de 24. B. late of manganese. Obtained by adding malic acid lation of the preceding salt. It is a white powder lissolves in hot water, and forms translucent red crystals. which 51. they do not melt, but are gradually decomposed. ble in 41 times their weight of cold water.* tanganese. A gum like matter not capable We aƒ inangrantese. Succinic acid dissolves manand its carbonate very readily. The solution has a red 181 excar and yields when evaporated crystals which are Sometimes four-si led pristas, sometimes four-sided tables, and sometimes, octale irons, composed of two four-sided pyramids leioase to base. These crystals are transparent. They arless when viewed singly; but when laid in numwe each other they assume a rose-red colour. When come opaque, white, and similar in appearance to T..y are insoluble in alcohol. At the temperature require ten times their weight of water to dissolve stilled they yield water, brown oil, and an Accor : g to John they are composed of file of manganese, and 69-73 acid and water. show that the constituents of the crystals are necnie add xile of manganese 6.25 4.5 3.375 14-125 Benzoic acid dissolves manga. Late slowly. The solution yields thin prisIS, wide, are colourless, transparent, and are not sure to the air. They have a sweetish astrinwaves a litterish impression. At the tem idol, they require 20 times their weight of water to They are soluble likewise in alcohol. When yield a very little water, but a good deal of oil. Accetto Jola. they are composed of 24 oxide and 76 acid It is obvious from this that the salt is anhydrous, 33. Camphorateof manganese. Camphorate of soda occa- Sect. XIX. sions no precipitate in the salts of manganese. But when carbonate of manganese is boiled with camphoric acid, camphorate of manganese is formed. When the solution is left to spontaneous evaporation, the salt crystallizes in plates which are very soluble in water.* 34. Suberate of manganese may be obtained by the same process as the preceding salt. It does not crystallize, but by spontaneous evaporation may be obtained in a yellowish-white translucent matter, having the lustre of enamel. It is soluble in water. Its taste is sweet, saline, and astringent, and has a good deal of resemblance to suberate of magnesia.† 35. Pinate of manganese. It may be obtained by precipitating sulphate of manganese by pinate of potash. It is a gray powder, which agglutinates into a resinous like mass, at the heat of boiling water. It dissolves in ether, but not in water nor alcohol. The alcohol separates a portion of the pinic acid.‡ 36. Silvate of manganese dissolves easily in absolute alcohol. The colourless solution becomes brown by exposure to the air, and deposites brown manganese.§ It is 37. Sulphonaphthalate of manganese. It constitutes a neutral crystallizable salt. The taste is slightly austere. soluble in water and alcohol, and is decomposed by heat.|| SECTION XIX.-SALTS OF SESQUIOXIDE OF MANGANESse. These salts have been very little examined, and indeed are almost unknown. Their colour is reddish, and so far as I know they cannot be obtained in a neutral state, or in crystals. The few facts which I have observed are the following: 1. Sulphated sesquioxide of manganese. When concentrated sulphuric acid is poured over sesquioxide of manganese, reduced to an impalpable powder, and the mixture is left to digest at the common temperature of the atmosphere, we obtain a violetblue liquid, which when diluted with water, becomes carmine-red, and by still farther dilution, blood-red. It may be concentrated somewhat in a gentle heat without alteration, but if we boil it oxygen is disengaged, and the liquid becomes nearly colourless. Alcohol reduces it to the state of common sulphate of manganese when assisted by a moderate heat. This solution cannot be neutralized nor obtained in crystals, + Ibid. xxxiii. 103. Unverdorben, Poggendorf's Annalen, xi. 232. § Ibid. p. 400. Faraday, Aunals of Philosophy (2d series), xii. 210. * Brandes, Schweigger's Jour. xxxviii. 299. Class I. Characters. When the acid is dilute the same saline solution is obtained, but the quantity of oxide dissolved is less. When we boil deutoxide of manganese in dilute sulphuric acid, oxygen gas is given out, and we obtain a red solution containing common sulphate of manganese, mixed with sulphated sesquioxide. 2. Nitrated sesquioxide of manganese cannot be formed. 3. Oxalated sesquioxide of manganese. When oxalate of potash is dropt into sulphated sesquioxide of manganese, a rosered coloured precipitate falls, which is probably oxalated sesquioxide. 4. Carbonated sesquioxide of manganese. An alkaline carbonate throws down from the same solution a reddish-brown powder. 