to use lime in the building of the ovens, but what was described in the paper was loam-mortar, and he (Mr. Steavenson) understood this to mean the use of loam instead of lime-mortar. The cost of manufacture was a little above that of this district, namely, 1s. 7d. against 1s. 5d. to 1s. 6d. per ton; wages, however, were high, and he was not surprised at the cost being a little more. The paper described a seam of good coking coal, and under such conditions it was not surprising that the coke was obtained cheaply, and it was no fault of the managers of collieries here that they could not compete with them in price,

It was stated in the paper that no attempt had been made to utilize the waste-products, and in this respect America is very far behind this country. He (Mr. Steavenson) did not go so far as Prof. P. P. Bedson, who contended that they were bound to extract from the coal every product which it was capable of yielding. To put down a plant capable of extracting bye-products from 700 coke-ovens would involve an outlay of £90,000, or more than twice the cost of ordinary bee-hive coke-ovens. Before entering upon such a very large outlay, it was necessary to consider whether the bye-products would justify the expenditure, and it would be seen by referring to an article on "Cokeoven Residuals "* that some of these bye-products had a very limited market, and had recently experienced a very serious fall in prices. He had supplied blast-furnaces with coke from beehive coke-ovens for the last 50 years, and during that time he had been at least once a week to the furnaces, and therefore knew exactly what kind of coke they wanted. He found that if they used coke from retort coke-ovens, 2 cwts. more of such coke were required per ton of iron than of coke from beehive cokeovens. Many engineers had experimented with a few retort cokeovens, but they were generally very shy of giving their results; and merely contented themselves with stating that the coke was just as good.

With 28 beehive coke-ovens, they could boil, with a Lancashire boiler, 80 tons of water in 24 hours. Assuming that this quantity of water was boiled by coal, it would be found that this alone represented something like 1s. per ton of coal put into the oven, and this he contended was a very useful mode of utilizing what might be termed a bye-product. At three large collieries * Colliery Guardian, 1902, vol. lxxxiv., page 360.

raising about 1,000 tons per day, they were using no coal whatever for their boilers, and he would defy anybody to come forward and say that retort-ovens were giving better results than this: taking into account, in the case of retort-ovens, the extra cost per oven for distilling the bye-products, and the great doubt there was as to the value of the material compared with the known value of the gases used under the boilers.

Mr. F. R. SIMPSON suggested that in all papers of this kind it would be an advantage if the unit of weight was the ton of 2,240 pounds. The special feature in the plant of beehive coke-ovens described was the low cost of producing coke, due chiefly, as Mr. Steavenson had pointed out, to the low cost of the coal. Reducing the figures to the British ton, the total cost amounted to only 7s. per ton. Taking the yield of coke at 67 per cent., the coal put into ovens only cost about 3s. 3d. per ton, a very low figure. The cost of labour in converting the coal into coke, was about 1s. 9d. per ton, or slightly higher than the cost at many coke-yards in the North of England, and this was accounted for by the higher rate of wages paid to the men. The cost of materials was low, being about 0-80d. per ton of coke produced. The average cokeproduction per day from 300 ovens drawn was 675 to 700 short tons, or 603 to 625 long tons; and at the rate of three drawings of each oven per week, this gave 12 tons per oven per week, a result which could only be obtained by regular working. Messrs. Oliver supplied the coke to their own blast-furnaces, and any small variations in the quality would be treated with greater leniency than in the open market. Over 9 per cent. of ash, on the average of the analyses, appeared high when the whole output was converted into coke, and many collieries in Durham could manufacture coke from small coal with the percentage of ash quite as low.

The statement that the establishment of 700 beehive cokeovens was until recently the second largest in the world, was rather sweeping, and might perhaps be modified into an expression of opinion.

Mr. J. C. B. HENDY (Etherley) said that all who had read Mr. Keighley's paper would agree that the writer had every reasou to congratulate himself upon the nature and quality of the coal that he had to coke. A coal which could be thrown into

the ovens as it came out of the mine, without any cleaning, crushing or any treatment whatever, and yield 67 per cent. of coke which only contained about 9 per cent. of ash and 0.7 per cent. of sulphur, was very valuable, especially if it could be put into the coke-ovens at a cost of 4s. 4d. per ton. The Connellsville seam is naturally an excellent coking coal, but when we come to consider the manner in which it is treated and the construction of the coke-ovens described in the paper, there are several points. which are open to discussion.

Setting aside the question of the recovery of the bye-products, there is apparently at the Oliver coke-works no attempt whatever to utilize in any way the waste-gases from the ovens, either for raising steam or any other purpose. The ovens are burnt out of the top-eye. There may be some special reason for it, not explained in the paper, but it is rather surprising to find, in such a large plant and where so much money has been expended, that there is no arrangement of flues to the ovens. He (Mr. Hendy) thought that if a properly constructed main flue had been made between the rows of ovens, with branch flues from each oven into the main flue, and dampers so arranged in the branch flues that the coke-burner could regulate the proper proportion of air-supply to each oven and shut off the oven from the main flue when necessary, a much better and more economical result would have been obtained.

