MATTER (OF. matii.re, matcre. matire, Fr.
mat from Lot. ma lerift, matter; connected with Skt. , to measure, build). A concept of physical science. The essential nature of matter is generally considered to be unknowable. Broad ly, the material world is discriminated from the world of mind, although it is conceded that all our knowledge of the former conies to us through sensation. In so far as matter is con ceived as the basis of the reality of the ply% sical world, the term designates the of all physical science. It is defined in physical wholly by its properties.
PRoPERTILS or .NiArrEft.
From the standpoint if physics. the properties of matter may be classified its inertia, weight. and various characteristic, Of size. shape, and molecular connections. When one changes the motion of a piece of matter in any way one is conscious of a definite sensation. the intensity of %cilia depends upon two suddenness of the change and the quantity of the matter, using this word in a general sense. This sensation, being associated with matter. is said to be due to a definite property of matter.
which is called its (q.v.). Again. if a portion of matter is held in the hand and so kept from falling toward the earth. there is a definite sensation whieh is attributed to a property of matter called It can be shown that if our senses were delicate eninigh they would ex perience a similar sensation when any two pieces of matter, e.g. two bullet., wore held a small distance apart. See GRAVITA1 foN.
There are a great many priqierties csimmon to all kinds of matter. hut to different degrees: while other properties are confined to certain forms of matter, e.g. solids or liquids or gases. A so/id has a definite shape and size of its own, which can. however, be changed by the tion of certain forces. Some solids. e.g. copper, have ductility 1 q.v.) and can be drawn out into wires; some have miafrobi/ity (q.v.). and can be hammered out into thin sheets; some have porosity (q.v.). and allow various other portions if matter to pass through them; some are and are nearly impervious to other por tions of matter; some are hard. others soft ; some are brittle. others tough; some are plastic,
like putty. ete.
A liquid is a form of matter that if left to itself in air (or in any gas or other liquid with which it not mix) it forms a spherical drop, or. if contained in a hollow solid here out the surface of the earth, it takes the shape of the vessel, keeping a constant volume. .\ liquid then certain molecular properties in its sur face which makes it contract as far as possible. i'"ee CAPILLARITY.
A 9,/.« is such a form of matter that, being contained within any closed vessel, it distributes itself uniformly throughout the space open to it : thus having neither a shape !Mr a size of its myth (sic, (;Asr.s, or.) (lases and liquids are called fluids because they eat) (IOW they yield to any forte, hOWeVer which is acting in such a direction as to make one layer move over the other. (See Ilvonosr.vrics.) Some bodies behave as liquids to feeble hot longwootinued fortes, but as solids to intense and sudden forces; wax will now -II as to fill a timilder if time is given. but it may lie broken by a blow, just like n piece of glass.
\II forms of matter are divisible into smaller parts. following paragraphs Tlo "ries of oq frr.) They are also more or less `elastic' that is. if the shape or size of a solid is deformed slightly by a small force, or if the volume of a fluid is so changed, they will return to their previous conditions more or less perfectly when the deforming force is removed: this proves the existence of internal molecular forces of restitu tion. (See El...t.sirterrv.) Whenever the shape of a solid is changed—not the shape of the whole solid necessarily. but the shape of the little cubical portions out of which the body may be itnained is always to some degree a slipping of the layers of matter over each other, and corresponding internal or molecular friction. Similarly if currents are produced in fluids, there is more or less friction between the layers, which is attributed to a property called risvosi I y In the ease of liquids there is a superfieial viscosity also, which is made mani fest. when a Wily floating in the surface is moved.