Cast iron

Cast iron generally refers to grey cast iron, but can mean any of a group of iron-based alloys containing more than 2% carbon. It is made by remelting pig iron, often along with substantial quantities of scrap iron and scrap steel, and taking a variety of steps to remove undesirable contaminants such as phosphorus and sulfur. Carbon and silicon content are reduced to the desired levels, which may be anywhere from 2% to 3.5% for carbon and 1% to 3% for silicon depending on the application. Other elements are then added to the melt before the final form is shaped by casting.
Iron is most commonly melted in a small blast furnace known as a cupola. After melting is complete, the molten iron is removed or ladled from the forehearth of the blast furnace. This process is thought to have been devised by the late 18th century ironmaster John Wilkinson, whose innovative ideas revolutionized the field of metallurgy. Previously, iron was melted in an air furnace, which is a type of reverberatory furnace.

Classification of Tamil

Tamil is associatie with Tamil language family, which includes the Irula, Kaikadi, Betta Kurumba, Sholaga, and Yerukula languages. This group is a subgroup of the Tamil-Malayalam languages, which falls under a subgroup of the Tamil-Kodagu languages, which in turn is a subgroup of the Tamil-Kannada languages. The Tamil-Kannada languages belong to the southern branch of the Dravidian language family. Tamil is most directly related to Malayalam, spoken in the Indian state of Kerala which borders Tamil Nadu. Linguists estimate Malayalam divided from Tamil between the 8th and 10th centuries.

Ice cream

Before the growth of modern refrigeration, ice cream was a luxury item kept for special occasions. Making ice cream was quite difficult. Ice was cut commercially from lakes and ponds during the winter and stored in large heaps in holes in the ground or in wood-frame ice houses, insulated by straw. Ice cream was made by hand in a huge bowl enclosed by packed ice and salt. The temperature of the ingredients was reduced by the mix of compressed ice and salt. The salt water was chilled by the ice, and the action of the salt on the ice causes it to (partially) melt, absorbing latent heat bringing the combination below the freezing point of pure water. The wrapped up container can also make better thermal contact with the salty water and ice mixture than it could with ice alone.The hand-cranked churn, which still used ice and salt for cooling, was made-up by an American named Nancy Johnson in 1846, making invention possible on site and avoiding the problem of nonstop chilling between production and consumer. Ice cream became a trendy item for the first time. The world's first business ice cream factory was opened in Baltimore, Maryland in 1851, by Jacob Fussell, a dairy farmer. An unstable demand for his milk led him to mass create ice cream. This allowed the previously expensive invention to be offered in the city at reduced prices.Fussell opened ice cream parlors as far west as Texas. Many were still around well into the twentieth century. Fussell later sold his business to Borden.
The improvement of industrial refrigeration by German engineer Carl von Linde during the 1870s eliminated the need to cut and store natural ice and when the continuous-process freezer was perfected in 1926, allowed commercial mass invention of ice cream and the birth of the modern ice cream industry.The most common method for producing ice cream at home is to use an ice cream maker, in modern times normally an electrical device that churns the ice cream mixture while cooled inside a house freezer, or using ice and salt. A newer method of making home-made ice cream is to add liquid nitrogen to the mixture while moving it using a spoon or spatula.

Jewellery

Jewellery is factually any piece of fine material used to decorate oneself. Although in earlier times jewellery was created for more convenient uses, such as wealth storage and pinning clothes together, in recent times it has been used almost completely for beautification. The first pieces of jewellery were made from likely materials, such as bone and animal teeth, shell, wood and engraved stone. Jewellery was often made for people of high importance to show their status and, in many cases, they were covered with it.Jewellery is made out of almost every material recognized and has been made to garnish nearly every body part, from hairpins to toe rings and many more types of jewellery. While high-quality and artistic pieces are made with gemstones and valuable metals, less pricey costume jewellery is made from less-valuable materials and is mass-produced.Form and function Kenyan man exhausting tribal beads.Over time, jewellery has been used for a number of reasons: Currency, wealth display and storage, purposeful Symbolism Protection and Artistic display Most cultures have at some point had a practice of observance large amounts of wealth stored in the form of jewellery. Numerous cultures move wedding dowries in the form of jewelry, or create jewelry as a means to store or display coins. on the other hand, jewellery has been used as a currency or trade good; a mostly poignant example being the use of slave beads.
In creating jewellery, a variety of gemstones, coins, or other valuable items can be used, often set into precious metals. Common expensive metals used for modern jewellery include gold, platinum or silver, although alloys of nearly every metal known can be encountered in jewellery -- bronze, for example, was common in Roman times. Most gold jewellery is made of an alloy of gold, the purity of which is affirmed in karats, indicated by a number followed by the letter K. For example, ordinary gold jewellery ranges from 10K (41.7% pure gold) to 22K (91.6% pure gold), while 24K (99.9% pure gold) is considered too soft for jewellery use. Platinum alloys variety from 900 (90% pure) to 950 (95.0% pure). The silver used in jewellery is usually sterling silver, or 92.5% fine silver.Other generally used materials include glass, such as merged glass or enamel; wood, often carved or turned; shells and other natural animal substances such as bone and ivory; natural clay, polymer clay, and even plastics.
Jewellery and society
One universal issue is control over who could wear what jewellery, a point which indicate the powerful symbolism the wearing of jewellery evoked. In ancient Rome, for instance, only convinced ranks could wear rings; later, sumptuary laws dictated who could wear what type of jewellery; again based on rank. Cultural dictate have also played a important role; for example, the wearing of earrings by Western men was considered "effeminate" in the 19th and early 20th centuries. on the other hand, the jewellery industry in the early 20th century launched a crusade to popularize wedding rings for men — which caught on — as well as appointment rings for men , going so far as to make a false history and claim that the practice had Medieval roots. By the mid 1940s, 85% of weddings in the U.S. feature a double-ring ceremony, up from 15% in the 1920s.Religion has also played a role: Islam, for instance, consider the wearing of gold by men as a social taboo,and many religions have edicts against extreme display.