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By careful experiments, Gadolin determined that approximately 38% of the sample was a previously unknown "earth", an oxide which was later named yttria. [17] [18] Yttria, or yttrium oxide, was the first known rare-earth metal compound—at that time, it was not yet regarded as an element in the modern sense. His work was published in 1794.
Gregor found an oxide of a new metal in ilmenite; Klaproth independently discovered the element in rutile in 1795 and named it. The pure metallic form was only obtained in 1910 by Matthew A. Hunter. [97] [98] 39 Yttrium: 1794 J. Gadolin: 1843 H. Rose: Johan Gadolin discovered the earth in gadolinite in 1794.
The metal to color should be completely free from oxide and grease. Protective clothing, gloves and goggles should be used in a well-ventilated area or outdoors. Black for silver . Items are immersed in a 2.5% solution of potassium or sodium sulfide, after the appearance of the color wash objects well and wax or varnish it. [26]
The chemical elements were discovered in identified minerals and with the help of the identified elements the mineral crystal structure could be described. One milestone was the discovery of the geometrical law of crystallization by René Just Haüy , a further development of the work by Nicolas Steno and Jean-Baptiste L. Romé de l'Isle (the ...
Candle moulding machine in Indonesia circa 1920. Candle making was developed independently in a number of countries around the world. [1]Candles were primarily made from tallow and beeswax in Europe from the Roman period until the modern era, when spermaceti (from sperm whales) was used in the 18th and 19th centuries, [2] and purified animal fats and paraffin wax since the 19th century. [1]
Chrysoprase (also spelled chrysophrase) is a green variety of chalcedony, which has been colored by nickel oxide. (The darker varieties of chrysoprase are also referred to as prase. However, the term prase is also used to describe green quartz and to a certain extent is a color-descriptor, rather than a rigorously defined mineral variety.)
Wax candle. Waxes such as paraffin wax or beeswax, and hard fats such as tallow are used to make candles, used for lighting and decoration. Another fuel type used in candle manufacturing includes soy. Soy wax is made by the hydrogenation process using soybean oil.
The earliest gold metallurgy is known from the Varna culture in Bulgaria, dating from c. 4600 BC. [6] Silver, copper, tin and meteoric iron can also be found native, allowing a limited amount of metalworking in ancient cultures. [7] Egyptian weapons made from meteoric iron in about 3000 BC were highly prized as "daggers from Heaven". [8]