Carbonated water, also known as sparkling water, fizzy water, soda water, club soda, seltzer water,or pop water is plain water into which carbon dioxide gas has been dissolved. The process of dissolving carbon dioxide gas is called carbonation. It results in the formation of carbonic acid (which has the chemical formula H2CO3).
In the past, soda water was produced in the home by "charging" a refillable seltzer bottle by filling it with water and then adding carbon dioxide. Club soda may be identical to plain carbonated water or it may contain a small amount of table salt, sodium citrate, sodium bicarbonate, potassium bicarbonate, potassium sulfate, or disodium phosphate, depending on the bottler. These additives are included to emulate the slightly salty taste of homemade soda water. In the UK Soda Water is nearly always made with Sodium Bicarbonate. The process can also occur naturally to produce carbonated mineral water, such as in Mihalkovo in the Bulgarian Rhodopes.
Joseph Priestley first discovered a method of impregnating water with carbon dioxide when he suspended a bowl of water above a beer vat at a local Leeds, England brewery. The air blanketing the fermenting beer—called 'fixed air'—was known to kill mice suspended in it. Priestley found water thus treated had a pleasant taste and he offered it to friends as a refreshing drink. In 1772 Priestley published a paper entitled Impregnating Water with Fixed Air in which he describes dripping oil of vitriol (or sulfuric acid as it is now called) onto chalk to produce carbon dioxide gas, and encouraging the gas to dissolve into an agitated bowl of water.
In 1771 Swedish chemistry professor Torbern Bergman independently invented a similar process to make carbonated water. In poor health at the time yet frugal, he was trying to reproduce naturally-effervescent spring waters thought at the time to be beneficial to health.
Today, carbonated water is made by passing pressurized carbon dioxide through water. The pressure increases the solubility and allows more carbon dioxide to dissolve than would be possible under standard atmospheric pressure. When the bottle is opened, the pressure is released, allowing the gas to come out of the solution, thus forming the characteristic bubbles.
Carbonated water was commonly known by the name of soda water until World War II. In the 1950's new terms such as sparkling water and seltzer water began to be used. The term seltzer water is a genericized trademark that comes from the German brand Selters, which is produced and bottled in Nieder-Selters, Germany. 
Flavored carbonated water is also commercially available. It differs from sodas in that it contains flavors (usually fruit flavors such as lemon, lime, orange, or raspberry) but no sugar.
Sparkling mineral waters show slightly greater tooth enamel dissolution potential than still waters, but levels remain low and are of the order of one hundred times less than soft drinks. De-gassing of a sparkling mineral water reduces its dissolution, but the total levels are still relatively low, suggesting that carbonation of drinks may not be an important factor per se in respect of erosive potential. (PMID 11556958)
Intake of carbonated beverages has been associated with increased bone fracture risk in observational studies, but the net effect of carbonated beverage constituents on calcium economy of the body is negligible. Thus, the skeletal effects of carbonated beverage consumption are likely due primarily to milk displacement (drinking club soda and thus drinking less milk). (PMID 11522558)
|Wikimedia Commons has media related to Mineral waters.|
- The Priestley Society
- Priestley's paper Impregnating Water with Fixed Air 1772
- Interview with one of New York City's last seltzer delivery men
- Carbonating at Home