Bitumen

“ Even with the proper proportion of petrolenes and asphaltenes a bitumen may still be valueless as a cement, if the petrolenes are not of a proper character, that is to say, not sticky. These are all facts to be determined by the chemist, and his contributions to the subject have been of the greatest importance to the development of bituminous highway construction. ”

“ As free bitumen does not exist in nature, deposits of bitumen in the rocks are an anomaly as long as the origin of bitumen cannot be positively indicated. Moreover, there is a great difference between bitumen, or rocks impregnated with bitumen, and coal beds. Hardened or oxidated bitumen has been found in a few instances filling crevices of rocks, as in Canada and in West Virginia ”

“ The stone is usually taken from open quarries, but at Val de Travers shafts are sunk and the general treatment is similar to a coal mine.
Bitumen, it must be borne in mind, is itself a mineral product found in Trinidad and some other places; it is composed of carbon, hydrogen, and oxygen.
The weight of a cubic yard of natural asphalte is about 3874 lbs., its specific gravity is 2·114, but this of course varies with its percentage of bitumen. ”

“ From peat we should expect but a mixed matter, varying between the bitumen of wood and true bitumen, according to the degree of change previously undergone; for that the process of bituminization is the effect of water, and not of fire, is rendered probable, as much by these trials as by the geological observations above mentioned. ”

“ The common bituminous coal kindles readily, emits much smoke, and throws out so much liquid bitumen that the whole soon cakes into a solid mass. It contains about forty per cent, of bitumen. The second kind, or cannel coal, contains twenty per cent., and inflames easily, but does not agglutinate. The stone-coal, or anthracite, contains scarcely any bitumen, ignites with difficulty, emits but little smoke, and produces a very intense heat. The bituminous varieties are always found in the least disturbed portions of the coal districts ”

“ So soon as the light has sufficiently acted, which may be seen by means of photometric bands equally transparent at the plate, all the bitumen not acted upon is dissolved. As it is a positive which has acted as matrix, the uncovered zinc indicates the design, and the ground remains coated with insoluble bitumen. The plate is then etched with a weak solution of nitric acid in water, and the lines of the design are thus slightly engraved; the surface is then re-coated with another layer of bitumen, which fills up all the hollows, and is then rubbed down with charcoal. ”

“ Others think that the natural heat of the crust of the earth generated by pressure and, perhaps, other causes, has distilled bitumens from pyrobituminous minerals, and, in some instances, from coal, and they have penetrated the surrounding and overlying porous formations, often filling crevices and forming veins, when the pressure becomes sufficient to rupture the overlying formations. I am inclined to think this latter theory, of 'distillation,' will best account for all the varying conditions under which the various forms of bitumen occur. ”

“ Bitumens occur in all periods of the geological history of the earth's crust, but are mainly confined to the formations anterior to the coal period and to the later formations of the tertiary. While asphaltum is found in some of the oldest formations, the greater number of the deposits of solid bitumen and bituminous rocks occur in the more recent formations. ”

“ The other mineral curiosities are, a number of wells of bitumen Judaicum, in the Wady at one hour below the village on the west side, after recrossing the bridge; they are situated upon the declivity of a chalky hill; the bitumen is found in large veins at about twenty feet below the surface. The pits are from six to twelve feet in diameter; the workmen descend by a rope and wheel, and in hewing out the bitumen, they leave columns of that substance at different intervals, as a support to the earth above; pieces of several Rotolas in weight each [The Rotola is about five pounds.] ”

“ That which is poor in bitumen is hard, and rings like ordinary limestone; but the fatter rock, when struck with a hammer, gives forth a dull thud, like a block of wet plaster, and takes an impression from the blow. If it contains more than ten per cent, it crumbles in the hand, and can be cut with a knife, like chocolate. Good stone, with about ten per cent of bitumen, has a specific gravity of 2·1. Some asphalt-stone is of a spongy, hygroscopic nature, and consequently lighter. ”

