The first to publish his studies, Daniel Rutherford received credit for the discovery of nitrogen in 1772. Others such as Henry Cavendish made similar discoveries. Gases were new to chemists of the period and had been previously thought of as different types of air. As a result, chemists made the same discoveries about gases around the same times. Later, another chemist, Jean Chaptal, named nitrogen because of its presence in nitrates and nitric acid.
Nitrogen has a wide array of applications. Nitroglycerin activates the explosion in dynamite, which emits no smoke and moves 25 times faster than a gunpowder explosion. It also functions as the charge in other explosives. Nitrous oxide, or laughing gas, acts as an anesthetic. Potassium nitrate forms gunpowder and fertilizer. Joined with hydrogen, nitrogen forms ammonia, commonly used in cleaners. Different types of refrigeration use liquid nitrogen as the cooling agent. Nitrogen oxide is used to treat erectile disfunction by increasing blood flow.
Nitrogen can have negative effects on an organism's health and the environment. Nitrates are used as preservatives in food and cause low vitamin A, a decrease in oxygen content of blood, cancer through the formation of nitro aminesa and disruptions in thyroid functioning. Nitrogen-based fertilizers increase the presence of nitrogen in the water and soil. This, in turn, increases the nitrates in nitrate-rich foods eaten by both humans and certain animals such as cattle more susceptible to the effects of nitrogen.
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Although nitrogen is naturally present in the atmosphere, it must be processed for usability by life on Earth. Microorganisms in soil and on plant roots convert atmospheric nitrogen into nitrates absorbed by plants. Animals deposit nitrogen into the soil, where bacteria convert it into ammonium. Other bacteria convert this ammonium into nitrates absorbed by plants that are then eaten by animals. These processes involve organic nitrogen; the nitrogen cycle is also fed by inorganic nitrogen such as man-made fertilizers and various industrial runoff.