Mr. H. L. Pattinson on Smelting Lead Ore, §c. 169 



in front, 6 inches wide, by 9 inches high, as shewn at e, Fig, 3. The 

 two flues ff, Figs. 2 and 3, communicate with the chimney, and in 

 other respects, except those to be afterwards noticed, the furnace is 

 finished in the usual manner. 



The bed or bottom of the furnace when in operation, is formed by a 

 shallow elliptical vessel, called a test or test-bottom, the construction of 

 which merits particular attention, as it is an important part of the re- 

 fining apparatus. Plate I. Fig. 8, represents an elliptical iron ring, 4 

 feet long, 2 feet 6 inches broad, and 4 inches deep, outside measure. 

 The thickness of the iron is five-eighths of an inch, and across the bot- 

 tom of the ring, are five bars, each 3i or 4 inches broad, and £ an inch 

 thick, firmly rivetted into the ring, with the under surface of each level 

 with its lower edge. The ring is filled with a mixture of one part by 

 measure of fern ashes, and ten parts of ground bone ashes, well incor- 

 porated and moistened with a little water, until a small quantity, when 

 compressed in the hand, is found to cohere slightly together. In filling 

 the test ring, it is placed upon a level floor, and this composition strong- 

 ly beat into it, with an iron rammer 5 or 61bs. weight (similar to those 

 used by founders for compressing sand into moulds), until it is quite full, 

 and the surface of the mixture perfectly level with the upper edge of 

 the ring. A sharp spade is then taken, with which a part of the com- 

 position is removed, so as to form the test into a flat dish of the shape 

 represented in Fig. 6, and in section, Fig. 7> a longitudinal section of 

 which, in its proper situation, is also shewn at Fig. 3, and a cross sec- 

 tion at Fig. 4. The bottom of this dish is about If inch thick between 

 the bars, and the part g, Fig. 6 and 7, called the breast of the test, is 

 5 inches thick, the remainder of the circumference being 2 inches thick, 

 and sloping inwards to increase its strength, as shewn in the figures. 

 Across the breast of the test, a furrow or small channel, called a gate- 

 way h, Fig. 6, is cut diagonally, one inch wide and three-quarters of an 

 inch deep, as a passage for the Litharge ; and it is made near one side 

 of the breast, in order that a similar passage may be cut on the other 

 side, after the test has been some time in operation, and the first gate- 

 way has become worn down by the stream of Litharge. A space 1£ 



