IN CHEMISTRY. 



Common phosphorus. 



i. Specific gravity 1.83. 

 a. Burns at iu. 



3. Odor of garlic. 



4. Soluble in CS 2 . 



5. Colorless,, or straw-yellow. 



6. A deadly poison. 



Amorphous phosphorus. 



1. Specific gravity 2.14. 



2. Burns at 500'. 



3. Odorless. 



4. Insoluble in CS a . 



5. Red often rivalling vermilion. 



6. Harmless. 



19. What causes the difference between fine and coarse 

 salt? 



(See Chemistry, page 132.) 



The rapidity of evaporation in the process of manu- 

 facture. 



20. Why do the figures in a glass paper-weight look larger 

 when seen from the top than from the bottom ? 



The form of the glass acts like a convex lens to mag- 

 nify the apparent size of the figures. 



21. What is the difference between water-slacked and air- 

 slacked lime ? 



The former is simply calcium hydrate, CaO, H 2 O, while 

 the latter is hydratecl calcium carbonate, CaO, CO 2 , 

 H 8 (?). 



22. Why do oyster-shells on the grate of a coal- stove pre- 

 vent the formation of clinkets ? 



The lime of the shells acts as a flux with the iron in 

 the coal, thus dissolving the clinkers, if any form. 



23. How is lime-water madej/om oyster-shells ? 



The shells are burned, driving off the CO 3 combined 

 with the CaO in the CaCO 3 , and the lime thus formed is 

 slightly soluble in water. 



