J. Phys. Chem. 1994,98, 1948-1952
I948
Calorimetric Principles and Problems in Measurements of Excess Power during Pd-DZO Electrolysis Melvin H. Miles,’ Benjamin F. Bush,t and David E. StilweU* Chemistry Division, Research Department, Naval Air Warfare Center Weapons Division, China Lake, California 93555-6001 Received: June 30, 1993; In Final Form: November 29, 1993”
A major experimental problem in many isoperibolic calorimetric studies is the fact that the decrease in the electrolyte level due to electrolysis produces a significant decrease in the apparent calorimetric cell constant if the temperature is measured in the electrolyte of the electrochemical cell. Furthermore, heat transport pathways out of the top of the cell can produce large errors, especially a t low power levels. There is no steady state in electrochemical calorimetry, so accurate results require the evaluation of all terms in the differential equation governing the calorimeter. These factors have contributed to the controversy involving measurements of excess power during Pd-D20 LiOD electrolysis experiments. A critical analysis is presented for several key publications that have impacted this scientific topic.
+
Introduction A critical assumption made by many laboratories is the steadystate approximation for their isoperibolic calorimetric system. In point of fact, there is no steady state during D20 + LiOD electrolysis experiments for either the cell voltage or the cell temperature. Exact calorimetric measurements, therefore, require either the numerical evaluation of the nonlinear, inhomogeneous differential equation that governs the behavior of the calorimeter or the solution of this equation to yield the integral form. Approximate solutions require, at the very least, an experimental evaluation of the terms involving the time dependency of the cell temperature, cell voltage, and cell contents in order to justify the omission of any of these terms. This has not been done by most laboratories reporting electrochemical calorimetric results including studies by Lewis et aL,1 Williams et a1.,2 Albagli et al.,3 and Wilson et aL4
Experimental Section Two types of isoperibolic calorimetric cells were used in this study. The Dewar-type cell consisted of a Thermos flask (Model 3700) containing the electrochemical cell as well as added insulation.5 A precision thermometer was placed directly in the H20-LiOH or DZO-LiOD electrolyte.s This calorimetric cell design is therefore similar to designs used by Lewis et al.,’ Miskelly et a1.,6 Williams et al.?Albagli et al.,3 Wilson et a1.,4 Fleischmann et al.,7 and others who measured the temperature directly in the electrolyte of the electrochemical cell. The second type of calorimetric cell design consists of a polyethylene bottle ( d = 7.5 cm) fitted with a large glass tube ( d = 3.1 cm) and packed with insulation.* The electrochemical cell (d = 1.5 cm, L = 15 cm) was positioned within the large glass tube which contains water that serves as a heat-transfer medium. The temperature inside the calorimeter is measured to within fO.O1 OC by two thermistors positioned a t different levels on the surface of the electrochemical cell. The large, constant volume of water outside the cell minimizes the calorimetric effect of the changing electrolyte level within the cell. This calorimetric design is similar in principle to the improved heat-flow calorimeter (IHF) reported by Williams et a1.2 where the temperature is measured
* To whom correspondence should be addressed.
Present address: SRI International, Menlo Park, CA 94025. address: Connecticut Agricultural Expeximent Station, New Haven, CT 06504. * Abstract published in Aduance ACS Abstracts, February 1, 1994. f
8 Present
within an aluminum can that surrounds the cell. In our studies, two identically designed calorimetric cells (cells A and B) are generally run in series. The level of the electrolyte exerts a major calorimetric effect when the temperature is measured directly in the electrolyte.2J-5s7 This effect limits the accuracy to about f10% in our studies using the Dewar-type cells.5 The effect of the electrolyte level is much smaller when the temperature inside the calorimeter is measured in a secondary compartment containing a fixed mass that serves as the heat-transfer medi~m.~s’-~ Therefore, this type of calorimetric cell design was used in most of our experiments.