5. Tartrated sesquioxide of manganese. When sesquioxide of manganese in the state of a fine powder is digested in tartaric acid without the application of heat, a dark brown solution is obtainedwith a shade of yellow. 6. Citrated sesquioxide of manganese. Citric acid when digested in the same way gives a similarly coloured solution. SECTION XX.-SALTS OF PROTOXIDE OF NICKEL. The soluble salts of nickel have a beautiful emerald-green colour, while that of the insoluble salts is usually light green, though in some cases it is leek-green. 1. Prussiate of potash when dropt into the solution of these salts, throws down a milk-white precipitate. 2. The hydrosulphuret of potash occasions a black precipitate. 3. Sulphuretted hydrogen gas occasions no precipitate. 4. Gallic acid, and the infusion of nut-galls, occasion no precipitate, at least in the sulphate of nickel. 5. The ammoniacal solution of oxide of nickel has a blue colour. 6. Potash throws down an apple-green precipitate, not redissolved by adding an excess of the alkali. 7. Carbonate of ammonia throws down an apple-green precipitate redissolved in an excess of the carbonate, rendering the liquid bluish-green. 8. The greater number of the salts of nickel when heated with borax before the blow-pipe, fuse into an orange-yellow or reddish glass, which becomes yellow or almost colourless on cooling. When the quantity of salt of nickel is considerable, compared to the borax, the glass is opaque, and of a dull brown while in fusion; but on cooling it becomes dull red and transparent. 1. Sulphate of nickel. This salt is easily formed by dissolv- Sect. XX. ing carbonate of nickel in dilute sulphuric acid, and concentrating the solution. When the solution contains an excess of acid the crystals are rectangular prisms with square bases. When the solution is neutral the crystals are usually right rhombic prisms, very nearly the same as the form of sulphate of zinc. The inclination of the lateral faces of the prism to each other is 91° 10', according to the measurement of Mr. Brooke.* The colour of this salt is a fine deep emerald-green. Its taste is styptic and slightly acrid, and it remains long in the mouth. At the temperature of 60°, 100 parts of water dissolve 75-6 parts of these crystals. When exposed to the air the rhombic prisms lose a little water, but this does not happen to the square prisms.+ When heated they swell up but do not melt, and they assume a yellow colour when the water is driven off. The salt may be heated to incipient ignition without losing any acid. It has been repeatedly analyzed with nearly the same result by different chemists. Its constituents are 1 atom sulphuric acid 1 atom protoxide of nickel 5 4.25 7.875 17.125 Mr. Phillips found in the square prism about two per cent. of the water replaced by sulphuric acid. How far this replacement is the cause of the different form of the crystals is not clear. 2. Disulphate of nickel. When the preceding salt is mixed with a quantity of potash not sufficient to decompose it completely, a green powder is precipitated which constitutes the present salt. It is very little soluble in water, and possesses alkaline properties. 3. Nitrate of nickel. Carbonate of nickel dissolves readily in nitric acid; the solution, when sufficiently concentrated, deposites crystals of nitrate of nickel in very flat four-sided oblique prisms, of an emerald-green colour, not quite so fine as that of sulphate of nickel. They dissolve in twice their weight of cold water. They are soluble also in alcohol. When heated they give out water. When exposed to the air they either deliquesce or effloresce according as they want or retain 4. S nitrate of nickel. This salt was first obtained by Proust. His method was to Leat the preceding salt cautiously in a retort till it assumed a yellowish-green colour. It is insoluble in water, and composed. according to Proust, of 12 nitric acid, and SS protoxide of nickel.* This approaches 1 atom Pitric acid 11 atoms oxide of nickel 6.75 46.75 53.50 5. Carbmate of nickel. This salt is obtained by precipitating a solution of sulphate of nickel by carbonate of soda, washing the precipitate. and drying it in the open air. It is a light apple-green powder, nearly tasteless, and not sensibly soluble in water, but dissolving with effervescence in acids. Its constituents are 1 atom carbonic acid 1 atom protoxide of nickel 2.75 4.25 3.375 10:375 6. Sube zrbonate of nickel. This salt was obtained by Berthier, by precipitating sulphate of nickel by a bicarbonate of potash. The precipitate is greenish-white, pulverulent, and very light. He found its constituents to be |