Flotating Raisins Toy

If you put raisins in 7-up they will go up and down in the glass untill all the carbonation wears off. When you first drop rainins in 7 up they will sink to the bottom. Then gradually, bubbles form on the surface of the raisin and get caught in the wrinkles and make it boyant until it is boyant enough to rise to the top of the 7- up. When it gets to the top of the 7-up. enough of the bubbles pop to sink it back down to the bottom again. Then the bubbles start to form again. If you put about 15 rainins in a glass of 7-up there will always be one or two on their way up or down at any one time.

Now for the stroke of genus. Encase the 7 up glass in plastic and have a little carbonator motor that constantly re- carbonates the 7 up. Now make some plastic raisins and put them in. Presto permanent-floating-raisins-in-7-up exhibit.