How do you tell the difference between fixed air and dephlogisticated air?

Fixed air, known as carbon dioxide, is a gas that does not support combustion and can be absorbed by water, forming carbonic acid. In contrast, dephlogisticated air, which is oxygen, supports combustion and is necessary for fire to burn. To differentiate between them, you can perform a simple test: bubbling fixed air through lime water will turn it milky due to calcium carbonate formation, while dephlogisticated air will reignite a glowing splint. These reactions clearly demonstrate their distinct chemical properties.