Iro&. 
Ble= stand, should be 6 inches high from the centre of the 
grate, wherein there should be an even platform of 4 inch- 
es diameter to receive it and enable it to stand steady* 
At 6 inches from the top of the furnace there should be 
an horizontal side flue of 6 inches by 6 inches, and 9 inehes 
long, with one end opening into the furnace, and the other 
into the upright chimney . The chimney should be 6 inches 
by 9 inches or thereabout, and not less than 20 feet high 
The cover should be of fire clay mixed with burnt bricky 
well beaten, and burnt, and enclosed in a wrought iron 
frame with a handle to lift it on and off by. This cover 
should fit accurately to the surface of the furnace, and be 
at least 14 inches square. With such a furnace, heat 
enough may be given for most experiments, especially if 
about 1-2 of the coak of pitcoal be mixed with the char- 
eoal ; neither of these ought to be used in lumps bigger 
than a small egg. The inside of the furnace ought to be 
lined with refractory or infusible lire clay over fire brick ; 
©r else with a mortar of pounded clay mixed with pound- 
ed soap stone. Mushet’s assay furnace with a pyrome- 
tor measuring the degrees of heat, is to be found in 4 
Philos. Mag. 255. blit I like my own as well* The powv 
erful three-blast assay furnace of the French school of 
mines, is delineated in 14 Philos. Mag, 69. It is work- 
ed by 3 equidistant tweers, It should be remembered that 
both in England and France, the men of science in their 
laboratory, and the men of experience in the iron manu- 
facture, have gradually encreased the admission of air into 
their furnaces, and divided the quantity between two 
fweers. 
The first process I would advise should be to ascer- 
tain whether there be any limestone in your ore, and 
how much. For which purpose 
Take 400 grains of the ore in fine powder, from among 
piepowder of at least half a dozen fair specimens of the m ine. . 
