英语听力文摘 English Digest 324、可乐的神奇清洁能力

　　The Cleaning Power of Soft Drinks!
饮料的神奇清洁能力
Let’s begin with a cleaning tip: If you have some tarnished² or corroded³ brass⁴ that you want to clean, an old brass candlestick for example, you can use Coca-Cola, or any other cola soft drink, and that brass will come clean.
How Does This Work?
And if Cola is such an effective cleaner of corroded metal , what is it doing to the inside of your stomach?
Cola cleans brass because it’s mildly acidic.
Here’s what happens: When brass or another metal alloy⁵ becomes tarnished, this means that there has been a chemical reaction between the oxygen in the air and one of the metals in the alloy.
Oxygen atoms combine with metal atoms to form what’s called an oxide⁶, and this oxide is what makes the metal appear tarnished. Acids, like the weak acid present in your can of Coke, can react with oxides to effectively reverse the process of tarnishing⁷. The acid dissolves the metal oxides that make the tarnish¹, leaving only shiny metal behind.

　　Try It At Home!
You can try this at home, even if you don’t have a brass candlestick. Leave a tarnished old penny in a glass of cola overnight. In the morning it will be shiny and fresh.
Your Stomach And Acid
If the acid in cola is so good at attacking tarnished metal, what might it do to your insides? Actually, your stomach already contains its own supply of acid which it uses to digest food.
This stomach acid is a great deal stronger than the acid in a can of Coke. Indeed, stomach acid would be an even better tarnish remover than cola!
有个去污点子：如果你想要清除铜锈，例如铜烛台，可以使用可口可乐或者其它可乐饮料，清洗后的烛台光亮如新。
饮料是如何清洁的呢?
如果可乐能有效清洁金属锈斑，那么可乐对人体的胃会产生什么影响呢？
可乐能清洁铜锈是因为可乐呈弱酸性。
铜或其它金属合金生锈是因为空气中的氧气和合金中的某种金属发生了化学反应。
氧原子结合了金属原子，形成所谓的氧化物。氧化物就是金属锈。而酸，比如可乐中的弱酸，和氧化物产生化学反应，能有效避免生锈。酸可以分解金属氧化物，化学反应后的金属锃亮。
在家试验
即便家里没有铜烛台，你可以做这样的试验：晚上，将一枚旧硬币丢进装有可乐的杯里。第二天早上，硬币就变得闪亮如新。
酸对人体胃的影响
如果可乐能有效清洁金属锈斑，那么可乐对人体的内脏会产生什么影响呢？事实上，人体的胃里就有分泌的酸液来消化食物。
胃酸的酸性比一听可乐还强。说真的，胃酸甚至比可乐更能除锈。

1 tarnish   

n.晦暗，污点；vt.使失去光泽；玷污

参考例句：

• The affair could tarnish the reputation of the prime minister.这一事件可能有损首相的名誉。
• Stainless steel products won't tarnish.不锈钢产品不会失去光泽。

2 tarnished   

（通常指金属）（使）失去光泽，（使）变灰暗( tarnish的过去式和过去分词 )； 玷污，败坏

参考例句：

• The mirrors had tarnished with age. 这些镜子因年深日久而照影不清楚。
• His bad behaviour has tarnished the good name of the school. 他行为不轨，败坏了学校的声誉。

3 corroded   

已被腐蚀的

参考例句：

• Rust has corroded the steel rails. 锈侵蚀了钢轨。
• Jealousy corroded his character. 嫉妒损伤了他的人格。

4 brass   

n.黄铜；黄铜器，铜管乐器

参考例句：

• Many of the workers play in the factory's brass band.许多工人都在工厂铜管乐队中演奏。
• Brass is formed by the fusion of copper and zinc.黄铜是通过铜和锌的熔合而成的。

5 alloy   

n.合金，(金属的)成色

参考例句：

• The company produces titanium alloy.该公司生产钛合金。
• Bronze is an alloy of copper and tin.青铜是铜和锡的合金。

6 oxide   

n.氧化物

参考例句：

• Oxide is usually seen in our daily life.在我们的日常生活中氧化物很常见。
• How can you get rid of this oxide coating?你们该怎样除去这些氧化皮？

7 tarnishing   

（印花）白地沾色

参考例句：

• The causes of tarnishing gold and silver-plated connectors were studied respectively. 分别探讨了接插件镀金和镀银层变色的原因。
• Bright tin electrodeposits on copper wire are susceptible to tarnishing. 铜线材经光亮镀锡后易产生腐蚀变色。