(212) 
Frrmine D. The measurements of LINDE are concerned with those 
gases which become liquid under high pressure at relatively high 
temperatures and are not in direct relationship with the following 
work. On the contrary Dewar and FLEMING have sought the 
diclectric-coefficient of liquid oxygen under the same condition as I, 
namely at the temperature of the normal boiling point under atmos- 
pherie pressure. 
The gases were liquefied in the eryogenic laboratory of the University 
of Leyden, the arrangement of which is described in another place ®). 
I shall hence confine myself to mentioning here the special arran- 
gements used in the determination of the dielectric-coefficients. During 
the experiments the cryogenic apparatus was under the personal 
care of Prof. KAMERLINGH ONNEs, through whom alone my research 
was brought to a satisfactory conclusion. I wish to express here, 
for this and much other valuable assistance, my warmest and 
most sincere thanks. 
1. The Method. 
Efecto meter The method I used was a modification of 
ik GoRDON’s, the principle of which is clearly 
and diagramatieally shown in Fig. I. The in- 
ner surfaces of two condensors Cj, and C, 
are connected to the quadrant pairs of a 
THomMsoN electrometer, and the outer sur- 
c, faces to one pole of an induction coil the 
other pole which is earthed together with the 
needle of the electrometer. Then, if the 
capacities C,; “and C, are equal, the needle 
will not be deflected on starting the coil. 
If C is an adjustable condenser, then the 
capacity of C, with different media can be 
obtained and hence immediately the dielectric 
coefhicients of these media. But this assumes 
that the electrometer is constructed symmetrically and that the capacity 
of the leads and also of the non-inductive parts of the condenser 
(i.e. other than the plates) are the same on the two sides. The 
simultaneous elimination of these two sources of error offers consi- 
derable difficulties. 
If we call y, and yg the capacities of the quadrant pairs together 
Miumkyc ff 
Fig. 1. 
1) Dewar and Fremine, Proc. R. S. Lond. 
2) KAMERLINGH ONNEs, Comm. Phys. Lab. Leiden N°. 14, Marutas, Le Laboratoire 
eryogène de Leyde, Rev. Gén. d. Sciences, 1896 p. 381. And-especially KAMERLINGH 
OnxneEs. Methods and apparatus used in the cryogenic laboratory L. loc. cit. No. 51. 
