CHAPTER VIII.

100. Define specific gravity.

101. What is the most obvious way of ascertaining the specific gravities of different liquids? Explain the sinking of heavy substances in water. Explain the rising of light substances in water. Explain what is illustrated in Fig. 87.

102. Explain Fig. 88. Explain Fig. 89.

103. Give the illustrations in § 138: lifting a stone; raising a bucket; and raising the arm in a bath. Relate the anecdote of Archimedes. What is said of boats and life-boats? What of estimating the weight of the load in a canal-boat?

104. What is said of the specific gravity of birds? Of insects? Of fishes? What of the specific gravity of the human body, and of the prevention of drowning?

105. Give the reasons why so many are drowned that might easily be saved?

106. What is stated about children in China? Why does the body of a drowned person sink? Why does it after a while rise? What is said about wading in rivers?

107. Explain the manner in which the specific gravity of a solid may be ascertained? Give the experiment of weighing water. What is stated of Archimedes and the crown?

108. Describe and explain the hydrometer. Relate the anecdote of the Chinese. What is said of the selling of milk in Switzerland?

109. What is said of the centre of gravity in floating bodies? Give the illustrations.