Early fixed images

The first partially successful photograph of a camera image was made in approximately 1816 by Nicephore Niepce[7][8] using a very small camera of his own making and a piece of paper coated with silver chloride, which darkened where it was exposed to light. No means of removing the remaining unaffected silver chloride was known to Niepce, so the photograph was not permanent, eventually becoming entirely darkened by the overall exposure to light necessary for viewing it. Later, in 1826, he used a sliding wooden box camera made by Charles and Vincent Chevalier in Paris, France. He made his first permanent camera photograph in 1826 by coating a pewter plate with bitumen and exposing the plate in this camera.[9] The bitumen hardened where light struck. The unhardened areas were then dissolved away. This photograph still survives. Nicephore Niepce (born Joseph Niepce) March 7, 1765 Ц July 5, 1833)[1] was a French inventor, most noted as one of the inventors of photography[2] and a pioneer in the field. He is most noted for producing the world's first known photograph in 1825.[3] Among Niepce's other inventions was the Pyreolophore, the world's first 'internal combustion engine', which he conceived, created, and developed with his older brother Claude. Silver chloride is a chemical compound with the chemical formula AgCl. This white crystalline solid is well known for its low solubility in water (this behavior being reminiscent of the chlorides of Tl+ and Pb2+). Upon illumination or heating, silver chloride converts to silver (and chlorine), which is signaled by greyis or purplish coloration to some samples. AgCl occurs naturally as a mineral chlorargyrite. Pewter is a malleable metal alloy, traditionally 85Ц99% tin, with the remainder consisting of copper, antimony, bismuth and sometimes, less commonly today, lead. Silver is also sometimes used. Copper and antimony act as hardeners while lead is common in the lower grades of pewter, which have a bluish tint. It has a low melting point, around 170Ц230 ∞C (338Ц446 ∞F), depending on the exact mixture of metals.[1] The word pewter is probably a variation of the word spelter, a term for zinc alloys (originally a colloquial name for zinc). The primary use of asphalt/bitumen is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs. The terms asphalt and bitumen are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, asphalt (or asphalt cement) is the carefully refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called bitumen. Geological terminology often prefers the term bitumen. Common usage often refers to various forms of asphalt/bitumen as "tar", such as at the La Brea Tar Pits. Another term, mostly archaic, refers to asphalt/bitumen as "pitch". The pitch used in this mixture is sometimes found in natural deposits but usually made by the distillation of crude oil.