A gas can be easily compressed in a close vessel to a pressure of 100 atmospheres, which would enable it to hold 100° of heat due to that compression; in fact, were it compressed to that degree by a piston in a cylinder, without any loss of heat, it would be raised to that heat by that act alone, but that would raise it to only 102° instead of 374° of what is called absolute temperature according to present usage; because as a gas it could not hold any more heat at that pressure. It is, therefore, evident that this usage has not been derived from the laws of gases. Neither has it been derived from the other two states of liquid and solid to which all gases can be reduced, as can be very easily demonstrated.
To cool steam at atmospheric pressure from its gaseous to its liquid state 519° of heat of one kind and another—as measured by the Centigrade thermometer—have to be abstracted from it, which leaves the liquid at its boiling point of 100°—a quantity that has been arbitrarily adopted to mark the difference between the freezing and boiling points of this liquid. In order, after this, to reduce the liquid, now water, to the freezing, or what is called 0° of heat, these 100 degrees of heat have to be extracted from it, which is not very difficult to do because the heat put into it arbitrarily can be extracted from it; but if it is now wanted to change the steam from its liquid to its solid state, the work, or operation assumes a very different character, because heat cannot be extracted from a substance which contains none at all. It is well known that 80° of heat are required to change one pound of ice at 0° into a pound of water also at 0° of heat; but it is equally well known that 80° of heat cannot be taken out of the pound of water which has none in it; how then, is the water to be changed into ice?
Even in cooling water to 0° it has to be put into a bath of some kind, either of cold water or some cold mixture of other substances at least as cold; because, otherwise, extraneous heat from any source might find its way into it, and prevent it from cooling down to zero of heat. In the same manner, to change the water into its solid state of ice it has to be put into a similar bath, not to extract heat from it, because it has not any to extract, but to prevent extraneous heat from getting into it. This being the case, it is evident that if water is put into a bath at what is called -1° of heat, or even a fraction of that amount, it will be converted into ice though very gradually, by keeping extraneous heat from getting to it to sustain the collisions, or vibrations, of its constituent atoms necessary to maintain it in its liquid state. All for the very same reason why a stone, a piece of metal, or of anything assumes the same degree of heat, or absence of heat, as the medium by which it is surrounded; be it derived from sun-heat, earth-heat, or heat produced chemically or mechanically, and is not cooled down to a lower degree than the surrounding bath, be it what it may.
The heat required to change a solid into a liquid is called latent heat, which in the case of ice and water may be a fraction of -1° or -80°, or minus almost anything according to the time it is necessary for it to act; so that no quantity of what is called absolute temperature can be ascribed to ice without the element time being involved in it. The absolute temperature of water and ice, just changing from freezing to frozen, might be counted as the same, seeing that a fraction of a degree of heat may make all the difference between them; but no fixed absolute temperature can be applied to ice, as it, in conjunction with all solid bodies, may have any degree of absolute temperature between its melting point and the absolute zero of heat, as far as is at present known. The same, of course, must be the case with any gas or vapour, or nebulous matter changed into its liquid and then solid state; and this fact enables us to go a little further.
We have seen that what, according to present usage, is called the absolute temperature of solid hydrogen may be anything between -257° and -274° of heat, that is, between the absolute temperature of 0° and 17°, which, of course, is no measure at all; and, therefore, absolute temperature can only be looked upon as a conventional term, which, when added to positive Centigrade, or other, heat, conveys no clear idea to the mind, as it must always be mixed up with the concomitant idea of latent heat and its time of action. This leads us to think of what remains in the vessel, in which pure hydrogen has been changed into its liquid and then solid state, after these operations have been performed; and our first conclusion comes to be that there can be nothing in it but a small piece of solid hydrogen; but from the limited accounts we have seen of these operations, there does appear to be something remaining, because it seems that by it the degree of negative heat in the vessel can be measured. What that remaining something may be can hardly be anything but a matter of conjecture. The first and most probable idea that occurs is that it may be some lighter gas mixed with the pure (?) hydrogen that was put into the vessel; the next is that it may be the vapour of solid hydrogen; and the last refuge for speculation is that it may be radiant matter, whatever that may turn out to be. At one time it was supposed to be impurities mixed with the gases operated upon, which in the case of common air, were found to be removed to a certain extent by means of absorbents; but the numerous components of common air discovered since that time, have gone far to throw light upon that supposition, and we are thus led to think of what a true gas really is. But we are not yet prepared to follow up this thought.
