424 
The course of the curve makes it evident that also for a constant 
field the double refraction approaches asymptotically a maximal value. 
Further the double refraction of the B-modificatton has been 
measured. This was done by means of a telescope with an ocular- 
micrometer. This modification was investigated in a constant field 
only. The researches were made in the following way. A cloud 
was blown into the condensator vessel. Then the place of the band, 
the field being not switched on, the zero position, was determined. 
Then the field was excited, successively the tensions V, and V,, and 
the position of the band was read in these cases. As soon after 
each other as was possible this was repeated twice with the same 
cloud and finally the zero position was again determined. Here 
follows a set of observations. 
_ Position Position, Displacement patio 
‚ Zero Tension Tension | band band _| of the 
position, V, Vs | for for is fe displace- 
| tens. V, tens. il tens tens an ments 
34 |. 9100 | 730 | 5% | 4% | 2 ! ie 
Observed | | | a7 
2100 | 120 5 } 41/, 13 4 i 1 | 
quantities — | | | 176 
| EA ape en NR AN Oe OE Pee et 
oda al a Suk os ie 2 Rr TE Oul | 
Mean | 31, | 2100 | 725 er a) BN ae 1.7 
values 
The last column has been derived from the two preceding ones 
by combining each time two successive values of one column with 
the value 
from the other column that has been observed between. 
For nearly equal tensions | made for each of a series of clouds 
sueh a set of observations. The 
i 
V, \ 
2125 ibd 
mean of this series was 
Latio 
1.68 
Also for other tensions series of observations were made. The mean 
values found from them have been arranged in this table. 
V,; in volts 
V. in volts 
Ratio double 
refraction 
| 
1460 | Ca eno 1.45 
2125 720 1.68 
2670 700 1.77 
3470 625 1.9 