“ By preparing the bitumen as described below and taking care to have a very thin film of the sensitive bitumen upon the zinc plate, then the exposure either to sunlight or electric light is not more than double that of albumen.
There is one especial virtue in a bitumen film. If by chance too much exposure to light has been given, a prolonged immersion in the developing liquid (turpentine) will remedy the defect, whereas if an albumen image be over-exposed it is quite spoiled, and the work must be done again. ”

“ There is a kind of bitumen found at Aniches, in France, in the department of the north, which is black, very fusible, and soft. It burns with flame. Alcohol, ether, and oil of turpentine extract from it a fatty substance, which may be saponified with alkalis.
The bitumen of Murindò, near Choco, in Columbia, is of a brownish-black colour, soft, and has an earthy fracture. It has an acrid taste, burns with a smell of vanilla, and is said to contain a large quantity of benzoic acid. It appears to be the result of the decomposition of trees containing benzoin. ”

“ The greater part of the asphaltum to be met with in commerce comes from the Dead Sea, on whose shores it is cast up and gathered; whence it has got the name of Jewish bitumen. In its black colour and fracture it resembles ordinary pitch. By friction it affords negative electricity. Its average density is 1·16. It melts at the temperature of boiling water, kindles very readily at the flame, burns brightly with a thick smoke, and leaves little ashes. Distilled by itself, it yields a peculiar bituminous oil, very little water, some combustible gases, and traces of ammonia. ”

“ BITUMEN, the name applied by the Romans to the various descriptions of natural hydrocarbons, the word petroleum not being used in classical Latin. In its widest sense it embraces the whole range of these substances, including natural gas, the more or less liquid descriptions of petroleum, and the solid forms of asphalt, albertite, gilsonite or uintahite, elaterite, ozokerite and hatchettite. To distinguish bitumen intermediate in consistency between asphalt and the more liquid kinds of crude petroleum, the term maltha (Latin) is frequently employed. ”

“ Whatever value a bitumen may have as a binding material for highway construction, is due to the presence and the character of the petrolenes. The solid material in itself has no binding power, but by its solution in or mixture with the petrolenes it gives to the latter their binding power, and also adds to their stability. ”

“ There are several circumstances which indicate that bitumen and asphalt are more nearly related to petroleum than to coal-tar, and that, whether asphalt was made from petroleum or not, they have a similar or common origin. Nor is it an unfortunate circumstance that coal-tar can not be used as a substitute for bitumen, since the former contains many constituents that are more valuable for other purposes, while Trinidad offers an inexhaustible supply of the latter. ”

“ The last combination produces the mineral commonly called asphalt. When the bitumen contained in any of these substances is chemically isolated, it appears always a nearly identical substance, in composition, consistency, and appearance, except that the empyreumatic odor that characterizes it may become alliaceous in volcanic countries. Asphalt is doubtless one of the most considerable and valuable of the forms in which bitumen appears. It is a soft limestone, naturally and closely impregnated with that substance. ”

“ The origin of bitumen is as little known as that of most of the productions of nature. Some regard it as an empyreumatic oil, a matter analogous to liquid resin or essential oil, resulting from the destruction of that astonishing multitude of animals and vegetables buried in the earth, whose solid remains are daily brought to view in mineral researches. It has been also supposed that naphtha and petroleum are the product of coals decomposed either by the fire of volcanos, by the subterranean combustion of coal itself, or by the decomposition of pyrites. ”

“ Blind coal may therefore be found where no bitumen has been actually extricated. In like manner, bitumen may have been separated, where the coal was not reduced to the state of coke, as a part of the bitumen only may have been driven off, and enough left to prevent the coal from becoming absolutely infusible. ”

“ The native asphalt rock consists for the most part of carbonate of lime, more or less impregnated with bitumen, the quantity of which varies from about six to twelve per cent, that from the Val de Travers, in the canton of Neufchâtel, containing rather more bitumen than that of the Seyssel. The prepared asphalt, as sold by the makers under the name of "mastic," is made by crushing the asphalt rock under a steam-hammer and grinding it to powder by edge-runners. ”

