B.P. Platinum Foil.

A heavy whitish metal Sp. gr. 8.921. Withstands considerable heat. The foil is convenient for holding salts of organic acids which it is wished to char.

B.P. Solution of Perchloride of Platinum. PtCl4; 339.

Preparation. - By dissolving thin platinum foil in a mixture of nitric acid and hydrochloric acid and diluting.

Uses. - Used to distinguish potassium from sodium and to precipitate salts of ammonium, and of compound ammonias, e.g. organic alkaloids.

Action. - Soluble salts of platinum are as poisonous as arsenic. In frogs they appear to paralyse the centres for voluntary motion in the cerebral lobes, and irritate the motor centres between them and the cord, so that voluntary motion is diminished, but reflex convulsions occur. The excitability of voluntary muscle is much lessened, that of the heart is not apparently altered. In mammals the most prominent symptom is paralysis of the peripheral ends of the vaso-motor nerves. In consequence of this, diarrhoea, blood in the motions, hyperemia of the abdominal viscera, and ecchymoses of the mucous membrane of the stomach and intestine and bladder occur.

B.P. Platinum Black.

Preparation. - Platinum in a state of minute division, obtained by adding excess of carbonate of sodium and some sugar to solution of perchloride of platinum, and boiling until a black precipitate is formed, which is washed and dried.

Action. - Platinum-black appears to have a greater power than even charcoal to condense gases, and especially oxygen, in its pores. By giving the oxygen off again it acts as an oxidising agent.

Use. - To test amylic alcohol by oxidising it into valerianic acid.