Hormell— Dielectric Constant of Paraffins. 433 



Akt. XLYI. — Dielectric Constant of Paraffins ; by Will Gr. 



Hoemell. 



The following paper presents some experiments in which 

 by means of a modified form of the Blondlot oscillator the 

 dielectric constants of four commercially different paraffins 

 were obtained for 40, 60, and 80 centimeter waves. The 

 paper also contains an investigation of the relative velocities 

 of 80 centimeter waves along magnetic and. non-magnetic 

 wires of different diameters. And finally there is given in 

 the table, by way of comparison, the light index of refraction 

 of the different paraffins for the D x line as obtained by means 

 of the Abbe refractometer. 



Apparatus. 

 Figure 1 is a diagram of the connections made to the vari- 

 ous pieces of apparatus used in the experiment. The terminals 



B 2 



a and b are connected to a commercial line delivering an alter- 

 nating current with a pressure of 52 volts. The resistance R 

 is used to regulate the quantity of current flowing through the 

 circuit. T is a transformer whose primary of about 200 turns 

 is wound around a core of soft iron wire. The secondary of 

 the coil contains about 2000 turns. C is a battery of four 

 Leyden jars each having a capacity of 5900 electrostatic units. 

 T x is a Tesla coil made after the formula given by Tesla and is 

 capable, when fed to its full capacity, of giving a ten-inch 

 spark. In all the following experiments a current of about 

 7 amperes was taken from the commercial line which would 

 give in the Tesla coil a spark of not more than 3 cm . G is a 

 spark gap consisting of two small iridium* cylinders inserted 

 in f-in. brass spheres. The length of the spark gap can be 

 nicely adjusted by means of a screw thread on the axle of one 

 of the spheres. 



The constancy of the spark at this gap is of the greatest 



* G. W. Pierce, this Journal, vol. ix, p. 256, 1900. 



Am. Jour. Sci. — Fourth Series, Yol. XII, No. 12. — December, 1901. 

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