“ The several varieties of coal are supposed to consist of charcoal and asphaltum, or of charcoal and bitumen, combined in as many different proportions. Charcoal is undoubtedly found mixed with coal, but it does not appear correct to consider pit coal as either a mixture or combination of any bitumen with charcoal. The action of naphtha on its varieties, often none and always sparing, shows that bitumen does net exist in it in a mixed state. ”

“ At other times the quantity sinks to five per cent, or less, while nodules of limestone entirely free from it are also found. The value of the rock depends on the percentage of bitumen, and on other circumstances. If the stone is to be used for making mastic, the higher the percentage the more valuable it is; but, if used directly for paving, a uniform distribution, not exceeding eight or ten per cent, is desirable.
Asphalt-stone, to which Malo limits the name of asphaltum, varies in color from gray to brownish-black, according to the richness in bitumen ”

“ The heaping of the vegetable remains must then have attained in favorable localities a thickness at least double that of the present peat deposits. The supposition that the plants at the carboniferous epoch contained more bitumen than those of our time has no foundation whatever, as bitumen is obtained from peat in as large proportion as from coal. Mineral oil, which also results, in its essential part at least, from the decomposition of vegetable matter, is in this particular only comparable to coal ”

“ These, with steady march, have conquered the markets of the world. The deposits known as Neufchâtel rock contain, with a constancy not found anywhere else, from 11 to 12 per cent, of bitumen—a most favorable proportion. Besides, they have absolutely greater toughness as a result of their degree of oxidation. They were formerly extensively used as a mastic for sidewalks, and form an excellent material for carriage-ways. ”

“ It is, that neither petroleum, nor any fossil bitumen, is found in the vicinity of the Kilkenny coal, as might be expected, - 198 - if that coal was deprived of its bituminous part by subterraneous distillation. [85] This, however, admits of explanation. Though a general connection, on the above hypothesis, might be expected between bitumens and infusible coal, we cannot look for it in every instance. The heat which drove off the bitumen from one part of a stratum of coal, may only have forced it to a colder part of the same stratum ”

“ But if the fine details are buried in undissolved bitumen, a further immersion in the turpentine bath will soon clear them; then again wash under the tap, immerse in the graining bath, again wash, then, with a sheet of clean blotting paper, remove the surplus water, and allow the surface to dry in a cold current; but beware of using heat, as it has a tendency to make the bitumen image refuse ink in rolling up.
The zinc being dry, it is gummed in, fanned dry, then the gum is washed off, and the image rolled up with a leather roller charged with transfer ink. ”

“ The proportion of bitumen present in asphalt rock usually ranges from 7 to 20%, but it is found that rock containing more than 11% cannot be satisfactorily used for street pavements, and it is accordingly customary to mix the richer and poorer varieties in fine powder in such respective quantities that the proportion of bitumen present is from 9 to 10%. The richer rock is utilized as a source of asphalt “mastic,” which is employed for footpaths, floors, roofs, &c. Excellent foundations for steam-hammers, dynamos and high-speed engines are made of asphaltic concrete. ”

“ Where petroleum has escaped through pores in the rocks, or by way of fissures, and has come to the surface of the 229 earth, the lighter components, thus exposed to the air, have vaporized and escaped, leaving behind a more or less solid residue, which is known as bitumen. ”

“ Bitmumen. Mineral pitch, of which the tar-like substance which is, often seen to ooze out of the Newcastle coal when on the fire and which makes it cake, is a good example. Etym., Bitumen,pitch.
Bituminous shale. An argillaceous shale, much impregnated with bitumen, which is very common in the coal measures.
Blende. A metallic ore, a compound of the metal zinc with sulphur. It is often found in brown shining crystals, hence its name among, the German miners, from the word blenden, to dazzle. ”