Questions and Exercises.
1. Boil some river-water in a flat dish until all the water is gone. Do the same with some sea-water, or, if this is not at hand, make some brine. Examine the two dishes, and tell what you see. 2. Take a glass gas chimney, and tie a piece of bladder, or parchment, over one end of it. Half fill it with sugar and water. Now place it with its tied-up end bottommost in a tumbler of clear cold water. After an hour or so taste the water in the tumbler. What have you to say about it? 3. What takes place when brine and clear water are separated from one another by a piece of skin (parchment)?
A Box of Mustard Seeds.