Okay.. so I've found what I was thinking of on Erowid but it actually isn't much different from what's already available to read through, unfortunately. It's still a good resource, however. Some neat art in there, too.

Golden Guide to Hallucinogenic Plants by Richard Evans Shultes

The desired information is seen through the bottom pages of 121-130 to above pages on 131-140. Interestingly enough, the amount of seeds used still perplexes me. Only 13(a thimble) seeds are utilized according to this book(I thought it was 26!) That doesn't make very much sense from what we know regarding the alkaloid content of morning glory seeds. Anyone using these seeds knows/needs at least 50 of these seeds to work with even threshold effects. Have fun figuring that one out!

It helps that they are freshly harvested but I'm not sure what else to add that would justify that small of an amount of plant material.

There's no info regarding the amount of time reserved for extraction purposes.

https://erowid.org/libra...de/g01-10.shtml#contents

Yeah this dosage has been a much discussed topic even among researchers. Often you also read, as you said, they used 13 pairs of seeds (26 total).

But honestly from the many stuff I have read so far I wouldn't be too confident about the actual correctness of single reports. There could have well been a misunderstanding between each other.
But even 26 seeds is not much.
I could well think 13 or 26 seed pods (for I. Tricolor). That would make sense to me.
OTOH T Corymbosa, which is the base for most of these reports, only has one seed per pod.
And it even has less ergolines.

Wasson said the amount of seeds that fits into the cup of a hand.



Really a pity. I actually believe you that you once read these 30min to 1h.

For as I said in Voogelbreinder's book there's a similar indication of such a time frame. So there must be a source for this.
I have high hopes it is in "The Botany and Chemistry of Hallucinogens". When I get the time, I will have a look at it in the library.

Again thank you for your efforts.

Had now a look into the book "The Botany and Chemistry of Hallucinogens" from Hofmann and Schultes.

Unfortunately they don't indicate any detail about the traditional preparation in it.

So I remain still wondering where these 30Mins soaking time originally come from.

If anybody by accident stumbles upon this, please report.

Excellent post entropymancer, this history is what you will find nowhere else, the detail is incredible, very good post, I used to write about morning glory but find this to well exceed anything I have researched or read for myself.