英國學(xué)生科學(xué)讀本 Lesson 43 一塊粘土(1)
第43課 一塊粘土
Do you know where clay comes from? If you take a long walk near the town in which you live, you will very likely find some deep hole or pit in the ground from which men are digging out the stuff we call clay.
你知道粘土是從哪兒來的嗎?如果你在居住的城鎮(zhèn)附近走上一段很長的路，就很可能發(fā)現(xiàn)地上有一些深洞或者深坑，人們就是從這些洞里，把一種叫“粘土”的東西挖出來的。
Clay is found in thick beds or layers in the earth, and we may therefore call it a rock. We may also call it a mineral.
粘土在一些很厚的泥土層中可以找到，我們也可以管粘土叫“巖石”或者“礦物”。
Let us ask the men in the clay-pit to give us a lump of clay. Its colour will most likely be brown. Pure clay is white, but a little red iron-rust is often found mixed with it. As we press the clay between our fingers, we find that we can mould or knead it into any shape we please.
咱們朝挖粘土的人要一塊粘土吧。粘土的顏色大部分是棕色的。純粹的粘土是白色的，但經(jīng)常混有少量的紅色鐵銹。我們把粘土放在手指之間捻一下，發(fā)現(xiàn)可以把它“塑成”或者“捏成”任何我們想要的形狀。
Let us make the clay into a ball. Now let us try to play a game of cricket with our clay ball. We shall soon find that the clay ball will not bounce as the leather ball does.
咱們把粘土團(tuán)成一個(gè)球吧，用這個(gè)粘土球來玩玩板球!我們很快就會(huì)發(fā)現(xiàn)，粘土球不會(huì)像皮球那樣彈跳。
When we press a piece of clay out of shape, it does not spring back to its old shape again as a ball made of leather or of india-rubber does. We therefore say that clay is not elastic.
我們把一塊粘土捏得變形之后，粘土不會(huì)彈回原來的形狀，而皮子或者天然橡膠做的球，就可以彈回原來的形狀。所以我們說，粘土“沒有彈性”。
We shall next put our lump of clay in the oven, and let it dry for several hours. The dry clay will break into powder, if we drop it on the ground; so we say that dry clay is brittle.
然后，我們把那個(gè)粘土大塊，放進(jìn)爐子里，烤上幾個(gè)小時(shí)。干燥的粘土，一掉到地上就會(huì)碎成粉末。所以我們說，粘土很“脆”。
But let us put the dry clay into a saucer half full of water. Soon all the water will disappear, while the clay will become soft once more.
不過，咱們?cè)侔迅稍锏恼惩?，放進(jìn)盛了一半水的碟子里。用不了多久，所有的水就都不見了，而粘土又會(huì)變軟了。
