CHEMISTRY. 



Element* 



of 

 Chtmiirrr. 



Ammo. 



*ptath, 



how pro- 

 cured. 



I:, proper- 

 tie* 



tombiru- 

 lion with 

 tulphur. 



precipitating by lime-water, drying the precipitate in 

 a titter, and then keeping it for twelve hours in li- 

 quid ammonia. Its tendency to explode it so strong, 

 tnat it i dangerous to prepare it except in unall 

 quantities. 



If a globule of mercury be put into a hollow in a 

 moistened piece of sal ammoniac, and exposed to the 

 energy of a powerful galvanic battery, it increases in 

 bulk, and acquires the consistency of butter. Its 

 sp.-citic gravity is reduced to 3. The mercury has 

 obviously amalgamated with some metallic body. IF 

 this amalgam be thrown into water, the mercury re- 

 sumes its original state, a little hydrogen gas is exha- 

 led, and the water is impregnated with a weak sola- 

 tion of ammonia. Hence it would appear, that the 

 amalgamating metal is the basis of ammonia ; that it 

 decomposes water, emits the hydrogen, and retains 

 the oxygen ; and that, by this combination, it is con- 

 verted into ammonia. This unknown metallic basis 

 of ammonia has been called ammonium. 



SECT. II. Of Potash. 



Potash, called also vegetable alkali, is obtained from 

 the ashes of trees, and of vegetables tint grow at a 

 distance from the sea shore. These ashes are lixivia- 

 ted with water ; the water evaporated to dryness ; 

 the residual salt mixed with twice its weight of quick- 

 lime, and a sufficient quantity of water to make the 

 whole into a thin paste. The water is drawn off in 

 24 hours, boiled to dryness in a clean iron pot, and 

 then mixed with a quantity of alcohol, equal in weight 

 to half the original salt. The alcoholic solution, after 

 standing some days in well-closed phials, is decanted 

 off, and the alcohol distilled away in a silver still. 

 The substance which remains behind is pure potash. 



Potash is a brittle substance, of a white colour, and 

 a smell like that which is perceived during the slack- 

 ing of quick lime. Its taste is extremely acrid, and 

 it is very corrosive, destroying the texture of most 

 animal and vegetable bodies to which it is applied. 

 Its specific gravity is 1.7085. 



When heated, it melts. At a red heat, it evapo- 

 rates in a white acrid smoke. 



It contains about one-fourth of its weight of wa- 

 ter, even after being exposed to a red heat. When 

 exposed to the air, it speedily absorbs moisture, and 

 runs into a liquid. At the same time, it combines 

 with carbonic acid, for which it has a strong affinity. 



Water dissolves twice its weight of potash. The 

 solution is limpid and colourless, and almost of the 

 consistency of an oil. It is in this state that potash 

 is commonly used by chemists. When evaporated to 

 the proper consistency, the potash crystallizes. 



2. Potash docs not combine with any of the 

 simple combustibles, except sulphur. The com- 

 bination takes place by simple trituration of the 

 two substances in a mortar, or by fusing them in a 

 crucible. This compound is called sulphuret ofjiot- 

 ath. It was formerly distinguished by the name of 

 fiepar sulpfinris, or liver of' sulphur. Its colour is 

 brown j it is hard, brittle, and has a glassy fracture. 

 It* taite is acrid and bitter, and it leaves a brown 

 stain on the skin. It converts vegetable blues to 



green, and soon destroys them. When exposed to the 

 air, it acquires a green colour, and emits the smell of 

 ulphureted hydrogen. In this state it is a triple 

 compound, being competed of sulphur, potash, and 

 Biilphureted hydrogen. The last ingredient is form- 

 ed by the decomposition of the water absorbed from 

 the atmosphere. It dissolves in water, and forms 

 greenish yellow solution. In this state it is called 

 hydrogitreted sulji/iuret rj'i.otn.'.li. 



When liquid potash and phosphorus are heated in 

 a retort, water is decomposed, and p/ioff/titieted hy- 

 drogen gas is formed arid conies' over. This gas pos- 

 sesses the curious property of taking fire when it 

 comes in contact with the air. 



3. Potash does not unite with azote. 



4. Several of the metals, when kept in liquid pot- 

 ash, are oxidized, water being decomposed. This is 

 the case with iron, zinc, and molybdenum ; and pro- 

 bably also with tin and manganese. 



Potash dissolves tUc oxides of lead, tin, nickel, ar- 

 senic, cobalt, manganese, /.inc, antimony, tellurium, 

 tungsten, molybdenum. 



Mr Davy has lately succeeded in decomposing pot- Potassiurti. 

 ash, and in showing that it is a compound of oxygen 

 and a peculiar metal.'to which he has given the name of 

 putiissium. The decomposition was accomplished by 

 exposing potash to the action of the galvanic battery. 

 The metallic base separated at the negative extremi- 

 ty, while oxygen was evolved at the other. More 

 lately, Thenard and Gay-Lussac have ascertained, 

 that potash is decomposed, and potassium obtained, 

 when it is made to come in contact with iron turn- 

 ings heated to whiteness in a gun-barrel. 



Potassium, the base of potash, possesses the follow- It$ Jer< 

 properties. It is white like mercury. At 50, it is t ; OSi ' 

 a sott malleable solid, which becomes imperfectly li- 

 quid at 60", and perfectly so at 100. While at 32, 

 it is hard, brittle, and crystallized in facets. It is not 

 only lighter than water, but lighter than any known 

 liquid. Its specific gravity dots not exceed 0.885. 

 Its affinity for oxygen ia very great. In the opea 

 air, it is covered with a crust of pot ish in a few? mi. 

 mites. When thrown upon water, it decomposes lhat 

 liquid with rapidity ; hydrogen gas, holding potas- 

 sium in solution, is disengaged and takes fire, which 

 occasions the combustion of the whole potassium. 



When heated in a small quantity of oxygen gas, it 

 loses its metallic appearance, and assumes a reddish 

 brown colour. In this state it may be considered as 

 a peroxide of potassium. 



Chlorine sets potassium on fire, and converts it in- 

 to muriate of potash. 



It combines with phosphorus, and forms a phos- 

 phuret, which has the colour of lead, and remains so- 

 lid at a heat little short of that of boiling water. In 

 the open air it burns, and is converted into phosphate 

 of potash. 



It combines rapidly with sulphur by heat, and heat 

 and light are emitted at the moment of combination. 

 The sulphuret has a grey colour, and in the open air, 

 is soon converted into sulphate of potash. 



It combines and forms alloys with all the metals 

 tried, but these alloys are suon destroyed in the open 

 air, or in water, and the potassium converted into 

 potash. 



