A L K

A L K

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out doubt the alloys of the other metals thatrequire a high heat for their fusion might beobtained in this way.

Potassium and Gasseous Oxyd of Carbonhave' no mutual action at a common tempera-ture, but when heated they readily decomposeeach other. -About 200 measures of carbonicoxyd (obtained from iron filings and carbonatof barytes previously ignited strongly) wereheated with a portion of potassium. On thefirst impression of heat the potassium becameblue, but presently took fire, a great and im-mediate absorption of gas took place, carbonwas precipitated, almost all the potassium waschanged to potash and the whole gas disap-peared except about twelve measures, whichwere afterwards decomposed in a similar man-ner by a fresh portion of potassium.

Potassium a/ul Metallic Oxyds. It hasbeen already mentioned that the celebrateddiscoverer of the alkaline bases ascertained theextreme affinity of potassium for oxygen inevery combination, which therefore rendersit a most valuable re-agent for an infinitevariety of chemical purposes. Among thesehe discovered that many and probably all themetallic oxyds when heated with potassium,are reduced to the metallic state by yieldingtheir oxygen to the potassium ; and if the lat-ter is in excess, the newly reduced metals willalloy with this excess, or will unite with thepotash newly formed in case the metals aresoluble in this alkali.

Similar experiments have been repeated bythe above Trench chemists on a great varietyof metals, and with the same general results.They were all performed in a small glass tube,one end open, tire other closed. A layer ofthe metallic oxyd was first put ill, and over itthe potassium, well cleaned from oil by blot-ting paper, and upon this another layer of theoxyd. The tube was then heated over a fireas required. In almost all the cases the re-duction of the oxyd was attended with light,and generally the potassium passed to thestate of potash, and not to that of either of itsother oxyds.

The particulars of these experiments neednot be specified in this place.

Potassium and the Mineral Acids. Car-bonic acid gas and potassium do not act uponeach other at a common temperature, but at aheat approaching a cherry-red, the decompo-sition is rapid and compieat. The -approachto this is shewn by the potassium becomingblue. It then takes fire, and the gas is ab-vol. i n.

sorbed almost entirely, leaving a little residueof carbonic oxyd, and an abundance of carbonprecipitates. The potash thus generated ispartly carbonated.

Potassium and sulphureous acid act on eachother when heated, the gas is almost totallyabsorbed if the potassium be in sufficient quan-tity, and the solid residue is siilphuret of pot-ash.

In nitrous acid gas potassium inflames even atan ordinary temperature, and burns with a redflame.

With oxymuviatic acid gas the appearancesare nearly similar. The potassium burns witha red flame, and muriat of potash is produced.

When potassium is heated with muriaticacid gas, hydrogen is disengaged, and solidmuriat of potash results. The quantity of hy-drogen is the same as would be given out by theaction of water on the potassium, and it is halfthat of the muriatic acid absorbed.

Vitreous phosphoric acid heated witli potas-sium produces a pretty strong combustion, andred phosphuret of potash is left, which whenwetted gives phosphuretted hydrogen not in-flammable by exposure to air.

Potassium and Alkaline, Earthy , and Me-tallic Salts. The action of these .substanceswas ascertained in the same manner as that ofpotassium on the metallic oxyds.

In all cases the potassium abstracted oxygenfrom those saits which are known to contain it,and the potassium was generally changed intopotash, and not into either of its other oxyds.In many instances light was disengaged at themoment of mutual action. The salts employedwere all previously dried as much as possible.

The sulphats heated with potassium weremore or less perfectly converted into sulphurets.

The phosphats were in like manner changedto phosphurets, giving when moistened thatspecies of phosphuretted hydrogen which isnot spontaneously inflammable.

The carbonats with potassium were decom-posed into carbonic oxyd, the base of thecarbonat employed, and potash from the potas-sium. . -

Muriat of barytes and muriat of soda werenot altered by potassium, which sublimedthrough them, being itself unchanged.

The floats of soda and lime were equallyunaltered.

Borax was unaltered by potassium.

SODIUM.

This substance was discovered by Sir II.Davy a few days after the disco-/cry of potas-