_a._ Phosphorus introduced into pure nitrous oxide at common temperatures, is not at all luminous. It is capable of being fused, and even sublimed in it, without undergoing acidification, and without effecting any alteration in its composition. About 2 grains of phosphorus were fused, and gradually sublimed, in 2 cubic inches of pure nitrous oxide, over mercury, by the heat of a burning lens. No alteration was produced in the volume of gas, and a portion of it absorbed by water, left a residuum of one twelfth only. Phosphorus was sublimed in pure nitrous oxide over mercury, in a dark room, by an iron heated _nearly_ to ignition; but no luminous appearance was perceptible, nor was any gas decomposed. _b._ Phosphorus decomposes nitrous oxide at the temperature of ignition, with greater or less rapidity, according to the degree of heat. We have already seen, that when phosphorus in active inflammation is introduced into nitrous oxide, it burns with intensely vivid light. Phosphorus was sublimed by a heated wire in a jar filled with nitrous oxide, standing over warm mercury. In this state of sublimation an iron heated dull red was introduced to it by being rapidly passed through the mercury; a light blue flame surrounded the wire, and disappeared as soon as it ceased to be red. To phosphorus sublimed as before, in nitrous oxide, over warm mercury, a thick wire ignited to whiteness was introduced; a terrible detonation took place, and the jar was shattered in pieces. By employing thick conical jars,[172] containing only a small quantity of nitrous oxide, I effected the detonation several times with safety; but on account of the great expansion of the elastic products, the jar was generally either raised from the mercury, or portions of gas were thrown out of it. Hence I was unable to ascertain the exact changes produced by this mode of decomposition. [172] Experiments on the detonation of nitrous oxide with phosphorus in this way require great attention. The detonating jar should be very conical; the nitrous oxide employed should never equal more than one eighth of the capacity of the jar. The wire for the inflammation must be very thick, and curved so as to be easily introduced into the jar. When ignited, it must be instantaneously passed through the heated mercury into the jar. Perhaps the electric spark might be advantageously applied for detonating phosphoric vapor with nitrous oxide. _c._ As my first attempts to ascertain the constitution of nitrous oxide were made on its decomposition by phosphorus, I employed many different modes of partially igniting this substance in it over mercury, so as to produce a combustion without explosion.