Many bottlers of carbonated beverages, instead of using merely the compressed carbonic gas, employ in its stead liquefied carbonic acid. This is obtained as follows: The carbonic acid is derived chiefly by the burning of coke and absorbing the gas in a cold alkaline solution. The gas is then driven out by heat. It is washed, passed through a permanganate of potash solution and charcoal, and then reduced by cold and pressure to a liquid state. It is sold at about five cents per pound, and has been found to be very pure and much cheaper than it can be made on a small scale by the bottler.

1 Mineral Waters. American Medical Association, 535 North Dearborn Street Chicago.