Children's story series about a chemistry set

Question

In elementary school in the US in the 1970's, our teacher read to us from a series of stories about a boy who receives a chemistry set from a mysterious old woman. She then gives him recipes to make concoctions that do fantastic things. (I don't remember any specifically, but have a vague recollection that they were similar to potions from the Harry Potter books - invisibility, shape changing, and the like.)

The only specific detail I (think I) remember was that one of the chemicals used in a recipe had a long, convoluted, and contrived name that our teacher had trouble reading aloud; it started with "bluborax". The old woman in the story admitted she couldn't handle the full name and just called it "blub".

I think the old woman had a large car; today I think of it as similar to Cruella DeVille's roadster from Disney's 101 Dalmatians.

The story lines were similar to others of the genre: the boy makes the concoction and uses it, gets into some kind of trouble as a result, and has to get out of it using his wits and the help of his companions.

Answer 1

This was "The ____ Trick" series by Scott Corbett. Kerby keeps meeting Mrs. Graymalkin and her Model T car in the park. Whenever he asked for her help, she would lay her finger on her nose for a moment, then tell him to take (made up example) "three drops from the third bottle from the right in the back row, and two drops from the fourth bottle from the left in the first row" mix it with water, then either drink it, brush it on something, pour it on something, etc. to get a magical effect.

The Trick Series by Scott Corbett at Goodreads.