Divisibility, that property of matter which enables it to undergo extreme subdivision without loss of its distinctive qualities. In modern chemical theory infinite subdivision is regarded as impossible. A stage is reached with any substance beyond which further division will give us particles of new type. When this stage is reached the substance is said to have its constituent molecules isolated. Further division of each molecule will give atoms of matter, of like or unlike kind. An atom may conceivably be cut, but a portion of an atom would not possess the properties of matter - in perhaps the same way as a portion of a smoke-ring would not exhibit the curious characteristics possessed by the complete ring. The extent to which subdivision may be carried is readily instanced by many mechanical processes. A pound of cotton may be spun into a thread eighty miles long, the diameter of the thread being then only 1/350th of an inch. Lines have been engraved on glass for certain optical purposes, so close to one another that 20,000 are ranged to the inch. A skilful gold-beater can hammer out this extremely malleable metal to a thickness of 1/300000th of an inch, and by a simple mechanical process a layer of gold may be deposited on white satin or ivory of a thickness not exceeding the ten-millionth part of an inch. A fibre of spiderweb is only 1/30000th of an inch in diameter, but Professor Boys has devised an ingenious method for obtaining quartz fibres that are far thinner. The fact that the marble steps leading to many sacred shrines are so little worn away in the course of centuries by the feet of innumerable pilgrims give some idea of the slightness of the rubbing at each contact. That certain substances such as iron, musk, or lavender possess distinct effluvia shows that they must be emitting particles continually. A single grain of musk will give a distinct perfume to a room for over twenty years. An estimate of the number of particles that must have been emitted in that time to produce the observed effect can only be rough; nevertheless, it is safe to say that the number must be estimated in quadrillions. Numerous instances can be adduced in the case of liquids, but the above are sufficient to illustrate the astonishing tenuity of matter that can be attained before the atomic limit is reached.