Taken from: Mellor's Modern Inorganic Chemistry, revised ed. by G.D.Parkes, 1963 p 422 :
Nitrogen is easily obtained from air by removing the admixed carbon dioxide and oxygen. Carbon dioxide is removed by passing the air through a solution of sodium hydroxide; the oxygen is then absorbed by means of an element which will form a non-volatile oxide. Copper turnings are generally considered best for the purpose; the "turnings" offer a large surface of oxidizable metal to the air. The process is as follows:
Air freed from carbon dioxide in a wash-bottle of sodium hydroxide, and from moisture by passage through sulfuric acid, is then passed through a red-hot tube containing copper turnings. The copper removes the oxygen and forms cupric oxide:
2Cu + O2 __> 2CuO
The nitrogen passes on to be collected in a gas jar, or gasholder, etc. (Cold boiled water should be used in the gasholder as to lessen the risk of contamination owing to the presence of oxygen dissolved in ordinary water.)