The Prince of the Gelatin Isles

This storybook/cookbooklet was one of four commissioned by the Royal Baking Powder Company to promote their products to children, mailed free to homes on request. footnote footnote The other titles, which include The Comical Adventures of Captain Cooky and The Little Gingerbread Man, were centered around Royal Baking Powder, but The Prince of the Gelatin Isles highlighted the company's new gelatin dessert powder, introduced only a few years prior. (See a box in the collection here.)

The Prince of the Gelatin Isles is set in a fantastical world where gleeful, quivering creatures called "Gela-tinies" float on a custard sea in aluminum mould sailboats, and live in castles made of shining gelatin. The Prince tasks his fleet with delivering gelatin desserts to boys and girls around the world, but frets that he doesn't have the resources to reach every child in the world. He consults with a wizard, who encapsulates the magic of the Gelatin Isles into Royal Fruit-Flavored Gelatin powder, so "mothers can make it too!" 

Interspersed in this story are various gelatin recipes, along with fanciful illustrations widely attributed to Gertrude Alice Kay. The book is uncredited, but was written by Ruth Plumly Thompson, a children's author who is best known for continuing the Wizard of Oz series after the original author's death in 1919.