Mr. J. Wilson's Researches into the Alum Manufacture. 419 



9961 10109 100-33 



The ore is thrown into square cisterns of stone having wooden 

 hottoms ; mother-liquor is run upon it, and the liquor percolates 

 slowly through the bottom of the steep into cellars beneath. 

 After three or four washes with mother-liquor, pure water is 

 employed. From four to eight washes in all are drawn off; but 

 this varies with the quality of the calcined ore. When the 

 proper number of washes has been taken off, the insoluble 

 residue is removed and used for covering the ridges of calcining 

 ore. This exhausted material consists of — 



Silica 40-39"] 



Alumina 17-25 I T , , , ,. n e ~ 



Peroxide of iron . . . 30 - 6 6 f Insoluble 90 "° 2 



Lime 2-22 J 



Sulphuric acid .... 1-92 | 



Peroxide of iron and alumina "92 c , , , n ^™ 



Lime 1-00 f Soluble 10 " 20 



Water 6-36J ^0^72 



The composition of the first four washes from the steeps I 

 have found to be as follows in the gallon : — 



No. 1. No. II. No. III. No. IV. 



Sp.gr. 1188. Sp.gr. 1129. Sp.gr.1100. Sp.gr.1090. 

 Sulphuric acid 93305 59505 456-90 415-35 

 Peroxide of iron 346*75 118-68 112-42 53-31 



Alumina . . 194-59 149-99 5942 91-50 



Protoxide of iron 73-18 126-92 85-11 13845 



Chlorine . . 27-44 42-85 38-54 3660 



Magnesia . . 14-13 14-83 16-06 21-48 



Lime 



Potash . . 75-67 60-98 28-90 27*05 



Grs. per gallon 1664-81 110930 797'35 7837 L 



The potash found in these analyses is derived from the mother- 

 liquor which is thrown upon the raw shale previous to calcination ; 

 and as muriate of potash is the salt employed, it accounts also 

 for the chlorine. The shale from which these liquors were ob- 

 2E2 



