If

I

440 Preparations and Compositions. Part III.

Hydrargyrum prjecipitatum album. I,ond.White Precipitated Quicksilver.

Take of

Oxymuriate of quicksilver, half a pound;Muriate of ammonia, four ounces.Solution of subcarbonate of potass, half a pint;Distilled water, four pints.

Dissolve first the muriate of ammonia, and afterwards the oxy-muriate of quicksilver, in the distilled water, and add tothese the solution of subcarbonate of potass. Wash theprecipitate until it become insipid, and then dry it.

Muriate of quicksilver is about thirty times more solublein a solution of muriate of ammonia than in pure water; and,during the solution, there takes place a considerable increaseof temperature Now, as these facts sufficiently prove a reci-procal action of the two salts, and as there is no decomposi-tion, it is evident that they must have combined to form atriple salt;'especially as they cannot be again separated eitherby sublimation or crystallization. This compound may there-fore, with propriety, be termed Muriate of Mercury and Am-monia. It is the Sal Alembroth of the alchemists. It isvery soluble in water, and is sublimed by heat without de-composition. When to a solution of this salt we add a solu-tion of an alkaline carbonate, either of potass, as directed bythe London college, or of soda, as by that of Berlin, thereoccurs a partial decomposition. The alkali combines with aportion of the muriatic acid, and reduces the muriate of mer-cury and ammonia to the state of a submuriate, which beinginsoluble, falls to the bottom of the solution. The propor-tion of muriate of ammonia has been reduced in edition 1815to one-half, probably in consequence of a remark of Mr Phil-lips.

The process of the Dublin college is new and well contri-ved, as it converts to use the washings of the precipitated sub-muriate, and thus partly obviates the objection of want ofeconomy in the directions given by the college for preparingit. By the simple addition of ammonia, the whole muriateof mercury contained in the washings is precipitated, in theform of submuriate of mercury and ammonia.

The submuriate of mercury and ammonia thus precipita-ted, has at first an earthy, and afterwards a metallic taste. Itis not soluble in water. It is decomposed by heat, furnishingwater, ammonia, and nitrogen gas,.while 0.86 of submuriateof mercury remain behind. Sulphuric and nitric acids par-tially decompose it, and convert it into muriate of mercury,