276 
Proceedings of the Royal Society 
cooling and resolidification of two typical groups of fused salts and 
also of molten glass. 
The salts (analytically pure) employed were — 
Group I. — Potassium chloride, potassium iodide, potassium 
bromide (three salts of the halogens). 
Group II, — Potassium carbonate, potassium nitrate, potassium 
chlorate, potassium bisulphate and glass. 
The glass used in the observations was a powdered sample show- 
ing the following composition : — 
Analysis of the Glass employed. 
The sample, dried at 212° Fahr., gave the following results : — 
Silica. 
Alumina. 
Peroxide 
of Iron. 
Oxide 
of Man- 
ganese. 
Magnesia. 
Lime. 
Potash 
and traces 
of S da. 
Carbonic 
Acid. 
Total. 
1 
72-35 
The s 
1-00 
ample con 
0-40 
itained no 
0-65 
■ lead, cop 
0-77 
per, or 1 
776 
iarium. 
15-31 
traces. 
98-24 
The fusions were made in a platinum crucible, using a Fletcher’s 
Bunsen burner, either with or without blast as required. The 
galvanometer employed was an astatic one (the R. of which at 20° C. 
was 521 ohms) of known constants, and which, to ensure accuracy, 
was carefully calibrated during the investigation. With the salts 
in fusion and raised to the high temperatures given, it was found 
that when a Daniell’s element (zinc in cold saturated solution of 
zinc sulphate, copper in concentrated sulphate of copper with 
crystals) was placed in circuit (using two platinum wires as 
electrodes), the resistance of the fusing salts or glass varied of course 
very greatly with the temperature. On allowing cooling to com- 
mence, the conductivity in the case of the salts (Group I.), almost 
immediately ceased, although the temperature would only be just 
below their fusing points. It will be seen, however, from Table A. 
that the current from the Daniell’s continued to pass, in the case of 
the other salts and glass, for a considerable time. 
Owing to the difficulty of obtaining a steady and gradual rise of 
temperature in melting the salts and powdered glass, the reverse 
method of taking the time change resistances during gradual cooling 
from the highest temperature to recrystallisation was adopted. A 
