Abstract: A gypsum mold having good water absorbing properties, which is suitable for cast molding pottery, can be prepared by stirring a mixture of hemihydrate gypsum cooled to -40.degree. to 5.degree. C. and water to form a slurry of gypsum in water having a temperature of -5.degree. to 10.degree. C., pouring it into a water-impermeable mold, maintaining it therein until the setting reaction thereof is completed and then releasing the set product from the mold.

Abstract: A mixture of vegetable oil, surfactant, and sometimes water is used to remove halogens from a mixture. The vegetable oil-surfactant mixture is contacted with the halogen containing mixture whereupon the halogen is instantly and irreversably chemically bonded to the vegetable oil mixture. The vegetable oil mixture is then removed by an appropriate method. The method can be used for solid, liquid, or gaseous mixtures containing halogens, but is especially useful for treating gasses. Vegetable oils used include soybean, corn, sunflower, safflower, and linseed oils. Surfactants used include various soaps, detergents and their commercial mixtures.