308 On a method of treating Mineral Sulphur ets. 



fig. 2, side view ; a, is a little feeding door at the top of 

 the head, just large enough for the purpose of admitting a 

 shovel with fresh supplies of ore ; b, b, b, are doors, 

 three on each side, for the purpose of raking out the 

 burnt ore and slag ; c is the neck about 4 or 5 inches 

 wide — the ore is broken into pieces about J or \ the size of 

 the first, just large enough not to drop through the neck 

 until diminished by burning. For the first time of charging, 

 the furnace is filled from top to bottom with the ore mixed 

 with one-third its quantity of coal or charcoal, and when once 

 well-set a burning, it only requires being regularly fed with 

 ore, taking care never to allow the fire to get lower than the 

 neck part ; it may thus be kept burning without any fresh 

 supply of fuel whatever for any number of years, the heat 

 and flame of the burning ore being sufficient to set alight 

 the fresh supplies ; the height of these furnaces is about 4| 

 feet high, the head part about \\ foot, the neck between 4 

 and 5 inches broad. The length of the furnace is 6 feet, 

 and the size of the three side-doors in proportion. 



Eight of these furnaces are placed round a domed reser- 

 voir or alembic, to which they are connected by as many 

 pipes ; d, at the end opposite the feeding door «, fig. 3, 

 shows a bird's eye view of the 8 furnaces, e, e, e, e, e, e, e, e, 

 arranged round the domed reservoir, f ; to which they 

 are connected by the 8 connecting tubes d, d, d, d y d, d, d t d. 

 Fig. 4 presents the view of 2 furnaces with the domed re- 

 servoir, the others being removed for the purpose of showing 

 the action more clearly; e, e, are the two furnaces;,/, the 

 domed reservoir; d, d, the connecting tubes ; g, an aper- 

 ture admitting a stream of vapor of water for the purpose 

 of uniting with the sulphurous vapors arising from the com- 

 bustion of the sulphur in the mineral which enters the dom- 

 ed reservoir /, through the pipe d, from the head of 

 the furnace e; on uniting with the vapor of the water it 

 becomes liquid sulphureous acid, whence it passes through 



