of Edinburgh, Session 1884 - 85 . 
277 
weighed portion (300 grains) of each salt, &c., contained in the 
platinum crucible was first melted and raised to the high temperature 
given (consistent with the nature of the substance), which was 
measured by a special arrangement with a Siemen’s pyrometer. 
The ends of two strong platinum wires (0‘063 inch diam.), connected 
with the Daniell’s element, remained deeply immersed in the salt 
from commencement, at equal distances apart in each case (^ inch) ; 
the galvanometer and resistance coils were also in circuit. The 
resistance was then taken at the highest temperature, the source of 
heat instantly removed, and the fused salt or glass allowed gradually 
to cool. The time changes of the deflections of the galvanometer 
were then recorded every 15 seconds (the resistance, values, &c., of 
which were known from the calibration of the galvanometer), until 
final solidification of the salt or glass ensued, and the current from 
the Daniell’s ceased to pass. 
This method afforded an indication of the nature of the resistance 
of both groups of the fusing salts and glass through considerable 
ranges of temperature, during the varying molecular changes incident 
to recrystallisation on cooling. 
The curves of the resistances thus obtained are given in Table A. 
Remarks on Table A. 
Potassium Carbonate. — This salt allowed a feeble current to pass 
until 8 minutes from commencement, at a comparatively low 
temperature. 
Potassium nitrate and Potassium chlorate. — A very faint current 
continued to pass (through higher resistances) after the above 
measurements were taken, until the salts were quite cold. 
Potassium chloride , Potassium iodide , and Potassium bromide . — 
The resistance of these fused salts was observed many times with 
the above results, after a very short time from the commencement 
of cooling in each experiment, the resistance almost instantly 
increased to an enormous extent, allowing only the feeblest current 
from the DanielFs to pass, although the salt was still at a high 
temperature, the KC1 quite a bright red, and the KI still show- 
ing distinctly red. The property of bad conductivity during such 
high temperature appears peculiar to these salts. In the case of 
KBr, when at 845° C., there was a free passage of the current, but 