This is not an inappropriate place to say that when we adopted the Centigrade scale for our work, we thought that a special thermometer, decimal throughout and consequently more handy, might be arranged for science alone, leaving every man the free use of whatever scale he liked best; but our experience acquired in this chapter put an end to that thought, and has left us totally unable to see how any decimal scale can be contrived, which will start from absolute zero of heat and will admit of any combination with any existing scale, or will assist humanity in any of its operations in connection with heat and temperature, whichever science may choose to call it. We therefore see that no known thermometer scale is superior to another, and end where we began by saying that the Centigrade is the fashionable one at the present time. It is decimal as far as boiling water and resulting steam are concerned, but all the world is not boiling water; even steam has to be complicated with latent heat.
[TABLE III].— Abstract of Measurements, etc., resulting from
the Calculations made in Chapter V.
| — Nebulæ — | Volume of the Mass of each Separate System at Density of Water | Times less Dense than Water. | Increase of Density | Volumes at Densities of Respective Nebulæ | ||
| Name. | Diameter (Miles). | Explanations. | (Cubic Miles). | in times. | (Cubic Miles). | |
Neptunian | 6,600,000,000 | 311,754,100,720 | ||||
| Volume of Neptune's Ring | 29,107,964,680,925 | 311,754,100,720 | 150,532,847,222,000,000,000,000,000,000 | |||
| Volume of Nebula less Ring | 9,074,530,000,000,000,000,000,000 | |||||
Uranian | 4,580,000,000 | Condensed from Neptunian Nebula | 2.9923 | 150,523,772,692,000,000,000,000,000,000 | ||
| Volume of Uranus' Ring | 25,876,388,977,000 | 104,184,535,721 | 50,303,255,814,000,000,000,000,000,000 | |||
| Volume of Nebula less Ring | 2,695,918,851,000,000,000,000,000 | |||||
Saturnian | 2,672,000,000 | Condensed from Uranian Nebula | 5.0357 | 50,300,559,895,149,000,000,000,000,000 | ||
| Volume of Saturn's Ring | 154,370,734,774,315 | 20,689,000,000 | 9,988,700,000,000,000,000,000,000,000 | |||
| Volume of Nebula less ring | 3,193,775,478,000,000,000,000,000 | |||||
Jovian | 1,370,800,000 | Condensed from Saturnian Nebula | 7.4037 | 9,985,506,224,522,000,000,000,000,000 | ||
| Volume of Jupiter's Ring | 479,368,921,317,000 | 2,794,417,420 | 1,348,720,186,335,000,000,000,000,000 | |||
| Volume of Nebula less ring | 1,339,557,155,000,000,000,000,000 | |||||
Asteroidal | 744,000,000 | Condensed from Jovian Nebula | 6.2484 | 1,347,380,629,180,000,000,000,000,000 | ||
| Volume of Asteroidal Ring | 367,792,000,000 | 447,218,905 | 215,634,925,373,133,820,000,000,000 | |||
| Volume of Nebula less ring | 164,482,717,200,000,000,000 | |||||
Martian | 402,000,000 | Condensed from Asteroidal Nebula | 6.3392 | 215,634,760,890,416,620,000,000,000 | ||
| Volume of Martian Ring | 160,728,460,000 | 70,547,110 | 34,015,582,677,165,354,000,000,000 | |||
| Volume of Nebula less ring | 11,338,927,154,000,000,000 | |||||
Earth | 234,620,000 | Condensed from Martian Nebula | 5.0302 | 34,015,571,338,237,200,000,000,000 | ||
| Volume of Earth Ring | 1,489,310,236,000 | 14,024,781 | 6,762,303,076,923,031,000,000,000 | |||
| Volume of Nebula less ring | 20,887,249,553,000,000,000 | |||||
Venus | 160,210,000 | Condensed from Earth Nebula | 3.1410 | 6,762,282,189,673,478,000,000,000 | ||
| Volume of Venus Ring | 1,131,960,000,000 | 4,465,512 | 2,153,120,792,079,207,921,000,000 | |||
| Volume of Nebula less ring | 5,054,780,604,651,000,000 | |||||
Mercurian | 103,232,000 | Condensed from Venus Nebula | 3.7379 | 2,153,115,737,298,603,270,000,000 | ||
| Volume of Mercurian Ring | 92,735,000,000 | 1,194,666 | 576,026,613,333,333,333,000,000 | |||
| Volume of Nebula less ring | 110,787,355,300,000,000 | |||||
Solar | 63,232,000 | Condensed from Mercurian Nebula | 274,546 | 4.3514 | 576,026,502,545,978,033,000,000 | |
| 58,002,920 | Volume at 1/274 of 1 atmosphere. | 211,911 | 1.2956 | 132,376,310,975,609,756,000,000 | ||
| 8,930,309 | Volume at density of 1 atmosphere. | 274.0000 | 102,176,129,412,000,000,000,000 | |||
| 972,895 | Volume at density of water. | 773.3950 | 372,905,560,345,000,000,000 | |||