Potions picture from Wizards of the Coast
In most games, potions are crafted by spellcasters and thus have the tinge of magic running through them. They often replicate the effects of spells and detect magic often reveals them as such.
In a rather popular OSR retroclone, Swords & Wizardry Core Rules, I noticed an interesting exception on pages 122-123:
I went through some other retro-clones (Adventure Conqueror King System, Astonishing Swordsmen & Sorcerers of Hyperborea, Dungeon Crawl Classics, Labyrinth Lord, Lamentations of the Flame Princess, Scarlet Heroes, and Spears of the Dawn to name a few) and noticed that while some of them allow non-spellcasting alchemists to independently create potions or with the assistance of a spellcaster, Swords & Wizardry is unique in its default description of potions being non-magical.Strange alchemical brews, in dusty, stoppered bottles, are to be found in many of the forgotten or forbidden places of the world. Time has often worn away any markings once left to identify the contents of these mysterious mixtures, if the alchemist ever chose to label them in the first place. The consequences of drinking the products of alchemy can be varied: some of these can produce wondrously useful effects, but others might be deadly poisons!In general, since potions are the product of alchemy rather than magic, they will neither be apparent to Detect Magic spells, nor easily identified without tasting and experimentation. If the Referee decides that alchemy instead manipulates magic, as opposed to fantastical but otherwise natural chemistry, then Detect Magic and Dispel Magic would work upon potions.Potions are usable by all character classes. Unless otherwise noted, potion effects have a duration of 1d6+6 full turns.
In Labyrinth Lord Revised Edition (page 122), potions are a joint effort between alchemists and spellcasters. In Spears of the Dawn (page 143), magic items are capable of being crafted by noncasters provided they meet skill prerequisites but are still imbued with the essence of ashe or spirits. In Adventurer Conqueror King System (page), alchemists can independently create potions, but the time and cost is doubled and they're pretty much stuck at the lowest level of power (equivalent to a 5th-level Magic-User).
Intrigued, I grabbed my copy of the Original D&D boxed set and looked through Books I and II (Men & Magic, Monsters & Treasure). I noticed that only magic-users could create potions, and there was no description stating exactly to what extent they were truly "magical." Are they the result of alchemy and natural law, otherworldly knowledge, or both?
All in all, I found this to be an interesting find. Potions are a rather unique affair in D&D Editions and retroclones, straddling the line being magic and weird science. I'm rather curious now as to the design process behind S&W potions. Perhaps Matt Finch was drawing upon more obscure material at the time, or decided to be different in regards to magic items.