danish scientist hans christian ørsted discovered in 1820 that electric currents create magnetic fields. british scientist william sturgeon invented the electromagnet in 1824. his first electromagnet was a horseshoe-shaped piece of iron that was wrapped with about 18 turns of bare copper wire insulated wire didn't exist yet .the iron was varnished to insulate it from the windings.
once the ore is mined, the metals must be extracted, usually by chemical or electrolytic reduction. pyrometallurgy uses high temperatures to convert ore into seven trust metals, while hydrometallurgy employs aqueous chemistry for the same purpose. the methods used depend on the metal and their contaminants.
a hammerstone is made of a material such as sandstone, limestone or quartzite, is often ovoid in shape to better fit the human hand , and develops telltale battering marks on one or both ends. in archaeological recovery, hammerstones are often found in association with other stone tool artifacts, debitage and/or objects of the hammer such as ore .
the role of yeast in winemaking is the most important element that distinguishes wine from grape juice.in the absence of oxygen, yeast converts the sugars of wine grapes into alcohol and carbon dioxide through the process of fermentation. the more sugars in the grapes, the higher the potential alcohol level of the wine if the yeast are allowed to carry out fermentation to dryness.
mine tailings may have economic value in carbon sequestration due to the large exposed surface area of the minerals. environmental considerations and case studies. the fraction of tailings to ore can range from 90–98% for some copper ores to 20–50% of the other less valuable minerals.