ALUM.—Manufacture fboji Alum Shale.
157
Locality
unknown.
D’Aubisson.
Pumncniss,
I/uvoiishire.
Stokes.
Gagpcnan,
Badt-u.
Iloltzinann.
Nicdesseltcn,
Xjtssau.
‘Wimph.
Gnslnr,
Himz.
Trick.
BreiiudnfF,
N. Coblontz.Trick.
Lebsten,
TliuriJijrenvald.
Frick.
riersclil.
48-6
59-4
G4-34
79-17 -
G0-03
G2-83
64-57
G7-50
Alumina,.
23-5
17-4
23-90 -
10-42
. 14-91
17-11
17-30
15-89
Sesquioxide of iron,.
11-3
11-0
9-70
0-27
8-94
8-23
7-46
5-85
Oxide of manganese,.
0-5
—
—
—
—
—
—
0-08
Lime,.
—
2-1
—
—
2-08
0-83
1-16
2-24
Magnesia,.
1-G
2-2
_
—
4-22
1-90
2-GO
3-G7
Potash,. . .
4-7
—
—
—
3-87
4-17
1-99
1-23
Soda, ...
_
_
—
—
—
—
—
2-11
Strontia, .
_
_
—
—
—
—
—
0-30
Oxide of copper, ..
—
—
—
—
0-28
0-27
0-30
—
Fluoride of calcium,.
—
—
—
—
—
—
—
] 1-13
Phosphoric acid, .
—
—
—
—
—
—
—
Sulphur, .
0-1
—
—
—
—
—
—
—
Carbon ...
0-3
—
—
—
—
—
—
—
Carbonic acid, .
Water, .
7-6
6-4
2*22
2-78
| 5-67
4-GG
4-G2
—
Loss, .
1-8
0-9
—
1-36
—
—
—
—
100-0
100-0
100-16
10O-O0
100-00
100-00
100-00
[ 100-CO
The annexed is the composition of some shales from Whitby, in Yorkshire, and Oampsie, near Glasgow :—
Richardson.
Iron bisulphide, .
Top rock.
52-25 .
Bottom rock.
•••
. . 51-16 .
Top rock.
22-36
18-16
15-40
Top rock.
. 23-44 )
. 15 04|
. 15-40
Bottom rock.
-Pyrites, 9’63
. 0-47
8-49
. 6-11 .
. 2-18
18-75 ..
.. 18-30 .
11-35
. 11*64
. 18-91
1-25
... 2-15 .
1-40
. 2-22
. 0-40
. 0-91 ..
... 0-90 .
0-50
. -32
9-17
0-15
. 0-55
. . 1-37
2-50 .
. 0-05
. . 0*13 ..
0-90
. 1-26
_ 0 20 .. .
_
. 0-21
_
_
_ 4-97 ...
29-78
. 8-51
2-68 ..
. .. 2-00 .
. 8-54
.... 4-80 ...
. .. 8-09 .
—
. 3-13
. 0-59
100-00
100-00
100 00
99-99
100 -00
The Campsie alum ores, especially the upper,contain a large excess of pyrites, yielding of coursemore sulphuric acid than the alumina can take up,while the lower have a considerable excess of alumina;it is, therefore, the object of the manufacturers ofalum to mix these ores in such a manner that thedifferent ingredients may be made available as faras possible.
The composition of the residue from the Campsieores, after calcination and washing out the alum, is:—
Alumina,. 12*70
Sesquioxide of iron,. 20'80
Oxide of manganese,. traces .
Magnesia,. 2-00
Potassa,. 1-00
Sulphuric acid,. 10 76
Water,... 12-27
100-00
It is well known that alum earth belongs to themore recent deposits occurring below the first strataof the tertiary coal formation, which are of a laterperiod than the chalk. It is a massive but soft pul-verizable mass, stratified, but not slaty, and of adark-brown colour; it occupies basins of variabledimensions, according to the position of the neigh-bouring rocks. Very large deposits of this formationoccur in the valley of the Oder, and are worked at
Freienwalde and Muskau . It is no uncommonphenomenon, in the coal formations, for the clay andcoal strata to permeate each other in those localitieswhere they meet. These deposits, which frequentlycover the coal formation, and are at other parts inalternate layers with the coal, play the part of alumores, and may be worked for the production of alumwhen they contain a sufficient quantity of sulphideof iron, which is often the case. To this class belongthe Scotch ores. In Upper Silesia it is even foundprofitable to make the refuse coal, or Irees , whichcannot well be used as fuel, subordinate to the pro-duction of alum; these coals leave an aluminous ash,and those which are rich in iron pyrites are onlydistinguished from a real alum ore by their largeexcess of combustible matter, and which in thiscase cannot be turned to account.
Iron pyrites, or the bisulphide of iron, is quite asindispensable to the production of alum as aluminaitself. It is disseminated through the alum ores,partly in the well-known brilliant yellow crystals, orcrystalline deposits, but chiefly in a very fine state ofdivision, as a dull black powder, somewhat resem-bling the mass obtained by precipitating a salt ofiron by ammonium sulphide. Hence, inasmuch as itwas not perceptible to the eye, its presence has notonly been overlooked in the following analyses, butactually denied:—