_f._ I have before mentioned, Division III, that nitrous oxide, during its combination with spring water, expels the common air dissolved in it. This common air generally amounts to one sixteenth, the volume of the water being unity. A correction on account of this circumstance must be made for the apparent deficiency of diminution, and for the common air mingled in consequence, with nitrous oxide during its absorption by common water. _g._ Water impregnated with nitrous gas absorbed nitrous oxide; but the residual gas was much greater than that of common water, and gave red fumes with atmospheric air. Nitrous gas agitated for a long while over water highly impregnated with nitrous oxide, was not in the slightest degree diminished, in one experiment indeed it was rather increased; doubtless from the liberation of some nitrous oxide from the water by the agitation. _h._ Nitrous oxide kept in contact with aqueous solution of sulphurated hydrogene and often agitated, was not in the slightest degree diminished. Sulphurated hydrogene, introduced into a solution of nitrous oxide, was rapidly absorbed, and as the process advanced, the nitrous oxide was given out. _i._ Water impregnated with carbonic acid, possessed no action upon nitrous oxide, and did not in the slightest degree absorb it. When carbonic acid was introduced to an aqueous solution of nitrous oxide; the aëriform acid was absorbed, and the nitrous oxide liberated. _k._ From these observations it appears that nitrous oxide has less affinity for water, than even the weaker acids, sulphurated hydrogene and carbonic acid; as indeed one might have conjectured a priori from its degree of solubility: likewise that it has a stronger attraction for water than the gases not possessed of acid or alkaline properties; it expelling from water nitrous gas, oxygene, and common air; probably hydrocarbonate, hydrogene, and nitrogene. II. _Combinations of Nitrous Oxide with Fluid Inflammable Bodies._ _a._ Vitriolic ether absorbs nitrous oxide in much larger quantities than water. A cubic inch of ether, at temperature 52°, combined with a cubic inch and seven tenths of nitrous oxide. Ether thus impregnated was not at all altered in its appearance; its smell was precisely the same, but the taste appeared less pungent, and more agreeable. Nitrous oxide is liberated unaltered from ether at a very low temperature, that is, at about the boiling point of this fluid. For expelling nitrous oxide from impregnated ether, and for ascertaining in general the quantity of gases combined with fluids, I have lately made use of a very simple method, which it may not be amiss to describe. The impregnated fluid is introduced into a small thin tube, graduated to,05 cubic inches, through mercury. The quantity of fluid should never equal more than a fifth or sixth of the capacity of the tube.