50 . ANNUAL REPORT 
Sree | ane Ore 
1 0.00 1570°C 
yy 0.05 EAB 
3 (OAL 1492 “‘ 
4 0.18 | 1468 “ 
5 ORZ5 A 
6 0.33 1439 “ 
7 0.43 1430 “ 
8 0.54 Ay 
9 0.67 ANTE ot 
10 0.81 VAT2) et 
Lil 1.00 1410 “ 
ey I, YZ 1430 “ 
13 IL a) 1468 “ 
14 1.86 into Olle 
15 Dh Ox) IOs 
The curves on page 51 are taken from Jueptner’s Siderology and 
illustrate the heats of fusion for various stages of acidity and lime-mag- 
1 
nesia combinations. 
In regard to the structure of slags we can distinguish glassy, sto, 
and crystalline slags. Silicious slags, on rapid cooling, invariably change 
to the glassy condition, but any slag assumes the stony appearance if 
cooled sufficiently slowly. Highly basic slags are always stony and fre- 
quently show fine crystals in the interior especially if ferrous iron be pres- 
ent in larger amounts. Silicious slags show but slight tendency to crys- 
tallize. Highly basic slags or such low in alumina on exposure to air grad- 
ually fall to a powder due to the action of carbonic acid and water. On 
examining strongly basic slags with the microscope Dr. Passow* found 
crystals very much analogous to the crystals found in Portland cement, 
known as alite. Certain slags possessing a peculiar tendency to fall to 
powder due to an inter-molecular change similar to the dusting of Portland 
cement were found to contain a definite mineral showing double refrac- 
tion and pronounced parallel striation. Dusting Portland cement clinker 
was found to contain the same crystals, known as felite. 
T. Hi. L: Vogt, of Christiania, has made the most thorough and 
searching examination of the crystalline structure of slags. He has 
succeeded in identifying a considerable number of minerals in various 
slags by cooling them very slowly. In the table on page 52 a number of 
these mirerals.are enumerated and their composition given together with 
the type of slag in which they were found:§ 
* Stahl und Hisen, 1908, Aug. Ist. 
§Jueptner’s Siderology, p. 298. 
