According to the material from which the containers are made, different methods must be adopted. It is necessary to give the liquid such form as to prevent its flowing out when the vessel is inverted; this is important, as the bottles are often carried in dress pockets and the ammonia destroys most colors. As a rule the vessels are filled with indifferent porous substances which are moistened with the perfume. If the container is made of box wood, ivory, porcelain, or some other opaque material, it is filled with fibres of asbestos or with very small pieces of sponge, and as much perfume is poured in as the substance can take up; the vessels are then inverted into a porcelain plate and allowed to drain, and are finally closed with a loose plug of cotton. If the container is transparent, it is better to use, instead of the asbestos or sponge which do not look neat, either small pieces of white pumice stone, powdered glass, small white glass beads, or crystals of sulphate of potassium which is insoluble in the perfume. WHITE SMELLING SALT (SEL BLANC PARFUMÉ). While the first-named ammoniacal preparation is called a salt, it is really nothing but perfumed caustic ammonia; but white smelling salt is what its name indicates and can be perfumed as desired by the consumer; but as only certain scents harmonize with ammonia, not every odor can be employed; the most appropriate are oils whose odor resembles that of rose, and the oils of nutmeg and cinnamon. Mix in a large porcelain jar— Carbonate of ammonia 2 lb. Caustic ammonia 1 lb. Cover the jar and leave it at rest. After some days the mixture will have changed into a firm mass of monocarbonate of ammonia which is rubbed to a coarse powder, perfumed, and filled into bottles. The above quantities require: Oil of bergamot 15 grains. Oil of lavender 15 grains. Oil of nutmeg 8 grains. Oil of clove 8 grains. Oil of rose 8 grains. Oil of cinnamon 75 grains. The oils are poured into a mortar and rubbed up with about one-tenth of the salt; of this perfumed salt enough is added to the several portions of the mass, and triturated until the odor is equally distributed. For cheaper smelling salts oils of geranium and cassia may be substituted for the oils of rose and cinnamon. PRESTON SALT (SEL VOLATIL). In this perfume ammonia is continually generated; the salt is prepared by mixing chloride of ammonium or sal-ammoniac in fine powder with freshly slaked lime. Fine or cheap perfume is added, according to the grade desired. The mixture of sal-ammoniac and slaked lime continually develops small amounts of ammonia—it takes a long time until the decomposition is complete, and for this reason a bottle filled with Preston salt retains the odor of ammonia for several years. EAU DE LUCE. This is the only ammoniacal perfume used in a liquid form. It is made according to the following formula: