Life could not exist without sodium compounds. These compounds retain water in the body's tissues, and severe sodium deficiency can cause death. Blood contains sodium compounds in solution. Sodium compounds are used in the chemical and pharmaceutical manufacturing industries, in metallurgy, in sodium vapor lamps, and in the production of hundreds of everyday products. One of the most common sodium compounds is table salt or sodium chloride. In its pure form sodium is a silver-white, soft, waxy metallic element. It is the sixth most abundant element on Earth and is present in quantities greater than trace amounts in stars and the sun. The secret that led to low-cost production was learned in 1789, when the French chemist Nicolas Leblanc discovered how to produce soda from common salt. The compound called soda is sodium carbonate. Raw soda ash is called soda ash. Carbonate also combines with water into crystals known as sodium bicarbonate or sodium bicarbonate. Soda is used in the production of soap, glass, dyes, and explosives, and as a base for the production of other sodium compounds. Other sodium compounds, with some of their uses, are: sodium bicarbonate (sodium bicarbonate), an ingredient in yeast; borax (sodium borate), a food preservative; and caustic soda, or lye (sodium hydroxide), used in soap making. Some properties of sodium are: symbol Na, atomic number 11, atomic weight 22.9898, boiling point 1,621.2 F, and melting point 208.06 F. Sodium belongs to the group of elements known as alkali metals. It is never found uncombined in nature and was first isolated by the English scientist Sir Humphry Davy in 1807. Lighter than water, pure sodium can be cut with a knife at room temperature and is brittle at low temperatures. It easily conducts heat and electricity and exhibits a photoelectric effect, that is, it detaches its electrons when exposed to light. In its pure form, sodium oxidizes