147 
METALS. 
Tron (electcolytic). The dispersion curve remains throughout in the 
negative region, numerically increasing from violet to red with an 
indication of a minimum in the ultraviolet. The iron investigated by 
pu Bors, loc. cit., showed a dispersion of a similar but more marked 
character. The material was not saturated. 
Cobalt. The curve showed a flat numerical minimum in the blue- 
green near 530 gu. Otherwise there is nothing particular to be 
noticed. In the case of the impure cobalt investigated by pu Bors the 
minimum was even less marked. 
TAB LEE Se 
= F(a) Cobalt (unsaturated) WEISS 
N > (wr) A (mm) = (min.) +d: 
| 
25 435 — 141,7 | — 21,25’) 0,12 = 0,560/9 
20 483 — 134,6 | — 20,20 O05 = 025". 
20 530 —131,5 | —19,74 0,02 = 0,10 ;, 
20 567 —132,8 | — 19,92 0;01,= 0,055, 
20 615 — 135,3 | — 20,28 0,01 = 0,05 ,, 
20 675 — 141,0 | —21,15 0,03 = 0,14 ,, 
Nickel. The curve showed a minimum in the yellow but otherwise 
no singularities. The dispersion of the original nickel-mirror of 
pu Bors was exactly proportional to this. The metal was not completely 
saturated. 
tA BLE 14 
e= 7 0) Nickel (nearly saturated) WEISS 
N 4 (wr) £ (mm) | ¢(min.) + dz 
20 435 — 57,6 — 8,64' 0,05'= 0,56/, 
20 483 — 56,0 — 8,39 0,02 0,24. 
20 530 — 54,3 — 8,15 0.0L 0,12; 
20 567 — 53,3 — 8,00 0,0T = 6,12. 
20 615 — 55,5 — 8,32 COL Ob, 
20 675 — 59,7 — 8,96 0,02 = 0,22, 