Methods and Problems The measured output power from an electrolysis cell erroneously shows a steady increase with time following the addition of H20 or D2O for calorimeters where the temperature is measured directly in the ele~trolyte.~-’The output power trace, therefore, shows a saw-tooth pattern with a sharp decrease in power when H20 or D2O is added to restore the electrolyte l e ~ e l . ~ This J sloping baseline for the output power is a significant problem in most isoperibolic calorimetric studies. A consequence of the sloping baseline problem is that any calibration is only valid for a particular liquid leveL2 The decrease in the electrolyte level with the electrolysis time and the corresponding increase in the gas volume in the head space change the rate of heat transfer out of the cell, thereby producing an apparent calorimetric cell constant that decreases with time. This effect is due to the fact that the convectionheat-transfer coefficient for air or other gases is 20-40 times smaller than that for water.9 We reported this major effect of the electrolyte level in our initial calorimetric studies that failed to produce any detectable excess power.’ The liquid level of the water bath must also be carefully regulated due to the much better insulating property of air compared to that of water.10 Figure 1 presents a measurement of the large electrolyte-level effect for our Dewar-type calorimeter where the temperature is measured directly in the electrolyte solution. The apparent cell constant decreases linearly with the loss of solvent. At a typical constant current of 500 mA used in our studies, the loss of solvent would correspond to approximately a 15% calorimetric error over a 24-h time period. Other early investigators also noted this obvious effect, including Williams et al.,2Albagli et a1.,3 Miskelly et a1.,6 and Fleischmann et al.,7 but it is surprising that no mention of this electrolyte-level effect was reported in the initial calorimetric studies by Lewis et ale1considering their extensive
This article not subject to US.Copyright. Published 1994 by the American Chemical Society
The Journal of Physical Chemistry, Vol. 98, No. 7, 1994 1949
Measuring Power during Pd-D20 Electrolysis
series) is shown in Figure 2. Since the bath temperature is constant, changes in AT reflect changes in the cell temperature. Note that there is never any steady state for either the cell temperature or the cell voltage, although the changes in both are approximately linear with time. The additions of DzO produce sudden changes in the cell voltages following which there would be no valid calorimetric measurements for several hours based on our methods (the time constants for these calorimetric cells are about 25 min).*JO The differential equation governing the behavior of our calorimeter can be expressed as
5.5 APX. 3.5% DECREASE IN K PER GRAM
OF SOLVENT LOSS (Mp INITIAL)
Y
s
;;4.5 Y
4.0
-
( E ( t ) - yE,)Z
I 0
2
4
6
8
10
SOLVENT LOSS@
Figure 1. Decrease in the calorimetric cell constant due to solvent losses for a Dewar-type calorimeter where the temperature is measured in the electrolyte. discussions of various factors that may affect the calorimetric measurements. Calorimetric cell designs where the temperature is measured in a secondary liquid or solid phase surrounding the electrochemical cell minimizes this sloping baseline problem.2.5~8 Based on the isoperibolic calorimetric cells used at our laboratory, other major error sources arise from heat flow pathways through the top of the cell, room temperature changes, and fluctuations in the cell voltage due to gas bubble effects. The effect of the room temperature depends on the extent of heat flow through the top of the cell and can be minimized by reducing the cross-sectional area of the cell, by insulating the cell top, and by precisely controllingthe room temperature or the air temperature adjacent to the cell. Gas bubbles that collect at or near the electrodes yield large oscillations in the cell voltage, making it difficult to obtain precise measurements. This error source can be minimized by designing the electrochemical cell to eliminate surfaces that hinder the detachment of gas bubbles. The formation of large gas bubbles which became trapped under the Teflon supports was a reported problem for the calorimetric cell designed used by Albagli et aL3 Calorimetric accuracy is improved by systems of small volume with one short dimension and by intense stirring; thus, long narrow calorimeters are favored by Fleischmann et ala7 The small cell diameter promotes rapid radial mixing of the electrolyte by the electrolysis gas bubbles and minimizes heat transport through the top of the cell relative to that through the cell wall to the water bath. Furthermore, smaller calorimetric cells will have smaller cell constants due to smaller surface areas for heat transfer;2.4 thus larger differences between temperature inside and outside the calorimter can be obtained. This will minimize errors in measurements of the output power due to uncertainties in temperature measurements. It is essential to properly scale the calorimeter and the electrodes so that the excess enthalpies become large compared to the experimental errors.7 The significance of these calorimetric principles and problems was not obvious when various laboratories reported their attempts to measure excess power in 1989.
