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ADVANTAGES OF THE

tity of coke obtained from a given quantity of coalis upon an average 25 per cent, increase bymeasure from the best kind of Newcastle and Sun-derland coal, but taking into account the wasteincurred in breaking out and removing the red hotcoke from the retort, which requires the applica-tion of rakers and crow bars, a considerableportion of it becomes reduced to dust or breeze,and hence no more than hulk for hulk of the coaldecomposed can seldom be depended upon as theultimate saleable quantity of coke.&

In the new mode of carbonizing coal by meansof the horizontal rotary retorts, the increase of cokeis 150 per cent, by measure, so that one chaldron ofNewcastle coal produces two and a half chaldron ofcoke—this is the quantity produced upon an average.But when the retort is worked at a temperature to

* There is a vast difference with regard to the quality as wellas quantity of coke obtained from different kinds of coal. Some kindsof coal produce a species of coke which is so friable that it will hardlybear being moved from place to place without crumbling into dust,others produce coke in pieces of the size of small pebbles, while athird sort affords coke of a stony hardness.