_Cohesion_: This term is used to indicate the attraction between Molecules, by which they are combined into Ma.s.ses or Bodies. Cohesion causes the Molecules to unite and cling together, thus forming the Ma.s.s.

_Adhesion_: This term is used to indicate the attraction between Ma.s.ses which causes them to "stick together" without a cohesion of their Molecules. Adhesion operates through the adjacent surfaces of the two Ma.s.ses. It may be considered as a "lesser" form of cohesion.

_Chemical Affinity_ (sometimes called Chemism or Atomic Attraction): This term is used to indicate the attraction between the atoms, by which they combine, unite and cling together, forming the Molecule.

Science has before it the task of naming, and cla.s.sifying, the attraction between the Corpuscles, by which they combine and form the Atom. But whatever the name, it will be seen that it represents but another manifestation of "Attraction."

Arising from Molecular Attraction, or Cohesion, are several "Properties"

peculiar to Ma.s.ses having Molecules, and resulting from the tendency of the latter to resist separation. We had better consider them briefly, in order to understand the power of Molecular Attraction, and its incidents.

_Porosity_: That property indicating the distances observed by the Molecules in their relation to each other, which varies in different "kinds" of Substance. All Substance is more or less Porous, that is, has more or less s.p.a.ce existing between the Molecules--the degree depends upon the "closeness." Compressibility and Expansibility, sometimes mentioned as "properties," are but results of Porosity.

_Elasticity_: That property whereby bodies resume their original size and form, after having been compressed, expanded or "bent." The result is caused by the inclination of the molecules to resume their original positions. What is sometimes called "Plasticity" is merely the reverse of Elasticity, and denotes a limited degree of the latter.

_Hardness_: That condition resulting from Molecular Attraction resisting the forcible entrance and pa.s.sage of other Substance between the molecules.

_Tenacity_: That condition resulting from Molecular Attraction resisting the forcible pulling asunder, or tearing apart of the Ma.s.s. This condition sometimes is called "Toughness."

_Malleability_: That condition resulting from Molecular Attraction resisting the forcible separation of the Ma.s.s by pounding, hammering or pressure. The resistance is "pa.s.sive," and consists of the Molecules allowing themselves to a.s.sume a spread-out formation, rather than to be forced apart.

_Ductility_: That condition resulting from Molecular Attraction resisting the forcible separation of the Ma.s.s by a "drawing out"

process. The resistance is "pa.s.sive," and consists of the Molecules allowing themselves to be drawn out into a formation of the shape of wire or thread, rather than to be pulled apart.

In any of the above cases, we may intelligently, and with propriety, subst.i.tute the words, "_Molecules, by means of cohesion, resisting, etc._," for the terms above used, "Molecular Attraction, resisting, etc."

All Ma.s.ses of Substance (probably Molecules as well) are capable of _Expansion and Contraction_, both phenomena, in fact, and in degree, resulting from the relation of the Molecules. Contraction is a "crowding together" of the Molecules; Expansion a "getting apart" of them.

_Density_: The amount of Substance in relation to a given bulk.

_Volume_--the "size" or "bulk" of a body of Substance. _Ma.s.s_--Besides being used to designate a "body" of Substance, composed of two or more Molecules, the term "Ma.s.s" is used to designate the "total quant.i.ty of Substance in a Body." An application of the above terms may be seen in the following ill.u.s.tration:

A quart of water occupies a certain s.p.a.ce--and has a certain "volume,"

"ma.s.s" and "density." Convert the same "ma.s.s" of Water into Steam, and it expands to a "volume" of 1700 times that of Water--but, as no molecules have been added, the "ma.s.s" remains the same--but as a quart of Steam weighs 1700 times less than the same "volume" of Water, the "density" of Steam is 1700 times less than that of Water. As the "volume" of a given "ma.s.s" increases, the "density" decreases in the same proportion--but the "ma.s.s" remains the same. "Ma.s.s" therefore has two factors, _i.e._, "Volume" and "Density." The "Density" of a "Ma.s.s"

is determined by the _weight_ of a certain "Volume" of it.

