<-l!KMI<TUV. 



[l-oTAXSU'M. 



containing an iron tube, t.lV.i nl, iron-turning* 



UM left u another t imp the pota**, which U 



ftuwd by a miiall furnaoa hung beneath it KIMUI this 



fu*od potas* run* iron-turning*, when. 



, deoampuMKl, tho |..! I--!MIH 1- pr-lun-d. This 



.t over, and fall* into a basin holding naphtha true 



from oxygen. Thu tuU-, <>u tho 1. it hand Mo, 



aeU at a kind of saffty-ralw fur thu enc]>o of va]M.nr, 



and pWTeata any risk of aocideut in cane the iron tube 



ahould booome filled up. 



There are other mode* of making potaiwium on the Urge 

 cafe ; but that we have derailed will acquaint our 

 reader* with the general principle* of it* manufacture. 



Potaiaium ha* a specific gravity of -80; it* qrmbd is 

 K (kalium); and iu equivalent, 39 'J. In its ordinary 

 i. a* sold at the shops, it is in tho shape of pea*, 

 having, externally, a black appearance, owing to the de- 

 cuui|>uutio!i of tho naphtha in which it U preserved for 

 the purpose of preventing it* oxidation. If one of these 

 globule* be cut ojiun, a .shining metallic appearance is 

 presented, which, however, i* *oou lost, owing to the 

 action of tin- oxygen in the atmosphere. If a piece of 

 potassium bo citat on to water, that liquid is at once 

 decomposed, and the liberated hydrogen combining with 

 a portion of potassium in the form of potassiuretted 

 hydrogen, cat. This fact was applied l>y Mr. 



Macintosh to the construction of a in-u kind of shell for 

 warlike purpose*. An ordinary bomb shell waa to be 

 fillod with any inflammable liquid, and at the opening a 

 few tiuall piece* of potassium were fixed. This shell, on 

 being fired from a mortar and striking an object, would 

 break, and it* contents falling out, the potassium would 

 inflame thu liquid. A simple experiment, illustrating 

 the principle, may l>e ra.sily tried by tilling a thin glass 

 globe with ether, and dropping into it a pea of potassium. 

 If the glass be then thrown into a vessel of water, so that 

 it may oe broken at it* sides, the shell will break, and 

 the poUuwiuiu, coming in contact with the water, will at 

 OHM inflame the ether. However ingenious this plan 

 may be, the practical difficulties existing iu its application 

 have prevented it* adoption. \Vc need scarcely add that 

 ether and potassium are article* scarcely tit to be en- 

 trusted in the hands of our sailors. Potassium fuses at a 

 temperature of 150, and may bo distilled over like 

 water, if out of contact with the atmosphere. It may 

 aim be, in one sense, welded together at common tem- 

 peratures, a* it ha* a kind of paste-like consistency. 



Potass, potash, or [>earlaxh, is an oxide of potassium 

 ; the two latter names lieing applied to the article as 

 found iu commerce. It i* produced as a hydrate when 

 potassium is exposed to the action of the atmosphere. 

 Commercially, it U obtained by burning various plants ; 

 hence it* name of potash. The salt* set free are then 

 duuK.h. ,1 out by water, when tho carl>onatc of potash, 

 one of the products, is decomposed by boiling with lime. 

 The Utter seize* tho carbonic acid, forming chalk, and 

 the liquor u then concentrated in iron vessels, until a 

 nearly solid xiibstauco i* produced. The temperature 

 Ix-mg raised, the potass becomes fused, and is poured 

 into moulds. In thu ordinary state it U a rough mass ; 

 but as sold by the ehetnists, it i* generally in the shape 

 of email sticks, which, from tlu-ir action on animals, 

 are used a* a caustic. Potash readily absorbs, in tins 

 state, both moisture and carbonic avid. As a liquid, 

 it forms what i* termed "oil of tartar." 



1 1 is largely employed for various purposes. 

 With oils it form* *oft soap*. It* d.t.n.'.nt pi. , 

 make it of groat value to the bleacher, the laundress, 

 and others. A peroxide of potassium is produced when 

 natal is burm-d in oxygen gas. 



