the Oxidation of Phosphorus.

85 idło m819°) 4

vapour from the ether bottle. In a few seconds the fumes entirely disappear, and the air around the phosphorus becomes perfectly, transparent. If the bottle is now stopped, white fumes do not again appear in it, till the ether has passed entirely into acetic acid by combining with oxygen, which requires a few days.

Phosphorus is not luminous in the dark in air slightly impregnated with any other essential oil, as well as oil of turpentine. In an open two-ounce phial, phosphorus will appear brightly luminous in the dark; but the moment the phial is stopped with a cork, which has formerly confined an essential oil, and still sensibly retains its odour, the light begins to fade, and disappears entirely in a few seconds. The light from phosphorus in air at 63° F. is extinguished by the addition of 4 per cent. of chlorine gas, or 20 per cent. of sulphuretted hydrogen, The vapour from strong alcohol of about 80° in temperature extinguishes luminous phosphorus. But the vapours from camphor, sulphur, iodine, benzoic acid, carbonate of ammonia, iodide of carbon, do not produce that effect,— thermometer 67°. Held in the mouth of a bottle, containing strong muriatic acid, phosphorus appears to become more brilliant. But this is not the case with nitric or nitrous acids, which sensibly impair the light. The vapour from the liquor condensed in the vessels of the Portable Oil Gas Company, and coal gas, protect phosphorus from oxidation.

Do It is evident from these experiments, that phosphorus cannot be used to withdraw oxygen from gaseous mixtures, containing olefiant gas, or the different compounds of carbon and hydrogen allied to that gas. It may be employed as a test of their presence even in very minute quantity.

The influence of those gases in preventing the oxidation of phosphorus in air appears even at elevated temperatures. Phosphorus may be melted and kept for any length of time at 212°, without alteration, in air containing an equal volume of olefiant gas. In three parts air, with two parts sulphuric ether, phosphorus became faintly and transiently luminous in the dark at 215°,-weak lambent flashes, which disappeared entirely at 210°, and were repeatedly revived and extinguished by alternately elevating and lowering the temperature between

these limits. A pretty strong combustion occurred at 240°.The following table exhibits the temperature at which phosphorus first becomes faintly luminous in the dark in air containing different gaseous substances:

In 1 volume of air and 1 volume of olefiant gas, at

200° F.

The manner in which the influence of these gases is modified by barometric pressure is the most curious part of the subject. The proportion necessary to prevent combustion depends entirely upon the density of the gases. Thus, although less than one four-hundredth part of olefiant gas prevents the combustion of phosphorus, barometer 29 inches, phosphorus has been observed in a luminous state, under the pressure of half an inch mercury, in air containing so much as an equal volumé of that gas.

In the following table the first column of fractions expresses the largest proportion of olefiant gas, in a mixture of air and that gas, which allows phosphorus to be luminous under the pressure placed against it. A greater proportion of olefiant gas extinguishes at that pressure.

Thermometer at 70°. When phosphorus is luminous above

the mercurial column in a barometer tube at the greatest pres

sure possible for a particular mixture, a slight inclination of the tube from its vertical position, which has the effect of condensing the gas, extinguishes the light; while, on bringing back the tube to its vertical position, the phosphorus again becomes luminous.

The influence of other vapour on the oxidation of phosphorus at various pressures did not present any material differences from that of olefiant gas just detailed.

Naphtha and turpentine vapours appeared to lose their negative influence very rapidly as the pressure was reduced.

Carburetted hydrogen of marshes impedes to a certain degree, but does not altogether prevent, the oxidation of phosphorus. Its effect vanishes over a mercurial column of a few inches, a circumstance which will be attended to with advantage in removing, by means of phosphorus, the small portion of oxygen generally found in that gas.

The sulphuret of phosphorus and phosphuretted hydrogen gas are likewise protected from oxidation, to a certain extent, by olefiant gas, sulphuric ether, &c., although less powerfully than phosphorus, in proportion to their higher accendibility.

The oxidation of potassium appears likewise, from several comparative experiments, to be considerably retarded in dry air, containing a fourth or a fifth of its bulk of ether-vapour or olefiant gas, particularly of the latter. A piece of potassium, about the size of a pea, confined for a month in dry air, containing a fifth of its bulk of olefiant gas, was merely covered by a thin coating of grey oxide; while another piece of potassium, in similar circumstances, with the exception of the olefiant gas, was deeply penetrated with fissures of a kernel white.

