书城教材教辅科学读本(英文原版)(套装1-6册)
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第115章 第二册(32)

"What else could we use besides gum to stick the leaves?""Some paste would do as well."

"Have you ever seen any one use paste to stick paper?" Fred asked again.

"Oh, yes," said Norah. "The man used paste when he put the paper on the wall of the parlor the other day.""And the men who post up the bills in the streets," said Willie, "always do it with paste.""But," said Norah, "you can stick paper with sealing wax. I have seen father melt the wax in the flame of the candle, and drop it on the paper. When it gets hard it sticks fast to the paper.""Now look at this postage stamp, Norah," said Fred. "How do we stick it on the letter?""We wet the back of the stamp," said Norah, "and press it on the paper.""Quite right," said Fred, "and you know we stick our envelopes in the same way. The part that we wet is covered with an adhesive substance.

"Teacher says," he added, "that this adhesive substance is known as British gum. Let us see what it really is.