CHEMISTRY. 



95 



Element! water, filtering the solution and evaporating it till a 

 pellicle forms on the surface. It deposites regular 

 ^' crystals of tartar emetic. This salt is white, cry- 

 "~ y '""* ' stallizes in regular tetrahedrons, and gradually ef- 

 floresces when exposed to the air. It dissolves in 

 about 14^- parts of cold water, and in about two 

 parts of boiling water. Heat decomposes it by de- 

 stroying the acid. It is composed of 35.4- tartaric 

 acid, 39.6 peroxide of antimony, 16.7 potash, and 

 8.3 water. 



GENUS XVII. Salts of Tellurium. 



Salti of Tellurium is too scarce a metal to expect that its 



tellurium, salts should be completely examined. The fixed al- 

 kalies throw down, from their solutions, a white 

 powder, which is re-dissolved by an excess of alkali. 

 Prussiate of potash occasions no precipitate, hydro- 

 sulphuret of potash throws down a brown or blackish 

 precipitate, and infusion of nutgalls a flaky yellow 

 precipitate. 



Sp. 1. Nitrate of Tellurium. Nitric acid readily 

 dissolves tellurium. The solution is colourless, and 

 not rendered turbid by water. When concentrated, 

 it yields small crystals in needles. 



Sp. 2. Muriate of Tellurium. Nitro-muriatic acid 

 dissolves tellurium. Water throws down a white pre- 

 cipitate from the solution, which is re-dissolved by 

 adding more water. 



Sp. 3. Sulphate of Tellurium. Sulphuric acid dis- 

 solves tellurium. Water precipitates a white powder 

 from the solution. 



GENUS XVIII. Salts of Artenic. 



Salts of Arsenic is readily converted into an acid, and even 



itsenic. its white oxide has acid properties. Hence it does 

 not form permanent salts with acids. The acids, how- 

 ever, dissolve it. Prussiate of potash occasions a 

 white precipitate in these solutions, and hydrosul- 

 phurct of potash a yellow precipitate, while the in- 

 fusion of nutgalls produces no change. 



Sp. 1. Nitrate of Artenic. Nitric acid dissolve* 

 arsenic with violence, and separates a white powder 

 scarcely soluble in water. 



Sp. '2. Muriate of Ar genie. Muriatic acid dissolves 

 arsenic when assisted by heat. It dissolves also the 

 white oxide, especially if a little nitric acid be added. 

 The muriate of arsenic may be obtained in small 

 crystalline grains. 



Sp. 3. Sulphate of Artenic. Sulphuric acid oxi- 

 dizes arsenic by the assistance of heat; the sulphate 

 is a. white powder very imperfectly soluble in water. 



Sp. 4. Acetate of Arsenic. Acetic acid dissolves 

 the white oxide of arsenic, and deposites crystals 

 scarcely soluble in water. 



Salts of 

 cobalt. 



GEVLS XIX. Saltt of Cobalt. 



Most of these salts are soluble in water, and the 

 solutions have a red c lour, unless a great excess of 

 acid be present. Alkalies precipitate a blue powder; 

 prusaiate of potash throws down a browninn yellow 

 precipitate; h)drosulphuret of potash, a black precipi- 

 tate; infusion of nutgalls, ayellowuh white precipitate. 



Sp. 1. Nitrate of Cobalt. Nitric acid dissolves Element 

 cobalt when assisted by heat, and yields red prismatic . ( 

 crystals, which deliquesce in the air. Chemistry. 



Sp. 2. Muriate of Cobalt. Muriatic acid dissolves 

 cobalt when assisted by the presence of a little nitric 

 acid. The solution is green, or, if there be no excess 

 of acid, blue, but it becomes red when diluted with 

 water. This solution forms the oldest and best known 

 sympathetic ink. It is very much diluted with water. Sympathe- 

 Characters drawn with it on paper in that state are uc ' 

 colourless when cold, but acquires a fine green co- 

 lour when heated. When the muriate is heated, it 

 sublimes in grey coloured flowers, which dissolves 

 with great difficulty in water. The solution consists 

 of common muriate of cobalt. 



Sp. 3. Sulphate of Cobalt. Sulphuric acid dis- 

 solves the peroxide of cobalt with difficulty. The 

 solution is red, and yields needle-form crystals, con- 

 sisting of rhomboidal prisms, terminated by dihedral 

 summits. It is soluble in 24 parts of cold water, in- 

 soluble in alcohol, and not altered by exposure to 

 the air. It is composed of 26 acid, 30 oxide, 44 

 water. 



This salt readily combines with potash and ammo- 

 nia, and forms triple salts with each. 



GENUS XX. Salts of Manganese. 



These salts are mostly soluble in water. Alkalies Salts of 

 throw down from them a red or white precipitate, manganese, 

 which becomes black when exposed to the air. Prus- 

 siate of potash occasions a yellowish white precipi- 

 tate, hydrosulphuret of potash a white precipitate, 

 gallic acid produces no change. 



Sp. 1. Nitrate of Manganete. Nitric acid dis- 

 solves the black oxide of manganese with the assist- 

 ance of heat, provided a little sugar be added. The 

 solution is colourless, and does not yield crystals. 



Sp. 2. Muriate of Manganese. Muriatic acid readi- 

 ly dissolves black oxide of manganese when assisted 

 by heat, abundance of oxymuriatic acid separating. 

 The solution is colourless, and deposits small crystals 

 of muriate of manganese. These crystals are not 

 easily formed. When obtained, they are hard, very 

 soluble in water, and deliquesce in the air. Muriatic 

 acid appears also to combine with red oxide of man- 

 ganese, and to form a red solution containing oxy- 

 muriate of manganese. 



Sp. 3. Sulphated Manganese. Sulphuric acid 

 readily dissolves the white and red oxides of manga- 

 nese. Upon the black it has no action, unless it be 

 assisted by heat. In that case, oxygen gas is emitted 

 in abundance, and the oxide is dissolved, being con- 

 verted into red or white oxide, according to circum- 

 stances. There are two combinations of sulphuric 

 acid and the oxides of manganese ; one with the white, 

 and another with the red oxide. 



1. Sulphate. The solution of this salt is colour- 

 less, and yields, by evaporation, rhomboidal crystals. 

 They have a very bitter taste, and are decomposed 

 by heat, which drives off the acid. 



2. Oxysulphate. The solution of this salt has a 

 red colour. It does not readily crystallize, but when 

 evaporated, easily passes into a jelly. When evapo- 

 rated to dryness, it yields red -coloured saliue crust*, 



4. 



