SODA.— Black-ash Composition.
817
or, when caustic lime is used, by the reduction ofNa 2 S0 4 with C. Scheurer-Kestner’s explanationof the reaction in the ball-furnace, which is thelatest, but will hardly be the last, is as follows:—The materials in the ball-furnace are always form-ing a mass of a certain depth on the bed. Thereduction begins in the upper layers which aremostly heated; Na 2 S and some CaO are formed.By turning over the mass, the mass is again car-bonated by the CO., arising from the reaction ofNa 2 S0 4 in the lower layers. As the Na 2 S fuses, itpenetrates the calcium carbonate, and sodium car-bonate and calcium sulphide are formed. Whenthe reduction of the sulphate has been finished, andthe evolution of C0 2 ceases, the temperature of themass rises, and then only the chalk present in excessis reduced by the coal, and CO is formed. Thearising of flames of that gas is a sign of the end ofthe reaction.
Composition of Black Ash .—The following tableof analyses made by different chemists gives a goodidea of how little use a complete analysis of blackash is for practical manufacturing purposes. Thisproduct is not only of a most complex character,but its analysis is exceedingly difficult;, and theresult, even of the same black ash and in the handsof the same chemist, will vary very much indeed, ac-
cording to whether he has used quite fresh black ash,or the same exposed to air; whether he has washedit with cold, lukewarm, or boiling water; whetherthe solution has been allowed to stand for sometime over the residue or not, &c. Some of theanalyses seem particularly suspicious — such asUnger’s No. 2 and Richardson’s —on account ofthe large quantity of sodium hydrate, whose presenceis denied by the best observers; Danson quotessimilarly sodium oxide ; and not one of the analysesof black ash found in text books gives any statementof that portion of the soda which is known to existin every black ash in a form insoluble in water,whether it be as sodic-ferric sulphide, or as sodic-calcic-aluminic silicates, or in any other. Thismakes the close approximation of most analyses to100-00 quite futile, and proves it to be merelyapparent. Stohmann, for instance, whose analysesadd up to 100-93, 100-00, and 100-26 respectively,and who does not in them mention soda in any otherform but that of sulphate, chloride, carbonate, and(once) of hydrate—all of which certainly are solublein water—yet states further on that of 100 partssodium sulphate, 3‘2 to 5-42 are only recovered inthat portion of the black ash insoluble in water;but in what shape his analyses do not show, andthey cannot therefore be considered as reliable.
ANALYSES OP BLACK ASH.
By Unger, from,ftingkuhl.
By Brown,
By Bichard-
By Kynas-ton (Liver-pool).
By Danson,Muspratt’sWorks.
By Stohmann, from Jarrow.
Newcastle.
Newcastle.
Ordinary Furnaces.
Revolver
Sodium sulphate,.
1.
1*99
1-160
1-130
3-64
■748
*395
•8
•4
1-5,1
1*54
T06
“ chloride,.
“ carbonate,.
“ silicate,.
1 1CO
2-54
23-57
11*12
1-913
35-640
■60
9-89
25-64
1-308
41-489
1-162
2-528
36-879
1-182
3-1
28-9
1-42
44*41
1-75
38-45
3-17
1-48
43-27
“ oxide,.
1'6
■609
2*350
'392
*689
8-2
—
—
12-90
15-67
*857
3*315
14-2
3-20
7-52
“ oxysulphide, OaO,3CaS
40-0
34-76
29*172
35-57
2-178
38*98
36*91
25-48
‘* hyposulphite,.
“ sulphide,.
—
—
-
—
33*193
1-152
28-681
•435
25-8
—
—
9-38
8'5
_
6-301
_
9*320
9-270
( 0*33
■61
_
Magnesia,.
•8
—
3-744
—
* —
•254
\ 0*10
•51
•19
4'74
•88
_
_
12
_
1-020
1-132
)
( o'ra
•72
2*10
•700
2-17
•219
2-658
t 6-2
6-71
3-020
( 1*75
2-40
1-48
1-2
2-45
4-917
1-22
•371
_
_
_
2-0
0*89
1-36
1-74
2-02
4-285
■44
2-259
■901
2*20
1-16
2-66
2-6
1-59
7-998
4-28
4-724
7-007
_
5-32
5-43
5-28
•295
•959
_
99-1
99-78
100-214
100-00
99-492
100-205
89*8
100*93
100-00
100*26
Black ash may be considered as essentially amixture of sodium carbonate, calcium sulphide,oxide, and carbonate; all other matters being un-essential, although to some extent unavoidable ad-mixtures, carried into the mixture partly by theimpurities of the raw materials, partly by the wearand tear of the furnaces and tools. Apart fromthose matters mentioned in the above analyses,black-ash generally contains very small proportionsVOL. II.
of ammoniacal and of cyanogen compounds (al-though most probably not as ferrocyanides), andsometimes rarer elements, of which Unger hasfound the following — titanium, copper, molyb-denum, phosphorus, tantalium, fluorine, barium,nickel, cobalt, manganese, lead. Rammelsberg hasfound vanadium.
The following analyses by G. E. Davies are allfree from the above-mentioned faults, and account103
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