Nitrogen

ni'tro-jen, an important element. In nature it is a gas without color, taste, or odor. It has been converted into a liquid and also frozen. It is a trifle lighter than air, but does not burn; that is to say, it does not combine readily with oxygen. If it did our atmosphere would burn up, for air is a mixture of seven parts of nitrogen to two of oxygen, or, to be more exact, seventy-nine to twenty-one by volume, and seventy-seven to twenty-three by weight. Nevertheless, nitrogen forms five distinct compounds with oxygen. Of these the most noted is nitrous oxide or laughing gas. It is made up in the ratio of two atoms of nitrogen to one of oxygen. Since 1844 laughing gas has been administered by surgeons and dentists. By inhaling this gas a patient becomes unconscious and insensible to pain.

Nitric acid is a compound of hydrogen, nitrogen, and oxygen. It is a strong, yellowish, disagreeable, acrid acid. It is often called aqua fortis or strong water, because it eats or dissolves metals with avidity. Nitric acid is used in etching steel and copper, in dissolving, tin, in dyeing, in assaying, in small quantities as a medicine, and as a caustic. It is present in delicate perfumes and vile odors, aniline dyes, medicines and poisons, dynamite, and gunpowder.

Nitrogen is an essential element of animal and plant life. Plants derive nitrogen from the air or from the soil. The human body secures the needful amount from nitrogenous foods, especially milk, eggs, cheese, beans, peas, lean meat, and oatmeal.

See Ammonia; Clover; Nitroglycerin; Saltpeter; Gunpowder; Photography; Etching