About a fortnight ago, I respired, after forced voluntary exhaustion of my lungs, my nose being accurately closed, three quarts of hydrogene in a silk bag, at four intervals, for near five minutes. After this it was highly inflammable, and burnt with a greenish white flame in contact with the atmosphere; but was not so explosive as before.[237]
c. From what we have lately heard of the curious experiments of Mr. Volta and Mr. Carlisle, it is very probable that the conversion of nitrous gas into nitrous oxide when exposed to wetted zinc, copper and tin, in contact with mercury, as described in [Res. I. Div. V]. may in some measure depend on the action of the galvanic fluid. Whilst I was engaged in the experiments on this conversion, Dr. Beddoes[238] mentioned to me some curious facts noticed by Humboldt and Ritter, relating to the oxydation of metals by the decomposition of water, which induced me to examine the phænomena with more attention than I should have otherwise done.—I recollect observing that some of the wetted zinc filings in nitrous gas on the side of the jar not in contact with the surface of mercury, were very slowly oxydated. Whilst on the surface of the mercury where small globules of that substance were mingled with the filings of zinc, the decomposition went on much more rapidly; possibly through the medium of the moisture, a series of galvanic circles were formed.
d. In [Res. II. Div]. I. it is stated, that nitrous oxide during its solution by common water, expels about ¹/₁₆ of atmospheric air the volume of the water being unity.
From the delicate experiments of Dr. Pearson, on the passage of the electric spark through water, it appears however probable, that much more than ¹/₁₆ of atmospheric air is sometimes held in solution by that fluid,[239] possibly the whole of the air is not expelled by nitrous oxide, owing to some unknown law of saturation by which an equilibrium of affinity is produced, forming a triple compound.
No. IV.
DESCRIPTION OF A MERCURIAL AIRHOLDER.
Suggested by an inspection of Mr. Watt’s Machine for containing Factitious Airs.
By WILLIAM CLAYFIELD.
Several modes of counteracting the pressure of a decreasing column of mercury having been thought of in conjunction with Mr. W. Cox, the following was at last adopted as the most simple and effectual.
[Plate 1 Fig. 1], represents a section of the machine, which consists of a strong glass cylinder A cemented to one of the same kind B, fitted to the solid block C, into which the glass tube D is cemented for conveying air into the moveable receiver E.