Pristine bituminous coals from the United States principally contain pyrite and organosulfur compounds. Coals that have been exposed to the atmosphere contain these substances as well as elemental sulfur and inorganic sulfates. Although there are only minor uncertainties about the quantities of pyrite and sulfate, the situation for elemental sulfur remains modestly controversial. Further, chemists have not reached agreement upon the most suitable method for the determination of the organic sulfur content. Advanced physiochemical methods and the conventional ASTM procedures provide essentially equivalent results. Nevertheless, research workers continue to voice reservations about the ASTM methods. It is not clear that any major discrepancies remain when the presence of elemental sulfur and the idiosyncratic characteristics of certain samples are taken into consideration. The quantities of sulfur in demineralized maceráis can differ. Generally, the maceráis that have been separated from low sulfur coals contain comparable amounts of organic sulfur compounds. However, the sulfur contents of the maceráis from high sulfur coals can vary appreciably.Sporinite, for example, may contain 50% more organic sulfur than the associated vitrinite from the same coal. The inertinite maceráis contain less organic sulfur than the other maceráis. These results have not been convincingly explained, and present fascinating geochemical issues. Important qualitative progress has been made in the identification of the organic sulfur compounds in coal and its reaction products. Literally hundreds of different substances including thiols, sulfides, and heterocyclic compounds have been observed. Heterocyclic derivatives are particularly prevalent. Unfortunately, the quantitative aspects of the matter are not secure. Major doubts remain about the distribution of sulfur among the plausible set of functional groups in coal and about the abundances of different kinds of organic sulfur compounds.

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recently, Trifunac, Sauer, and Jonah35 have specifically addressed the question of the identity of the high mobility cation. They propose that the high mobility species are R+ and/or RH2+, the means of rapid charge movement being H" and H+ transfer, respectively. The production of R+ by decomposition of RH+• into R+ and H is very endothermic and must occur from excited ions. Iwasaki36 has also presented evidence in favor of R+ and RH2+ being mobile species. Trifunac, Sauer, and Jonah35 have suggested a mechanism for cyclohexane radiolysis in which the initial ionization leads to G(R+) = G(RH+•) = 2.5. Insofar as (34)

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