(_Eyrypharyx pelecanoides._)] An ingenious instrument has been invented to capture these flying objects of the air. It is called by the inventor, Doctor Miguel, the æroscope, and is really a net for animals invisible to the naked eye. Many objects are phosphorescent when struck, or when divided into thin laminæ. Some simple materials for such experiments are chlorate of potash, fluor-spar, feld-spar, sugar, etc. By placing any of these in a mortar, and grinding them in the dark, flashes of light will be seen, powdered sugar often making a striking display. A beautiful and effective exhibition can be produced by placing a small amount of phosphuret of calcium in water; decomposition follows, and phosphuretted gas is evolved. As the bubbles of gas rise and come in contact with the atmosphere, they seem to take fire. If in a dark room, luminous rings are seen rising, and they can be made to take various shapes by using a fan. A trick often performed by magicians is to hand around a marble, and then pretend to render it luminous by blowing upon it. This trick consists in having small balls at hand, of a material that can readily be rendered luminous by the application of heat. These substances can be easily made. A fine light is produced by taking,-- Barium sulphate (C P.) 32 parts Magnesium carbonate (C P.) 1 part Sulphur (C P.) 1 part Gum tragacanth q. s. This should be made into balls of a convenient size, dried at a moderate temperature, and kept in a crucible at a red heat for about an hour. Allow them to cool slowly, and then place in a glass-stoppered bottle before their heat has disappeared. When required for use, expose them to the sun or any strong light, and they will become luminous, and continue so for many hours. Another formula is:-- Strontium sulphate (C P.) 22 parts Sulphur (C P.) 1 part Gum tragacanth q. s. This should be heated as above described. A most interesting experiment is to make a selection of artificial flowers, and, having brushed them over with glue or mucilage, dust them with the powder from one of the balls made as described. If the flowers are exposed to the sun a short time, they will emit a phosphorescent light, each flower standing out in the darkness with extreme brilliancy,--a striking and remarkable spectacle. Canton’s phosphorus is easily made by calcining clean oyster-shells, until they are perfectly white, in a crucible. The clearer and finer portions should then be reduced to powder, and placed in layers with alternate layers of flowers of sulphur in a crucible. Cover, and heat to a dull redness for about half an hour, then allow to cool slowly.