This section is from "Scientific American Supplement Volumes 275, 286, 288, 299, 303, 312, 315, 324, 344 and 358". Also available from Amazon: Scientific American Reference Book.
By Jacob Reese
In the consideration of this subject it is not my purpose to review the steps of discovery and development of electrical phenomena, but the object of this paper is an effort to explain what electricity is; and having done this, to deduce some reasonable conclusions as to what may be expected of it. And while I am profoundly sensible of the importance of the subject, and the difficulties attending its consideration, still with humble boldness I present this paper and ask for it a serious and careful consideration, hoping that the discussion and investigation resulting therefrom may add to our knowledge of physical science.
It is now a well established fact that matter, per se, is inert, and that its energy is derived from the physical forces; therefore all chemical and physical phenomena observed in the universe are caused by and due to the operations of the physical forces, and matter, of whatever state or condition it may be in, is but the vehicle through or by which the physical forces operate to produce the phenomena.
There are but two physical forces, i.e., the force of attraction and the force of caloric. The force of attraction is inherent in the matter, and tends to draw the particles together and hold them in a state of rest. The force of caloric accompanies the matter and tends to push the particles outward into a state of activity.
The force of attraction being inherent, it abides in the matter continuously and can neither be increased nor diminished; it, however, is present in different elementary bodies in different degrees, and in compound bodies relative to the elements of which they are composed.
The force of caloric is mobile, and is capable of moving from one portion of matter to another; yet under certain conditions a portion of caloric is occluded in the matter by the force of attraction. That portion of caloric which is occluded (known by the misnomer, latent heat) I shall call static caloric, and that portion which is in motion, dynamic caloric.
The force of attraction, as I have said, tends to draw the particles of matter together and hold them in a state of rest; but as this force is inherent, the degree of power thus exerted is in an inverse ratio to the distance of the particles from each other. The effective force so exerted is always balanced by an equivalent amount of the force of caloric, and that modicum of caloric so engaged in balancing the effective force of attraction is static, because occluded in that work.
In solid or fluid bodies, where the molecules are held in a local or near relation to each other, the amount of static caloric will be in direct proportion to the effective force of attraction, but in gaseous bodies the static caloric is in an inverse ratio to the effective force of attraction; hence the amount of static caloric present in solid and fluid bodies will be greatest when the molecules are nearest each other, and greatest in gaseous bodies when the molecules are furthest apart.
Caloric, whether static or dynamic, is not phenomenal; therefore the phenomena of light, temperature, incandescence, luminosity, heat, cold, and motion, as well as all other phenomena, are due to the movement of matter caused by the physical forces. Thus we find that temperature is a phenomenal measure of molecular velocity, as we consider weight to be the measure of matter.
An increase of temperature denotes an increased molecular velocity, and this in solid and liquid bodies unlocks a portion of the static caloric and converts it into dynamic caloric, while an increased temperature of gases occludes additional caloric, thus converting dynamic into static caloric; and a reduction of molecular activity reverses this action. From this we see that a change of temperature either converts static to dynamic or dynamic to static caloric.
Thus we find that the amount of static caloric which a body possesses is in direct relation to its temperature, but, as I have already explained, temperature is a phenomenal indication of molecular velocity, and as increased velocity separates the molecules to a greater distance, which reduces the effective force of attraction and unlocks a portion of caloric, it will be seen that the separation of the molecules from any other cause will have the same effect. I desire now to explain a second method by which the molecules are separated and static caloric is changed to dynamic caloric.
It is not definitely known how much static caloric is occluded in either of the elementary bodies, but it is believed that hydrogen possesses the greatest amount and oxygen the least. Now if we take a molecule of hydrogen containing two atoms, and under proper conditions interpose these atoms between 16 atoms of oxygen (one molecule), the phenomenon of combustion is exhibited, and a molecule of water is formed containing 18 atoms; and if one pound of hydrogen is thus consumed, the atoms of hydrogen are separated from each other to such a distance by the interposing atoms of oxygen as to unlock 34,662 units C. of static, and convert it into dynamic caloric. And if we thus bring a molecule of carbon containing 12 atoms in contact with a molecule of oxygen of 16 atoms, combustion ensues and a molecule of carbonic oxide of 28 atoms is formed, and if we then present another molecule of oxygen, combustion again takes place, and a molecule of carbonic acid, containing 44 atoms, is produced. Now, in the combustion of one pound of carbon in this manner, when the carbon is converted into carbonic oxide (CO), 2,473 units C. of static is converted into dynamic caloric; and when this CO is converted into carbonic acid (CO) 5,607 additional units C. are unlocked. Thus by the combustion of one pound of carbon to CO, 8,080 units C. of static caloric are changed to dynamic caloric.
When caloric is thus unlocked from its occlusion it escapes with great velocity until an equilibrium is attained, and in doing so it pushes the particles of matter out of its path. In solid bodies this produces such a high degree of molecular movement as to exhibit the phenomena of incandescence and luminosity, and in liquids increased mobility, while in gases the molecular activity may be so great as to produce the phenomena of sound and light; and the more rapidly combustion takes place the greater will be the volume and velocity of dynamic caloric escaping therefrom; consequently with a slow combustion, the phenomena produced by dynamic caloric will be different from those exhibited at a high degree.
Combustion, as I have before shown, is merely the oxidation of the material; nothing is consumed nor annihilated, and, the phenomena vary with the velocity of oxidation. Now, if we take one pound of zinc and place it in the acid cell of an electric battery, the oxygen of the acid attacks the zinc and oxide of zinc is formed. In this operation the Zn molecule containing 65 atoms is united with one molecule of oxygen of 16 atoms, forming a molecule of oxide of zinc (ZnO) of 81 atoms; and owing to the comparatively small number of oxygen atoms interposed between the 65 atoms of zinc, only 1,301 units C. of static caloric are unlocked to the pound of zinc, and the velocity of oxidation is so low, and the insulation of the vessel so perfect, that the dynamic caloric is caused to flow outward through the copper wire.