Art. LV.—On the Apparent Occlusion of Sulphuretted Hydrogen in a Bituminous Goal.
[Read before the Philosophical Institute of Canterbury, 2nd November, 1898.]
Whims pulverising a sample of coal from the Westport-Cardiff Company's Hannah Hector outcrop a distinct odour of suit phuretted hydrogen was noticed, and a sensitive lead acetate paper held in the mortar was coloured light-brown. This result was the more remarkable as the Westport-Cardiff coal had been proved by repeated analyses to be freer from sulphur than the average hard coal of the West Coast district.
The finely pulverised coal lost all trace of the sulphuretted-hydrogen smell in a few minutes, and then contained 0.54 per cent. of sulphur. The coal in question is a fairly hard black coal, very lustrous, and often shows a finely developed conchoidal fracture. It does not soil the hands at all, and contains, as is the case with all the Westport-Cardiff coal, only a very small percentage of ash* (0.62 per cent. as average of many determinations). To the naked eye the coal is, except for the fissures parallel to the bedding-planes, as homogeneous as a coal could be expected to be, and quite unlikely to contain any large cavities filled with gaseous matter. When, however, we remember that even the densest of rock-forming minerals often contain cavities filled with compressed or liquefied gases, there seems no à priori reason to doubt the possibility of such gas-filled hollows existing in a piece of apparently solid coal.
Sulphuretted hydrogen is certainly formed in large quantities by the reduction of sulphates in the presence of organic matter and subsequent elimination of the sulphur from the resulting sulphides.
That brown coals have the power of absorbing a. large quantity Of sulphuretted hydrogen is also a well-established fact, and the large percentage of sulphur in many brown coals-known to contain but little iron-pyrites has been attributed by Mr. Skey to this absorption of sulphuretted hydrogen.† So far, however, I have not succeeded in finding any recorded
[Footnote] *For other analytical details see above Art. LIT., “Analyses of New Zealand Coals,” No. 18.
[Footnote] † Appendix A to Jurors' Reports, New Zealand Exhibition, 1865, p. 369, where several interesting experiments by Mr. Skey are briefly outlined.
instance of a hard bituminous coal giving off sulphuretted hydrogen at the temperature of the air.* One or two European coals, all more or less hydrous, give off small quantities when boiled in water, but it is very difficult to say whether these are parallel instances. Water may have power to den compose many of those complex organic sulphur compounds whose existence in coal is almost certain, but of whose actual properties we are still entirely ignorant.
[Footnote] *As the gas was evolved during the act of pulverisation, local increase of temperature due to mechanical action may have to be taken into account.