In the modified Solvay process developed by Chinese chemist Hou Debang in 1930s, the first few steps are the same as the Solvay process. However, the CaCl2 is supplanted by ammonium chloride (NH4Cl). Instead of treating the remaining solution with lime, carbon dioxide and ammonia are pumped into the solution, then sodium chloride is added until the solution saturates at 40 °C. Next, the solution is cooled to 10 °C. Ammonium chloride precipitates and is removed by filtration, and the solution is recycled to produce more sodium carbonate. Hou's process eliminates the production of calcium chloride. The byproduct ammonium chloride can be refined, used as a fertilizer and may have greater commercial value than CaCl2, thus reducing the extent of waste beds.