The ovens appear to have been built (in the first instance) of ordinary fire-bricks, which after about 4 or 5 years have fallen in, partly owing, no doubt, to the poor quality of the bricks and partly to the construction of the oven. Mr. Keighley also appears to have used a brick made of flint-clay containing about 64 per cent. of silica and 26 per cent. of alumina, but he (Mr. Hendy) could not make out from the paper where these bricks had been used. The latter is evidently a mixed brick, or a brick made of a mixture of clays yielding together the above proportions of silica and alumina. Mr. Keighley is now, however, using a brick containing about 97 per cent. of silica. Such a brick, no doubt, is eminently suitable for very high temperatures, but he (Mr. Hendy) doubted whether it would stand the constant heating and cooling to which a coke-oven was subjected, and he believed that if the coke was slacked in the oven, the water and steam would have the effect of cracking this brick and causing it to splinter and fall

into the oven in small pieces. He (Mr. Hendy) was of opinion that the best brick for use in building beehive coke-ovens contained about 70 per cent. of silica and 23 per cent. of alumina, and was made from a clay naturally yielding of itself these proportions of silica and aluminia. He had known several instances of such a brick lasting in beehive coke-ovens for 20 to 25 years: of course the back-eyes and door-jambs had been repaired during that time, but the body of the coke-ovens had stood for that period.

He (Mr. Hendy) agreed with Mr. Steavenson that a diameter of 11 feet was the most convenient and useful size for a beehive coke-oven.

In the ovens at the Oliver works, the doors were only 2 feet 8 inches wide and 2 feet 8 inches high to the spring of the arch; he thought that this door was rather narrow for a 12 feet oven, and that the drawer might experience some difficulty in drawing out the coke from the sides of the ovens.

Further, it would be noticed that there was only one line of rails running along the centre, for loading both rows of ovens-an objection to only one line of rails was, of course, that the ovens. could not be loaded so quickly as with two lines, and that if a stoppage or breakdown occurred on the only line, the loading was stopped on both rows of ovens. He preferred a line of rails. running over each row of ovens, with a lighter and smaller locomotive and smaller coal-tubs.

He

A striking feature in this paper was the low cost of production compared with the rate of wages paid for coke-making. noticed that chargers were paid 7s. 8d. per day; ash-carters, 6s. 8d.; track-cleaners, 6s. 3d.; car-shifters, 9s. 4d.; masons, 10s. 5d.; and labourers, 6s. 3d. The cost of the coal put into the ovens was low, but something more than this appeared to be necessary to account for the low total cost of coke-production, when the above rates of wages were considered; and it would be interesting to know the number of hours and amount of work done per day by the above workmen, and compare the same with those prevalent in this district.

Mr. Keighley had told the members that he had sold coke for 2s. 11d. per ton. They were accustomed to hear of startling things. from America, and, certainly, the most extraordinary sellingprice that he had heard of for blast-furnace coke was 2s. 11d. per ton.

Mr. W. C. BLACKETT (Sacriston) thought that it was remarkable that so little account was taken, in comparing the different kinds of coal, of the temperatures at which the coal carbonized. One gentleman, who found his coal, carbonizing as it did at a high temperature, to be best suited for a beehive coke-oven, would condemn another for using retort-ovens, although the latter might be better adapted to his particular class of coal, which coked at a lower temperature. A colliery-owner might be driven at last to work an inferior seam, and from bye-product ovens, he would obtain as good, and sometimes better, coke than he would obtain, perhaps, from the same coal burnt in bee-hive ovens. In bee-hive ovens, their fine Durham coal carbonized at a very high heat, and when they had a very high heat they got a deposit of carbon-similar to that in gas-retorts-upon the coke, giving it a fine silvery and hard looking appearance. Some of the inferior coal did not carbonize at that high heat, and they did not get the same fine crystalline appearance and the same hardness, and it was comparable with the black-looking coke, watered outside, produced at bye-product ovens.

Mr. W. O. WOOD (South Hetton) wrote that, judging from the particulars given in Mr. Keighley's paper, coke-making was one of the things that could be done better in England. From a coal, containing 5.73 per cent. of ash, the resulting coke ought to contain 8-12 per cent of ash, and the 9-25 per cent. was no doubt due to the fact that "no cleaning or slate-picking is done." Iron-masters in this country would certainly not be satisfied with a coke containing so high a percentage of ash. The yield appeared to be fairly good, and the breeze was apparently wasted.

Without knowing the country, it was difficult to judge, but unless the region was very arid, the supply of water necessary for cooling the ovens could have been collected in reservoirs at a very small proportion of the cost of the pipe-line, 12 miles in length, to say nothing of the cost of pumping the water.

The PRESIDENT (Sir Lindsay Wood, Bart.) said that Mr. Blackett had raised an important point respecting the temperatures at which coal was carbonized, and this would make a considerable difference in the results obtained from the ovens.