348 
PEOEESSOE W. G. ADAMS AND ME. E. E. DAY ON THE 
Selenium changed in Character by the action of time. 
Since these investigations were made in December last, the pieces of selenium have 
been placed in a box and laid aside, and no experiment was made with them until May 
1877. On determining their resistances afresh, and repeating some of the experiments, 
we find that some of the pieces have changed very greatly, both in resistance and even 
in their position in the thermoelectric scale, through the action of time. 
Those pieces which were at first not so completely annealed, and which were still of 
high resistance, appear to have become more completely annealed, and their resistance 
is very greatly diminished. This change seems to be accompanied by a rise of selenium 
in the thermoelectric scale. 
In the following Table the resistances of several pieces, as determined in May 1876 
and May 1877, are compared: — 
Table of Eesistances. 
Besistance in ohms. 
Number. 
May 1876. 
May 1877. 
No. 7. 
.... 1525000 
. . 3950 
„ 8. 
.... 612500 
. . 5000 
„ io. 
.... 7600000 
. . 745 
„ 11. 
.... 14900 
. . 19000 
„ 14. 
.... 460000 
. . 207000 
„ 21. 
.... 120000 
. . 1123 
„ 22. 
.... 570 
. . 272 
„ 24. 
. . . . 55 
. . 60 
„ 25. 
.... 68 
. . 28-5 
Immediately after sending currents through these pieces, even from a single 
Leclanche cell, their resistances are usually increased and change very rapidly. 
Those pieces (Nos. 7, 8, 10, and 14) which in December last were below platinum in 
the thermoelectric scale have risen higher in the scale. 
No. 7. — On heating the marked end by contact with the finger there is a current of 
240 from platinum to selenium at the marked or heated junction; but on heating the 
unmarked end there is a current of 200 from selenium to platinum at the unmarked or 
heated junction. 
On heating the whole there was a current of 190 from the marked to the unmarked 
end. 
No. 8. — On heating the unmarked end there is a strong current from platinum to 
selenium at the heated junction (the needle was deflected beyond the scale) ; on heating 
the marked end there was a current of 70 from selenium to platinum at the heated end. 
Repeating the two experiments with a shunt to the galvanometer, the deflections were 
70 and 9 respectively. 
