429 
had a distance of + 10.5 mm and which was placed in a box of 
cardboard, which had been filled with a cloud. All the experiments 
described in this chapter were made with ammonium-chloride and 
in an alternating field. 
9. Summary of the observed phenomena. The following may serve 
as an interpretation for the tables below, in which the results have 
been collected; the letters in the second and third columns indicate. 
that oscillations of the direction denoted by it (see fig. 8) are trans- 
mitted. If a letter has been omitted, there is no polarizer or 
analyzer. The intensity of the field has been given in volts per cm. 
It is easily seen that with these three numbers the cases are 
exhausted. For a polarizer e.g. B cannot give anything new. 
The numbers 20 and 21 clearly show the dichroistie character 
of ammonium-chloride. Formerly Prof. Zeeman and the author) had 
CASE 1. 
LIJR, V//Q, W//P. 
Method of observation: microscopically. 
Intensity Phenomena at the switching on 
Number | Polarizer Analyzer PoRthe held of the field. 
| 
1 = — 5400 Strong increase of intensity. 
2 — cc 5400 “Idem. 
3 — D 5600 Weak incr. of int. Without field 
‚_ Cloud blue and not intense. 
4 | A — | 5600 | Strong incr. of int. 
OENE ne NE et |, BOO A Ident. 
6 | A D | 5600 | Without field some particles 
| visible. At the switching on 
| | of the field they vanish or 
become weaker. At the vanish- 
ing they reappear. Another time 
general decrease of intensity 
under influence of-the field. 
7 B — 5600 Moderate but observable incr. 
of int. 
8 B Ë 5600 The particles disappear or the 
int. diminishes, Without field 
very weak. 
9 B D 5600 | Nearly as 7. 
}) Zeeman and Hoogensoom, Communication II. 
