Alchemical powders made from...?
Normal substances then when mixed in the proper amounts and stirred counterclockwise exactly 3.75 times, combine to make a magical potion of healing!
Alchemy being magic is a piece of weird cruft from the 3.5 update that needs the loving care of a captive bolt pistol.
From 2e PHB page 80: "Thus a wizard must check to see if he learns each new spell (according to his Intelligence-see Table 4). Furthermore, there is a limit to just how much of this strangeness-illogical mathematics, alchemical chemistry, structuralist linguistics-a wizards mind can comprehend" - Look! Alchemical Chemistry can cast spells...................which are magic!!
From 2e DMG page 84 using the practical method of magic item creation: "The practical method says that
magical item manufacture is somehow lied to common sense; the materials needed to make the item reflect the properties of the item being constructed and the steps required are fairly well-defined. For example, a potion of climbing might require the hair of a climbing creature such as a giant spider or the legs of a giant insect." - or in other words, non-magical things that make sense to become magical when mixed. Which alchemy accomplishes.
From the 2e DMG page 85: "Wizards must do more than acquire ingredients: They must also need a complete
alchemical laboratory. Potions are not something you can brew up over the kitchen stove." - Alchemy!
1e DMG page 116 under
Manufacture of Potions: "Potions may be made by any magic-user of 7th level or above,
if he or she enlists the aid of an alchemist." The wizard also needs the alchemical lab that 2e mentions.
So it was not 3.5 that brought alchemy into the magical fold. It was Gygax and 1e.