NITROGEN AND ITS OXIDES. 



75 



form you can heat nitrate of lead in a glass retort and col- 

 lect the deep red fumes 

 in a tube surrounded 

 by a freezing mixture. 

 At a low temperature 

 the fumes condense to 

 a red liquid. The proc- 

 ess is represented in 

 Fig. 16. It also forms 

 in the gaseous state by 

 exposing nitric oxide Fitr 1(J 



to the oxygen of the 

 air. This does not form an acid on dissolving in water. 



QUESTIONS. 



66. Where does nitrogen occur in nature ? 66 a. How can it be obtained? 

 67. What are the properties of nitrogen? 68. WTiat are its relations to 

 life ? 69. How many and what are the compounds of nitrogen with oxy- 

 gen ? W r hat are the proportions of these elements in laughing-gas ? What 

 in nitric oxide ? 70. What is said of nitric anhydride ? What does it 

 form when dissolved in water ? 71. Describe the preparation of nitric acid. 

 72. What are its properties ? 73. Explain the action of nitric acid on met- 

 als. 74. What metal does not dissolve in nitric acid ? WTiy ? 75. What 

 are nitrates ? 76. Give an example of combustion produced by nitric acid. 

 77. What is said of the formation of nitric acid in the air ? 78. What is 

 the action of acids on blue vegetable solutions ? How do anhydrides form 

 acids ? 79. Explain the method of naming acids. What does the prefix 

 * ' hypo " mean ? How are bodies derived from acids by replacement of hydro- 

 gen named ? 80. W T hat are bases ? How do they act on reddened litmus ? 

 What is a salt ? What do nitric acid and potassium hydrate form by com- 

 bining ? What is a neutral salt ? W T hat an acid salt ? 81. How is nitrous 

 oxide prepared ? 82. WTiat are its properties ? 83. How is nitric oxide 

 obtained ? 84. What are the reddish fumes given off when copper is put 

 into nitric acid ? 85. What is said of the contrast between air and nitric 

 oxide ? What does this illustrate ? 86 and 87. What is nitrous anhydride ? 

 How does it occur in nitric acid ? 88. How is nitric peroxide obtained ? 



