Methane

“ If wood, coal, or many other vegetable or animal substances are decomposed by the action of heat without access of air—that is, are subjected to dry distillation—they, in addition to many other gaseous products of decomposition (carbonic anhydride, hydrogen, and various other substances) , evolve a great deal of methane. Generally the gas which is used for lighting purposes is obtained by this means and therefore always contains marsh gas, mixed with dry hydrogen and other vapours and gases, although it is subsequently purified from many of them. ”

“ Starting with a solid hydrocarbon of definite composition, it would be theoretically possible to decompose it entirely into carbon, hydrogen, ethylene and methane, and, by rapidly removing these from the heating zone before any secondary actions took place, to prevent formation of tar. But any such ideal is hopeless in practice, as the coal is not a definite compound, and it is impossible to subject it to a fixed temperature. ”

“ They do not think that the decomposition of hydrocarbons can be adequately represented by ordinary chemical equations owing to the complexity of the changes which really take place. Methane, which is the most stable of the hydrocarbons, appears to be resolved at high temperatures directly into carbon and hydrogen, but the phenomenon is dependent mainly on surface action; ethane, ethylene and acetylene undergo decomposition throughout the body of the gas (loc. cit. p. 1197 et seq.) ”

“ The identity of the four valencies of the carbon atom follows from the fact that the heats of combustion of methane, ethane, propane, trimethyl methane, and tetramethyl methane, have a constant difference in the order given, viz. 158.6 calories; this means 69 that the replacement of a hydrogen atom by a methyl group is attended by a constant increase in the heat of combustion. ”

“ Second, in the instance of two carbon black plants total hydrocarbon data was eliminated because it was known to be methane. These reductions, which amount to only 11,000 tons, are offered in the second memo as the explanation for the statement in Document 30 that a 0.6 reactivity factor was used because the inventory "was adjusted to eliminate obvious methane sources." Since our review is for the purpose of determining whether an agency determination is arbitrary or capricious, we are constrained to consider the EPA's post hoc statements. ”

“ Properties of the hydrocarbons. The lower members of the first two series of hydrocarbons mentioned are all gases; the succeeding members are liquids. In some series, as the methane series, the higher members are solids. The preparation and properties of methane and acetylene have been discussed in a previous chapter. Ethylene is present in small quantities in coal gas and may be [Pg 401] obtained in the laboratory by treating alcohol (C2H6O) with sulphuric acid:
C2H6O = C2H4 + H2O.
Benzene, the first member of the benzene series, is a liquid boiling at 80°. ”

“ Water gas is very effective as a fuel, since both carbon monoxide and hydrogen burn with very hot flames. It has little odor and is very poisonous. Its use is therefore attended with some risk, since leaks in pipes are very likely to escape notice.
Natural gas. This substance, so abundant in many localities, varies much in composition, but is composed principally of methane. When used for lighting purposes it is usually burned in a burner resembling an open Bunsen, the illumination being furnished by an incandescent mantle. ”

“ This saturated hydrocarbon, CH4, is called marsh gas or methane. If vegetable or animal refuse suffers decomposition in a space where the air has not free access, or no access at all, then the decomposition is accompanied with the formation of marsh gas, and this either at the ordinary temperature, or at a comparatively much higher one. On this account plants, when decomposing under water in marshes, give out this gas. [29 bis] It is well known that if the mud in bogs be stirred up, the act is accompanied with the evolution of a large quantity of gas bubbles ”

“ With the exception of the small amount of carbon in combination with hydrogen as methane, and a very small percentage of free hydrogen, ordinarily less than 0.1 per cent, the calorific value of blast furnace gas is due to the CO content which when united with sufficient oxygen when burned under a boiler, burns further to CO2. ”

“ Both species also produce fatty acids and CO2. It is probable that these organisms operate in the soil under conditions of inadequate aeration. In swamp soils, in which rice is grown, it has been shown that methane, hydrogen, and CO2 are evolved in the lower layers. In these soils, however, the methane and hydrogen are oxidised when they reach the surface layers. This oxidation is also effected by micro-organisms. ”

“ The gallery can be controlled so as to provide rapidly and easily a current of known velocity and known percentage of methane. In the explosive current of gas and air, safety lamps of any size or design can be tested under conditions simulating those found occasionally in mines, air-currents containing methane in dangerous proportions striking the lamps at different angles, and the relative safety of the various types of lamps under such conditions can be determined. ”

“ Compounds of carbon with hydrogen,—the hydrocarbons. Carbon unites with hydrogen to form a very large number of compounds called hydrocarbons. Petroleum and natural gas are essentially mixtures of a great variety of these hydrocarbons. Many others are found in living plants, and still others are produced by the decay of organic matter in the absence of air. Only two of them, methane and acetylene, will be discussed here. ”

“ Moreover, these secondary products cannot be successfully reduced, by further heating, to simpler hydrocarbons of any high illuminating value, and such bodies as naphthalene and anthracene have so great a stability that, when once formed, they resist any efforts again to decompose them by heat, short of the temperature which breaks them up into methane, carbon and hydrogen. ”

“ In carburetting poor coal gas with hydrocarbons from mineral oil it must be borne in mind that, as coal is undergoing distillation, a rich gas is given off in the earlier stages, but towards the end of the operation the gas is very poor in illuminants, the methane disappearing with the other hydrocarbons, and the increase in hydrogen being very marked. ”

“ Although the details of the process vary considerably, according to the presence or absence of air, the ultimate products of decomposition and putrefaction are in both cases the same: namely, free nitrogen, free hydrogen, ammonia, methane, carbonic acid and sulphuretted hydrogen. These are also the end-results of the disintegration of the human body. ”

