urldownloadtofile

or pinholing. A reducing fire helps to cure this fault, as sulphur dioxide more easily escapes than the trioxide. The Berlin porcelain works formerly introduced their calcium as gypsum with some success, owing to the reducing fire employed. The best way to avoid body losses is by a slow and regular burning of the kiln, especially on the up-fire, with regard to evolution of gas, and on the down fire for loss by thermal contraction. CERAMIC CHEMISTRY. 75 CHAPTER XL INDUSTRIAL DISEASE. Allied to the^expense caused by loss in manufacture is that arising out of industrial disease. Potters are peculiarly liable to two forms of disease, lead poisoning and lung troubles, caused through the inhalation of dust and flint, clay and other raw materials. Of these, lead poisoning is the more notorious, but its prevalence not nearly so great. Taking the actual number of excess deaths of potters over other artisans in North Staffordshire, between thirty and forty die annually from lung diseases to one from plumbism ; and, taking the rate per 1,000 exposed to risk, the former are eight times more fatal than the latter. Obviously, the only cure for lung disease is the prevention of dust by installation of exhaust fans and provision of respirators to workpeople. The elimination of plumbism is more difficult. Lead