At 6:26 PM 8/23/4, Keith Nagel wrote: >Hi Horace. > >I have tried this in the past, using a nickle based electrolyte. >I was hoping that the magnetic field would cause some obvious >morphological changes, or that I would see some remanent magnetism/polarization >in the deposited metal after electroplating on the cathode. > >Sadly, the simple experiments I did showed no such effect. I may >return to this in the future; for reasons wholy unrelated to >the subject at hand. But if you have any suggestions for things >to look for, I'd like to hear them. > >That said, I suppose with a strong enough field I could effect >the pH at certain areas on the cathode. Not what I intend though.... > >K.
If you still have the cathode(s) around you might look at them under sunlight through polaroid sun glasses, both with and without magnetic field lines parallel to the surface. The actual effect of interest is the effect of the surface on polarized light, so you might also look at the surface when the sunglasses are placed between the sun and the electrode. I'd be surprised if you noted anything, but you never know. Unfortunately the electrode of most interest is a Pd cathode fully and freshly loaded with deuterium. At 2:53 PM 8/22/4, Keith Nagel wrote: >An electrolytic cell was constructed ... [snip details] >Now, presuming that heat is being liberated at both electrodes >in differing quantities, it's no great leap to suggest that >thermal gradients would be affected accordingly. In a calorimeter >which is sensitive to gradients, heat artifacts will be noted. Yes of course. I have already suggested a solution to this minor problem, which I think should not be singled out as a problem with using magnetic fields, but rather is already an identified problem with isoperibolic calorimeters. It is well known that fluids in isoperibolic calorimeters cause instability problems and the well known solution to that problem is to stir the fluid(s). In fact Ed Storms said: "Such a [isoperibolic] calorimeter is calibrated by assuming that the calibration method produces similar gradients and that these gradients are stable." To this I replied: "My experience with such assumptions is that they are false, even without magnets. Instabilities in convection currents are to be expected. There has been much open discussion in the past about the importance of stirring the electrolyte in order to avoid a lot of possible calorimetry problems. Magnetohydrodynamic forces are small at the small currents and fields involved compared to the effects of stirring of the electrolyte. Stirring of the electolyte in typical electrolysis experiments can often be achieved using a very small fraction of the total energy involved in the electrolysis, less than 1 percent." I can see I didn't make my point with clarity. Yes, of course magnetic fields can cause covection currents or convection current instabilities which affect calorimetry. However, convection currents and their instabilities are also problems whenever there is a heat source in a fluid. The magnetohydrodymics involved may well be detectable in the calorimetry, but are not atypical of ordinary convection instabilities one would expect in a calorimeter. The calibration of an unstirred isoperibolic calorimeter is not to be trusted *with or without* magnetohydrodymics present. The standard thing to do is stir the electrolyte. If (since) Letts did not stir then his results should not be trusted. I assumed Ed Storms would agree with this. I don't think he understood my intent. I think Letts experiment would benefit from being scaled up in order to accomodate stirring and other things. In other words, stirring should be used, magnetic field or no. The effects of normal thermal instabilites and magnetohydrodynamic instabilites (at the current levels and magnetic field strengths Letts used) are dwarfed by the effect of stirring. If you want experimental proof just include a stirrer in your electrolyte and see what happens. A stirrer I found useful for calorimetry I made from a 1.5 V DC motor attached to a glass rod using a piece of rubber tubing. The axially spinning rod does a good job of both setting up an electolyte current (vortex) and of mixing, and fits easily into small places. Regards, Horace Heffner
