
328 C. G. KNOTT AND J. G. MACGREGOR ON THE 
silver, charcoal, platinum, tin, lead(—). The position of platinum is known to 
vary very much according to the state of the wire which is used in the deter- 
minations. With regard to numerical values of the electromotive force of 
circuits containing charcoal, BECQUEREL’s results and ours do not agree so well. 
But considering the very variable constitution of gas-coke, more than a general 
agreement is not to be expected. With MarruirssEn’s results,* ours show 
also a general agreement. He gives charcoal the following position :—(+) 
cadmium, zinc, charcoal, silver, gold, platinum, lead(—). Ours for the same 
temperature is :—(+) cadmium, gold, zinc, charcoal, platinum, silver, lead (—). 
Il. Alloys. 
The alloys which we have investigated were all (except that of magnesium 
and thallium) prepared for Professor Tarr by Messrs Jonnson & MaArTTHEy, 
London. They were all in the form of very thin wires, and were prepared 
from pure metals. Their constitution is given in percentages of mass. 
Silver-Palladium Alloys. 
We have investigated two, one of which contained 20 per cent. the other 
25 per cent. of palladium. As both wires were thin, and a junction of four 
wires could be made so small as to be certainly at the same temperature 
throughout, we examined both wires at the same time. The following modifi- 
cations in the method described above were thus rendered necessary :—The 
junction in the tube was a junction of four wires. The connections were so 
made that there were three circuits, viz., each of the alloys with N, and M-N. 
The commutator was so arranged that, by being placed in various positions, 
contact was made in each of these circuits. Readings were taken at short 
and nearly equal intervals of time in the following order :—M-N, first alloy 
circuit, second alloy circuit, first alloy circuit, M-N ; and the averages of the 
deflections of the M-N and of the first alloy circuit gave deflections corre- 
sponding in time, and therefore in temperature, with those of the second alloy 
circuit. The time occupied in taking the five observations was so short as to 
warrant the taking of averages. 
We give in one table the results of our experiments with these alloys. The 
end of N was attached to the same terminal of the galvanometer in all three 
circuits. The direction of the deflection of the M-N circuit is considered 
positive. The temperature of the beakers was almost constantly 141° C., 
rising for a short time to 14:2°, and falling also for a very short time to 14. 
* «Poog, Ann.” Bd. ciii. p. 412. 

