ASPHALTUM AND BITUMINOUS ROCK 403 



pany has installed a plant for mixing and preparing asphallurn 

 for street paving work, which has a daily capacity of preparing 

 material to cover an area of 18,0U0 scjuare feet. 



An asphaltum company near Garfield, Breckinridge 

 county, has a 100 ton plant. The asphalt ic rock is l^roken in 

 two sets of beaters revolving about horizontal shafts, the first 

 making 600 and the second 1,200 revolutions per minute. 

 The coarsely broken material from the first beater is passed to 

 a 2-inch screen, the oversize being returned for a second treat- 

 ment. The material passing through is treated in the second 

 beater, which delivers to a screen. Material exceeding oi.e- 

 sixteenth of an inch in size is returned to the second beater for 

 another treatment. 



In recent years a small quantity of asphaltic limestone has 

 been produced from deposits in the eastern part of Utah, nearly 

 the entire output being consumed in the local markets. Tlio 

 chief asphaltum product, however, is gilsonite (also calh^l 

 grahamite), which is mined about 60 miles from Vernal, 

 Uinta coimty. Gilsonite is a ver}" high grade material, of 

 especial value for manufacture into varnishes, lacquers, j^aints, 

 and similar products. On account of the high price it com- 

 mands, the product can stand a long distance freight rate 

 to chemical works. 



The principal use for asphaltum is ui the const met ion of 

 pavements. In addition, a considerable quantity is consiunrd 

 for the manufacture of special varnishes; for waterproofing 

 buildings and other objects as a protection against dampness; 

 for coating vessels, as a protection agahist the teredo, or shii")- 

 boring w^orm; as an enamel for iron objects; for roofing pur- 

 poses in the form of asphaltum or tar paper; for electric cur- 

 rent insulation; and as an ingredient of cement. 



Asphaltum sidewalks were first used in Paris in 1838, 

 and to-day they extend to a distance exceeding in the aggregate 

 1,200 miles. The introduction of asphaltum pavements hi 

 the principal cities of the world is given by J. W. Howard in 

 the following chronological order: Paris, 1854; London, 1869; 

 Budapest, 1871 ; Dresden, 1872; Hamburg, 1872; Berlin, 1873; 

 followed shortly after^vards by Brussels, Geneva. Leipzig. 

 Frankfort, and others. In the United Statesasocalledtarpoul- 



