It is this tannin which makes leather durable and soft.

酸让皮革更加柔软，更耐用。

It takes years for a skeleton to vanish, but the shoes treated with tannic acid—they won't eat them.

需要几年才能消失，但是用酸处理过的鞋子——海水无法吞噬们。

During the summer the bark is peeled from the trees and taken to factories where the tannin is taken out.

在夏天，我们会从树上削树皮，之后进入工厂酸。

Turns out, it was made from the tannic acid of gall nuts.

原来，是用没食子（五倍子）中的酸制成的。

The water draws out of this bark a substance known as tannin; and the tannin changes the soft, jelly-like skins into tough, strong leather.

在水的作用下, 树皮能够分泌一种名叫酸的物质, 而就可以把凝胶一般柔软的毛皮变成结实、牢固的皮革。