258 ASPHALTUM 



Staffordshire, and elsewhere. It is generally said that masses of asphalt float on tho 

 surface of tho Dead Sea, or Lake Asphaltitos whence tho name but according to 

 modern observers, tho quantity found at present is but small. Tho vast deposit 

 of asphalt in the Great Pitch Lake of Trinidad is described under tho head of 

 BITUMEN. A substance known as chapapote, or Mexican asphalt, is imported from 

 Cuba. 



Large masses of rock impregnated with asphalt are found in certain localities on 

 the Continent, and are important as furnishing most of tho asphalt used commercially. 

 Perhaps the best known of those deposits is the great mass of Jurassic limestone in 

 the Yal do Travcrs, at Soyssel, on tho Rhone. Similar rocks occur at Limmer, near 

 Hanover ; in tho Islo of Brazza in Dalmatia ; at Holle, near Heidc, in Holstein ; in tho 

 Tyrol, and in Alsace. 



Under tho head of BITUMEN will be found some historical notices of the ancient 

 use of asphalt and kindred substances for building purposes. In modern times 

 attention has frequently been directed to tho utilisation of tho asphaltic rocks of 

 Switzerland, especially as a source of asphalt for paving. Without following tho 

 vicissitudes of the Swiss workings since they were originally commenced by Erinus, 

 in 1712, it may suffice to saythat within the last few years considerable attention has 

 bsen directed to their development, and that they are uow actively worked. Originally 

 the asphalt obtained from the rocks of these quarries was employed in the form of a 

 liquid, melted out from the limestone, and spread over the pavement durability 

 being imparted to the material by admixture of coarse sand and by sprinkling sand 

 or gravel over the surface. Tho following is the modern method of laying down 

 asphaltic foot-paths, as practised in Paris : A foundation is first formed by a layer 

 of concrete, the surface of which is carefully flattened. On this even surface, when 

 dry, the melted asphalt is spread. This asphalt is melted in a cauldron, and a proper 

 proportion of sand added the mixture being kept stirred to prevent subsidence of 

 the sand. The asphalt is spread with a wooden trowel over the concrete, and tho 

 surface is finally smoothed over. 



Of late, a very great improvement in tho construction of asphalt roads has been 

 introduced, the merit of tho new method being due to M. A. Merian, of Basle. Tho 

 asphalt is laid down in tho form of a hot powder, and the powder is then beaten into 

 a compact mass. The process has been thus described by M. Leon Malo : ' The 

 asphalt stone is brought direct from the quarries, and broken up into small pieces 

 about the size of those used for macadamized roads ; it is then heated over a stove, in 

 a drum-shaped iron vessel with feet, till it crumbles into powder ; and in order that 

 tho powder may not lose its heat, the whole apparatus is conveyed on to the street 

 where it is to bo applied. Then a foundation of blton (concrete) is laid, about 4 inches 

 deep, which may, however, be thicker or thinner according to tho nature of the soil.' 

 The concrete having hardened, its surface is brought to the required curve, and a 

 layer of powdered asphalt, 16 to 20 inches thick, laid down and compressed by 

 stamping, the surface being finally smoothed by a heavy roller. 



Tho Val do Travers asphalt quarries are now largely worked, and several experi- 

 mental patches of paving with this asphalt have been laid down in some of. the main 

 thoroughfares of London, and have in general proved highly successful. 



In addition to the use of asphalt for pavements and roadways, the material is of 

 value as a waterproof lining for cisterns, and as a cement. It also finds application 

 in tho arts as a component of certain varnishes. See BITUMEN and PAVEMENT, 

 ASPHALT. 



ASPHALTEBTE. A product obtained from asphaltum by volatilising the oily 

 and volatile product petrolene. 



ASPHAZiTIC MASTIC, used in Paris for largo works, is brought down tho 

 Rhone from Pyrimont, near Soyssel. It is composed of nearly pure carbonate of 

 lime, and about 9 or ten per cent, of bitumen. 



When in a state of powder it is mixed with about 7 per cent, of bitumen or 

 mineral pitch, found near tho same spot. Tho powdered asphalt is mixed with 

 tho bitumen in a melted state along with clean gravel, and consistency is given to 

 pour it into moulds. Sulphur added to about 1 per cent, makes it very brittle. 

 Tho asphalt is ductile, and has elasticity to enable it, with tho small stones sifted 

 upon it, to resist ordinary wear. Walls having cracked, and parts having fallen, 

 the asphalt has been seen to stretch and not crack. It has been regarded as a 

 sort of mineral leather. The sun and rain do not appear to affect it ; and it answers 

 for abattoirs and barracks, keeps vermin down, and is uninjured by the kicking of 

 horses. 



ASPHAXT OH. An oil obtained from asphaltum by dry distillation. 



ASPHAXiTUlVX. See ASPHALT. 



ASPHALTUM, GAS-TAH, or ARTIFICIAL. When, with the thick pitchy residue, 



