"You remember," said Fred, "our talk about the glass of sparkling spring water. Does that spring water contain any substance in solution?""Yes, it has lime dissolved in it," said Norah. "We cannot see the lime, but we can find it as a thick coating round the sides of the kettle, in which the water is boiled. We call it "fur"; and we say that the kettle is getting "furred."
"Oh," Norah continued, "I remember, too, about the brine springs which supply us with salt for the table. The water of these springs fell at first as rain, and as it sank through the earth it dissolved the salt that was there, and carried it away in solution.""Then, again," said Will, "the sea is salt too, and it gets its salt in the same way.
"Teacher says the sea is fed with water by the rivers, which are constantly flowing into it; but the water of all these rivers is fresh, not salt water. It fell in rain from the clouds. It got its salt by dissolving it out of the substance of the earth itself."SUMMARY
