21.   They sold it at high prices, often after diluting it with water and adding chemicals to give it the right color.

22.   This involves a flow of electrons, which the researchers have tapped into by adding a chemical called neutral red.

23.   Usually that involves adding chemicals to kill algae or adding more water, if possible.

24.   He then added a chemical that helps immune cells recognize an invader and consign its features to memory.

25.   Illegal distillers are said to sometimes add the chemical in small quantities to make their brews more potent.

26.   Negotiators are working out how to add new chemicals under the ban.

27.   One of those is the wording and placing of language detailing how new chemicals can be added to the list of those banned under the treaty.

28.   Since then, big cities including Los Angeles and Sacramento, Calif., have added the chemical.

29.   Some U.S. communities also add the chemical to municipal water.