Results Two major calorimetric topics were the focus of the experiments reported in this study. First, an isoperibolic calorimetric study was conducted to determine whether or not any steady state exists for either the cell temperature or the cell voltage. Second, the calorimetric cells were calibrated during electrolysis at various current settings to determine any possible errors due to the rate and/or form of gas evolution as proposed by Lewis et a1.I Our calorimetric cell design that minimizes the effect of the electrolyte level was used in these studies. The time dependence of cell potentials and cell temperatures for two simultaneous experiments (cells A and B connected in
+ Px = + KAT + P,,, + Pcalor
(1) where PXrepresents any excess power. The symbols in this equation are defined at the end of the paper. Excess power, as defined by this equation, is the difference between the cell output power and the electrochemical input power [E(t)Zl. This equation assumes that the bath and room temperatures are constant and that any power effects due to the deuterium loading or deloading of the palladium are negligible.1° The rate of enthalpy transfer outside the cell due to the D2,02, and D20 gas stream (P,,) is given by (I
P o*75(cp)cP,D20(v)]
AT+
P 0*75(n) (2)
and the time dependence of the enthalphy of the calorimeter is given by
These expressions are essentially the same as those reported by Fleischmann et aL7J1 The current efficiency for DzO electrolysis (y) should always be measured to substantiate any claims for excess power.z-8JO For our calorimeter at typical conditions of 0.2 M LiOD and Z = 500 mA, we calculate Pgas= 0.01 W and P a l o r -0.005 W using experimental measurements of ATand dAT/dt. Although Pwand Pal,varysignificantly with current (I)and theelectrolyte concentration, their sum remains positive and less than 0.020 W for our range of experimental conditions. Therefore, neglecting the sum PBas Palorin eq 1 will only underestimate our value for Px. Furthermore, other error sources in our calorimetry, such as room temperature fluctuations, contribute to an estimated error of i0.020 W. Calorimetric measurements of greater accuracy or over a wider range of experimental conditions, however, would require either the numerical evaluation or the integral solution of the differential equation (eq 1) as well as careful control of the bath and room temperatures and all liquid levels. The integral solution of an equation similar to eq 1 has been given by Fleischmann et al.7 A discussion of various methods used in evaluating the excess power has been presented elsewhere." It has been proposed by Lewis et a1.I that a change in the rate and/or form of gas evolution can be a significant error source in electrochemical calorimetry. Therefore, our calorimetric cells were calibrated during electrolysis over a wide range of current densities (20-280 mA/cmZ, A = 2.5 cmz). Results of these calibrations are presented in Figures 3 and 4. At low currents (Z < 100 mA) stirring by the electrolysis may not be sufficient, while at high currents any errors due to the neglect of the P , + Palorterms in eq 1 become larger. Nevertheless,the correlation coefficientsof 0.999 or better for each thermistor show excellent heat recovery for these calorimetriccells over the entire calibration range. These results show that the rate and/or form of gas evolution is not a significant error source in our experiments.
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1950 The Journal of Physical Chemistry, Vol. 98, No. 7, 1994
Miles et al.
10 I
I22
. F
0
+d I
-I
Y
0
4 -
- 10
3 -
- 8
2 -
- 6
1 -
- 4
I
I
I
I
I
I
I
I
I
2
2
TIME I HOURS
Figure 2. Time dependence of cell potentials and cell temperatures for cells A and B before and after DzO additions.
1.6
CALIBRATION BY ELECTROLYSIS POWER (I i5&7W ma) CELLA lD~O+O.ZMLIOD) P, i0.0375 f 0.7331 AT, ICORR COEFF i0.0091, n i13) @ i0.0261 f 0.1353 ATz ( C O W COEFF i0.9990, n i13)
-
3.2 -
-
*.I *.4
-
1.6
-
1.1
-
Jr" 1' ?.I
Figure 3. Calibrations for cell A by 3.8
ml>
I
further analyze these publications in terms of other possible error sources in their calorimetric measurements. For typical isoperibolic calorimetric cells, heat flows out of the top of the cell as well as into the constant-temperature bath. Therefore, at constant bath and room tempcrature, it can be shown that10
P = K,(Tb- T R )+ K A T = a + K A T
Ffgure 4.
4.0
Figure 5. Effect of the power level on the apparent cell wnstant ( K ) and heat-transfer mfficient (h).
electrolysis power.
CALIBRATION BY ELECTROLYSIS POWER (IiS I M
1.0
mew
Calibrations for cell B by electrolysis power.
