Nitrogen may be detected by the evolution of ammonia when the substance is heated with soda-lime.
The oxidation, which is effected by chromic acid and sulphuric acid, is conducted in a flask provided with a funnel and escape tube, and the carbon dioxide formed is swept by a current of dry air, previously freed from carbon dioxide, through a drying tube to a set of potash bulbs and a tube containing soda-lime; if halogens are present, a small wash bottle containing potassium iodide, and a U tube containing glass wool moistened with silver nitrate on one side and strong sulphuric acid on the other, must be inserted between the flask and the drying tube.
The increase in weight of the potash bulbs and soda-lime tube gives the weight of carbon dioxide evolved.
Finely divided vegetable charcoal added to a soda-lime glass gives a yellow colour.
Nickel with a potash-lead glass gives a violet colour, and a brown colour with a soda-lime glass.
