High Frequency Corona Discharge 159 
words, the circuit must be “tuned” according to the dimensions of 
each discharge tube used. 
Air dried by passing through sulphuric acid wash bottles and over 
freshly cracked potassium hydroxide was passed into one end of the 
corona tube at constant pressure. The flow rate was measured with 
the usual type of flowmeter. The corona tube was 193 cm. long and 
had an internal diameter of 4.65 em. The volume with side arms was 
3,402 cc. The wire was passed through small holes in glass plates 
which were cemented to the aluminum tube by a special wax’ which 
has shown itself to be very resistant to the action of ozone. Inlet and 
outlet tubes were made by screwing short lengths of aluminum tubing 
into holes in the side of the tube near the end, and inside of these, 
glass tubes were sealed tight with the special wax. The first part of 
the absorption apparatus was made entirely of glass and the absorb- 
ing liquid was standard alkali by means of which nitrogen pentoxide, 
formed in the discharge, could be absorbed. The amount of ozone 
absorbed by the small volume of solution used was found to be well 
within the experimental error. To absorb the ozone two Erlenmeyer 
flasks were used. The rubber stopper in the first Erlenmeyer flask 
was protected by a very thin coating of beeswax, which was unaffected 
by the ozone during experiments lasting more than a year. 
The procedure was to pass a corona discharge through still air 
enclosed within the tube or through air which was flowing through the 
tube at a definite rate. The pressure in the tube was maintained con- 
stant at 750 mm. The temperature was that of the room, 22-30°. 
Changes in temperature of 10° were shown to produce only very slight 
variations in yields. Results are given for different wires under vari- 
ous conditions of flow rate of air and under varying electrical condi- 
tions. The amperes, volts and watts of the primary circuit of the 
Thorardson transformer were recorded as well as the voltage across 
the spark gap. The current in the secondary of the Tesla coil was 
measured with a hot wire ammeter and reached values as high as 
half an ampere at 6,000-8,000 v. when the gross input into the system 
was less than 150 watts. A very poor power factor in this part of 
the circuit is thus indicated. The power factor of the circuit which 
excites the transformer ranged from a very low value for the feeblest 
coronas to 50-70% for the most intense discharges. 
The material as well as the size of the wire produced changes in 
the discharge with corresponding changes in the chemical reactions. 
A platinum wire was at first used because of its supposed chemical 
inertness, but platinum is a material which has been found to be one 
of the most active catalytic substances known. Its catalytic properties 
seem to depend upon surface absorption and it has been noted that with 
continued use, as in the oxidation of ammonia, it becomes, apparently, 
badly corroded. This is, of course, not a true corrosion but a very large 
7A wax that will withstand the action of ezone and oxides of nitrogen and yet 
possesses desirable mechanical properties, is made by melting 5 parts of rosin, adding 
3 parts of red sealing wax and then stirring in 2 parts of beeswax. Harding and 
McEachron, J. Am. Inst. Elec. Eng., April, 1920. 
