368 REPORT—1846. 
Analysis tabulated. Oxygen. 
ST OA ier ee aaa CTE) nies «02. ASH 
Protoxide of iron ........ BSNS Gel», », 0,0 11°02 
Sesquioxide of iron........ 1h eee 5:24 
Protoxide of manganese*.. 1°13 ...... 0°25 
RTI... nd: ti0 ns hela asl SI dal bs, ohn 0°59 
PLING 5. xiniin'b Seven wks sca REEL Golkeaus ¥ 013 
Dp gnesih .:.5.cieips tie ducetdn Da a aiaas Son 0°13 
Phosphoric acid.......... Dein atti, 0°75 
Sulphuret of iron ........ 1°61 
101°32 
These crystals closely resemble olivine in their form. The faces of the 
crystals are denoted by the same letters as the faces of olivine in Naumann. 
t, k, n of Naumann correspond to p, e, 5, of Phillips respectively. 
Crystals similar to these in form, composition and mode of occurrence, were 
described by Mitscherlich in the Annales de Chimie, t. xxiv. Measurements 
of crystals of the same form, and a comparison of their angles with those of 
olivine, were given by one of the authors (W. H. M.) of the report in the © 
third volume of the Transactions of the Cambridge Philosophical Society. 
Estimating the whole of the iron as protoxide, the composition would be 
nearly that of Fe’ Si, the formula assigned by Thomson to the mineral from 
Ireland, named “ Anhydrous silicate of iron.” Now, this slag had evi- 
dently been in a position favourable to the absorption of oxygen, namely, 
the flue of a puddling furnace; and we shall probably be justified in sup- 
posing that, after crystallization as silicate of protoxide of iron, oxygen may 
have been absorbed, and that the crystal may consequently be regarded 
to a certain extent pseudomorphous. In the case of the following slag, 
which is similar to the one in question, it was found by experiment that the 
powder of the slag readily absorbed oxygen by calcination in the air. If 
this view be admitted, the slag will in constitution as well as form resemble 
olivine, the magnesia of the latter being replaced by protoxide of iron. 
14. 
This slag was found by Mr. Twamley at the Bloomfield iron-works, Tip- 
ton, in a heap of calcined puddling furnace slag, technically called “ tap 
cinder.” The proprietors of these works have secured by patent the appli- 
cation of calcined tap cinder for the beds of puddling furnaces. It is stated 
that, by the process of calcination, which is conducted in large kilns similar 
to brick-kilns during a fortnight or three weeks, the slag is rendered much 
less fusible, and is therefore well-adapted to the purpose to which it is ap- 
plied. The analysis will probably explain this fact. The heat of the kilns 
appears, from an examination which one of us has made (J. P.), to be suffi- 
cient to soften and agglutinate the pieces of slag together, but not to effect 
perfect fusion. 
This slag is a mass of large iron-gray crystals, the faces of which though 
even are much too dull to be measured with the reflective goniometer. The 
general resemblance of their forms, however, to those of No. 12 is so close 
as to leave no doubt of their crystalline identity. 
At 182°C. Specific gravity=4°1885. 
It attracts the magnetic needle strongly. 
* Probably a portion existed as a superior oxide. 