The interference of those gases in preventing the oxidation of phosphorus, &c., is probably allied to the influence of the same and several other gases in preventing the accension of the explosive mixture of oxygen and hydrogen by the electric spark, first observed by Sir H. Davy (Essay on Flame), and since confirmed and investigated by Dr. Henry (Phil. Trans. 1824), and Dr. Turner (Edin. Phil. Journal, vol. xi.) Olefiant gas was found to act most powerfully, half a volume preventing the combustion of the explosive mixture, that is, defending the hydrogen from oxidation; and here, as in the

case of phosphorus, the olefiant gas seemed to suspend the usual action between the supporter and combustible, without undergoing any change itself. If the nature of this influence of olefiant gas is the same in both cases, it forms a singular and interesting subject of inquiry, readily accessible in its most minute details in the case of phosphorus.

་།

Notice of the singular Inflation of a Bladder. By Thomas Graham," A.M., F.R.S. E., Lecturer on Chemistry, Glasgow.

IN the course of an investigation respecting the passage of mixed gases through capillary openings, the following singular observation was made.

A sound bladder with stopcock was filled about two-thirds with coal gas, and the stopcock shut; the bladder was passed up in this flaccid state, into a bell-jar receiver filled with carbonic acid gas, and standing over water. The bladder was thus introduced into an atmosphere of carbonic acid gas. In the course of twelve hours, instead of being in the flaccid state in which it was left, the bladder was found distended to the utmost, and on the very point of bursting, while most of the carbonic acid gas in the receiver had disappeared. The bladder actually burst in the neck, in withdrawing it from under the receiver. It was found to contain 35 parts of carbonic acid gas by volume in 100. The substance of the bladder was quite fresh to the smell, and appeared to have undergone no change. The carbonic acid gas, remaining without in the belljar, had acquired a very little coal gas.

The conclusion is unavoidable, that the close bladder was inflated by the insinuation of carbonic acid gas from without. In a second experiment, a bladder containing rather less scoal gas, and similarly placed in an atmosphere of carbonic acid gas, being fully inflated in fifteen hours, was found to have acquired 40 parts in 100 of this latter gas. A small portion nof coal gas left the bladder as before.

16.

16iliAsclose bladder, half filled with common air, was fully in1 flated in dike manner, in the course of 24 hours. Theben

trance of carbonic acid gas into the bladder depends, therefore, upon no peculiar property of coal gas. The bladder, partially filled with coal gas, did not expand at all in the same bell-jar 1 containing common air or water merely, turitele î ali M. Dutrochet will probably view, in these experiments, the discovery of endosmose acting upon aëriform matter, as he observed it to act upon bodies in the liquid state. Unaware of the speculations of that philosopher at the time the experiments were made, I fabricated the following theory to account for them, to which I am still disposed to adhere, although it does not involve the new power.

The jar of carbonic acid gas standing over water, the bladder was moist, and we know it to be porous Between the air in the bladder and the carbonic acid gas without, there existed capillary canals through the substance of the bladder, filled with-water. The surface of water at the outer extremity of these canals being exposed to carbonic acid, a gas soluble in -water would necessarily absorb it. But the gas in solution, 2 when, permeating through a canal, it arrived at the surface of the inner extremity, would rise, as necessarily, into the air in the bladder, and expand it. Nothing but the presence of carsbonic acid gas within could prevent the disengagement of that gaso The force by which water is held in minute capillary tubes might retain that liquid in the pores of the bladder, and senable it to act in the transit of the gas, even after the pressure within the bladder had become considerable.

ཝཱ ༥.

Account of an Apparatus for ascertaining the value of different

Alkalis.

To the Editor of the QUARTERLY JOURNAL of SCIENCE, &c.

SIR, 7.I HERÊWITH Send you some account of an apparatus which I have employed for many years in ascertaining the value of the different alkalis of commerce; it is more simple and less liable to variation in its results than any with which I am -acquainted as proposed for the use of persons not familiar -with the niceties of chemical analysis. You will observe that I