The invention of carbonated water is credited to Joseph Priestley, who discovered a method of infusing water with carbon dioxide by suspending a bowl of water over a beer vat at a brewery in Leeds. He published 'Directions for Impregnating Water with Fixed Air' in 1772. Later, J.J. Schweppe developed a process to manufacture carbonated mineral water in 1783, founding the Schweppes company. Soft drinks evolved when pharmacists began adding medicinal herbs and flavorings to carbonated water to create 'tonics.' The 'fizz' is caused by carbon dioxide being dissolved under pressure; when the bottle is opened, the pressure drops, and the gas comes out of the solution in the form of bubbles. This process is governed by Henry's Law of gas solubility.