"If you boiled the water," said Norah, "it would all pass away as steam, and the salt would be left behind.""Do you remember," Fred asked again, "that we once filled a tumbler with water to the brim, and then put in salt, a spoonful at a time?""Oh yes," said Norah, "and I thought you were so clever. I could not make out how you were able to put all that salt in without spilling any of the water." "But you know now, Norah, don"t you?" askedWill.
"Yes," said Norah, "you told me all about it. The water is porous and absorbs the tiny little particles of salt into its pores.""That"s right," said Fred. "The tiny dissolved particles, after being broken up and scattered in all directions, fill up the pores in the water. When the pores are all filled the water can hold no more, and the rest of the salt falls in a solid wet mass to the bottom. Remember that water absorbs air and gases in the same way by sucking them up into its pores."SUMMARY