the different quantities consumed during the tests. The comparisons given will be slightly in favour of the gas, but not to a sufficient extent to affect the value of the experiments.

The specific gravity of the various gases I have been unable to ascertain, but I am not sure that the specific gravity of gas is a reliable testimony of its value as an illuminating agent, as a large specific gravity may arise from the presence of carbonic acid, one of the many impurities of coal gas.

In some instances the illuminating power is given as from twenty-one to twenty-five, and an average; in these cases the photometer was read at different periods during the baking of the coal; on the Grey coal for instance, half an hour after starting the photometer gave twenty-two and a half candles; one and a half hours after starting, twenty-four candles; two and a half hours after starting, twenty candles, which was the lowest reading.

A fact worthy of observation, and one I am unable to explain, in reference to the Grey coal, is that the slack or coal dust gives a better illuminating power than the large coal.

In classifying the coals in accordance with their relative values, at the head of the list I must place the New Zealand coal, from the Brunner mine on the Grey River. It will be difficult, indeed, to discover any coal more suited to general purposes, and for this reason I think it entitled to the first place. It is not only a very good steam and house coal, but also gives a large quantity of gas of very fair illuminating power. It is more free from impurities than any coal I have tried, and the coke remaining after the gas is worked off is large in quantity, of first-class quality, and, in burning, clinkers less than the coke from any of the other coals.

The Collingwood coal is next best on the list, and for purely gas purposes is superior to the Grey coal. The quantity and quality of the gas obtained is equal to that from good English Cannel, but it possesses one great advantage over English Cannel, viz., that it leaves a large quantity of coke of fair quality. Coke obtained from Cannel is of very little value; the Collingwood coke, however, appears to be superior to some of the coke obtained from the Australian coals for heating purposes, but it makes a larger amount of clinker. The gas obtained from this coal possesses a great advantage over most, as it appears to be less affected by storage, and does not lose its illuminating power so quickly. This coal contains very little sulphur, or other impurity, and is a very good house coal. For steam purposes it has been tried by Mr. Kebbell, of Wellington, who informs me that he finds it superior to New South Wales coal, but has not yet reduced the result to figures.

Third on the list I should place the Newcastle coal, of New South Wales. Of the samples tried there is not a very marked difference, but the coal from the Australian Agricultural Company's mine is, for general purposes, the best

of these, the Old Lambton being second, and Co-operative Company's third.

Bay of Islands coal gives a large quantity of gas, of average illuminating power; the coke obtained is smaller in quantity, and not of such good quality as that obtained from the Collingwood coal; the large quantity of sulphur contained in this coal makes it difficult to work and expensive to purify; this defect reduces very considerably its value for general purposes.

A specimen of coal sent from Mount Somers, on the Ashburton River, in Canterbury, is entirely useless for gas purposes, in fact, appears to be a sort of lignite. The gas obtained from this sample burns with a small blue flame, giving no light whatever.

It is necessary to mention that the weight of coke is ascertained after being extinguished with water, on being removed from the retort, and it shows the weight available for sale. This accounts for the great difference observable in the weight of coke, as, if rapidly extinguished, it takes up more water than if extinguished gradually.

I may, in conclusion, state that the trials or experiments have been made with only a practical purpose in view, and that every endeavour has been made to obtain a large number of samples for comparison, but without success. I hope that at some future time I may be enabled to carry further these tests, and to report a more exact result. There can be no doubt, however, that New Zealand coal is superior for all purposes to that at present imported. The only cause of its not being more freely used is the difficulty of obtaining it, and the great price charged for it as compared with New South Wales coal; it appears only to be necessary te invest sufficient money in plant to work the mines economically, to make coal become an article of export instead of the colony depending on other places for its supply. The following will, I think, be found a correct statement of some of the circumstances that combine to shut out the New Zealand coal from the market.

At the Grey River the price of coal is twelve shillings per ton, delivered alongside the vessel; twelve shillings towage per ton is charged for vessels entering and leaving the river; making the price twenty-four shillings per ton before paying freight and dealer's profit. The report of Dr. Hector and Mr. Blackett^*

The Collingwood mine is situated on a small river, allowing vessels of only seven feet draft to enter, and the price charged for coal alongside is sixteen shillings and six-pence per ton. One disadvantage this mine labours under is, that the coal is only a thin seam of about three feet, and is always delivered wet.

At the Bay of Islands, a short time since, sixteen shillings and six-pence

was charged for the coal per ton, but I believe the price has lately been reduced. A more melancholy example of the result of incompetent management and want of means it was never my fortune to witness, than was exhibited at this mine in 1868. A seam of coal, twenty-four feet thick, only covered by an earth crust of a few feet in thickness, was being tunnelled, and in some cases the roof or covering had fallen in, leaving the coal exposed to daylight. After the coal had been obtained from the mine it was carried on a tramway worked by horses, a distance of about three miles, to the side of a tidal creek; the coal was then transferred to flat-bottomed punts, and at high water these proceeded about four miles down the creek, and delivered the coal. at the vessel's side—a staff of about fifteen or twenty men, thirty horses, and six or eight punts, being employed on the transport after the coal had left the mine. By extending the tramway little more than a mile, and erecting a small bridge about 150 feet in length over the creek, the anchorage of the colliers would have been reached, and the coal could have been delivered from the trucks to the vessel. Three men and one locomotive would have done the work, and about six shillings per ton expenses would have been saved; the expenditure required being about three thousand pounds to remove all this great expense, risk, and delay.

In New South Wales none of these disadvantages exist. A convenient harbour allows large vessels to enter, which are loaded at a very short notice, the coal on board costing only seven shillings and six-pence or eight shillings per ton.

I trust means will be adopted to develope the New Zealand mines, and so enable New Zealand coal to compete on more equal terms with the imported, with advantage both to the colony and to consumers.

Table showing Gas-producing Qualities of various Coals.

New South Wales Coal.

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