Researches on the chemistry of coal Part VII—An investigation of German brown coals and Irish peat

In continuance of investigations in the Fuel Research Laboratories of the Imperial College, London, on the chemical constitution and maturing of coals, it was thought advisable to examine some representative German brown coals in the hope of obtaining further light upon the origin of those constituents of bituminous coals which are mainly responsible for their coking propensities. The present paper summarizes the results thereof which are supplemented by some observations on a typical Irish peat. It may be recalled how in previous papers of the series it has been shown in regard to the dry organic substance of brown coals (e. g ., Morwell brown coal, Italian and Canadian brown lignites):—(i) that on being raised to a certain temperature, varying between 300 and 400º in different cases, it underwent an "internal condensation" characterized by the simultaneous elimination of oxides of carbon (but chiefly the dioxide) and steam without any appearance of oil, hydrogen, or more than a negligible amount of gaseous hydrocarbon; (ii) that on further raising the temperature there followed another range (up tocirca 500º) in which methane and heavy hydrocarbons also appeared, as though alkyl side-chains were being eliminated; but (iii) that hydrogen was not evolved until the temperature exceeded 500º. Moreover, it was shown that on being extracted with benzene under pressure it yielded neutral oils, phenols (plus acidic bodies) and phenolic estersplus a "residue" (constituting upwards of 80% of the whole coal substance) which was largely benzenoid in character.