158 GEHRS 



hypothesized that the disease was associated with particulate material 

 clinging to the clothing and the skin of the individuals. Butlin (1892) 

 strengthened the hypothesis when he found a much higher rate of 

 scrotal cancer in chimney sweeps working in countries consuming 

 coal than in countries where wood was the primary fossil fuel. 

 Although coal has been used for several centuries, it was not until the 

 1950s that a large-scale epidemiological investigation provided 

 valuable data (MacMahon, Pugh, and Ipsen, 1960). In 1952, smog over 

 London resulted in several thousands of deaths related to 

 emphysema. This smog was correlated with coal consumption. 



Unfortunately, quantitative and qualitative determinations of 

 the environmental responses to coal are more difficult. Among the 

 few exceptions have been several investigations relating acid mine 

 drainage to decreases in fish and benthic communities dov^nistream 

 from the source (Butler et al., 1973; Huckabee, Goodyear, and Jones, 

 1975). The best-known incidences of environmental insult resulting 

 from coal consumption on a regional scale is acid precipitation. In 

 this respect, the Scandinavian countries offer the greatest docu- 

 mentation. Decreases in productivity of forests (Tamm, 1976) and of 

 aquatic environments (Schofield, 1976) were associated with 

 decreases in the pH of rainfall. The changes in pH of rainfall were 

 directly associated with coal consumption in the Ruhr Valley of 

 central Europe and in England. Several recent studies in the eastern 

 United States have postulated similar responses. For example, 

 Shriner, McLaughlin, and Baes (1977) found acid precipitation with 

 pH as low as 3.2 in certain episodes in eastern Tennessee. Since 

 buffering Capacities of soils and waters in the eastern United States 

 are similar to those in the Scandinavian countries, it is feasible that 

 problems similar to those identified in the Scandinavian countries 

 have Eilready occurred in the eastern United States. 



COAL-COIMVERSIOIM TECHNOLOGIES 



The United States is committed to the development of coal- 

 conversion technologies, partly as a result of concern for acid 

 precipitation but also from a necessity to produce usable and 

 transportable fuels to replace dwindling supplies of crude oil and 

 natural gas. Coal conversion is a generic term referring to any of 20 

 some processes whereby coal is changed into a liquid, gaseous, or 

 solid product relatively free of sulfur and inorganic particulate 

 materials. 



To produce usable gaseous or liquid hydrocarbons from coal, we 

 must increase the atomic ratio of hydrogen to carbon (Fig. 1), and 



