Some very uncommon circumstances are attendant on the solution of platina: 1st. The immense quantity of acid required for the solution of a minute quantity of platina. 2d. The great quantity of gas produced during the solution of this minute quantity. 3d. The intense red color of the solution, and its perfectly acid properties after it ceases to act upon the metal. XI. _On the action of the Electric Spark on a mixture of Nitrogene and Nitrous Gas._ Thinking it possible that nitrous gas and nitrogene might be made to combine by the action of the electric spark, so as to form nitrous oxide, I introduced 20 grain measures of each of them into a small detonating tube, graduated to grains, standing over mercury, and containing a very small quantity of cabbage juice rendered green by an alkali. After electric sparks had been passed through the gases for an hour and half, they were diminished to about 32, and the cabbage juice was slightly reddened. On introducing about 10 measures of hydrogene, and passing the electric spark through the whole, no inflammation or diminution was perceptible. Hence the condensation most probably arose wholly from the formation of nitrous acid,[152] by the more intimate union of the oxygene of nitrous gas with some of its nitrogene, as in the experiments of Priestley. [152] For if nitrous oxide had been formed, it would have been decomposed by the hydrogene. As the nascent nitrogene, in the decomposition of nitrate of ammoniac, combines with a portion of oxygene and nitrogene, to form nitrous oxide; it is probable that nitrous oxide may be produced during the passage of nitrous gas and ammoniac through a heated tube. XII. _General Remarks._ There are no reasons for supposing that nitrous oxide is formed in any of the processes of nature; and the nice equilibrium of affinity by which it is constituted, forbids us to hope for the power of composing it from its simple principles. We must be content to produce it, either directly or indirectly, from the decomposition of nitric acid. And as in the decomposition of nitrate of ammoniac, not only all the nitrogene of the nitric acid enters into the composition of the nitrous oxide produced, but likewise that of the ammoniac, this process is by far the cheapest, as well as the most expeditious. A mode of producing ammoniac at little expence, has been proposed by Mr. Watt. Condensed in the sulphuric acid, it can be easily made to combine with nitric acid, from the decomposition of nitre by double affinity. And thus, if the hopes which the experiments at the end of those researches induce us to indulge, do not prove fallacious, a substance which has been heretofore almost exclusively appropriated to the destruction of mankind, may become, in the hands of philosophy, a means of producing health and pleasurable sensation. RESEARCH II. INTO THE COMBINATIONS OF NITROUS OXIDE, AND ITS DECOMPOSITION BY COMBUSTIBLE BODIES. DIVISION I.