Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteenth century, but until about 25 years ago miners did not realize that bacteria take an active part in the process.
a. as a method of the extraction of minerals, it was well established
b. as a method of the extraction of minerals well established
c. was a well-established method of mineral extraction
d. was a well-established method of extracting mineral that was
e. had been a method of mineral extraction, well established

                                                        water

a colorless, transparent, odorless, tasteless liquid that forms the seas, lakes, rivers, and rain and is the basis of the fluids of living organisms.

                                                        halon  

any of a number of unreactive gaseous compounds of carbon with bromine and other halogens, used in fire extinguishers, but now known to damage the ozone layer.

                                                  dry chemical

extinguishing agent used on class a, class b, and class c fires.

                                                  carbon dioxide

a colorless, odorless gas produced by burning carbon and organic compounds and by respiration. it is naturally present in air (about 0.03 percent) and is absorbed by plants in photosynthesis.

lifetime activities are certain actions that are either required throughout your life or you choose to do them. for example, eating is considered a lifetime activity, drinking water or other beverages, keeping your body clean, taking medicine. those types of actions are considered lifetime activities.