A pair of children decide that their neighbor is a witch and convince her to try flying

Question

I believe I checked this out from our library in Kentucky somewhere between 1986 and 1995. I remember it as a short book, less than a hundred pages, maybe less than thirty. A pair of children (at least. There could have been more. And I don't remember if they were related to each other) decide that a lady in their neighborhood is a witch. When they confront her on it, they either convince her or she decides to play along. Either way, they convince her to try a flying ointment they got from a library book (it involved some sort of grease and soot). After an abortive attempt to launch herself from a roof, the "witch" proceeds to make short hops in the yard, broom astride, and claiming that she was jumping higher than she could before, implying that the ointment was doing something. I was recently reminded of the book when a friend was mentioning how some of the old "flying ointments" had psychoactive components, implying that the "flying" was a matter of skyclad witches standing astride dosed brooms and getting a contact high through their mucous membranes. Of course, this book, being a children's book, involved a fully clothed witch.

I believe the illustrations were done in a pen-and-ink manner. I remember there being one of the attempted flight.

I don't think that it was Jennifer, Hecate, Macbeth, William McKinley, and Me, Elizabeth despite a common theme of a flying ointment and witches, as I clearly remember the "witch" as an older female. Neither do I believe it to be The Active Enzyme, Lemon Freshened Junior High School Witch, which some reviews also note has a flying ointment, but also that it's all kids trying it out.

Answer 1

The Witch on the Corner by Felice Holman perhaps.

From the Bulletin of the Center for Children's Books:

Well, everyone said she was a witch. Her garden flourished when others failed, and one neighbor said she had seen the witch planting poison ivy. Then her parrot, hearing the children taunt her, called "Witch!" That did it; Miss Pinchon herself believed she was a witch. She just couldn't seem to get a broomstick that worked, alas, even when a small neighbor gave her a good push as a running start. After a series of failures, Miss Pinchon conceded that she had a magic touch only with flowers; by that time several of the neighborhood children (who had been trying to help her fly and to conjure up storms) had become friends. The story ends with three children being taken on as apprentice flower witches. The style is sprightly and humorous, but everything else about the story is gentle: the relationships, the message about acceptance, and the engaging naivete of the protagonist.

Answer 2

Ayshe has the correct answer, and I started editing quotes into their answer, until I realized that it was a larger amount than was already there, and some of it was my mea culpas of bits I'd mistaken, so posting my own answer as an addendum. Quotes sourced from the Internet Archive copy of the book.

First off, it was not the children encouraging her to try to be a witch, but rather her decision that she must be one after hearing enough people accuse her of being one.

Miss Pinchon began to add it all up, and slowly, very slowly, it dawned on her... the astounding, the terrible, and finally the marvelous truth. "I'm a witch!" she whispered aloud. "I'm a witch! But, of course! That explains everything!"

She bases most of her witching on library books she reads, including the flying spell.

And she saved for the last the thing that was really first in her mind - transvection, which seemed to be the word the books used to describe the flight of witches. She was delighted to find some really helpful hints, such as it was best to leave the house through the chimney and - no wonder she had failed at first - to rub the body first with a very special ointment.

When Miss Pinchon had finished her work in the library she felt quite pleased. "Considering I'm trying to cram all this in very fast, I think I have got the hang of it," she said to herself as she walked home briskly. "The first thing to do, of course, is to get that broom working."

I misremembered the soot being part of the ointment. Instead, it's a consequence of her going up the chimney.

... It was dark and airless, but along the side of the flue were steps of brick that enabled her to place her hands and feet in such a way that she could squeeze herself a bit farther into the chimney. After the enormous effort Miss Pinchon was so tired - not to mention sticky and sooty - that she wasn't at all sure that she could go on.

....

"Oh dear," though Miss Pinchon, "I may be stuck here." And then an advantage of the flying ointment became apparent. An unannointed Miss Pinchon might have stayed in the chimney forever, unseen and unmissed - except by Gideon, of course. But a well-greased Miss Pinchon managed to slip and slide her way up the chimney.

....

"I might need a bit of a head start," she thought, so she started an even-paced trot around the garden, every once in a while making a small leap into the air, but earthbound she remained.

And it looks like I misremembered her feeling like she was hopping higher. Rather, the boy watching her claims he saw her flying, although he amends it to that he thought he saw her coming down.

Zigmund nodded, and then he said, "Well, I guess I saw you come down anyway. Maybe I didn't really see you in the air."

After a few more attempts, including a push start, attempting to get some height from an apple tree, and being suspended with kite string (the last seemingly having the string snap when the church bells ring, something that can end a witch's flight), Miss Pinchon decides she is not the flying sort of witch.