LUMINOUS SHOWERS. 155 



at the San Bernardino Pass in California. Quartz is pol- 

 ished, and hard gems left weathered out ; while at Cape Cod 

 ordinary sand has been known to wear holes through glass 

 windows by continually blowing against them. 



An ingenious instrument has been invented to capture 

 these flying objects of the air. It is called by the inventor, 

 Doctor Miguel, the seroscope, and is really a net for animals 

 invisible to the naked eye. 



Many objects are phosphorescent when struck, or when 

 divided into thin laminaB. 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 grind- 

 ing 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 bub- 

 bles 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 lumin- 

 ous 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. 



