- 
370 REPORT—1846, 
11. Our friend T. H. Henry, Esq. of London, determined the proportions 
of several of the ingredients of this slag, and has communicated to us the 
following results :— 
Si O° 23°77 per cent. Fe O 40:07. Fe*® O08 22-68 (quantity corresponding 
to sulphur not added). Al*O% with P?0* 1:6. P?0O® 6°40. 
Analysis tabulated. Oxygen. 
Pes sais ns. 5 aia ote union fc ar 12°41 
Protoxide of iron........ a ie 9°07 
Sesquioxide of iron ...... 2k ot ce mG 2 
Protoxide of manganese .. 6°17 ...... 1:38 
VANES, OF cra are 2 oon ania a a a 0°42 
ASAE «0 chute a sbaeclala wis cole. b'e O25 her iaers ; 0:08 
WeHCRIARE 0 3p i0's = = ny 6 RE AS ine 0:09 
PRGepHOTiG BENG Fo 5iy aie, ORE pomp at 3°60 
Sulphuret of iron,....... 0°62 
102-08 
We regard this slag as similar in constitution to the preceding, the alumina, 
some of the sesquioxide of iron, and the phosphoric acid being present as 
impurity. The presence of so large a quantity of sesquioxide of iron in this 
slag is probably to be explained by its long exposure in the kiln, during 
which it was in a condition favourable to the absorption of oxygen. The 
powder of the slag, when heated to redness in a platinum crucible, changes 
colour, acquiring a brown tint, and increases in weight. The quantity of 
phosphoric acid is also remarkable, and is well-deserving of the attention of 
those engaged in the smelting of iron. Berthier has given the analysis of a 
refinery slag from Dudley (Traité des Essais, t. 2. p. 289), containing 7-2 
per cent. of phosphoric acid. It is found that when puddling furnace slag 
(tap cinder) is worked with the ordinary ores of iron, such as argillaceous 
ore and hematite, the iron is liable to be “cold short,” or possess that 
property which is known to be dependent upon the presence of phosphuret 
of iron. Now it is evident that in smelting tap cinder, which will probably 
always be found to contain a sensible amount of phosphoric acid, the manu- 
facturer will be introducing into the furnace the very element, in a concen- 
trated form, which it is one object of the puddling furnace to remove, namely, 
phosphorus. An immense quantity of iron slag, far richer than many iron 
ores, is annually thrown away, and it may be that the presence of phos- 
phorus in sensible quantity is one of the causes which prevents the resmelting 
of this slag with advantage. This fact has not yet sufficiently attracted the 
attention of those engaged in the manufacture of iron. The discovery of a 
method of extracting economically good iron from these rich slags would be 
of great advantage to the country, and could not fail amply to reward its 
author. 
ioe 
The history of this slag is doubtful; though it is probable that it was 
produced in a puddling furnace. It has not yet been analysed; yet we in- 
troduce the results of its crystallographic examination in order to illustrate a 
new process of admeasurement of crystals of this kind, by W. H. M. 
One side of this piece of slag is bounded by a plane smooth surface, on 
which are traced the outlines of a number of crystals packed close together, 
separated by a lighter-coloured slag. Some of the outlines of crystals are 
rectangles, others rhombs, haying their obtuse angles cut off by parallel lines, 