Discussion
Several key publicationsl4.6 that greatly impacted the cold fusion controversy incorrectly assumed steady-state conditions for their isoperiboliccalorimetriccellsrather than the appropriate differential equation (eqs 1-3). The purpose of this section is to
(4)
where K = Kb + K,. Thus, there is a non-zero power intercept for AT = 0 as shown in Figures 3 and 4. The term K,(Tb- Tn) can became significant at low power levels, and the use of the approximate relationship P = KAT can produce large errors. This effect of the power level on the apparent cell constant ( K ) and heat-transfer coefficient ( h = l/K) is shown in Figure 5 for our experimental results for thermistor 1 in cell A (Figure 3). The neglect of the intercept term in eq 4 produces significant errors in the apparent cell constant for power levels below about 0.6 W. All of the calorimetric data reported by Lewis et al.l.6 are near or below a total power level of 0.6 W. hence, his use of the approximate relationship P = AT/h is likely a large source of error. The schematic of the calorimetric cell design used at the California Institute of Technology as reported by Miskelly et aL6showsarelativelylargeareaexposedtotheamhient temperature; hence the problem of heat flow out of the cell top would
The Journal of Physical Chemistry, Vol. 98, No. 7, 1994 1951
Measuring Power during Pd-D2O Electrolysis
TABLE 1: Cell Constant Determinations
PdjHiO Pd/D20 Joule heating' (Dz0) Joule heating' (D20 and H20) Pd/D2@ Pd/D20' mean a Calculated for P = 2.00 W.
TABLE 2
A- 1 14.7 A-2 16.0 B- 1 63.7 B-2 66.0 c-1 88.7 c - 2 94.5 D- 1 113.2 D-2 115.0 E- 1 161.0 E-2 164.5
0.135 0.139 0.136
0.138 0.143 0.144
0.133 0.137 0.133 0.136
0.132 0.134 0.134 0.138
1989 1989 1990 1990
0.141
0.148
0.132
0.133
1991
0.136 0.143 0.1 39 k 0.003
0.137 0.143 0.143 & 0.004
0.136 0.141 0.135 & 0.003
0.140 0.141 0.136 k 0.004
1991 1992
Analysis of Cal Tech Calorimetric Results.
108 14 74 110 110 140 72 108 140 115
31.80 31.82 32.04 32.01 34.69 34.64 32.13 32.08 34.69 34.71
0.464 0.466 0.48 1 0.479 0.671 0.667 0.488 0.484 0.671 0.672
0.463 0.467 0.442 0.429 0.619 0.607 0.433 0.426 0.595 0.600
0.001b -0.001 0.039 0.050b 0.052 0.060b 0.055 0.05gb 0.076b*c 0.072
Reference 1. The cell output power is given by Pout= (Toon- 25.30)/ h, where h = 14.0 "C/W. Higher current density. Px/Vw = 0.076 W/0.073 cm3 = 1.04 W/cm3.
et al.' Experiments reported by Lewis et al.1 in H20-LiOH suggestsmallerheatingcoefficients (12.6,11.7,and 13.1 "C/W) for their calorimetric cell that would yield even larger excess power effects. In the calorimetric studies by Lewis et aL,1 a series of duplicate experiments (A, B, C, D, E) were conducted where a portion of the electrolysis power (PEL)was replaced by resistor power (PR,) in a manner that maintained the cell temperature essentially constant, as shown in Table 2. Thus
+
PT = PEL Px
in one experiment where no resistor power is used (PR,= 0) and
a
bequite significant. Surprisingly, no mention of this error source is discussed by Lewis et a1.l A summary of our determinations of calorimetric cell constants over a 3-year period is presented in Table 1. Except for the first three studies, these cell constants are based on eq 4 rather than the approximate relationship P KAT. There is no significant change of these cell constants over this time period. Calibrations were performed in D2O as well as H20 and by Joule heating ( 2 0 4 resistor) as well as by electrolysis, yet excellent agreement is observed. The small differences in the measured cell constants could be attributed to the different methods of calibration and to differences in the insulation of the cell top from one experiment to another. In striking contrast to the stability of calorimeter cell constants in our experiments, as shown in Table 1, Lewis et a1.l report heat-transfer coefficients that range from 12.6 OC/W in HzO to 15.9O C / W after 115 h of D20 electrolysis. This 26% increase in heating coefficients, based on our experience, is highly unusual. Closer examination, however, shows that Lewis et a1.l erroneously define the heating coefficient as h = AT/PT where the total power (PT)is the sum of the electrolysis power and resistor power. According to the Newton law of cooling, the temperature difference, AT, defines the total output power from the cell to its surroundings; thus any excess power (Px)must be included in defining the total power. This neglect of PX by Lewis et al. in the equation defining h would lead to an increase in the heating coefficient as the excess power increases. An analysis of this error in the Lewis study is presented in detail elsewhere by Miles et a1.10 Table 2 presents an analysis of the results reported by Lewis etal. when aconstant heatingcoefficient of 14.0 "C/W isassumed based on the observation that there is rarely any excess power during the early stages of Pd/D20 ele~trolysis.~~*J0 Initially, there is no excess power. However, as electrolysis continues an excess power effect develops that becomes as large as 0.076 W after 161 h of Pd/DzO + LiOD electrolysis. The excess power density of 1.0 W/cm3 Pd for this analysis of the Lewis study is in excellent agreement with our experiments (1.3 W/cm3 Pd at 200 mA/cm2)lOas well as with the results reported by Fleischmann
