APPENDICES. 143 



first appearance of slag before the tuyeres. Afterwards it was increased 

 to a little over 31bs. pressure to the square inch, and to about 500 cubic 

 feet per minute in volume. At the end of the time named, I found the 

 hearth full of spongy iron, and though I raised the temperature by blank 

 charges and extra blast till I melted even the fire-bricks forming the 

 hearth, yet the iron would not liquify. On cooling down the furnace to 

 get the mass of iron out, which was over 30 cwt., I found a great portion 

 of it similar to what a puddled ball would be if it were left without 

 being shingled. A number of pieces were cut off and worked in a 

 smith's forge without any great difficulty. In the mass of iron in the 

 hearth were embedded pieces of ashes from the coal which had dropped 



Coal decrepitates at doWn P ast the ^7™ without being fused. At 

 tunnel head. the tunnel head I noticed that the coal rapidly 



decrepitated, which is doubtless due to the quantity 

 of moisture it contains. This impoverished coal then descended to the 

 zone of fusion just above the tuyeres, with little or nothing left to do 

 the work required of it." 



The sectional diagram, which was communicated with the paper, 

 showed that the furnace was 24' high ; that the 

 fuma C c fc r al diagl " am ° f t0 P of tne bosh was 6' 6" in diameter; that the top 

 of the hearth was 2' 6" diameter ; and that the 

 bottom of the hearth was 2' 0" diameter. The throat of the furnace was 

 3' 10" diameter, and the tunnel head 5' 6"; the tuyeres were 2|" diame- 

 ter in the nozzle. The hearth about 3' 6 // deep. The blowing engine is 

 a small horizontal one, with a receiver intermediate between the engine 

 and the hot-air stove, which has four pipes. The air is heated with an 

 ordinary grate and stove. 



In the discussion that took place after the reading of Mr. Ness' letter, 



one speaker showed how coal, not greatly inferior to 



ber S 1S of "south ^taS" tnat witn which Mr. Ness had to deal, had been 



SX^aSLS 88 made available for b]ast faa <* purposes, by holes 



being made in the furnace above the tuyeres and 



( 143 ) 