The above consideration of the "Properties" of Substance dealt only with the Molecular Properties, or Physical Properties, as they are sometimes called--that is, with properties depending upon the existence of the Molecules. When we consider the Molecules as being composed of Atoms, and when we consider the processes whereby these Molecules are built up of, or broken down through the separation of Atoms, we come to the subject of Atomic Properties, or Chemical Properties, as they are often called.

_The Atomic Properties of Substance_ consist princ.i.p.ally in the power and manifestation of Motion, in the direction of combination, separation, and the complex motions resulting from the same. This Motion is manifested by reason of Atomic Attraction, sometimes called "Chemical Affinity," which we shall consider a little later on in the chapter.

Atomic Principles, as above mentioned, are best ill.u.s.trated by a reference to Chemical changes, and we shall now examine the same. And, the better way to consider Chemical Changes is by comparing them with Physical Changes, or Changes of the Molecules.

_Some Physical Changes in Substance_ are brought about by Heat, which tends to separate the molecules, or rather to allow them to spread out away from each other, so long as the high temperature is maintained, the degree of their nearness being influenced by temperature. Other Physical Changes are produced by outside Forces separating the molecules to such an extent--to such a distance--that their cohesive force is lost, and the Solid matter is said to be "broken," or even reduced to dust. Other physical changes are brought about by Electricity, causing the Molecules to separate and disintegrate.

_Chemical Changes_, as distinguished from Physical Changes, do not involve or deal with Molecules, the action being solely upon the Atoms of which the Molecules are composed. Physical Changes _separate_ Molecules from each other, while Chemical Changes destroy and break up the Molecule, so that its ident.i.ty is forever lost, its Atoms thereafter either existing free from combinations, or else recombining with other Atoms, and forming new combinations. Chemical changes are occasioned by either physical or chemical agencies. The physical agencies generally employed are heat, electricity, light, pressure, percussion, etc. The principle of Chemical Changes is that the Atoms are possessed of, and subject to, what is called "Atomic Attraction" or "Chemical Affinity,"

which may be defined as an attraction or "love" existing in varying degrees between Atoms. This Affinity causes Atoms of one element to seek out and ally themselves to Atoms of another element, the element of "choice" or "preference" being strikingly in evidence.

Atoms of different elements form marriages, and cling together in harmony, until, perchance, by some physical or chemical agency, the Molecule is brought in sufficiently close connection with another Molecule composed of different elemental atoms, when, alas! one of the Atoms of our Molecule finds that it has a greater Affinity for some other elemental Atom in the second Molecule, and lo! it flies away, leaving its first partner, and seeking the new charmer. Divorce and re-marriage is a common thing in the world of Atoms--in fact, Chemistry is based upon these qualities.

Physical and Chemical Changes gradually transform solid rock to "earth"

or "soil." Disintegration, by the action of changes in temperature, rains and atmospheric influences, and other Physical Changes, have slowly worn down the rocks into "dirt," gravel, clay, loam, etc. And Decomposition by Chemical Change that set the atoms free from their combinations has aided in the work.

There is no rest in the world of Substance. Everything is changing--constantly changing. Old forms give way to new, and these, grown old while being born, are, in turn replaced by still newer. And on, endlessly. Nothing persists but change. And yet nothing is destroyed, although countless forms and shapes have succeeded each other. Substance is always there, undisturbed and unaffected by the varieties of forms it is compelled to undergo. Ma.s.ses may change--and do change. Molecules may change--and do change. Disintegration and decomposition affect both, and bring to them the death of form. But their substance endures in the Atom. Atoms may change, and decompose, or undergo whatever change that is their fate, and still the Corpuscles, or what lies beyond the Corpuscles will remain. The Atom was once regarded as Eternal, but now even it seems to be capable of dissolving into some finer division of Substance--and perhaps still finer subdivisions await it.

