In hot countries bricks are often used which have simply been dried in the sun in this way. But these sun-dried bricks will not stand much rain: the water soaks into them, and they once more become lumps of soft clay.
在炎热的地区，以前经常把砖直接在太阳底下晒干。但是用太阳晒干的砖经不住水，水会渗进砖里，砖就又变回了软软的粘土块儿。
The reason of this is that there is not only water in the pores of the clay, there is also water united with the clay itself, and this water can only be got rid of by the strong heat of a fire. So the bricks, after being dried in the air, are placed in a kiln. Fires are lighted beneath the kiln, and the bricks are baked or burned in it for some time.
这是因为，不只有粘土的孔洞里才有水，还有跟粘土融合在一起的水，这种水，只有用火焰的高热才能去掉。所以，在空气中晾干之后，砖坯就运进了砖窑，在砖窑底下烧起火来，把砖坯烤上或烧上一段时间。
Most bricks turn red when burnt. That is owing to the fact that the clay from which they were made contained a very little iron, and the burning changed this iron into iron-rust, which is of a red colour.
大多数砖在烧过以后，都会变成红色。这种变化的原因是，砖的原料——粘土含有很少的铁，烧砖的过程，把这些铁变成了铁锈，铁锈是红色的。
Bricks will stand a great heat without melting, especially those made from a kind of clay which is called fire-clay. Such bricks are called fire-bricks, and they are used for the backs and sides of fire-places, and for building furnaces in which metals are to be melted.
砖可以承受很高的温度而不熔化，特别是那些用“耐火粘土”做的砖。这样的砖就叫做“耐火砖”，用来做壁炉的后面和两个侧面，还用来做熔化金属的熔炉。