Here's where things get fun. Just like the number of reps, 3-6 sets is the best range of volume for this training method. If you like your workouts paced like clockwork, take 30-60 seconds rest between each exercise.
The natural attraction between positive and negative keeps the ions surrounded by water molecules and therefore dissolved in solution. Many biochemicals are either polar molecules or charged ions (or both) so water makes an excellent solvent for them.
Water is polar in nature while Ether is non-polar. Ethers are very slightly soluble in water at around 6.8g/100g. This is due to the presence of oxygen in ethers which interact with hydrogen in water to produce H-bonding to make it slightly soluble. And this low solubility is what makes a two-phase mixture of water and ether excellent for separation techniques.