40 THE ROYAL SOCIETY OF CANADA 
on the former indications. In all the experiments the temperature 
of the muffle was raised about 120°C per hour, and under these con- 
ditions the temperature at which each Seger cone melted, as shown by 
the thermo-couple, was about 80°C above its rated melting temper- 
ature. For the tests in the electric muffle the thermo-couple could not 
be used and Seger cones alone were employed. The temperature 
readings made in the gas muffle, below 1,500°C, may be accepted as 
reasonably accurate; above 1,500°C the temperature readings are 
only approximate. 
Some difficulty was experienced in finding a suitable base to 
support the cones in the furnace. It was found that some of the cones 
would flux with fire clay or alundum so that when supported on these 
materials the cones melted at the base and fell over before their melting 
temperature was reached. Carbon plates could not be used as they 
burned away before the tests were completed. Satisfactory results 
were obtained by the use of cone-holders, made of platinum foil, 
placed on an alundum plate. - 
The results of the fusibility tests have been plotted in Figure 2, 
in which shaded circles are employed to show relative fusibility. 
It will be noted that fusible slags can be obtained with as much 
as 70% of titania, providing the lime is kept low. There is a large 
‘area of fusible slags in the middle of the diagram; these slags con- 
taining about equal proportions of lime, silica and titania, and most 
of the mixtures having 10% of lime are fusible. Two isolated areas 
of high melting point mixtures occur on the line of 20% lime; corre- 
sponding, no doubt, to some chemical compounds. In general the 
least fusible mixtures are those containing much lime and little silica. 
Second Smelting Experiment. April 25th, 1916 
This was made in the same furnace and under the same conditions 
as the first, except that the charge was calculated so as to yield a 
fusible slag, and the amount of charcoal was reduced. An examina- 
tion of Figure 2 shows that a slag having the composition: 25% 
TiO:, 30% CaO, 35% SiOz, 10% AlsO3 would be readily fusible, and 
the charge was calculated as follows: 
