Tonic water and soda water may look the same, but the two drinks are actually quite different. Tonic water contains quinine, which is an all-natural crystalline alkaloid. Quinine has many medicinal properties including analgesic and anti-inflammatory effects. Club soda, or soda water, generally has sodium bicarbonate and potassium sulfate added to it, though these ingredients do not have any medicinal benefits.
Originally, tonic water was given to people who were suffering from malaria. The addition of quinine to regular water proved to be an effective tonic for sick people -- hence, the name tonic water. The malaria remedy was eventually brought from South Asia and Africa to British colonial India where the British population took to mixing the tonic with gin in order to dilute the tonic's strong taste.
The tonic water that was once used to cure malaria is slightly different from what can be purchased today. When it was first concocted, this type of tonic was particularly bitter due to the excessive amounts of quinine. Today, sugar is often added to this type of water, and the amount of quinine has been greatly reduced. More often than not, those who enjoy tonic water enjoy it for its distinctive taste.
Soda water was developed in 1767 by Joseph Priestley. Priestley devised the concoction when he noted that carbon dioxide could effectively be added to water in order to create carbonation. During the earlier part of the 20th century, affluent people often had soda water siphons inside of their homes. These siphons could instantly create carbonated water, which was often served on its own or with strong alcohol such as scotch.
Both tonic and soda water revolutionized the way that people drank alcohol. Prior to the invention of these beverages, alcohol was considered too strong to drink in polite company. When tonic and soda water were introduced, people were able to mix harsh alcoholic drinks with the water of their choice. The result was an increased amount of alcohol consumption.
While the difference between the tonic and soda water is apparent, the two are often, mistakenly, used interchangeably. Tonic is best combined with gin, since it is a natural compliment to gin's piney taste. Soda water is at its best when it is used to dilute strong drinks, since it would immediately overpower the subtle taste of lighter alcoholic beverages. Both tonic and soda water have an interesting history, but they are only tempting to one's tastebuds if they are used correctly.