways of getting hold of this stuff. When I was a kid it came in decent quantities in chemistry sets. But if you insist on playing James-Bond-behind-enemy-lines, then give this a shot. I’ve sure as hell never tried it.

Potassium nitrate can be extracted from many natural sources and can be used to make nitric acid, black powder and many pyrotechnics. The yield ranges from .1 to 10% by weight, depending on the fertility of the soil.

Materials	Sources
Nitrate bearing earth or other material, about 3.5- gallons (13.5 liters)	Soil containing old decayed vegetable or animal matter — old cellars/farm floors, earth from old burial grounds, decayed stone or mortar building foundations.
Fine wood ashes, about .5 cup (1/8 liter)	totally burned whitish wood ash powder, totally black paper
Bucket, about 5 gallons (19 l) in volume 2 pieces finely woven cloth, each slightly bigger than the bottom of the bucket Shallow pan or dish, at least as large as the bottom of bucket Shallow heat resistant container (ceramic, metal, etc.) Water- 1.75 gallons (6.75 l) Awl, knife, or screwdriver, or other hole punching tool Alcohol — 1 gallon (4 l) can be whiskey, rubbing, etc. Heat source Paper Tape

Note: Only the ratios of the amounts of ingredients are important. Thus, for twice as much, double all quantities.

Procedure

1. Punch holes in the bottom of the bucket. Spread one piece of cloth over the holes inside the bucket.

2. Place wood ashes on the cloth and spread to make a layer about the thickness of the cloth. Place the second piece of cloth on top of the ashes.

3. Place dirt in the bucket.

4. Place bucket over a shallow container. The bucket may be supported on sticks if necessary.

5. Boil water and pour it over the earth in the bucket a little at a time. Allow the water to run through the holes in the bucket into the shallow container. Be sure water goes through all of the earth. Allow drained liquid to cool and settle for 1 to 2 hours.
   Note: Do not pour all the water at once, as this may cause stoppage.

   Carefully drain off liquid into heat resistant container. Discard any sludge remaining in the bottom of the shallow container.

   Boil the mixture over a hot fire for at least 2 hours. Small grains of salt will begin to appear in the solution. Scoop these out as they form, using any type of improvised strainer (paper, etc).

   When liquid has boiled down to approx. half its original volume, remove from fire and let sit. After half an hour, add an equal volume of alcohol. When mixture is poured through paper, small white crystals will collect on top of it.

   To purify the potassium nitrate, re-dissolve the dry crystals in the smallest possible amount of boiled water. Remove any salt crystals that appear (step 7); pour through an improvised filter made of several pieces of paper and evaporate gently — heat the concentrated solution to dryness.

   Spread the crystals on a flat surface and allow to dry. The crystals are now ready to use.