"I saw father use some cement of another sort last week. He used it to mend a chair. He put the broken edges of the wood together, with some of this cement between. The chair is quite strong now. The cement has made the broken parts stick fast.""Why, you mean glue," said Norah. "I saw father mending the chair. Of course glue must be an adhesive substance. It is a cement for wood.""Those men who work with bricks and stone," said Fred, "use another sort of cement. Glue would not do.""I suppose you must mean mortar," said his sister. "Quite right," said Fred. "Mortar is an adhesive substance. It is the very sort of adhesive substanceto make bricks and stone hold fast together." "What do the men use to make their mortar,Fred?" said Norah.
"Mortar is made of lime and sharp sand mixed into a paste with water," said Fred.