S₁ : What soda-water is composed of you may see for yourself if you watch your glass as it stands on the table after you have slaked your first thirst. S₆ : 'Carbonic acid' is the old name for it, but it is more correct to name it, when it is out of the water, 'Carbon dioxide'. P: The liquid is plain water, as you will find out if you are too slow about drinking. Q: You will see that it is separating into two different things, a liquid and a gas. R: The gas is so heavy that you can fairly drink it from the glass, and it has, as you know, a tingle-tangle taste. S: The other is a heavy, sour and invisible gas that slips up through the water in little bubbles and collects in the empty half of the glass. The proper sequence should be: