Choice of what grade of water to use in a HHO generator: Rainwater, spring water and tap water all contain impurities. A typical analysis will show minerals, suspended solids and other contaminates contained in these varieties. These impurities will precipitate out of the water when subjected to electrolysis.
white race: people of european decent are all grouped together for simplicity(even though we all know of each others variations and tribes), includes skin types of thin brown, to yellow to very white(eye color and hair color has no significance).
Whiteness is defined by determining who is not white; it is defined as the superior opposite of non-white. Thinking back to colonial Virginia, this is a logical extension of a system which created value in whiteness by associating it with liberty and concurrently denying liberty to those defined as non-white.