Henry
Autoexreginated
paranoid said:These are the jokes I don't get:
First of all, Google is your Friend.

Antipathy - A lump of alum soaked in vinegar
Alum, especially combined with vinegar is not only an astringent, it smells and tastes horrible, and would drive away more sane people, even without the spell.
Darkvision - Either a pinch of dried carrot [Vitamin A?] or an agate
Agate is considered a stone that aids in improving vision; in fact, some varieties of Agate were given in Native American tribes in the past to newborns in the hope that that child would be the next "seer."
Disintegrate - A lodestone and a pinch of dust
Lodestones attract power or favor; the only relation I can see is to empower turning the enemy to dust?
Enlarge / Reduce Person - A pinch of powdered iron
The old folk wisdom that more iron in your blood makes young children grow stronger and taller
False Life - A small amount of alcohol or distilled spirits, which you use to trace certain sigils on your body during casting
couldn't find this one; the only thing I can see is that alcohol naturally makes you more resistant to pain?
Foresight - A hummingbird’s feather
Hummingbirds are known for their quick, agile movements in flight.
Ghost Sound - A bit of wool or a small lump of wax
Same as the "Pull the wool over your eyes" analogy; the ear wax is the same idea.
Haste - A shaving of licorice root
Licorice Root is purported to stimulate adrenal glad activity; it's apparently a homeopathic version of "uppers."

Illusory Script - A lead-based ink
"Cinnabar, or minium, the pigment obtained from red lead, was once used for the striking red lettering and decoration often to be found in the opening words of the text of a manuscript and in the page decoration." (quote)
Invisibility - An eyelash encased in a bit of gum arabic
gum arabic was used for applying stage makeup and prosthetics long ago; covering an eyelash represents clouding vision.
Legend Lore - Four strips of ivory (worth 50 gp each) formed into a rectangle
Ivory strip cards were used in divination in Chinese culture; I think the "formed in a rectangle is artistic license.
Levitate - Either a small leather loop or a piece of golden wire bent into a cup shape with a long shank on one end
Ever seen an egg holder used for dipping easter eggs?
Magic Weapon, Greater - Powdered lime and carbon
my supposition is that it is sympathetic to "reforging" the weapon into something stronger.
Persistent Image (and other Image spells) - A bit of fleece and several grains of sand
The "fleece" bit has probably been sufficiently explained.
Repulsion - A pair of small iron bars attached to two small canine statuettes, one black and one white
magnetic repulsion is the concept here - though why the dogs wouldn't be the same color, though, is beyond me. After all, opposites attract, as the saying goes.

Summon Monster - A tiny bag and a small (not necessarily lit) candle
From what I've been reading online, Charm bags and candles are used in all sorts of traditional "Magic rituals."
Incidentally, while I was looking, I found this fascinating tidbit:
The Egyptians were among the first to find it striking enough to use in places of importance or emphasis, such as text headings, and it has been used by scribes throughout history. The Latin name for this pigment, minium, gives rise to the term miniature. The person skilled in working with minium was called a miniator and the things he applied his craft to were called miniatures, whether they were tiny or not.