96 



CHEMISTRY. 



Element* rry soluble in water, and not altered by exposure to 



the air. 

 ChemiMry. 



GENT* XXI. Sails of Chrom'rim. 



Silitof The salts of chromium are but very little known. 



chromium. For the few facts ascertained, we are indebted to 

 Richtcr, Godon, and Vauqurlin. Prussiate of |> 

 occasions a brown solution in these salts ; infusion of 

 nutgallf, a brown precipitate ; bydrosulphuret of pot- 

 ash, a green precipitate, which a few drops of nitric 

 acid change to yellow. 



When the oxide of chromium is obtained by preci- 

 pitating chromatc of potash by means of a hydrosul- 

 phuret, it dissolves readily in acids. The solutions 

 have a green colour, and the compounds are easily 

 decomposed. Nitric acid seems to convert the oxide 

 into chromic acid. It does not appear that there so- 

 lutions are capable of affording crystalr. The acids 

 hitherto tried, and found capable of dissolving oxide 

 of chromium, arc the nitric, muriatic, sulphuric, phos- 

 phoric, sulphurous, and oxalic. 



GENUS XXI I. Halts nf Molybdenum. 



Salti of The salts belonging to this genus are as imperfect 



molybde- as those belonging to the preceding. None of them 

 num. seem capable of crystallizing. But many acids dis- 



solve oxide of molybdenum, and the solutions are re- 

 markable for the changes of colour to which they are 

 liable. 



Nitric acid dissolves molybdenum with difficulty. 

 If the quantity of metal be greater than the acid can 

 dissolve, the solution is blue; but when a small quan- 

 tity of molybdenum is dissolved in a considerable pro- 

 portion of acid, the solution is yellowish brown. 



Muriatic acid does not attack molybdenum, but it 

 dissolves its oxide, and forms a blue coloured solution. 

 Sulphuric acid dissolves molybdenum when assisted 

 by heat, and forms a yellowish brown or a blue solu- 

 tion, according to the proportion of metal acted on. 



Sain of 



GENUS XXIII. Salts of Uranium. 



Most of these salts are soluble in water, and the 

 ?auium. solution has a yellow colour. The pure alkalies oc- 

 casion in these a yellow precipitate, prussiate of pot- 

 ash a brownish red precipitate, hydrosulphuret of 

 potash a brownish yellow precipitate, and infusion 

 of nutgalls a chocolate coloured precipitate. 



Sp. 1. Nitrate of Uranium. Nitric acid readily 

 dissolves uranium and its oxides. The solution, when 

 sufficiently concentrated, yields crystals of nitrate, 

 either in hexagonal tables, or in four-sided flat prisms, 

 with a lemon yellow colour, and greenish edges. 

 Water dissolves more than twice its weight of this 

 salt, and alcohol more than thrice its weight of it. 

 These liquids, when hot, dissolve any quantity of the 

 salt whatever. Sulphuric ether dissolve* about one- 

 fourth its weight of this salt. Nitrate of uranium 

 deliquesces in a moist atmosphere, but when kept at 

 the temperature of 100 it soon falls to powder. 

 When heated it melts, and, by continuing the heat, 

 is decomposed. This salt is composed of 61 oxide, 

 2 acid, and 1* water. 



By exposing the nitrate to a moderate heat, it it Elnft 

 converted into a letnon-yellow powder, insoluble in 

 water, which is a tuii nitrate of uranium. 



Sp. '2. Mitrialt- i'/' I 'KIH:HI:I. Deliquescent crys- 

 tals of a yellowish green colour, having the form'cf 

 four-sidi.d tables. 



Sp. 3. Sulphate if I'ninium. Sulphuric acid 

 scarcely acts upon uranium, but it gradually dissolves 

 its oxide, and the solution yields small crystals of a 

 lemon-yellow colour in prisms or tables. This salt 

 dissolves in less than its weight of cold water, and in 

 about half its weight of boiling water. Alcohol dis- 

 solves ?r r th of its weight of it. Heat decomposes it, 

 driving olF the acid and water, but a violent tempera- 

 ture is necessary. This salt is composed of 

 Acid 18 

 Oxide 70 

 Water 12 



100 



Sp. 4. Acetate of Uranium. Acetic acid dissolve* 

 oxide of uranium, and yields beautiful crystals in the 

 form of long slender transparent four-sided prisms, 

 terminated by four-sided pyramids. 



GENUS XXIV. Salt* of Tungsten. 



This genus of salts is still unknown. None of Saluof 

 them, from the difficulty of obtaining the metal in a tungtcu. 

 state of purity, having been hitherto examined. 



GENUS XXV. Sails of Titanium. 



The salts of titanium are, in general, soluble in Salts of 

 water, and the solution is colourless. The alkaline litaniuau 

 carbonates occasion a flaky precipitate in these solu- 

 tions, prussiate of potash a yellowish brown precipi- 

 tate, hydrosulphuret of potash a dirty bottle-green, 

 and the infusion of nutgalls a very bulky blood-red 

 precipitate. When a rod of tin is plunged into a 

 solution of titanium, the liquid around it gradually 

 assumes a fine red colour. A rod of zinc occasions 

 a deep blue colour. 



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

 the carbonate of titanium, and yields transparent crys- 

 tals in the form of elongated rhombs, having two op- 

 posite angles truncated*, so as to represent six-sided 

 tables. 



Sp. 2. Muriate of Titanium. Muriatic acid dis- 

 solves the carbonate of titanium, and forms transpa- 

 rent cubic crystals. From the experiments of Vauque- 

 lin and Hecht, it appears that it is the peroxide 

 of titanium only that combines with muriatic acid. 



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

 solves the carbonate of titanium. The solution doea 

 not crystallize, but yields, when evaporated, a white 

 opake gelatinous mass. 



GENUS XXVI. Salts of Columbium. 



This genus of salts has been but imperfectly exa- Sa | t , ^ 

 mined. Hatchett, Ekeberg, and Wollaston, are the colum- 

 only persons who have hitherto made experiments on bium. 

 this scarce metal. Sulphuric, nitric, and muriatic 

 acids scarcely dissolve the oxide of columbium. The 



