Ammonium Sulphate: Gas Liquor through a Coffey Still into a Lead Saturator (London works, Lunge 1887)

Sulphate of ammonia as a London works made it from 100,000 gallons of gas liquor a day: the liquor is settled, its volatile ammonia driven out by steam in a lead-lined Coffey still into a lead saturator of dilute sulphuric acid, and the saturated solution boiled down in lead pans until the salt crystallises. The acid is diluted on purpose so that no salt crystallises inside the saturator. Lunge prefers this batch saturation to continuous acid feeding because the salt is better. Source: G. Lunge, Coal-Tar and Ammonia (1887), pp. 621-623 and Fig. 154. Picture: Fig. 154.