If we estimate the composition of nitrous oxide from the quantity of nitrogene produced in _E._ 2, it is composed of about 61 nitrogene, and 39 oxygene. VIII. _Decomposition of Nitrous Oxide by Charcoal._ An account of the analysis of nitrous oxide by charcoal is given in Res. I. Div. III. I have lately made two experiments on the combustion of charcoal in nitrous oxide, in which every precaution was taken to prevent the existence of sources of error. Of one of these I shall give a detail. _E._ Temperature being 51°, about a grain of charcoal, which had been exposed for some hours to a red heat, was introduced whilst ignited, under mercury, and transferred into a graduated jar, containing 3 cubic inches of pure nitrous oxide, standing over dry mercury. The focus of a burning lens was thrown on the charcoal; it instantly inflamed, and burnt with great vividness for near a minute, the gas being much expanded. The focus was continually applied to it for ten minutes, when the process appeared at an end. The gases, when the common temperature and pressure were restored, filled a space equal to 4,2 cubic inches. On introducing into them a few grain measures of solution of green muriate of iron, for the double purpose of saturating them with moisture, and ascertaining if any nitrous acid had been formed, no change of volume took place; and prussiate of potash gave with the muriate a white precipitate only. On the admission of a small quantity of concentrated solution of caustic potash, a diminution of the gas slowly took place; when it was complete the volume equalled about 3.05 cubic inches. By agitation in well boiled water, about,9 of these were absorbed; the remainder appeared to be pure nitrogene. The difference between the estimation founded upon the nitrogene evolved, and that deduced from the carbonic acid generated in this experiment, is not nearly so great as in that Res. I. Div. III. Taking about the mean proportions, we should conclude that nitrous oxide was composed of about 38 oxygene, and 62 nitrogene. Charcoal burnt with greater vividness than in common air, in a mixture of one third nitrogene and two thirds nitrous oxide. In equal parts of nitrous oxide and nitrogene, its light was barely perceptible. In one third nitrous oxide, and two thirds nitrogene, it was almost immediately extinguished. As charcoal burns vividly in nitrous gas, when it has been previously ignited to whiteness, I introduced it into a mixture of equal parts of nitrous oxide and nitrous gas; it burnt with a deep and bright red. IX. _Decomposition of Nitrous Oxide by Hydrocarbonate._ Nitrous oxide, and hydrocarbonate, possess no action on each other, except at high temperatures. When mingled in certain proportions, and exposed to the electric shock, a new arrangement of their principles takes place.