YORKSHIRE ALUM WORKS. g^j 



continually boiling, otherwise the superfluous alumine and 

 sulphate of aluniiae, deprived of its water of crystalliza- 

 tion, would be precipitated, and the pans melted, from the 

 crust formed between the liquid and the lead. 



Each pan will produce upon an average 4 cwt. of alum 

 daily, and the consumption of coals will be about 18 bushels 

 Winchester measure. 



The liquid contained in the whole of the pans is run off 

 every morning into a vessel called a settler, at the same time 

 a quantity of alkaline lee is brought along with the boiling 

 liquor, prepared either from kelp, soapers lees, (generally 

 called black ashes) or muriate of potash, of a specific gra- 

 vity from 1-037. to 1-075. The alum maker having pre- 

 viously ascertained the specific gravity of the liquid in hh 

 pans, estimates the quantity of alkaline lees to be added, 

 necessary to reduce the liquor from the pans from the spe- 

 cific gravity of sometimes 1*45 or 1'5 to 1'35. 



The liquor then stands in the settler about two hours, 

 that it may deposit the sediment it may contain, when it is 

 run off into the vessels (or coolers) to crystallize. 



If the alum maker should be below, or equal to the spe- 

 cific gravity of 1'35, in mixing the alkaline lee and liquor, 

 there is nothing more to be done. If he exceed this specific 

 gravity, he then adds urine in the coolers, until the liquid 

 is reduced to 1*35. It is then agitated to combine the heavy 

 and light liquids, and then left to crystallize. It must be 

 observed, that at a greater specific gravity than about 1-35, 

 the liquor, instead of crystallizing, would present us with a 

 solid magma resembling grease. 



After standing four days, the mothers are drained off, to 

 be pumped into the pans again the succeeding day. The 

 crystals of alum are conveyed into a tub, where they are 

 washed in water, and put into a bin, with holes in the bot- 

 tom, to allow of the water draining off from the alum. 

 They are then removed into a pan (twice as large as the 

 common leaden pans), and as much water added as is found 

 requisite to dissolve the whole of the alum when in a boil- 

 ing state: the moment this is effected, the saturated boiling 

 solution is run ofl[" into casks. These casks should stand 

 about l6 days ; as they require this time to become per- 

 fectly 



