Page:Various Forces of Matter.djvu/60

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48
COHESION.

up. I may even bend it without breaking it; that is to say, I may bend it in one particular direction without breaking it much, although I feel in my hands that I am doing it some injury. But now if I take it by the edges I find that it breaks up into leaf after leaf in a most extraordinary manner. Why should it break up like that? Not because all stones do, or all

Fig. 15.

Fig. 16.

Fig. 17.

crystals; for there is some salt (fig. 16)—you know what common salt is[1]; here is a piece of this salt which by natural circumstances has had its particles so brought together that they have been allowed free opportunity of combining or coalescing, and you shall see what happens if I take this piece of salt and break it. It does not break as flint did, or as the mica did, but with a clean sharp angle and

  1. Page 48. Common salt or chloride of sodium crystallises in the form of solid cubes, which aggregated together, form a mass, which may be broken up into the separate cubes.