It is also oxidized when fused with caustic potash and nitre, forming a ruthenate.
The hydrate, Bi(OH) 3 i is obtained as a white powder by adding potash to a solution of a bismuth salt.
Chem., 1865, 94, p. 44 2) separates them from potassium by conversion into alums, which C. Setterberg (Ann., 1882, 211, p. loo) has shown are very slightly soluble in a solution of potash alum.
All other soaps result from the combination' of fatty oils and fat with potash or soda solutions under conditions which favour saponification.
Potassium ruthenate, K2Ru04 H20, obtained by fusion of the metal with caustic potash and nitre, crystallizes in prisms which become covered with a black deposit on exposure to moist air.
The oxidation, which is effected by chromic acid and sulphuric acid, is conducted in a flask provided with a funnel and escape tube, and the carbon dioxide formed is swept by a current of dry air, previously freed from carbon dioxide, through a drying tube to a set of potash bulbs and a tube containing soda-lime; if halogens are present, a small wash bottle containing potassium iodide, and a U tube containing glass wool moistened with silver nitrate on one side and strong sulphuric acid on the other, must be inserted between the flask and the drying tube.
After having previously roasted the tube and copper oxide, and reduced the copper spiral a, the weighed calcium chloride tube and potash bulbs are put in position, the boat containing the substance is inserted (in the case of a difficultly combustible substance it is desirable to mix it with cupric oxide or lead chromate), the copper spiral (d) replaced, and the air and oxygen supply connected up. The apparatus is then tested for leaks.
Traces of bismuth may be detected by treating the solution with excess of tartaric acid, potash and stannous chloride, a precipitate or dark coloration of bismuth oxide being formed even when only one part of bismuth is present in 20,000 of water.
Resin soaps are compounds of soda or potash with the complex acids (chiefly abietic) of which coniferous resins consist.
From caustic potash are made (I) Potassii Permanganas, dose 1 to 3 grs., used in preparing Liquor Potassii Permanganatis, a I A solution, dose 2 to 4 drs.