PROOFS OF THE PROPERTIES OF MERCURY.

77

The water becomes sensibly acid from the'formation of phos-phoric acid.

Rationale. ..In this experiment the oxigen of the oxid ofmercury quits th.it metal to join a portion of the phosphorus,which it converts into phosphoric acid; the mercury, thus de-prived of its oxigen, and greatly divided, unites with the remainderof the phosphorus, and forms a peculiar combination, in whichphosphorus predominates. The product becomes soft in boilingwater, and regains its consistence when the water ceases to be\varm.

Experiment VI.

Mercury decomposes sulphuric acid.

Put into a glass retort two parts of mercury, and three of con-centrated sulphuric acid; convey tire neck of the retort under areceiver in the pneumatic apparatus, and expose the mixture toheat; a strong effervescence is gradually excited, the surface ofthe mercury becomes white, and a powder of the same colour isseparated, which renders the acid turbid bv dispersing itselfthrough it.

In this operation a great deal of sulphureous acid gas is dis-engaged. (Seepage 3tg).

If the heat be continued until no more gas issues from theretort, a white opaque mass will be obtained, which is exceed-ingly caustic, and attracts the moisture of the atmosphere. Thismass is an oxi-sulphate of mercury. When water is pouredupon it part of the acid is separated, and the salt assumes theform of a yellow powder, formerly called turpeth mineral.

The white saline mass is of various natures and properties,according as a greater or less quantity of acid has been used, andaccording to the length of time the heat has been applied. Aswill be seen in the following experiment.