书城教材教辅科学读本(英文原版)(套装1-6册)
47723000000240

第240章 第三册(65)

"We have had a lesson today on a new substance, Norah," said Fred. "It is a metal, but it is not solid, like iron, copper, lead, or any of those which we have talked about before. It is a liquid.

"Teacher showed us some of it in a bottle. It flows about, and can be poured out like water. It is a liquid metal. It is the only liquid metal that exists. Its name is mercury.""I think I have some mercury in a bottle upstairs," said his father. "I will go and bring it down for you; only be very careful with it."Presently back father came with the bottle of mercury, and they were soon ready to start.

Fred poured some of it into a saucer, and pointed out its silvery white color and its bright metallic lustre.

"Teacher says mercury never tarnishes when it is exposed to the air, but always keeps its bright surface," said he.

"Now look what happens when I let fall a drop ofthe mercury on this slate. It breaks up at once into an immense number of tiny round drops. If I tilt the slate ever so slightly, the little drops run about rapidly over the slate.""Then I suppose that is the reason why it is sometimes called quicksilver," said Norah.

"Yes, you are quite right," said Fred.