Asphaltum

“ The latter, along with native asphaltum, is undoubtedly the most important modern building-material, but it has its separate province, and lacks just those qualities of the native asphaltum which are so highly appreciated for paving-purposes. It will hardly ever be successful in the long-run when encroaching on the sphere of the competing material which it has fairly outrivaled as a cement for brickwork and masonry, for which, in ancient times, asphaltum enjoyed a just celebrity, as attested by the remnants of the walls of Babylon and Nineveh. ”

“ It is a compound of carbon and hydrogen, and varies in appearance from cobblers’ wax to tar. Asphaltum is of organic origin and is closely related to the mineral oils. Among the pigments usually employed by artists asphaltum plays an important part; it produces very warm shades between brown and deep black. The preparation of asphaltum for artists’ use is very simple. Good uniform lumps, free from sand and other impurities, are coarsely powdered and mixed with a solvent in a well-stoppered flask. ”

“ Shaft on Asphaltum Vein near Asphalto, from which mass was taken weighing 6,500 Pounds. found in practice that good streets and poor streets have been made from nearly all the different varieties of asphaltums and asphaltes that can be obtained in such quantity and at such a price as to render their use possible. The different results obtained appear to be due to causes external to the asphaltum or asphalte employed, such as the kind and quality of the materials with which they are mixed and the method, or lack of method, by which they are mixed. ”

“ One of the best, if not most of the processes in use to-day, will be found based upon discoveries in the early part of the 19th century that asphaltum, when it has been subjected to the action of light, is no longer soluble in its ordinary solvents. A plate therefore coated with asphaltum which has been exposed in the camera obscura to light and shade would possess a surface, part of which was soluble and part insoluble. ”

“ It leaves about one third of its weight of charcoal after combustion, and ashes, containing silica, alumina, oxide of iron, sometimes a little lime, and oxide of manganese. According to John, asphaltum may be decomposed, by different solvents, into three distinct substances. Water dissolves nothing; alcohol (anhydrous) dissolves out a yellow resin equal to 5 per cent. of the weight of the asphaltum; that resin is soluble in dilute alcohol and in ether. The portion not soluble in the alcohol gives up a brown resin to ether, amounting to 70 per cent. of the weight of the asphaltum. ”

“ While the artificial mixtures soon require expensive surfacing, the native asphaltum when taken up for piping, or otherwise, after many years' wear, may be used again by simply heating and treating it as at first. ”

“ The solution of asphaltum in turpentine, united with drying oil by heat, or the bitumen torrefied and ground in linseed or drying-oil, acquires a firmer texture, but becomes less transparent and dries with difficulty. If common asphaltum, as usually prepared with turpentine, be used with some addition of Vandyke brown, umber, or Cappah brown ground in drying oil, it will gain body and solidity which will render it much less disposed to crack. ”

“ Many deposits of this mineral are known, and two of them are particularly celebrated: those175 of the Dead Sea, in Syria, and the Lake of Asphalt, in Trinidad. Both deposits consist of craters filled with water on which the asphaltum floats in large cakes.
Several kinds of asphaltum are met with in commerce, ranging in colour from brown to black. The preparation of the material as a pigment is confined to grinding the mass, which is always of a low degree of hardness. ”

“ The asphaltum pavement is clean and fit for traffic a few hours after being laid, while new or repaved stone roadways must be covered for months with heavy layers of sand, to be drifted by the breeze in dry weather and added to the mud in rainy spells. Repairs can be made to the asphaltum pavement in dry days of a cold winter, while with stone pavements any defects must be endured until spring. ”

“ 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 ”

“ There is no doubt that asphaltum pavements may occasionally fail, but, when they do, this is attributable not to the material, if unadulterated, but rather to the method of its application, which requires skilled workmen, whose eyes and hands are quick and directed by an intelligent mind. ”

“ 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. ”

“ Asphaltum occurs abundantly at the surface of the salt lake Asphaltites, in Judea, produced from springs in the neighbourhood; it is floated down, gathers consistence, and accumulates upon the surface of the lake; the winds drive it on the shores, and the inhabitants collect it for sale. Its inspissation diffuses a disagreeable smell in the air of that region, which is supposed by the natives to be powerful enough to kill birds when they attempt to fly across the lake. ”

“ Asper ́ula, the woodruff genus of plants.
Asphalt, or Asphal ́tum, the most common variety of bitumen; also called mineral pitch. Asphalt is a compact, glossy, brittle, black or brown mineral, which breaks with a polished fracture, melts easily with a strong pitchy odour when heated, and when pure burns without leaving any ashes. It is found in the earth in many parts of Asia, Europe, and America, and in a soft or liquid state on the surface of the [280] Dead Sea, which, from this circumstance, was called Asphaltītes. ”

“ 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 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. ”