That familiar form of Substance that we call "earth," "dirt," "soil,"

etc., is but the result of disintegrated rock, which has crumbled and lost its former form through the action of air, water and atmospheric influences. And the rocks themselves, from which the "soil" came, were at one time a sea of melted, flowing liquid Substance, somewhat resembling volcanic lava. And this "melted rock" is thought to have been condensed from the same principles in the shape of vapor, that existed in the early days of our planetary system. Vapor, gas, liquid, semi-liquid, solid rock, "soil"--the Substance unchanged, the forms totally unlike. Helmholtz estimates the density of the nebulous vapors of Substance as being so rare that it would take several millions of cubic miles of it to weigh a single grain. Oh, Nature, what a wizard thou art!

We have spoken of Air and Water, in a former chapter, and their const.i.tuent atoms have been named. And from these three great reservoirs of Substance--the Earth, the Air, and the Water--are obtained all the material that goes to form the bodies of the animal and vegetable kingdoms. The plant draws its nourishment from the soil, the air, and water, and in its wonderful chemical laboratory is able to transform the elements so drawn from these sources into a substance called "Plasm,"

which consists princ.i.p.ally of carbon, oxygen, nitrogen and hydrogen, being nearly identical in composition to the white of an egg, and which const.i.tutes the basis of animal and plant bodily structures. All the material of the physical bodies, of men, animals and plants, are but forms of Plasm. The animals, and man, obtain their nourishment, directly or indirectly, from the plant body, and so at the last we are seen to draw from the soil, air and water all our bodily nourishment, which we convert into bodily structure, bone, muscle, flesh, blood, veins, tissue, cells, etc. And the chemical atoms of our bodies are identical with those in the rock, the air, the water. And so you see the universality of Substance and its countless forms and appearances.

Chemistry resolves Substance back into about seventy-five simple substances, of which Atoms are the Units, which simple substances are called "Elements." From these Elements (by their Atoms) all other substances are formed by combinations, the number of such possible combinations being infinite. An Element (in order to be an element) must be a "simple" substance, that is, must be incapable of further a.n.a.lysis into some other elements. The seventy-five elements, now recognized by science, have never been resolved into other elements, by chemical a.n.a.lysis, and therefore are accepted as "simple." But, it is true that other substances that were formerly considered as simple elements were afterward decomposed by electricity, and found to consist of two or more simpler substances or elements. Thus new elements were discovered, and old ones discarded as "not-elemental." And this fate may be in store for a number of the elements now on the list--and many new ones may be discovered.

For a long time Science was endeavoring to trace all elements back to Hydrogen, the latter being considered the "Ultimate Element," and its atoms composing all the other atoms, under varying conditions, etc. But this theory is now almost abandoned, and Science rests on its list of seventy-five elements, the atoms of which are composed of "Electrons."

Some have hazarded the theory that the Elements were all forms of Ether (see next chapter), their apparent differences resulting merely from the varying rate of vibration, etc. And, in fact, such theory was about finally adopted as a working hypothesis until the discovery of the Corpuscle. Everything in Substance now seems to be moving back to the Corpuscle, as we shall see a little further on.

The following is a list of the princ.i.p.al Elements, known to Science, to-day:

Aluminum.

Antimony.

a.r.s.enic.

Barium.

Bis.m.u.th.

Boron.

Bromine.

Cadmium.

Calcium.

Carbon.

Chlorine.

Chromium.

Cobalt.

Copper.

Fluorine.

Gold.

Hydrogen.

Iodine.

Iron.

Lead.

Magnesium.

Manganese.

Mercury.

Nickel.

Nitrogen.

Oxygen.

Phosphorus.

Platinum.

Pota.s.sium.

Radium.

Silicon.

Silver.

Sodium.