Volume 1

Fownes' manual of chemistry : theoretical and practical / [George Fownes].

  • Fownes, George, 1815-1849.
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: Fownes' manual of chemistry : theoretical and practical / [George Fownes]. Source: Wellcome Collection.

    538/586 (page 520)
    Ammoniacal Palladium Compounds.—A moderately con- centrated solution of palladium dichloride, treated -with a sli<;lit excess of anuuonia, yields a beautiful flesh-colom-ed or rose-coloured precipitate, consisting of N2HgPd'''Cl2. This precij^itate dissolves in a large excess of ammonia; and the ammoniacal solution, when treated with acids, yields a yellow precipitate having the same com- position. This yellow modification is liliewise obtained by heating the red compound in the moist state to 100°, or in the dry state to 200°. The yellow compomid dissolves abundantly in aqueous potash, forming a yellow solution, but without givmg off ammonia, even when the liquid is heated to the boiling-point; the red compound behaves in a similar manner, but, before dissolving, is converted into the yellow modification. These compounds, dis- covered by Hugo Miiller,* are analogous in their modes of formation, and probably therefore in constitution, to the two modifications of the platinum compoimd, NgHgPtClg (pp. 513, 514); the red com- The yellow compoimd, digested with water and silver oxide, yields palladammonium oxide, NgHgPdO, which is a strong base, soluble in water, having an alkaline taste and reaction, and absorbing carbonic acid from the aii-. Palladammonium sulphite, NjHgPd.SOg, is formed by the action of sulphurous acid on the oxide or chloride ; it crystallises in orange-yellow octohedrons. The sulphate, chloride, iodide, and bromide have likewise been formed. The compound 4NH3.PdCl2, or palladiodiawAnonium chloride, Pd[NH2(NH4)Cl]2, separates from an ammoniacal solution of palladammonium chloride in oblique rhombic prisms. The oxide, N^HijPclO, obtained by decomposing the solution of this chloride with silver oxide, is also a strong base jdelding crystallisable, salts. Palladious salts are well marked by the pale yello-^vish white pre- cipitate which they form with solution of mercuric cyanide. It con- sists of paUadious cyanide, PdCjg, and is oonvei-ted by heat into the spongy metal. Hydriodic acid and potassium iodide throw down a black pre- cipitate of palladium iodide, visible even to the 500,000th degree of dilution. Palladium is readily alloyed with other metals, as copper; one of these compounds—namely, the alloy with silver—has been applied to useful pui'poses. An amalgam of palladium is now extensively used by dentists for stopping teeth. A native alloy of gold with palladium is found in Brazil. pound being palladiosemidiam/moniwm chloride, Pd and the yellow compoimd, palladammonium chlo'''ide, Pd * Ann. Ch. Pharni. Ix.xxvi. 341.