78. Q. What are two of the most important sources of borax? A. Borax Lake, in California, and the borax lagos in Tuscany.
79. Q. What element constitutes about eighty per cent. of our atmospheric air? A. Nitrogen.
80. Q. As a simple and uncombined substance, by what is nitrogen characterized? A. By extreme inactivity. It does not burn; it does not support combustion; it can not be made to enter into chemical union with other substances, except by specially devised and circuitous processes.
81. Q. Of what is nitrogen a constituent? A. Of a very large number of compounds, which are themselves often characterized by a high degree of activity.
82. Q. What are two important compounds of nitrogen? A. Ammonia gas and nitric acid.
83. Q. In addition to oxygen and nitrogen what are some of the other substances always present in atmospheric air? A. Vapor of water, carbon di-oxide, and ammonia gas; minute quantities of a vast multitude of other gaseous substances; and it is likewise charged most of the time with still more minute quantities of solid dust materials of various kinds.
84. Q. To what do the principal explosives owe their activity to a very large degree? A. To the presence of nitrogen in them.
85. Q. What are the four explosives of chief importance? A. Gunpowder, the fulminates, gun cotton, and nitro-glycerine.
86. Q. What are the three principal constituents of gunpowder? A. Potassic nitrate, charcoal, and sulphur.
87. Q. Why is phosphorus a most interesting chemical element? A. Because of its exceptional chemical properties, the very important part it plays in the chemistry of animal and vegetable life, and its employment in the friction match.