( 596 ) 
§ 7 above. In Fig. 15 are represented some separations observed in 
the laboratory without Nicol or other analyzer, 5', 6', 7' have been 
taken in non-uniform fields. 5' is the quartet of D x observed across 
the field; 6' the sextet of D s observed axially in a non-uniform, 
in the central part very strong, field; 7' also refers to D s in a 
weaker field, the observation being made across the lines of force. 
The type 10' refers to the D % line, when observed in a direction 
parallel to the field. The field is uniform. The separation gives an 
example of the superposition phenomenon mentioned in § 7. 
The analogy of the type 10', Fig. 15 and the tjrpe of the “winged 
line” seems very remarkable. Of course observation of the state of 
polarization would be necessary in order to prove the analogy- 
EXPLANATION OF PLATES I—III. 
The figures 1—13 are about thirteenfold enlargements of the images given by 
the grating of the absorption lines D x and Do in a magnetic field. 
The upmost and lowest of the three stripes of these figures relate to (oppositely) 
polarized light; in the central part the phenomenon is represented as it is seen 
in natural light. 
Plate L 1, 2, 3, 4, observations _L lines of force with different vapour density. 
5, 6, observation // lines of force with different vapour density. 
Plate II. 7, 8, observation at 9 = 60° calcspar rhomb alone. 
9, $ = 60°, calcspar combined with Fresnel rhomb. 
10, 11, 5 = 45°. 
12, 5 = 89°. 
Plate 111. 18, a = 89°. 
14, Types of sun-spot lines (adopted from Mitchell). 
15, 5', 6' 7', separations in non-uniform laboratory fields. 10' super¬ 
position phenomenon § 7. 
Physics. — “The thermomagnetic properties of elements” By Prot. 
H. E. J. G. du Bois and Prof. Kotaro Honda. (Communication 
from the Bosscha-Laboratory). 
(Communicated in the meeting of January 29, 1910.) 
In 1895 Curie 1 ), though he had investigated relatively few substances, 
believed that he could formulate his results in the following rules: 
1. For paramagnetic substances the specific susceptibility is in¬ 
versely proportional to the absolute temperature. 
2. For diamagnetic substances, on the contrary, the susceptibility 
is almost independent of temperature. 
3. For the latter class of substances, changes of physical state 
generally have hardly any influence. 
9 P. Curie, Ann de Chim. el de Phys. (7) 5 p. 289.1895, - Oeuvres p.232 
Paris 1908. 
