The photo of this strange experiment was captured at the beginning of the 20th century. “Solid air” is not a unique chemical, but a piece of ice and this is really obvious for modern people. But for the scientists at the beginning of the 20th century, the studies had only just started. The person in the photo probably decided to check and see if the piece of ice would break or turn into a mixture of gases and evaporate. An experiment is a great way to check.