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PROPERTIES OF PHOSPHATES.

dissolved in the boiling acid. The piece of phosphorus whichproduces no further change in the acid is then to be taken out,and the fire raised to drive over the remainder of the nitric acid.The phosphoric acid will then be found in the retort, partly ina concrete and partly in a liquid form.

Rationale. ..In this process a decomposition of the nitricacid takes place, the phosphorus at the temperature of the heat-ed acid attracts its oxigen, and becomes converted into phospho-ric acid; and the nitrogen becomes free and flies off in the ga-zeous state.

The combination of phosphoric acid with different bases,forms the salts called phosphates.

PROPERTIES OF PHOSPHATES.

These salts are fusible, before the blow-pipe, into a globule ofglass. They are soluble in nitric acid, from which they are pre-cipitated by lime-water. Most of them do not afford phospho-rus when heated with charcoal.

METHODS OF OBTAINING PHOSPHATES.

The principal of these salts are the phosphates of soda, potash,ammonia, magnesia, barytes, and strontia. They are preparedby saturating the carbonates of these bodies with phosphoricacid, and proceeding in the manner directed for the preparationof sulphates. Phosphate of mercury is precipitated by minglinga solution of phosphate of soda, and nitrate of mercury. Phos-phate of copper is formed in a similar manner, by letting fall asolution of phosphate of soda into a solution of nitrate of copper.Phosphate of iron is precipitated by mixing a solution of phosphateof potash with a solution of sulphate of iron. Phosphate of leadand phosphate of bismuth, are produced by dropping a solutionof phosphate of soda into nitrate of lead or bismuth. Phosphateof tin or zinc is formed in a similar manner.