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When the sheets are very thin, they are called lead-foil. A great deal of lead-foil is used in China, to line the chests in which tea is sent to Europe.
特别薄的薄片儿就叫做“铅箔”, 中国就是用大量的铅箔来垫在茶叶箱里, 做成“铅衬里”, 把茶叶运到欧洲的。
Lead is much used for making water-pipes, and for lining water-systems. If the water which runs through the pipes is very soft and pure, it may dissolve a little of the lead, and make the water poisonous.
制造水管、蓄水池的衬里, 都要用很多铅。如果流过管子的水很软, 很纯, 就会把少量铅溶解掉, 让水带有毒性。
But the water which comes to our houses is almost always hard water. Now hard water soon forms a white crust on the inside of the pipe, and this crust keeps the water from touching the lead.
但是流到我们屋子里的水, 差不多总是硬水。硬水在管子内壁很快就会形成一层白色的水垢, 水垢就不会让水接触到铅了。
Lead is very heavy; it is much heavier than iron or copper. It is an easy metal to melt. Put some bits of sheet-lead in an iron spoon, and place the spoon on a clear fire. Soon the lead melts. Do you see the crust of dross or lead-rust on the surface?
铅非常沉重, 比铁或铜要重得多。铅很容易熔化。把一些碎铅皮放在铁勺子里, 把铁勺子放在明火旁边, 铅很快就会熔化。铅皮表面那一层渣滓的硬膜——也就是铅锈, 你看到了吗?
Skim this off with a bit of dry wood, and pour the melted metal slowly into a pail of cold water from a heightof two or three feet. The water cools the lead at once, and the metal becomes solid again. Some of the little pieces of solid lead which you will find in the pail will very likely have most curious shapes.
用干木头片儿把铅锈刮下来, 把熔化的铅, 从两三英尺的高度, 慢慢倒进一桶水中。水马上就把铅冷却了, 这种金属又会变回固态。在桶里找到的一些固态铅的小块, 很可能是奇形怪状的。
