441 



Resistance of certain Amalgams with Temperature. 



The curve in fig. 4, which is plotted from the numbers in 

 the first two columns, shows that these numbers lie very 

 approximately on a regular curve. 



Fig. 4. 

 80r 



£70 

 ^60 



50 



10 SO 30 40 



°/o OF Z/NC 



If we express the fall in the resistance at the temperatures 

 seen in column 2 as a percentage of the whole resistance just 

 before the fall commenced we get the numbers in column 3 

 of the above table. 



If we draw the curve of which the numbers in columns 1 

 and 3 are the co-ordinates we get that shown in fig. 5. 



me. 5. 



O- 



From this curve it appears that the amount by which the 

 resistance falls depends in a more or less regular manner 

 on the composition of the amalgam. 



The increase in resistance as the temperature is lowered 

 past 23° (fig. 3) is not due to a sticking of the amalgam to 

 the tube, for if it were we should expect it to be considerably 

 less when an amalgam was tried which was partially fluid ; 

 a reference to fig. 1 shows that this is not the case. 



In fig. 3 the temperature corresponding to Q is 68° ; by 

 means of a gas regulator the bath was kept at 65° for four 

 hours, after being cooled from 100°, to see if the resistance 

 showed a tendency to increase to anything like the value it 

 had at 65°, when the temperature of the bath was being 

 raised. Measuring the resistance at different times during 



