[Footnote: Read before the Society of Public Analysts on the 28th June, 1883.]
By OTTO HEHNER
Some discussion having recently taken place as to the value of New Zealand coal as a fuel, the following results of a somewhat full analysis may be worthy of being placed on record.
The sample to which the results refer consisted of large brownish black lumps, many of which showed woody structure; the fractures were conchyloid, the surface shiny and highly reflecting. It was interspersed with a considerable amount of an amber colored resin. When powdered it appeared chocolate brown. It burned readily, the flame being bright and very smoky. Its ash was light and reddish brown.
It consisted of--
Water (loss at 212° F.) 20.09 Organic and volatile matter 75.19 Ash 4.72 ------ 100.00
The organic and volatile constituents had the following percentage composition--
Carbon 71.26 Hydrogen 5.62 Oxygen 21.58 Nitrogen 1.06 Sulphur 0.48 ------ 100.00
The ash was composed of--
Silica 27.26 Alumina 26.48 Oxide of iron 12.98 Lime 20.19 Magnesia 3.42 Sulphuric acid 9.47 Alkalies and loss 0.20 ------ 100.00
From these figures the composition of the coal itself calculates as under--
Water 20.09 Carbon 53.58 Hydrogen 4.23 Oxygen 16.23 Nitrogen 0.80 Sulphur 0.36 Silica 1.29 Alumina 1.25 Oxide of iron 0.61 Lime 0.95 Magnesia 0.16 Sulphuric acid 0.44 Alkalies 0.01 ------ 100.00
One ton furnished 8,458 cubic feet of gas and 8 cwt. of coke.
The very high proportion of water contained in the sample is very remarkable. It was so loosely combined, that even at ordinary temperature it gradually escaped, the coal crumbling to small pieces. The large amount as well as the high percentage of oxygen characterize the so called coal as a lignite, with which conclusion the physical characters of the sample are in perfect harmony.
The resin to which I have referred has not been further analyzed. It was found to be insoluble in all ordinary menstrua, such as alcohol, ether, carbon disulphide, benzene, or chloroform, and neither attacked by boiling alcoholic potash nor by fusing alkali. On heating it swells up considerably and undergoes decomposition, but does not fuse.
The coal may be valuable as a gas coal and for local consumption, but the large proportions of water and of oxygen militate against its use as a steam producer, only 58 per cent. of it being really combustible.