SODA-WATER, strange to say, contains no soda at all in any form. As made at present, it is simply a solution of carbonic acid in water of the ordinary purity. It is true that a small proportion of the bicarbonate of soda is sometimes added, but no satisfactory reason is assigned for the practice, and it is believed to be a rare exception to the general rule.

Our readers who have not cared to remember much of their chemistry may need to be reminded that carbonic acid is, at ordinary temperatures and pressures, a colorless gas of slightly pungent…