In industrial practice, the reaction is carried out by passing concentrated brine (salt water) through two towers. In the first, ammonia bubbles up through the brine and is absorbed by it. In the second, carbon dioxide bubbles up through the ammoniated brine, and sodium bicarbonate (baking soda) precipitates out of the solution. Note that, in a basic solution, NaHCO3 is less water-soluble than sodium chloride. The ammonia (NH3) buffers the solution at a basic (high) pH; without the ammonia, a hydrochloric acid byproduct would render the solution acidic, and arrest the precipitation. Here, NH4 along with ammoniacal brine acts as a "mother liquor".