楚天指数，大涨长红!

kiwi-rr · 发表于 2007-8-22 23:28

黄秋生居然是中英混血，看不出来

猪哼哼 · 发表于 2007-8-22 23:29

口口番 · 发表于 2007-8-23 06:44

$支持$ $支持$ $支持$

stubor · 发表于 2007-8-23 08:42

Mattel, the world's biggest toy maker, has recalled millions of toys that were coated with lead paint. Lead's poisonous properties have been known for thousands of years, so why was lead ever added to paint, and why is lead paint still being made?

dascarol · 发表于 2007-8-23 09:54

$高$ $高$ $高$

stubor · 发表于 2007-8-23 11:23

What is 'lead paint'?

Any paint that relies on lead compounds for its colour. White lead, or lead(II) carbonate (PbCO3), is a typical example, and was once widely used to paint wooden surfaces in homes. Other lead compounds, like vivid yellow lead chromate (PbCrO4), were used as coloured pigments. As well as giving the paint its tint, lead pigments are highly opaque, so that a relatively small amount of the compound can cover a large area. White lead is very insoluble in water, making the paint highly water-resistant with a durable, washable finish.

Lead carbonate can also neutralise the acidic decomposition products of some of the oils that make up the paint, so the coating stays tough, yet flexible and crack-resistant, for longer.

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楚天指数，大涨长红!