NITROGEN. A simple gaseous body which forms a constituent part of nitric acid, and which, being unrespirable, has also been termed azote. It was identified as a peculiar gas by Dr. Rutherford in 1774, and shown to be one of the compo nents of atmospheric air by Lavoisier in 1774. It is generally obtained by burning a piece of phosphorus in a jar full of air inverted over water. The phosphorus during its combustion combines with the oxygen of the air to form phosphoric acid, which is dissolved by the water, and the remaining element of the air, namely, the nitrogen, remains. Nitrogen is a colorless, inodorous, and tasteless gas, not absorbed by water, and having no ac tion on vegetable colors. It extinguishes all burning bodies, and is itself uninfiam amble. It is a little lighter than atmos pheric air, 100 cubic inches weighing 80.16 grains. Its equivalent is 14, and it combines with oxygen iu 5 proportions, giving rise to the following compounds : By volume. By weight. Equiv. Symbols. N. 0. N. 0.
1. Nitrous oxide 100+ 50=14+ c.
2. Nitrous oxide 100+100=14-1-16=30=n+26 Ilyponitrons acid 100+150=14+24-...38:-.--n+8o 4. Nitrous acid 100+200=14+32=46=n+4o, 5. Nitric acid 100+250=14+40=51=7H-5o NITRO-biURIATIC ACID, Aqua regia, is the compound menstruum invented by the alchemists for dissolving gold. If strong nitric acid, orange-colored by sa turation with nitrous gas (deutoxide of azote), be mixed with the strongest liquid muriatic acid, no other effect is produced than might be expected from the action of nitrous acid of the same strength upon an equal quantity of water; nor has the mixed acid so formed any_power of acting upon gold or platina. But if colorless
aquafortis and ordinary muriatic acid be mixed together, the mixture immediately becomes yellow, and acquires the power of dissolving these two noble metals. When gently heated, pure chlorine gas rises from it, and its color becomes deep er; when further heated, chlorine still rises, but now mixed with nitrous acid gas. if the process has been very long continued, till the color becomes very dark, no more chlorine can be procured, and the liquor has lost the power of dis• solving gold. It then consists of nitrous and muriatic acids. It appears, therefore, that aqua regia owes its peculiar proper ties to the mutual decomposition of the nitric and muriatic acids • and that water, chlorine, and nitrous acid gas are the re sults of that reaction. Aqua regia does not, strictly speaking, oxidize gold and platinum ; it causes merely their combi nation with chlorine. It may be compos ed of very different proportions of the two acids ; the nitric being commonly of specific gravity 1.34; the muriatic, of specific gravity 1.18 or 1.19. Sometimes 8 parts, and at others 6 parts of the mu riatic acid are mixed with 1 of nitric. It may also be made by adding nitre to mu riatic acid.