lime-water turned white and milky- looking.""It did," said Fred, "and that proved the gas to be carbonic acid. "He next plunged a burning taper into one of the other jars,and it went out instantly. Then he put a piece of lighted candle in the bottom of an empty jar (I mean a jar containing nothing but air). We could not think what was coming next, but he took theother jar of carbonic acid gas, and poured it, as you would pour water, on the burning candle.
"The gas at once put out the light. Carbonic acid always does this. We now knew from the lime-water and the burning candle that the gas was carbonic acid.""But teacher made this gas in two other ways." said Willie. "He put a piece of burning candle in a bottle and closed the mouth. The candle burned for a little while, and then died out. When he tried the lime-water test, the gas in the bottle proved to be carbonic acid.