Alright, call me dumb but I've had few problems with this... What kind of soil would one recommend? What about topsoil?

And after boiling the mixture, is adding alcohol really necessary?

And when I pour it on paper, it takes days for it to go through... is this normal or did I miss something here?

Try REALLY hard to find book "Foxfire 5" printed 1979 by Anchor/Doubleday see pages 253 to 260 excelent pictures.
Nitrate bearing earth occurs in large areas of India, Spain, and USA. In particular Missisippi, Virginia areas. Smaller deposits are everywhere.

Alcohol may be a used as a solvent to remove organic content. Perhaps Acetone would be better or even ether. Anyways it's impossible to get pure KNO3 or even close to it. Many other mineral salts exist along side it. I'm not sure how you've gone about doing it so I don't know why it would take long to filter unless you have a build up of salts or have particle similar in size to the holes in your filter.

Tis better to buy tech grade KNO3, what you are making is a "dirty" way to do it and was used in obtaining KNO3 for making black powder.

Well, I don't plan on going to India some time soon, but thanks... As for the procedure I'm using, it is the one shown in TM 31-210 Improvised Munitions Handbook. Now I kind of knew this couldn't give a 100% pure product, I just want to see if I can do it. Buying tech grade KNO3 is an option but I don't want to arouse suspicion here. Anyways thanks, the more I learn the better it will be.

Alright, I fixed some problems but the main still remains : why the hell does it take so long for liquid to go through a piece of paper? No one seems astonished by this!
Would coffee filters do the same? I used all types of papers in my house and they just retain the water while letting a few drops through every 5 minutes...

the purpose of a filter is to filter crap out. the thicker your solution, the longer it will take to filter it. Sometimes it takes a while.

i really dont know shit about this but my friend would take 5 gallon buckets drill a few holes in the bottom near the center, fill them with dirt and poor water in to the bucket. then we would let the water collect in a bowl and boil it off and collect the percipitate. it did take a while. worth a shot (maybe).

You people dont know this but you can buy it a a garden center for $35 for 50 lbs

You can't find it anywhere around here. Blame McVeigh.

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Remember the golden rule:
Those with the gold make the rules.

you dont have to look really hard for foxfire 5 its right hear http://www.chapters.ca and sharch