246 



Method of 

 •working tiic 

 schistus. 



YOEKSHIRE ALUM WORKS. 



the alum rock (as It is generally called). The hewing of the 

 rock is performed with picks and javelins ; and it is con- 

 veyed to the calcining place in barrows, so contrived, that 

 the centre of gravity of the weight, is in a perpendicular line 

 pasting through the centre of the axle of the wheel ; by this 

 means the men have nothing more to do, than to keep 1)he 

 barrow steady, throw the wtight of the substance upon the 

 wheel, by raising the handles, and direct the barrow upon 

 the way, which is formed of cast iron plates, 6 feet in length, 

 6 inches iu breadth, and half an inch thick ; tliese plates are 

 fastened into cross pieces of wood fixed into the ground, at 

 the end of each plate. Ten of these barrows contain one 

 solid yard of the rock. The expenses of working the rock 

 vary according to the facility with which it can be hewn. 

 When the distance the rock is to be harrowed is about 200 

 yards, the rate for removing and hewing one cubic yard is 

 about Ci-d. It is unnecessary to state, that the price must 

 maintain a corresponding ratio with the distance to be con- 

 veyed. The men earn about 2s. 6d. per day in the winter 

 season, and 33. in the summer. 



The rock is poured out of the barrows upon a bed of fuel, 

 composed of underwood, furze, &c. The dimensions of this 

 pile of faggots is about four or five yards in breadth, and 

 two in height; as the rock is deposited upon the fuel, it is 

 necessary tiiat it should be broken into small fragments,, 

 that the combustion may take place with the greater faci* 

 lity. When they have got about four feet in height of thp 

 rock upon the faggots, fire is set to the bftttom, and, fresh 

 rock continually poured upon the pile; other piles of wood 

 are then placed alongside of the first, and they proceed as 

 before, adding more ;ock, firing the fuel, &c. This they 

 continue, uutil the calcined heap is raised to the height of 

 QO or 100 feet, and from 150 to 200 feet in length and 

 breadth. Some of these heaps of calcined mine (as it is 

 now called) will contain 100,000 solid yards of schistus or 

 rock. 



When the whole heap Is in a state of combustion, a con- 

 siderable quantity of sulphureous acid gas is disengaged, 

 ibis they endeavour to prevent, by moisteniug small schistus, 

 and forming a kind of clay; with thisthey plaster the out- 

 side 



