374 
NATURE 
[March 9, 1871 

PAPERS ON IRON AND STEEL 
II. 
THE BESSEMER PROCESS (CONTINUED) 
IX the first part of this paper* I described the 
facts of the Bessemer process, and now pro- 
ceed to a theoretical examination of these. In order 
to do this at all satisfactorily, it is necessary to have, at 
the outset, a clear idea of the composition of the raw 
materials,—the pig-iron and the spiegeleisen. I insist the 
more urgently upon this, because the descriptions or de- 
finitions of cast-iron or pig-iron usually given in our 
chemical text-books are by no means satisfactory, and are 
frequently erroneous. 
The following are the results of my own analyses of 
fourteen brands of pig-iron and five brands of spiegeleisen, 
all of which are rather extensively used in the manufacture 
of Bessemer steel. In addition to the substances there 
determined, most of the pigs contain a small quantity of 
calcium, but this and the small traces of the metals of 
the other alkaline earths, and of the alkalis, were not 
determined, as the analyses were made for commercial 
purposes, and I have not been able to detect any practical 
modifications in quality of the finished iron or steel, which 
is due to the presence of these metals in the pig-iron. 
For this reason the statement of “iron by difference” is 
but an approximation, and somewhat in excess. 
Composition of Bessemer Pig-Irons 











3 4 g 8 
il = ke We = 1 & | 85 
P-1e) £ n g a | cE 
oO 2) a Ss qa 
I 069 A412 192 "10 0°06 0°32 92°88 
2 trace 352 3°10 0°07 0'06 0°30 92°95 
3 0'70 2°68 3 60 o'09 o'12 116 gr 65 
4 O55 185 3°60 o'13 o'18 1'22 92°47 
5 O'55 292 3/65 "09 o'13 noue 9366 
6 o-'75 200 336 o"'10 0'23 trace 93/56 
7 o'54 2°20 3°15 o"10 0°26 2°00 QI'75 
8 0°72 2°10 2°90 0°06 16 1°00 93°96 
9 0 62 4°co 1°40 "02 0°06 0°38 93°52 
to 0'50 3700 2°00 003 o'10 trace 94°37 
Ir 0°20 2°80 233 o'02 o'Io 1"g2 g2°63 
12 trace 3°20 1°58 OIE O12 2°22 92°77 
13 0°37 1'95 4°08 O'15 0'23 IIs 92°06 
14 125 1 65 215 o'24 o'21 110 93°40 




For commercial reasons, which will be readily under- 
stood, I abstain from publishing the names of the above 
brands. No. 12 is a Swedish pig-iron ; all the rest are 
English hematite pig-irons, made expressly for Bessemer 
purposes. Nos. 9, 10, and 11 produced exceptionally 
good steel; Nos. 1, 2, and 3, good average qualities ; No. 
4, inferior ; No. 13, very inferior ; No. 14 produced such 
bad steel that the whole parcel was returned, though it 
came from a well-known firm, it was of the same brand 
as No. 4. 
Composition of Spiegeleisens 

nce; 








bo} g o 
Bde) Soe hh Bible Se 
° 5 < 
A 4 ee Ba Bol Bde BOF) Be 
Ts) = A 2 a Ft | 
1S) 1c) nm S A 
I 4°10 0°45 1'2 p12 o'16 4°60 89'34 
2 4°10 "40 oO" 0°03 0°26 5°86 88°39 
3 4°50 0'40 0 88 004 O10 9 6r 84°47 
4 4°10 0°42 0°65 0705 O15 864 85°99 
5 3/00 o"70 O14 o"04 0'07 6°44 89°61 




No. 3 is the best of these; No. 4, the next in quality, 
rather better than average ; No. 2, rather below average ; 
No. 1, inferior quality; and No. 5 so poor that it was 
rejected. 
* Nature, Vol. iii. No, 63, p. arr 


Excluding the rejected samples, the average of the above 
is as follows :— 
Average Composition of 13 Brands of Bessemer Pigs 

Combined Carbon . ... . 047 
Graphite) 5s ote «csv -elyiel so kee eee 
Silicon sie, ots, ns 9s. gh oe ee 
Phospnoris. in) sete’ seit eae CRS 
Sulphie 3), Us) Wes Fe) eae tema 
Manganese.) 20 8 5. | SS 9 0'ge 
Iron by difference, about . . , 92°85 
100'00 

Average Composition of four Brands of Spiegeletsen 

Combined Carbon . . .. . 4°20 
Graphite’ = he ts cn ea Soca 
Silicon 2°). Le tS ee ee mes 
Phosphords® «921.7. 3 29. 8 ores 
Salphurs7 ay v.54. see en Oe 
Manganese. 4) 6 ee 16168 
Iron by difference, about . . . 87°59 
100'00 

The sulphur of this average of the spiegeleisens is 
excessive, being raised unduly by the very unusual quantity 
contained in No. 2: o'12 per cent. would state the general 
average more correctly. In like manner the phosphorus 
average is raised by the excessive quantity in No. I. 
Excluding this the average is reduced to o'o04. 
I will pass overthe small amount of chemicalchangewhich 
results from the mere melting of the pig and speigeleisen 
in the cupola, and regard the above as the composition of 
the material which enters the converter. When a mixture 
such as these Bessemer pig-irons is fused and exposed 
to the action of atmospheric air, the silicon is the most 
readily oxidised, silicates of iron and manganese are 
formed, which separate and float on the surface, forming 
the “cinder.” The carbon oxidises simultaneously with 
the silicon, but in a much smaller degree, until the silicon 
is nearly all burnt out. When the silicon is reduced 
below one per cent., the combustion of the carbon 
takes the lead, and the small remainder of silicon is but 
slowly oxidised, the last traces resisting oxidisation with 
considerable stubbornness. 
I have made some special investigations of this subject, 
and shall show in the course of another paper that man- 
ganese is remarkably efficient in removing these last 
traces of silicon. I should also mention that the above- 
stated generalisations respecting the prior combustion of 
silicon and the suppression of carbon combustion by the 
presence of unburnt silicon, are based chiefly on examina- 
tions I have made of the actions which take place in the 
“refinery;” the difference between the Bessemer converter 
and the refinery being, that in the one, air is blown upon 
or a little below the surface of the melted pig-iron, while 
in the other, it is blown through it from below, and thereby 
acts with far greater efficiency and rapidity ; the Amd of 
action is, however, the same in both cases, the difference 
is only in degree, 
In order to test the accuracy of the above conclusions, 
I have requested my late assistant at the Atlas Works, 
Mr. G. C. Barker, to make analyses of the Bessemer 
material during different stages of the same blow. This 
he has kindly done, and the following are his results. 
The carbon, silicon, sulphur, phosphorus, and manganese 
only are determined. 
The first column shows the percentage of these consti- 
tuents in the pig-iron after being melted just before being 
poured into the converter. 
Second, the same after six minutes blowing. 
Third, the same after twelve minutes blowing. 

