书城教材教辅科学读本(英文原版)(套装1-6册)
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第110章 第二册(27)

"We will stand it down for a minute or two and let it rest.

"Look at the bottle now. The watery part of the mixture is at the bottom, a new substance is floating on the top. This is not oil, but oil dissolved in soda.

"Let us take some of it out and rub it in our hands. It is not greasy or oily now. It is soft and smooth.""It feels just like soap," said Norah, as she rubbed her hands.

"So it does," said Fred; "and it is soap, although it is not hard soap fit for use. It contains a great deal of water.

"How could we get rid of the water in it, Norah?" "I suppose," said Norah, "we should have to boilit."

"Quite right," said both the boys. "When the water boils away, the soap becomes solid. And now, Norah, you know how soap is made.""It is not always made of oil," added Fred. "Tallow, suet, fat, and grease of all kinds are used to make soap."SUMMARY

Soda dissolves tallow, suet, fat, oil, and grease of all kinds, and makes soap.

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