Today I learned that buoyant inflatable balloons have been around a lot longer than I thought.
“The first rubber balloons were made by Professor Michael Faraday in 1824 […] Latex rubber toy balloons were introduced by pioneer rubber manufacturer Thomas Hancock the following year in the form of a do-it-yourself kit consisting of a bottle of rubber solution and a condensing syringe. Vulcanized toy balloons, which unlike the earlier kind were unaffected by changes in temperature, were first manufactured by J.G. Ingram of London in 1847 and can be regarded as the prototype of modern toy balloons.”