In the (rather sober) appendix to Naked Lunch, Burroughs refers to a substance called LSD6.
Albert Hoffman’s problem child is, in fact, LSD-25. But had it ever been identified as LSD6 at any point? Or is the sixth lysergic acid derivative also psychoactive?
Or was Burroughs still lost in space, and the appendix only appeared to be well informed?
Web searching didn’t help… exclude all references to Burroughs or Naked Lunch, and what’s left is irrelevant…
there is only one form of lsd.
LSD-6 is the USS Lindenwald 
Albert Hoffman in 1938 was attempting to synthesize a compound based on ergot that would induce muscle contractions, to induce labor, since ergot was known to do that (but ergot by itself wasn’t very safe; Hoffman was trying to isolate a safe compound that would do the trick). He made up a number of batches, but somehow they didn’t seem like they were what he was looking for. He shelved the stuff.
Five years later, he started having dreams about this compound. His curiosity reawakened, he got out batch #25 of lysergic acid diethylamide and had another look at it. He must have absorbed some through his skin, because he noticed it doing odd things to his visual field. Then to investigate further he deliberately ingested what he thought was a minor dose of 500 micrograms, which was in fact a whopping big dose of LSD, although he couldn’t have known that at first. Then he pedaled away on that legendary bicycle trip into a new world…
So that’s why it was called LSD-25. Hoffman made his epochal discovery with the 25th batch of his experimental compound.
Burroughs in his Naked Lunch appendix wrote an article listing the addictiveness of pretty well every drug known to man, based on his experience. (He used as a running title, “The British Journal of Addiction, Vol. 53, No. 2”— was this facetious? Have I been whooshed?). In a footnote, he wrote
I found this in my copy of Naked Lunch with a copyright date of 1959. So… is there really such a publication as the British Journal of Addiction? Yes. There is such a title in the Library of Congress Database, so Burroughs didn’t just make up the title. Vol. 44 was dated 1947, so Vol. 53 would have been in 1956. Did Burroughs really publish this article as he claimed? He presented it as a letter sent to a doctor to fill him in on addictive properties, dated August 1956. This letter has been reproduced on countless web sites, but without looking up the actual back issue of the journal from 1956, I can’t verify Burroughs isn’t pulling our leg. But it does look genuine.
I looked up Albert Hofmann’s story in his own words: LSD, My Problem Child, Chapter 1.
I was mistaken above on one detail: Hoffmann’s whopping big experimental dose was a mere 250 micrograms. Now, he knew that he had a highly potent substance there, and was being deliberately cautious and prudent to start out with a miniscule dose, which he measured out very carefully. But even an expert chemist like Hoffmann could not have anticipated just how potent it really was. His supervisor couldn’t believe the report—until he tried LSD himself and was flabbergasted.
As for LSD-6, all I found with Google was an interview with Ken Kesey in which he mentioned the CIA mind-control experiments that first turned him on to LSD as a human guinea pig. Sinister, eh? Kesey named LSD-25 and LSD-6 as the drugs used in the CIA experiments.
I still haven’t answered the OP question of where this “LSD-6” name came from. It might mean the sixth in the series of lysergic acid derivatives prepared at the Sandoz lab in 1938, but I doubt that. Hofmann only reported on LSD-25. Going by the references from Burroughs and Kesey, LSD-6 was a name connected with those Army and CIA mind control experiments. It isn’t mentioned outside those contexts. Hofmann’s book does not mention the sinister American government experiments. It does have a chapter on the interesting study by serious psychologists like Dr. Stanislav Grof done quietly in the 1950s before Timothy Leary blew the whole thing up into a media circus which got it outlawed. But the only chemical name Hofmann uses in his book is LSD-5. No 6.
In the Poetic Irony department, I find it interesting that Hofmann was looking for a drug to induce labor. And so, indeed, he turned out to be the midwife at a very extraordinary birth. He called LSD his “child” in recognition of his maieutic function, one that Socrates may not have dreamed of.
The first time Hoffman took lsd it was actually 2.5 MG so 2500 micrograms and he rode his bike home!
Do you have a cite for 2500 micrograms?
All of Hoffmann’s test batches were derivatives of lysergic acid. AFAIK, no special use was found for any of them, and we don’t know what compounds were in the other batches. They were shelved for years until Hoffmann got an unexplained urge to go back and re-test batch #25. He determined that it was highly psychoactive, and the active component was LSD.
The other batches may have contained psychoactive analogs, or there may have been nothing interesting at all. You’d think after his serendipitous result with LSD-25, Hoffmann might have been curious enough to re-test the other supposedly useless batches, but I’ve never seen any information published to that effect. Hoffmann continued synthesizing lysergic acid derivatives for some time after that, which makes me think there really was nothing else of interest in the original 1938 series.