ON THE (CRYSTALLINE SLAGS, 357 
Analysis tabulated. Oxygen. 
ICR Pathe lore. Gi Sa ROG) eiev ee ore e's veee 20°81 
AlUmEM Ay eee aie Saved OOS "sol. oe red 6:05 
Dene wae ello PLE 32°53 .... 6. O14 
Gy le ar 1:06 ...... O41 U iy4¢ 
Protoxide of manganese... 2°26 ...... 0°51 
Protoxide of iron ...... 4°94 ...... 1°12 
POtaRsii ye see te eee ay DOR oe oewee ee §=O'46 
Phosphoric acid .. 0°19 ‘ 
Alumina ........ O12 O31" 
Sulphur ........ O45 Y 
Calcium ........ age 2? 
Error of loss .......... 0:19 
100-00 
From an examination of the preceding analyses, it is evident that the fol- 
lowing formula is the correct expression of the composition of this series: — 
Al?03, Si0’+2 (3(Ca, Mg, Mn, Fe) 0, SiO®). 
The formula differs from that of Vesuvian, in containing two equivalents of 
the silicate of lime series instead of one. Ivanov however has described a 
mineral from Slatoust, identical in composition with the preceding slags 
_ (Rammelsberg, Part 2. p. 258, and first supplement, p. 151); but Professor 
_H. Rosé informs us that the analysis of Ivanov has been clearly proved 
erroneous. Berthier has given the results of several analyses of slags 
from blast furnaces of nearly the same composition, but has incorrectly de-. 
duced the formula “(Ca, Mg, M, f)S+ AS,” which is that of Vesuvian. 
He has also omitted in his analysis of a slag from Dudley, protoxide of man- 
_ganese, potass and sulphur, which were found in all the preceding analyses 
_ of slags from the same locality. 
7. ANALysiIs. By J. P. 
__ This slag was obtained from one of Mr. Dawes’s hot-blast furnaces at 
Oldbury. It was found mixed with coke and other matters; it contains 
globules of iron, and sulphur may be readily observed deposited here and 
_ there upon the crystalline plates. 
__ The crystals are thin square plates, the lateral faces of which are perpen- 
dicular to each other, and to the terminal faces. They appear to belong to 
the pyramidal system. They are white, and when very thin transparent. 
# Hardness =5°7. 
7. ANALysis a. By J. P. 
__ 1. Weight of slag, after heating carefully over a spirit-lamp to expel the 
free sulphur 20°19. 
2. Silica 5°71. 
_, 8. Alumina 4°89. 
_ 4. Sulphate of lime 20°97. 
_ 5. Phosphate of magnesia 1°64. 
_ 6. Oxide of manganese 0°016. 
_ 7. Sesquioxide of iron 0:06. 
__ 8. Potass. After heating to expel the free sulphur, weight of slag 14°74. 
‘Chloride of potassium 0:15. The presence of soda in minute quantity was 
also clearly detected, as follows :— 
a, By heating before the blowpipe a platinum wire, and making a com- 
* Estimated as 2Al? 03, 3PO05 (51°44 x 2+55°44 x3). 
