Resembling the metals in all these properties, it is, however, remarkably different from any of them in specific gravity ; for it will not sink in double distilled naphtha, whose specific gravi ty is only .770, that of water being con sidered a 1.000. Mr. Davy has deter mined by experiment, that its specific gravity is to that of mercury as 10 to 223, which gives a proportion to that of water nearly as 6 to 10 ; so that it is the lightest fluid body known. When this substance is introduced into oxy muriatic acid gas, it burns spontaneous ly with a bright red light, and muriate of potash is formed. When thrown up on water, it decomposes it with great vio lence, and an instantaneous explosion is produced with brilliant flame, and a so lution of pure potash is the result.
When a globule is placed upon ice, not even the solid form of the two sub stances can prevent their union ; for it in stantly burns with a bright flame, and a deep hole is made in the ice, which is found to contain a solution of potash. When a globule is dropped upon moist cued turmeric paper, it immediately burns, and moves rapidly upon the pa per, as if in search of moisture, leaving behind it a deep reddish brown trace. So strong is the attraction of the basis of potash for oxygen, that it discovers and decomposes the small quantities of water contained in alcohol and ether, even when they are carefully purified. When thrown into the mineral acids, it inflames and burns on the surface. In sulphuric acid, sulphate of potash is formed; in nitrous acid, nitrous gas is disengaged, and nitrate of potash form ed. When brought in contact with a piece of phosphorus, and pressed up on, there is a considerable action : they become fluid together, burn, and pro duce phosphate of potash. When a glo gide is made to touch a globule of mercury about twice as large, they com bine with a considerable heat ; the com pound is fluid at the temperature of its formation : but when cool it appears as a solid metal, similar in colour to sil ver. If this compound be exposed to air, it rapidly absorbs oxygen ; potash which deliquesces is formed ; and in a few minutes the mercury is found pure and unaltered.
When a globule of the amalgam is thrown into water, it rapidly decompo ses it with a hissing noise, potash is formed, hydrogen disengaged, and the mercury remains free. The basis of pot ash readily reduces metallic oxides when heated in contact with them. It de
composes common glass by a gentle heat, and at a red heat effects a change even in the purest glass. Mr. Davy has discovered that its base, like that of potash, is white, opaque, and has the lustre of silver. The property of welding, which belongs to iron and platina, at a white heat only, is possess ed by this substance at common tem peratures. It is very similar, in its more obvious properties, to the base of potash ; but it has greater specific gra vity, being to that of water nearly as nine to ten, or as 9348 to 1.0000. In oxygen gas it produces a white flame, and sends forth bright sparks, occasion ing a very beautiful effect. In oxy-mu riatic acid gas it bums vividly, with numerous scintillations of a bright red colour. In the quantity of it ren ders mercury a fixed solid, of the co lour of silver, and forms an alloy with tin. When amalgamated with mercury, the amalgam will combine with other metals.
Mr. Davy tried this with iron and pla tina, and had reason to believe that these latter metals remain in combination with the mercury, even when deprived of the new substance by exposure to the air. From several curious and ingenious ex periments to ascertain the proportions of the bases and oxygen in the two fixed al kalies, he concludes that 100 parts of potash consist of about 84 basis, and 16 oxygen ; and 100 parts of soda consist of about 76 or 77 basis, and 24 or 23 oxygen ; or that potash may be consi dered as consisting of about 6 parts basis, and 1 of oxygen ; and soda of 7 basis, and 2 oxygen. In reply to the ques tion, whether the bases of potash and soda should be called metals, it may be said that they agree with metals in opacity, lustre, malleability, conducting powers as to heat and electricity, and in their qualities of chemical combination. Even their low specific gravity does not ap pear a sufficient reason for making them a new class ; for amongst the metals themselves there are remarkable diffe rences in this respect, platina being near ly four times as heavy as tellurium ; and tellurium is not much more than six times as heavy as the basis of soda. Conceiving the basis of the two fixed alkalies to be metals, Mr. Davy has named one Potasi um, and the other Sodium ; adopting that termination which, by common consent, has been applied to other newly discover ed metals.