﻿Geoege. — On Experiments on Coal for Steam Puriwses. 151 



Art. XY. — On Experiments made to determine the Value of Different Coals 

 for Steam Purposes. By J. E-ees George. 



[Read before the Welling ton Philosophical Society, 14d,h October, 1871. J 



The value of different New Zealand, coals for steam purposes will be best 

 illustrated by comparing the work performed with coal from longer established 

 and more deeply worked mines. Mr. John Kebbell, of Wellington, having 

 kindly furnished me with the result of several trials made at his mill, togietlxer 

 with his notes on the subject, I now lay the same before the Society as a con- 

 tinuation of the paper read a short time back on the New Zealand coal for 

 gas purposes. 



Mr. Kebbell's trials were made by bui^ning half a ton of coal, and ascer- 

 taining the time the engine was kept at work with the consumption of this 

 weight of coal ; care was taken in each case that the height of water in 

 the boiler, the pressure of steam, the work being performed by the engine, 

 and all other circumstances, should in each case present exactly the same 

 conditions when the trials were commenced and completed. 



The result of three experiments in 1869 was as follows : — 



h. m. 

 No. 1. — English steam coal . . worked engine 3 35 

 No. 2.— Newcastle, N.S.W., . . „ „ . 3 50 



No. 3. — Bay of Islands (Kawa Kawa) coal „ . 4 20 



No. 1, English coal, would generate steam very rapidly if required. 



No. 2, New South Wales coal, made 114 pounds waste from the half ton. 



No. 3, Bay of Islands ; this coal made twenty-eight pounds pure clinker. 

 The clinker is as injurious to the fire bars as the South Wales coal of England; 

 it adheres very strongly, and can only be removed by allowing the bars to 

 cool down. If it were not for this fault it would be a good steam coal. 

 With narrow spaces between bars, say five-eighths of an inch or less, it 

 might give a better result ; the ashes should be returned quickly to the 

 furnace or they waste away. 



Experiments made with the same weight of coal, during the present year, 

 gave the following results ; the improvement will be due to alterations in the 

 engine and boiler : — 



No. 1. — English steam coal 

 No. 2. — Collingwood coal. No. 1 trial 

 No. 3. — Collingwood coal, No. 2 

 No. 4. — Grey coal 





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worked engine 



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