“ Refined Asphalt.—Refined asphalt produced from native crude asphalt shall be free from water and shall not contain an injurious quantity of light oils or foreign matter. It shall not contain more than four per cent. (4%) of organic matter nor more than thirty-six per cent. (36%) of inorganic matter other than bitumen, and not more than eighteen per cent. (18%) of fixed carbon, and not less than fifty-five per cent. (55%) of bitumen soluble in cold carbon di-sulphide. Of the bitumen soluble in carbon di-sulphide not less than sixty-three per cent. ”

“ 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. ”

“ COMPRESSED ASPHALTE ROADWAYS. The word asphalte in its generally accepted sense implies a natural rock consisting of pure carbonate of lime, intimately combined and impregnated with mineral bitumen in very variable proportions; that used for roads or footpaths should not contain less than 7 or more than 12 per cent. of bitumen.
The rock when broken takes an irregular fracture without definite cleavage; it is principally derived from Val de Travers, Seyssel, Sicily, Chieti, Auvergne, Lobsann, and Limmer. Its grain should be regular and homogeneous, the finer the grain the better. ”

“ Asphalt is produced artificially in making coal-gas. During the process much tarry matter is evolved and collected in retorts. If this be distilled, naphtha and other volatile matters escape, and asphalt is left behind. It is sometimes called Jew's Pitch.
Asphalte (or Asphalt) Rock, a limestone impregnated with bitumen, found in large quantities in various localities in Europe, as in the Val de Travers, Neufchâtel, Switzerland; in the department of Ain in France; in Alsace, Hanover, Holstein, Sicily, &c. ”

“ The exposed asphalt, whether this exposure is made by printing or whether a drawing is first made and then exposed to the light, adheres more firmly to the stone or zinc plate than if it was not exposed. An asphalt drawing prepared in the dark and inked up does not adhere to the stone, and this may be explained in that the grease cannot act through the asphalt film. ”

“ A fluid residuum of heavy petroleum or mineral tar. which has also been deprived of water and light oils, is mixed with the asphalt in the proportion of 20 parts by weight of oil to 100 parts of asphalt. It is of the highest importance that this mixture should be very complete. If the blending is imperfectly done, the oil will wash out from the asphalt after the street is laid and the surface will dry out, crack and disintegrate. This asphaltic cement should be plastic and very tenacious and should preserve these properties through a wide range of temperature. ”

“ It has been found that of the bitumen extracted from asphalts which have given the most satisfactory results in making street pavements, sixty-nine per cent or more is soluble in petroleum naphtha having a specific gravity of 72° Beaumé.
An asphalt pavement can not be economically kept in good condition unless every defect which may develop is immediately repaired. When the smooth, hard surface is once broken, disintegration proceeds very rapidly, and a large hole is soon formed. ”

“ 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. ”

“ All kinds of asphalt have a pungent and peculiar smell, melt at a low temperature, are very combustible, and while dissolving in turpentine, and more readily in coal tar naphtha, are insoluble in water and in alcohol. Very little asphalt is now used as a pigment, but it continues to find a limited application in varnish making, notwithstanding the tendency of varnishes containing it to suffer from minute cracks with the lapse of time. ”

“ From the cellar to the roof, asphalt has been used where the requirements have been water and fire proof floors. Its principal merits are its utter imperviousness to water or damp, and its elasticity, whereby cracking, especially from the influence of frost, is prevented. Also from a sanitary point of view the advantages of asphalt are incontestable, for it possesses great antiseptic properties, and, owing to its having no joints, it is impossible for particles of animal or vegetable matter to lodge in crevices and putrefy. ”

“ A course or two of Staffordshire blue bricks in cement is excellent where heavy weights have to be considered. Glazed stoneware perforated slabs about 2 in. thick are specially made for use as damp-proof courses. Asphalt (fig. 9) recently has come into great favour with architects; a layer 1⁄2 or 3⁄4 in. thick is a good protection against damp, and not likely to crack should a settlement occur, but in hot weather it is liable to squeeze out at the joints under heavy weights. Felt covered with bitumen is an excellent substitute for asphalt, and is not liable to crack or squeeze out. ”

“ In order to do this there is usually added to each one hundred pounds of refined asphalt about eighteen pounds of heavy petroleum oil. After this addition we have the asphaltic cement ready to combine with mineral matter, which is so selected that when asphaltic cement is added at the rate of about seventeen pounds of the cement to eighty-three pounds of the other all the particles will be coated, and more could not be added without making the pavement too soft. What is found to accomplish this best is fine stone dust and sand. ”

“ The relative proportions of sticky petrolenes and cohesive asphaltenes is the most important element in bitumens which are used in the construction of asphalt pavements and bituminous highways. It has been found that the asphalt cement, that is to say, a solid asphalt combined with a suitable flux to provide the proper consistency for practical use, if it contains less than 15 per cent, of asphaltenes will lack cohesiveness and stability or body, while, on the other hand, if it contains less than 70 per cent, of petroleum it will not be sufficiently adhesive. ”