250 YORKSHIRE ALUM WORKS. 



pose the muriate of soda. These, and other anomalies 

 might be produced, but they are foreign to the purpose. 

 Making the 130 tons of calcined mine will produce 1 ton of alum. I 



alum. iiave deduced this number from an average of 150000 tons 



of calcined mine consumed. 



The calcined mine is steeped in water, contained in pits, 

 that usually hold about 60 cubic yards. The water thus 

 impregnated with sulphate of alumiue, called alum liquor, 

 is drawn off into cisterns, and afterward pumped up again 

 upon fresh calcined mine. This is repeated until the liquor 

 becomes concentrated to the specific gravity of I'lS ; or 12 

 pennyweights of the alum maker's weight. The half ex- 

 hausted mine is then covered with water, successively, to 

 take up the whole of the sulphate of alumine; these liquors, 

 thus impregnated, are denominated strong liquor, seconds, 

 and thirds. 



The strong liquor is drawn off into cisterns, to deposit 

 the sulphate of lime, iron, and earth suspended in it. In 

 order to free the liquor from these substances, they clarify 

 it by boiling for a short time, which enables the sulphuric 

 acid to exert its affinities with greater energy. After run- 

 , ning it from the pans, and suffering it to cool, the whole of 



the sulphate of lime, iron, superfluous alumine, and earth, 

 are deposited; and the alum liquor is nearly pure. Where 

 this precaution is used, the alum is much better in quality, 

 and almost entirely divested of the sulphate of iron. This 

 method is only practised at some of the works, owing to the 

 additional quantity of fuel required, and consequently in- 

 creased expense. 



The liquor in this state is carried by means of pipes, or 

 wooden gutters, into leaden pans. These pans are made of 

 sheet lead (cast by the workmen in the alum house) 10 feet 

 long, 4 feet y inches wide, 2 feet 2 inches deep at the hinder 

 part, and 2 feet 8 inches at the front end : this difference is 

 allowed to give a rapid current in running off. 



A quantity of mothers is pumped into the pans every 

 morning; and, as this evaporates, the deficiency is supplied 

 with fresh alum liquor, every two hours, or, as the liquor 

 in the pans becomes more concentrated, the additions are 

 made more frequently. It» is necessary to keep the pans 



continually 



