Test No. 105 - "Comparison of Readings of Self-Potential at Constant
Temperature"
(R-25 and EL-11)
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June 18 - 28, 1977
Stewart Ct. Laboratory
Sunnyvale, CA
Copyrighted © by The Townsend Brown family. All rights reserved.
PURPOSE:
To compare the self-potential readings of Catalina granite R-25
(same as used in the UC Berkeley mineshaft) with the electrolytic capacitor
EL-11.
PROCEDURE:
As tested in the mineshaft at Berkeley, Rock R-25 (without
polyurethane coating) was placed in a cast aluminum box with flanged lid
secured in place by 6 screws. Although the lid fitted tightly there could
have been air seepage concurrent with changes in barometric pressure. The
question as to a possible contribution by the high humidity deep within the
mineshaft and moisture upon the surface of the rock remained unanswered.
In preparation of the present test, the aluminum box containing
rock R-25 was filled with new oil (Quaker State No. 10) so as to completely
immerse the rock. The lid was hermetically sealed in place with GE silicone.
This was to insure against any leakage of air into the box and any possible
effect of changes due to humidity and barometric pressure. The box was
placed within constant temperature chamber No. 1 and held at
100
oF +/- .2
oF.
Capacitor EL-11 was also placed in the constant temperature
chamber alongside the metal box containing the rock. The capacitor (G.E.
90,000 ufd 10 V DC) is sealed during manufacture so that no effects of
humidity or pressure are expected. Both the capacitor case and the cast
aluminum box containing the rock were electrically grounded.
This series of observations continued for 10 days. Results are
shown on the attached chart.
RESULTS:
The attached charts show pronounced diurnal variations for both
the rock and the capacitor. They appear essentially in phase. No "glitches"
were observed with either sensor during the period of this test.
CONCLUSIONS:
Catalina granite R-25, under carefully controlled conditions at
Sunnyvale, showed virtually the same diurnal pattern as in the mineshaft at
Berkeley.
A chart is attached comparing the results.
Graphic -
Figure 1
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