This is because if you add more FASA then needed, there is no way for the excess fumaric acid to precipitate out along with the alks that your extracting. Its completely soluble in the acetone and will stay in the acetone, while the fumarates on the other hand crash out. A FOAF was going to try this soon and was going to just add either the same amount of FASA that there is CASA, or maybe 1.5 to 2 times the amount. Like I said, the fumaric acid wont precip out, and this will just ensure there is enough to completely convert every alk to its fumarate salt.

I do not know if it works better for dry vs. wet leaf material. I myself have not performed this extraction yet, but understand how it works.

The epson salts however need to be added to the acetone BEFORE any of the extraction process is done and before the citric or fumaric acid is added as well. Also, you do need to cook the epson salts in the oven (not sure of temp. or how long, but a search here or on google should answer that), and this creates anhydrous magnesium sulfate. It pretty much just evaps all the moisture out of the salts. However, they will readily absorb moisture from the air, so make sure to get them into a sealed container to cool down as fast as you can safely do.

Once this is done, you add the anhydrous magnesium sulfate to the acetone to absorb all the water and alcohol that could possibly be mixed in there to create anhydrous acetone. This is the acetone you will then add the citric acid and fumeric acid too, and use for the extraction processes. This also allows for the maximum amount of citric and fumaric acid to be absorbed into the acetone.

Hope that cleared more up for ya

Even if the MSDS states that its 100% acetone, there are still byproducts that get put into there from batch to batch. Every batch that comes into a hardward store has different amounts of water and alcohol added to it, even though the container says 100%. Since this is the case and we can not get access to the manufacturers info about that specific batch, its better to just be safe and dry out the acetone. Worst comes to worst you spent a few hours cooking epson salts for nothing, but you know that you for sure wont be left with a gooey tarry mess in the end that the alks are trapped in. This would be ok if you making changa with it, but if your looking for crystals you need to make sure the acetone is anhydrous.

I bought some klean-strip acetone that said the same thing on the MSDS, there is a post in extraction help about it, and I was told the same thing. Its better to be safe then sorry and have a nasty mess to work with and clean up in the end.

I found a few threads regarding the CASA/FASA method, but I can't seem to find the OP from infundibulum about it... Any help?

Or does anyone have an idea why this concept seems to have been abandoned?

It was abandoned because it was not meant to be a tek per se; more like a proof of principle that came out in a time when there were feverish novel teks developed and many different approaches were revolutionised. Some abandoned, some taught us about principles and some were further evolved to today's tried and tested teks.

This tek uses a lot of acetone; close to 200 or more ml of acetone are needed to extract 10g of mhrb; this does not sound cheap and given the flammability of acetone, certainly not safe. In the end you have loads of used acetone that cannot be used again, so you have to do something with it like disposing it in a properly manner.

Thanks, that makes total sense...

However, does the initial solution need to be CASA? Why not use water + citric acid?
And what is/was the idea behind saturating the initial solution?

As you said, today's methods are tried and tested, so it's unlikely I'll be able to contribute to their improvement... But perhaps some older ideas were abandoned prematurely or could be re-evaluated based on knowledge or experience that wasn't available at the time of abandoning?

However efficient and useful today's teks may be, and they are, not seeking new ways to improve existing teks or come up with new extraction methods would take a lot of the fun out of it, wouldn't it?

PLUR

Because the whole idea of this approach is that no water should be involved. The resulting dmt fumarate will be insoluble in acetone, but presumably soluble in an acetone+water mixture

Re your saturation query, well, it may not be necessary. But when you have to start from somewhere when you develop something where do you start from? 1% citric acid? 2% citric acid? Why not saturated since that will definitely guarantee enough of it. More, or a lot of acid (especially if it is a weak acid) is never a issue in an extraction.

You are absolutely right, I just experienced this last night - in the case of back-salting with citric acid I'd say use triple the amount of what would be necessary if the acid was fully dissociated (which it won't, obviously)...

But it's so cheap, food-safe and a lot less of a hassle than vinegar - gotta love it

And since it's not fumarates that I'm after I really can't be bothered with dehydrating epsom salts and drying acetone - citric acid soak, then NaOH then water crystallisation is my current line of thought/experimentation...

Thanks for your answer and more importantly the inspiration

edit - my current experience is limited to back-salting of toluene with citric acid, then NaOH, then water crystallisation and so far it is going great, absolutely