英國(guó)學(xué)生科學(xué)讀本 Lesson 35 蒸汽往上冒(1)

所屬教程:英國(guó)學(xué)生科學(xué)讀本

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2020年02月20日

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Lesson 35 Getting up Steam

第35課蒸汽往上冒!

Do you want to know what steam is? Let us get a lump of ice, or a snow-ball, and place it in a saucer in a warm room. It soon melts, and then the saucer is half full of water. If we leave the saucer in the warm room for a few hours, we shall find that it has become quite empty.

小朋友，你想知道蒸汽是什么東西嗎?咱們拿一塊冰或者一個(gè)雪球，放在一個(gè)碟子里，放到溫暖的房間里。冰雪很快就會(huì)熔化，碟子里會(huì)盛上半碟子水。要是把碟子留在溫暖的房間里幾個(gè)小時(shí)，里面就會(huì)空了。

The ice or snow was solid water. The heat changed it into liquid water, such as we drink. And then, by more heat, the liquid water was changed into water-vapour, which mixed with the air and was lost to our sight.

冰和雪都是“固態(tài)”水。熱量讓固態(tài)水變成了“液態(tài)”水，就是我們喝的水。然后，如果再加熱，液態(tài)水就會(huì)變成“水蒸氣”，水蒸氣和空氣混在一起，我們就看不見(jiàn)了。

This shows that water can exist in three forms—first, as the solid we call ice or snow; second, as the liquid water we drink; and third, as the gas we call water-vapour.

這說(shuō)明，水的存在形態(tài)有三種——第一種，我們叫做冰雪的“固態(tài)”;第二種，我們喝的“液態(tài)”;第三種，我們叫水蒸氣的“氣態(tài)”。

If we put the liquid water into a little sauce-pan on the fire, the heat of the fire will change it into vapour in a few minutes. Vapour made by the boiling of water is called steam.

要是我們把液態(tài)水倒進(jìn)湯鍋，放在火上煮，火焰的熱量，只要幾分鐘，就能把液態(tài)水變成水蒸氣。水開了散發(fā)出來(lái)的水蒸氣，就是三點(diǎn)水的“蒸汽”。

Now hold a tea-spoon, or something cold, in the steam as it rises. In a moment the spoon will be covered with little beads of water. The cold spoon has turned the steam back into water. Heat turns water into steam; cold turns steam into water again.

拿一把茶匙或者別的冷東西，放在往上冒的蒸汽里面。馬上，茶匙就會(huì)蓋上一層小水珠。冷的茶匙又把蒸汽變回了水。熱可以把水變成蒸汽，冷又能把蒸汽變回水。

Suppose we were to put some water into a kettle, and then close up its spout, fasten down its lid, and put it over a hot fire, what do you think would happen?

假如，我們把水倒進(jìn)水壺，堵住壺嘴，封死了壺蓋，再放在火上燒，會(huì)發(fā)生什么事?