_b._ Spring water boiled for some hours, and suffered to cool under mercury, absorbed a quantity of nitrous gas equal to one thirteenth of its bulk; which is not much less than that absorbed by pure water. _c._ I exposed to spring water, 10 measures of nitrous gas; the composition of which had been accurately ascertained; the diminution was one twenty-eighth, the volume of water being taken as unity. On placing the residuum in contact with solution of sulphate of iron, the nitrogene remaining was nearly one twentieth more than had been contained by the gas before its exposure to water. _d._ Distilled water was saturated with common air, by being agitated for some time in the atmosphere. Nitrous gas placed in contact with this water, underwent a diminution of ¹/₁₈; the volume of water being unity. The gas remaining after the absorption contained about one twenty-seventh nitrogene more than before. _e._ Nitrous gas exposed to water combined with about one fourth of its volume of carbonic acid, diminished to ¹/₃₂[112] nearly. The remainder contained little or no superabundant nitrogene. [112] The water still being unity. From these observations it appears, that the different degrees of diminution of nitrous gas by different kinds of water, may depend upon various causes. 1. Less nitrous gas will be absorbed by water holding in solution earthy salts, than by pure water; and in this case the diminution of the attraction of water for nitrous gas will probably be in the ratio of the quantities of salt combined with it. _a._ _b._ 2. The apparent diminution of nitrous gas in water, holding in solution atmospheric air, will be less than in pure water, though the absolute diminution will be greater; for the same portion will be absorbed, whilst another portion is combined with the oxygene of the atmospheric air contained in the water; and from the disengagement of the nitrogene of this air, arises an increased residuum. _c._ _d._ 3. Probably in waters containing nitrogene, hydrogene, and other gases, absorbable only to a slight extent, the apparent diminution will be less, on account of the disengagement of those gases from the water, by the stronger affinity of nitrous gas for that fluid. 4. In water containing carbonic acid, and probably some other acid gases, the diminution will be small in proportion to the quantity of gas contained in the water: the affinity of this fluid for nitrous gas being diminished by its greater affinity for the substance combined with it. _e._