_E._ 3. 47 nitrous oxide, and 14 sulphurated hydrogene, inflamed. After the explosion, the gases filled a space nearly equal to 65; then white fumes formed, and they gradually diminished to 52. On the introduction of muriate of strontian, a copious white precipitate was produced; and on the addition of water, no further absorption took place. To the residual 52, about 20 of nitrous gas were added; they filled together a space equal to about 67. _c._ In none of the experiments made on the inflammation of sulphurated hydrogene and nitrous oxide, could I ascertain with certainty the precipitation of sulphur. In one or two processes the detonating tube was rendered a little white at the points of contact with the mercury; but this was most probably owing to the oxydation of the mercury, either by the heated sulphuric acid formed, or from nitrous acid produced by the ignition. The presence of nitrous acid I could not ascertain in these processes by my usual tests, because the combustion of sulphur over white prussiate of iron, converts it into light green. When I introduced an inflamed taper into about 3 parts of sulphurated hydrogene, and 2 parts of nitrous oxide, in which proportions they could not have been fired by the electric spark, a blue flame passed through them, and much sulphur was deposited on the sides of the vessel. But this sulphur most probably owed its formation to the decomposition of a portion of sulphurated hydrogene not burnt, by the sulphureous acid formed from the combustion of the other portion. We may then conclude with probability, that sulphurated hydrogene and nitrous oxide will not decompose each other, when acted on by the electric spark, unless their proportions are such as to enable the whole of the sulphurated hydrogene to be decomposed, so that both of its constituents may become oxygenated, by attracting oxygene from the nitrous oxide: likewise, that when the sulphurated hydrogene is at its _maximum_ of inflammation, the hydrogene and sulphur form with the whole of the oxygene of nitrous oxide, water and sulphureous acid; _E._ 2: whereas at its _minimum_ they produce water, and chiefly, _perhaps_ wholly, sulphuric acid; at the same time that the nitrous oxide partially decomposed, is converted into nitrogene, and a gas analogous to atmospheric air, or into nitrogene, nitrous acid, and atmospheric air. _E._ 1. _E._ 3. By pursuing those experiments, and using larger quantities of gas, we may probably be able to ascertain from them with accuracy, the composition of sulphuric and sulphureous acids. I own I was disappointed in the results, for I expected to have been able to ascertain from them, the relative affinities of sulphur, and hydrogene for the oxygene of nitrous oxide, at the temperature of ignition. I conjectured that nitrous oxide, mingled with excess of sulphurated hydrogene, would have been decomposed, and one of the principles of it evolved unaltered, as was the case with phosphorated hydrogene.