I would like to increase the density of a given oil (or anything that repels water) so that it is slightly heavier than water; to be able to precisely control how slow the oil would fall in the water.
What can I add to the oil (or the water) to accurately set its density?
I am looking for a cheap solution, that I can easily do at home.
Another way to create slow and tiny drops would be to drop water into oil. Yet, the oil surface tension prevents water from falling down ; I asked another question for this problem.