33

0.—4.

district, from 831,200 tons of coal mined, 230,049 tons of slack, equivalent to 27-7 per cent, of the total output. It is a reasonable assumption that at least 25 per cent, of the output of the mines in the future will be slack. It was with a view of trying to discover a use or market for this otherwise waste product that our investigations were mainly directed. So far as we could learn there have been only two uses to which this slack has been put—firstly, as bunker coal for steaming purposes; and, secondly, for the manufacture of briquettes and eggettes at Westport by the Government. In regard to the former the market is limited, and the demand is not nearly sufficient to utilize the large quantity of slack produced during the operations of mining. A small quantity may in the future be used for manufacture into coke, the Westport Coal Company having recently erected six coke-ovens at Granity in connection with their Millerton mine. But, again, the New Zealand market in this direction is limited, and the demand for coke is not likely to absorb any great "quantity of the surplus soft coal and slack. Our attention has been directed to a new steam boiler in which pulverized coaldust is used as a fuel. If this type of boiler were to come into general use in New Zealand no doubt a market would be created for slack coal, but, so far as we are aware, no such boilers are in use in New Zealand, and there is nothing to indicate that they will come into such considerable use in the near future as to create any such market. Dealing with the question of the manufacture of briquettes and eggettes by the Government, the evidence before us goes to show that these operations have not resulted in a financial success, though the article produced is of a good marketable quality. The works were established in 1907, and up to the present the bulk of the output has been used by the Government Railway Department. The returns for the year ending 31st March, 1911, show that out of a total of 8,564 tons manufactured 7,343 tons were used by the Railway Department, 4 tons by other Government Departments, and 1,217 tons by the general public. It has been shown in evidence that the value per ton of briquettes and eggettes for railway purposes is less by 2s. and Is. 6d. respectively than that of screened coal. The following analyses made by the Dominion Analyst show the relative values in calories and evaporative powers between coal from different mines and briqiiettes :—

The outside market has been particularly small. It has been suggested that this market has not been sufficiently pushed, but the evidence before us does not 5—C. 4,

Mines. I ; j A o rO r5 p <D K o ,o 5 o p -a rH H © j i rg 3 rB"5 CO -rf! -p O H M O O c o bl: -fa a o rEvaporatii in Po Water at ! "3 '•£> IB u o rd re Power mds; 2I2°Fahr. <3 fl c c •J s-s 1 »r?!8 Cm CG* o 6 " i 'i i Coal. Denniston 57-36 56-62 55-73 58-75 39-61 38-40 40-08 37-24 i i 1-55 4-30 2-37 3-61 1-48 0-68 1-82 o-4a 2-18 0-56 0-55 1-74 58-84 57-30 57-55 59-15 8,230 7,762 7,923 7,708 15-35 14-48 14-78 14.38 9.21 8-69 8-87 8-63 Millerton 57-67 60-50 41-14 34-39 < ( 0-91 0-83 0-28 4-28 4-62 3-92 57-95 64-78 8,227 8,135 15-35 15-18 9-21 9-11 Seddonville . . 51-12 52-27 42-24 41-20 I ' 4-36 4-65 2-28 1-88 4-94 4-99 53-40 54-15 7,402 7,345 13-81 13-73 8-29 8-24 Seddonville — Briquettes.. Eggettes .. 48-84 46-93 41-46 42-05 5-54 8-03 4-16 2-99 3-62 3-74 7,249 6,969 13-53 13-00 8-12 7-80