“ In general, it may be stated that the members of an homologous series show a regular gradation in most physical properties and are similar in chemical properties. Thus in the methane group the first four members are gases at ordinary temperatures; those containing from five to sixteen carbon atoms are liquids, the boiling points of which increase with the number of carbon atoms present. Those containing more than sixteen carbon atoms are solids. ”

“ The iron gas producer, lined with firebrick, is filled with anthracite or coke and heated by blowing hot air through it. This causes producer gas to escape, after which steam is blown through, causing water gas to escape—containing hydrogen and carbonic oxide to the extent of 45-50 per cent., carbon dioxide and nitrogen 2-6 per cent., and a little methane. ”

“ Gas, the staple product from the distillation of coal three-quarters of a century ago, now, to all intents and purposes, is the by-product. The world could roll along very comfortably without it. Indeed, we may have to do so in the near future when the gas is stripped of every other marketable constituent, leaving only a mixture of methane and hydrogen gases to be burned under boilers to raise steam for the generation of electricity in enormous bulk. ”

“ The most important of these is methane, with smaller quantities of many others, some of which are liquids or solids at ordinary temperatures. The great bulk of the carbon remains behind as coke and retort carbon.
The manufacture of coal gas. In the manufacture of coal gas it is necessary to separate from the volatile constituents formed by the heating of the coal all those substances which are either solid or liquid at ordinary temperature, since these would clog the gas pipes. Certain gaseous constituents, such as hydrogen sulphide and ammonia, must also be removed. ”

“ Acetic acid, for example, boils at a higher temperature than water, and has a higher specific gravity than it, whilst its metameride, methyl formate, is lighter than water, and boils at 30°—that is to say, it evaporates very easily.
Let us now turn to carbon compounds containing two atoms of carbon to the molecule, as in acetic acid, and proceed to evolve them from methane by the principle of substitution. ”

“ Carbon burned in protoxide of nitrogen, or laughing gas, N2O, produces about 38 per cent. more heat than the same substance burned in pure oxygen, notwithstanding that the work of decomposing the protoxide of nitrogen has to be performed. In marsh gas, or methane, CH4, again, the energy of combustion is considerably less than that due to the burning of its carbon and hydrogen separately. ”

“ Hydrocarbon appears ordinarily as methane gas, but out there it rings up as CH. Methane is CH4. And there are also scandium oxide molecules making unfamiliar faces at us. And oxide of boron—with an equational limp."
"Gee," muttered Slashaway. "We're up against it, eh?"
Lawton was squatting on his hams beside an emergency 'chute opening on the deck of the Penguin's weather observatory. He was letting down a spliced beryllium plumb line, his gaze riveted on the slowly turning horizontal drum of a windlass which contained more than two hundred feet of gleaming metal cordage. ”

“ The flames of all solid and liquid substances is extinguished by almost the same percentage of CO2 or N2, but the flames of different gases vary in this respect, and hydrogen continues to burn in mixtures which are far poorer in oxygen than those in which the flames of other combustible gases are extinguished; the flame of methane CH4 is the most easily extinguished. The percentage of nitrogen may be greater than that of CO2. ”

“ Ethane, when heated to this degree, splits up into ethylene and hydrogen, whilst ethylene decomposes to methane and acetylene, and the acetylene at once polymerizes to benzene, styrolene, retene, &c. A portion also condenses, and at the same time loses some hydrogen, becoming naphthalene; and the compounds so formed by interactions amongst themselves build up the remainder of the hydrocarbons present in the coal tar, whilst the organic substances containing oxygen in the coal break down, and cause the formation of the phenols in the tar. ”

“ The oxygen, nitrogen, hydrogen, methane and carbon monoxide are either harmless or are present in such small quantities as to be neglected. The phosphoretted hydrogen and silicon hydride are self-inflammable gases when exposed to the air, but their quantity is so very small that this possibility may be dismissed. The ammonia and sulphuretted hydrogen are almost entirely dissolved by the water used in the gas generator. The surest way to avoid impure gas is to use high-grade calcium carbide in the generator and the carbide of American manufacture is now so pure that it never causes trouble. ”

“ According to it, for example, it is evident that there can be no isomerism in the cases of the saturated hydrocarbons C2H6 and C3H8, because the former is CH4, in which methyl has taken the place of H, and as all the hydrogen atoms of methane must be supposed to have the same relation to the carbon, it is all the same which of them be subjected to the methyl substitution—the resulting product can only be ethane, CH3CH3 ”

“ This and other reports were exchanged between the life-boats. Presently a complete picture began to appear. It was even more favorable than suggested by Murray's notes. The thin atmosphere was largely nitrogen, helium and oxygen, with indications of negligible amounts of other gases in unstable equilibrium. Methane was present in small amounts. This, being the product of organic decomposition, indicated vegetable life. ”

“ The choice of absorbents and the order in which the gases are to be estimated is strictly limited. Confining ourselves to cases where titration methods are not employed, the general order is as follows: carbon dioxide, olefines, oxygen, carbon monoxide, hydrogen, methane and nitrogen (by difference) . This scheme is particularly applicable to coal-gas. Carbon dioxide is absorbed by a potash solution containing one part of potash to between two and three of water; the stronger solution absorbs about 40 volumes of the gas. ”

“ We must content ourselves with saying that most modern producers are of the form of a tower in which a thick bed of fuel is partially burnt and partly gasified under the action of a blast of air mixed with steam. The chemical actions that take place are complicated, but the final result is the production of a gas containing from 2 to 8 or 10 per cent. of carbonic acid, 10 to 20 per cent. of hydrogen, 8 to 25 per cent. of carbonic oxide (CO) , 1 to 3 per cent. methane (CH4) , and 45 to 60 per cent. of nitrogen, with varying quantities of moisture, tarry matter, and ammonia. ”