Add to your blog??
Dave:
Thanks for posting the gravimetric procedure. When I get some time, I'll check how it matches up with hydrometer-based readings. I am a (home)brewer and have the necessary hydrometers in my brewery and in my lab at work.
You may want to add to your blog that both water and alcohol samples must be at the same temperature when being measured to the fill-line, since the gravimetric measurement you make starts out actually as a volumetric sampling. Differences you note early in your blog when discussing hydrometers having to do with temperature still hold for this procedure. Both samples should be at the same temperature when being filled to the measuring line, since you are essentially comparing relative specific gravities of the samples, water being the control and reference for the alcohol sample measurement.