A manual on dental metallurgy / by Ernest A. Smith.

  • Smith, Ernest A. (Ernest Alfred)
Date:
1903
Catalogue details

Licence: In copyright

Credit: A manual on dental metallurgy / by Ernest A. Smith. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    piece of pure gold upon it. Observe that the union of the metals takes place at once. Experiment 43.—Repeat Experiment 42, using lead instead of gold. A similar result is obtained. When cold place the strip of platinum thus treated in the vice and strike with a hammer. Notice that the presence of very little lead makes platinum brittle. Experiment 44.—Dissolve i gram, (or 15 grains) of platinum in aqua regia ; cautiously evaporate nearly to dryness; re-dissolve the residue in a small quantity of water; divide the solution into two portions; reserve one portion for Experiment 45 ; to the other add excess of a solution of ammonium chloride (sal-ammoniac), then about an equal bulk of alcohol; allow to stand in a warm place for a few hours until all the platinum is precipitated. Filter ; wash the yellow precipitate with alcohol; dry and ignite, A grey spongy mass of metallic platinum is left behind (see p. 187). Heat the sponge to a white heat for five minutes, quickly place on a bright anvil and hammer into a compact mass, which will have the appearance and metallic lustre of platinum. Experiment 45.—Further dilute the solution of i)]ati- num chloride reserved from Experiment 44 with a small quantity of hot water, add a few drops of hydro- chloric acid, place a clean strip of zinc in the solution, and allow the action to go on until the liquid is colour- less. Remove the zinc, wash off any adhering pre- cipitate of metallic platinum, allow the black spongy precipitate to settle, pour ofE the clear liquid, and then wash the residual platinum first with a little hydro- chloric acid, and then with hot water. Place the platinum in a heated mortar, and add a little mercury