.Sulphur and pot4unium unit<> to form a sulphide, on 

 potaas being fused, together with sulphur. The various 

 alto produced by tin- union of potass with acids requite 

 an individual milieu, from their general itii|xirtance. 



There are two sulphate* of potais. The sulphate is 

 pniduoed when sulphuric acid and potass, or almo*t any 

 of it* salt*, are added together. It is a crystalline sub- 

 sunce, and affords no acid reaction. Tho bisulphato is 

 product*! by heating the sulphate with sulphuric acid ; 



by means of which an extra equivalent of acid is added 

 Thu nitrate of potash common nitre, or salt- 

 is of great value ; forming the chief ingredient uf 

 _nnp..diT. It is imported in large quantities fi-m 

 India ; which, in fact, is the ehirf MUIIVU of its supply. 

 It is found on the surface of tho earth ; and result* from 

 the decomposition of animal matter. For the same 

 reason it is always present in wells situated near a 

 churchyard ; and is the cause of the peculiar cooling 

 taste water presents when obtained from such offensive 

 and dangerous sources. Saltpetre requires refining before 

 living employed in the gunpowder manufacture ; and 

 this is effected by means of repeated solution and en 

 lisation. In it* purest form, nitre is found in Ix-autiful 

 six-sided crystals. When fused into balk, it affords the 

 sal-prunella of the shops. Heated alone, it gives off 

 oxygen and nitrogen ; but in contact with carbonaceous 

 matter, it afford* its oxygen; and carbonic acid, and 

 carbonate of potash, are the result* of the combustion. 

 Nitre is extensively used by firework-makers ; it is an 

 anti-septic, and may be used in curing meat ; and for 

 similar reasons it was employed by the Egyptians in the 

 process of embalming. 



(.'Morale nf Potash. We shall describe this salt next 

 to nitre, because in almost every respect it resembles 

 that substance. It is produced by passing chlorine 

 through a solution of potass, by which the chloric acid 

 resulting unites with the base. The liquid is th--n 

 crystallised, and the chlorate is afforded iu small flat 

 crystals. This salt has become of great importance in 

 connection with the manuf;icture of lucifcr-matchus ; and 

 from being only a chemical curiosity, it is now an 

 article of extensive manufacture. On being heated it 

 affords pure oxygen gas. Carbonaceous matter mixed 

 with it uetiagrates with great violence. It was proposed 

 to use it in place of nitre ; but it so readily parts with 

 its oxygen, and forms with sulphur so explosive a com- 

 pound, as to present tho greatest danger iu such an 

 attempt. A few grains of chlorate of potash in pov.-dcr, 

 mixed with sulphur, and rubbed in a mortar, or struck 

 with a hammer, explode with great violence. If a little 

 sugar and chlorate of potass be mixed together, they 

 may be inflamed by means of a drop of sulphuric acid. 

 And so readily does this salt promote combustion, that 



Fig. 71. 



pieces of phospho- 

 rus iu a glass of 

 water, with a few 

 of its crystals, may 

 be intlanied under 

 water. This ex- 

 periment is best 

 accomplished by 

 pouring on to 

 the crystals and 

 phosphorus some 

 strong sulphuric 

 acid through a 

 funnel, in the 

 manner represented in the above engraving. 



Pcrchlorate of potash may be produced by adding sul- 

 phuric acid to the chlorate, when a portion of the base is 

 removed. The operation is attended with great danger, 

 and should, therefore, not be attempted at all by the 

 student. 



Carbonate of Potash. The ordinary potash is a car- 

 bonate in an impure form. A bicarbonate is readily 

 produced by passing a stream of carbonic acid through a 

 solution of the carbonate. Both of these salt* are used 

 in medicine, and for other purpose*. 



Tlie combinations of potash, besides those we have 

 named, are very i u morons. The chloride of potassium is 

 afforded when tho chlorate of potass is heated until all 

 its oxygen U driven off, when a white crystalline mas* 

 is left, which is very soluble in water produces great 

 cold during its solution, and is analogous to common 

 salt. The iodide of potassium has been frequently 

 named in our previous pages, especially in connection 

 with photography ; in which, also, the bromide is lat 

 used. With tjirtaric acid, potash produces the ordinary 



