书城教材教辅科学读本(英文原版)(套装1-6册)
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第98章 第二册(15)

"We cannot see the salt, sugar, and other things when they dissolve. The water looks quite clear. Itis a solution. This chalky water is as thick and white as ever. If we leave the glass to stand for a time, all the wet solid chalk will sink to the bottom, and the water will become clear, and may be poured off. But there will not be any chalk in it. All the chalk will be left at the bottom.

"If we dissolve a substance in water, we cannot pour away the water, and leave that substance at the bottom."SUMMARY

Things that dissolve are said to be soluble. When they dissolve they make a solution. If we dissolve a substance in water, we cannot pour away the water, and leave that substance at the bottom, as we can chalk. Chalk will not dissolve in water.

Lesson 07

Soluble Substances

"Come and help me, Will." said Fred. "I"ve got all ready, and I want to show Norah why some things dissolve in water.