4176. Peroxide of Nickel

4176.      Peroxide of Nickel. The peroxide (sesquioxide) is obtained by passing chlorine through water holding the hydrated oxide in suspension.

4177. Sulphate of Nickel

4177.    Sulphate of Nickel. By neutralizing the protoxide of nickel with dilute sulphuric acid, green prismatic crystals of sulphate of nickel are obtained.

4178. Oxalate of Nickel

4178.    Oxalate of Nickel. This is a pale bluish-green precipitate formed by adding a strong solution of oxalic acid to a like solution of sulphate of nickel.

4179. Tests for Solutions of the Salts of Nickel

4179.    Tests for Solutions of the Salts of Nickel. Caustic alkalies give a pale-green precipitate, insoluble in excess of the precipitant, but soluble in a solution of carbonate of ammonia, yielding a greenish-blue liquid. Ferrocyanide of potassium gives a greenish-white precipitate. Sulphuretted hydrogen occasions no change in solutions of nickel containing free mineral acid; but with alkaline solutions gives a black precipitate.

4180. Acetate of Potassa

4180.  Acetate of Potassa. Mix together 26 fluid ounces acetic acid with 12 fluid ounces distilled water; add gradually 1 pound or more, until saturation, of carbonate of potassa ; filter, and evaporate, by a sand-bath, to dryness.

4181. Carbonate of Potassa

4181.    Carbonate of Potassa. This is also known under tho name Salt of Tartar, and Salt of Wormwood. The crude carbonate is obtained by lixiviating (see No. 23 (Lixiviation)) wood ashes, evaporating the solution to dryness, and fusing in iron pots for several hours. This constitutes tho potash of commerce.

Another method of preparation is to transfer tho product of the first evaporation to an oven or furnace so constructed that the flame is made to play over the alkaline mass, kept constantly stirred with an iron rod. Tho ignition is continued until the impurities are burned out, and tho mass becomes of a bluish-white ; this is commercial pearlash. Tho U. S. Pharmacopoeia directs, for general purposes, tho impure carbonate to be dissolved in water, filtered, and evaporated until it thickens, and then granulated in the manner directed for tho pure carbonate.

4182. Pure Carbonate of Potassa

4182.     Pure Carbonate of Potassa. Put 12 troy ounces bicarbonate of potassa, in coarse powder, into a largo iron crucible; heat gradually until the water of crystallization is driven off, then raise the heat to redness and maintain it at that heat for 30 minutes. When cool, dissolve it in distilled water, filter, and evaporate over a gentle fire until it thickens, then remove it from the fire and stir it constantly with an iron spatula until it granulates. (U.S. Ph.)

4183. Bicarbonate of Potassa

4183.     Bicarbonate of Potassa. Dissolve 48 ounces carbonate of potassa in 10 pints distilled water; pass carbonic acid gas through the solution to saturation (the gas may be evolved from chalk by diluted oil of vitriol). Filter, and evaporate, that crystals may form, at a heat not exceeding 160° Fahr.; decant the clear, and dry the crystals. ( U. S. Ph.)