POTASIUM, and SODIUM, or Sorarom. Of these, and of the experiments which led to the discoveries, we shall proceed to give some account, having attended the repetition of his experiments at the lec tures delivered last spring at the Royal Institution. Mr. Davy, in his first at tempts to decompose the alkalies, made use of the aqueous solutions, and failed. He next made use of the potash in a state of igneous fusion, which he brought with in the sphere of the galvanic battery : with this also he was unsuccessful in the main point: but some brilliant phenomena were produced. The potash appeared a conductor in a high degree : a most in tense light was exhibited at the negative wire, and a column of flame, which seem ed to be owing to the developement of combustible matter, arose from the point of contact. Mr. Davy next tried several experiments on the electrization of pot ash rendered fluid by heat, with the hope of being able to collect the combustible matter, but he was still unsuccessful, "and I only," says he, "attained my ob ject by employing electricity as the com mon agent for fission and decomposition." Potash perfectly dried by ignition is a non-conductor ; by a very slight addition of moisture, whiCh does not perceptibly destroy it aggregation, it is rendered a conductor, and in this state it readily fus es and decomposes by strong electrical powers. A small piece of pure potash was placed upon an insulated disc of pla connected with the negative side of the battery, in a state of intense activity ; and a platina wire, communicating with the positive side, was brought in contact with the upper surface of the alkali, a vi vid action took place, and the potash be gan to fuse at both points of electrization. There was a violent effervescence at the upper surface ; at the lower, or negative surface, there was no liberation of elastic fluid; but small globules, having a high metallic lustre, appeared ; these were si milar in visible character to quicksilver : some of them burnt with explosion and bright flame as soon as they were formed, and others remained, and were merely tarnished, and finely covered with a white film, which formed on them. "These globules," said the professor, "numerous experiments soon sheaved to be the sub stance I was in search of, and a peculiar inflammable principle the basis of potash.
I found that the platina was in no way connected with the result, except as the medium for exhibiting the electrical pow ers of decomposition ; and a substance of the same kind was produced when pieces of copper, silver, gold, plumbago, or even charcoal, were employed for completing the circuit." Soda, when acted upon in the same manner, exhibited an analogous result, and these effects equally took place in the atmosphere, and when the alkali was acted upon in the vacuum of an exhausted receiver ; but these globules could not in either case be produced from crystal lized alkalies. When a globule of the base of potash was exposed to the atmo sphere, it immediately attracted oxygen, and a white crust formed upon it, which proved to be pure potash. When the globules were strongly heated, and then suspended in oxygen gas, a rapid com bustion with a brilliant white flame was produced, and these metallic globules were converted to an alkali, whose weight greatly exceeded that of the combusti ble matter consumed. When Mr. Davy bad thus detected the basis of the fixed alkalies, he had considerable difficulty to preserve and confine them, so as to ex amine their properties and submit them to experiments. He found, however, at length, that in recently distilled naph tha they may be preserved many days, and that their physical properties may be easily examined in the atmosphere, when they are covered by a thin film of it. The basis of potash, at 60° Fah renheit, is only imperfectly fluid ; at 70° it becomes more fluid ; and at 100° its fluidity is perfect, so that different globules may be easily made to run in to one. At 50° it becomes a soft and malleable solid, which has the lustre of polished silver ; and at about the freez ing point of water it becomes harder and brittle, and when broken in frag ments exhibits a crystallized texture, of perfect whiteness and high metallic splendour. To be converted into vapour, it requires a temperature approaching that of the red heat. It is an excellent conductor of heat, and a perfect con ductor of electricity.