-
in the second experiment with P'EL< PELand P$
-
PT. Thus
For a constant cell temperature, the total output power must remain constant (APT = 0), thus from simple algebra
-
+
(8) Px - P'x = P/EL P i , - PEL The experimental observation by Lewis' that P ~ +LPk, PEL simply cannot prove that there is no excess power but only that PX - P;C N 0; i.e., the change in PX is small when a portion of the electrolysis power is replaced by resistor power. It is interesting to note from Table 2 that the input power (PEL+ PR,)required to maintain a constant cell temperature in the Lewis study is always smaller for the experiment at the higher current density. This effect is consistent with the presence of an anomalous excess power that increases with the current density and is near the magnitude reported by Fleischmann et ala7Another error analysis of the Lewis calorimetry has been reported by Noninski and Noninski.12 In contrast to the Lewis experiments, the calorimetric studies by Williams et a1.2 (Harwell Laboratory), Albagli et al.3 (Massachusetts Institute of Technology), and Wilson et al.4 (General Electric) clearly identified the importance of the electrolyte level effect and the problem of the heat flow pathway through the top of the cell to the ambient atmosphere. However, these studies invoke steady-state approximations as well as questionable cell calibration procedures. The calorimetric error ranges of f 4 0 mW for the M.I.T. studies, 5-10% for the General Electric experiments, and f15% excess power (f2a) for the Harwell calorimetry fall far short of the f 1 mW or f 1% accuracy reported by Fleischmann et al.7J1 The M.I.T. laboratory reports their key calorimetric measurements over a rather short time period (100 h). We have never observed any excess power in less than 6 days in our experiments involving Pd/D20 LiOD electrolysis. Albagli et al.3 assume that both the cell current and the cell voltage can be held constant in order to obtain their equation for determining any excess power. As shown in Figure 2, this assumption is incorrect. Furthermore, their calorimetric equations do not include the P,,, and Palor terms given in eqs 1-3. In addition, the more sensitive phase I1 experiments reported by
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1952 The Journal of Physical Chemistry, Vol. 98, No. 7, 1994
Albagli et al.3 employ a small palladium cathode ( V = 0.07 cm3) at a current density (69 mA/cm2) that would yield only about 70 mW of excess power based on results reported by Fleischmann et al.' and others.8-10 This expected excess power is only about 4% of their typical cell input power (electrolysis power + heater power); hence it would be difficult to detect any anomalous power considering their reported 3-5% calorimetric error range.3 This M.I.T. study illustrates the importance of properly scaling the electrodes and calorimeter so that any excess power effect will be large compared to experimental errors.' A summary of additional error sources and problems for the study by Williams et al.2 includes their method of cell calibration during electrolysis when any excess power is unknown, their large power changes used during calibrations, the marked endothermic behavior following topping up of their cells with DzO, and their use of small electrodes in large electrolyte volumes that would minimize the detectability of any excess power effect as well as contribute to poor stirring and possible H2O contamination in these large cells. Furthermore, the unfavorable geometry of various cathodes (beads, ribbon, bar) would not provide for uniform electric fields and symmetry required for high deuterium loadings. These error sources call into question any calorimetric conclusions stemming from the Harwell experiments. This discussion of various calorimetric error sources shows that excess power effects could easily have gone undetected in the early studies reported by Caltech,',6Harwell,zand M.I.T.3 These errors stem from the use of steady-state approximations, inadequatecalorimetriccelldesigns including poor scaling of electrodes and cells, room temperature changes, the effects of liquid levels, and questionable cell calibration procedures. However, most early workers likely expected large excess power effects that could be readily detected despite the large uncertainties in their calorimetric measurements. Although the measured excess power is often sma11,7s8J0a recent study has reported a much larger effect (3700 W/cm3 Pd) for Pd-D20 cells operating in the region of the boiling point.13
Conclusions The calorimetric measurements involving Pd-D2O electrolysis reported by several laboratories in 1989-1990 contain serious errors that undermine their reports of no excess power. These publications by Lewis,' Williams,* Albagli3 and others, however, serve to illustrate important calorimetric principles, problems, and sources of error relating to attempts to measure excess power in the Pd-D20 system. Electrochemical calorimetric measurements accurate to within fl mW require the application of all terms in the differential equation governing the calorimeter as well as careful control of external experimental conditions such as the ambient laboratory temperature and all liquid levels.
