AAhh Kfp,

I believe I have found your problem.

I have just reviewed all 1,738 hours of Mr. Wizard experiments and have determined that your problem is tongue positioning.

As every successful scientist will attest, the method to insure provable outcome of experimentation is to insure that during the course of the experiment the scientists tongue MUST be held correctly.

For right handed scientists the tongue MUST be placed in the right corner of the mouth, extended no more than 15.4mm for scientists less than 1.8288 meters tall and of a mass of no more than 86.1826 Kg.

The conversion for larger scientists is a ratio of 1.48 to 1 for each increase of .1 meter of height and 1.0038 to 1 for each increase in .24 Kg.

For left-handed scientists the same figures hold true but the position of the tongue MUST be altered to the left side of the mouth.

The scientist may roll their tongue and expel air only if the experiment concerns the effects of Newton's three Laws of Motion.

For experiments concerning Bernoulli's laws or Venturi's Laws the lips may be pursed during the exhalation of breath.

The tongue MUST never be moved in a repeating vertical motion or or allowed to flap wildly about unless experimenting with alternating currents.

The lips MUST be kept moistened and sealed against the surface of the tongue to insure you do not contaminate your experiments with vapors of alcohol.

I believe that if you will re-attempt your experiments while following these simple but critical requirements you will find you have far more consistent results.