ALKALIES. 249 



for a more full account of its properties to Thenard, Vol. II, p. 413, 

 4th Ed. 



6. MISCELLANEOUS PHENOMENA. 



(a.) When thrown upon water, potassium floats , melts , becomes a 

 polished sphere, runs briskly about, takes fires, and emits brilliant 

 white red, and violet light, with fumes of caustic potash ; sometimes 

 rings of white smoke, from the combustion of potassuretted hydro- 

 gen are formed in the air, and the regenerated alkali, by becoming 

 red hot, often produces a slight explosion ; if the piece is as large as a 

 pea, the explosion is sometimes violent, and jets of the burning metal 

 are thrown about the room, followed by white streaks of caustic potash. 



The moving power that impels the floating metal, is potassuretted 

 hydrogen gas, aided by steam, both being generated beneath the 

 globule ; the explosion is caused by the ignited caustic potash, com- 

 bining with the water. 



(b.) On ice, potassium acts in a similar manner ; it burns and melts 

 a hole, in which, the existence of a solution of caustic potash is easi- 

 ly ascertained by turmeric paper ; it sometimes explodes on ice. 



(c.) Placed on ignited iron, it burns in common air, and brilliantly 

 in oxygen gas, producing abundant white alkaline fumes, which are 

 soon condensed on the interior of the glass vessel. 



(d.) On all the test fluids cabbage, turmeric, alkanet, fyc. it burns 

 and produces the effect of an alkali, and that although they may have 

 been first changed red by an acid : the experiment is strikingly exhib- 

 ited in a small glass flask, containing the watery solution of these colors. 



(e.) It flames on the three strong minerals acids, producing with 

 them salts of the respective acids : the sulphate of potash, on ac- 

 count of its insolubility, sinks through the fluid in white streaks. 



(f.) It dances about on alcohol and ether, gradually wasting away, 

 but generally without flaming, and the globule looks like polished silver : 

 in the very best ether it sinks, and when it rises it does not of course 

 prove that it is lighter than the ether, as it is often made buoyant by 

 the hydrogen generated beneath it. It discovers and decomposes 

 even the small quantities of water contained in alcohol and ether, and 

 being insoluble in the latter, it forms in it, a turbid cloud of potash, 

 while hydrogen is disengaged. 



(#) With M S it slowly forms soap, and when kept even under 

 naptha, in vials carelessly closed, it, in the course of some time, be- 

 comes entirely saponified ; absorbing oxygen first to form alkali, and 

 this uniting with the naptha to form soap. Potassium, when heated 

 in the concrete oils, (tallow, spermaceti, wax, &c.) acquires oxygen 

 even from them, gas rises, the base is slowly converted into potash, 

 and a soap is formed. 



(h.) On test papers, if moist, it runs about, changes the color, and 

 fires if there be moisture enough. We should never touch it with 



32 