Acknowledgment. We thank Drs. Vesco C. Noninski and Joseph L. Waisman for helpful discussions relating to the calorimetric results reported by various laboratories. List of Symbols a = &(Tb - TR),power intercept for A T = 0, W C, = heat capacity at constant pressure, J K-' mol-'
Miles et al. EH = thermoneutral potential, V E(t) = measured cell potential at time t , V F = Faraday constant, 96 485 C mol-' h = apparent heat-transfer coefficientdue toconduction, "C/W I = cell current, A K = apparent calorimetric cell constant due to conduction, W/"C Kb = calorimetric cell constant for heat flow from the cell into the bath, W/"C K, = calorimetric cell constant for heat flow out of the top of the cell, W/"C L = enthalpy of evaporation, J mol-1 Mo= heavy water equivalent of the calorimetric when topped up, mol P = partial pressure, Pa P* = atmosphere pressure, Pa Pcalor= rate of enthalpy change within the calorimeter, W PEL= power input due to electrolysis, W PS,, = rate of enthalpy transport by the gas stream, W P R =~ power input due to calibration heater, W PX = excess power, W Tb = temperature of bath, "c Tau = temperaturemeasuredat theouter walloftheelectrolysis cell, O C TR = temperature of room (ambient), OC AT = TWll - Tb, OC @ = dimensionless term allowing for D20 losses by evaporation or other means besides electrolysis y = current efficiency for D20 electrolysis u = standard deviation for series of measurements
References and Notes (1) Lewis, N. S.;Barnes, C. A.; Heben, M. J.; Kumar, A.; Lunt, S. R.; McManis, G. E.; Miskelly, G. M.; Penner, R. M.; Sailor, M. J; Santangelo, P. G.; Shreve, G. A.; Tufts, B. J.; Youngquist, M. G.; Kavanagh, R. W.; Kellogg, S.E.; Vogelaar, R. B.; Wang, T. R.;Kondrat, R.;New, R.Nature 1989, 340, 525. (2) Williams, D. E.; Findlay, D. J. S.; Craston,
D. H.; Sen& M. R.; Bailey, M.; Croft, S.;Hooton, B.W.; Jones,C. P.; Kucernak, A. R.J.; Mason, J. A.; Taylor, R. I. Nature 1989, 342, 375. (3) Albagli, D.; Ballinger, R.;Cammarata, V.; Chen, X.;Crooks, R.M.; Fiore, C.; Gandreau, P. J.; Hwang, I.; Li, C. K.; Lindsay, P.; Luckhardt, S. C.; Parker, R.R.;Petrasso, R. D.; Schloh, M. 0.;Wenzel, K. W.; Wrighton, M. S.J. Fusion Energy 1990, 9, 133. (4) Wilson, R.H.; Bray, J. W.; Kosky, P. G.; Vakil, H. B.; Will, F. G. J. Electroanal. Chem. 1992, 332, 1. (5) Stilwell, D. E.; Park, K. H.; Miles, M. H. J . Fusion Energy, 1990, 9, 333. (6) Miskelly, G. M.; Heben, M. J.; Kumar, A.; Penner, R. M.; Sailor, M. J.; Lewis, N. S.Science 1989, 246, 793. (7) Fleischmann, M.; Pons, S.;Anderson, M. W.; Li, L. J.; Hawkins, M. J. Electroanal. Chem. 1990, 287, 293. (8) Miles, M. H.; Park, K. H.; Stilwell, D. E. J. Electroanal. Chem.
1990, 296, 241. (9) Thomas, L. C. Heor Transfer; Prentice Hall: New Jersey, 1992; pp 16-18.
(10) Miles,M.H.;Hollins,R.A.;Bush,B.F.;Lagowski,J.J.J.ElectroanaI. Chem. 1993, 346,99. (1 1) Fleischmann, M.; Pons, S.J. EleCt"aI. Chem. 1992, 332, 33. (12) Noninski, V. C.; Noninski, C. I. Fusion Technology 1993, 23,474. (13) Fleischmann, M.; Pons, S.Phys. Lett. A 1993, 176, 1.
