Mercury with Chalk

Powder with metal (e.g. mercury with chalk) used as purgative. 

Hydrargyrum cum Creta [mercury with chalk] mdHydr. Cum Magnesia [mercury with magnesia] these are mild preparations, yet capable of producing salivation by their continued use. Dose, five to thirty grains or two to five grains for children. They are much employed in diseases of children attended with deficient biliary secretion. .. 

Powder of Mercury with Chalk, B.Vet.C. Tablets of Digitalis, Compound, B.P.C. 

To separate mercury from sulphur, it is necessary to seek among our elements a material which has more affinity with the sulphureous acid than mercury has lime is such a species, as it will detach the acid from the mercury by its alkali salt, but as the alkali salt is there in small quantity, it requires three parts of chalk for one of cinnabar, if one operates with tartar or another alkali salt, only equal parts are required. 

A solution of copper nitrate is mixed with an excess of pieces of chalk, and the mixture is placed in a large-diameter tube of strong glass connected to a mercury manometer. The tube is then sealed. The azurite forms at room temperature when the liberated COg creates a pressure of 5-8 atm. 

Priestley concluded that phlogiston is present in a combined state in metals, just as fixed air is present in chalk, both being expelled again by acids. He repeated the experiment with calx of mercury, the inflammable air being confined over mercury, and observed that even though the inflammable air was previously well dried with fixed ammoniac [calcium chloride], water was formed in sufiicient quantity . He thought this water was contained in the gas and is deposited when this kind of air is decomposed . Priestley was very undecided whether the water was contained in the calx or in the inflammable air or both, but the section is headed Experiments which prove that Water is a necessary ingredient in inflammable air . 

The affinity of fixed air for the different metallic earths is variable and it separates very easily from mercury. The metallic earths are always united with phlogiston, or fixed air, or an acid, and are never pure. Calces are compared with alkalis and chalk fixed air is contained in acids (which Newton said attract strongly and are strongly attracted see Vol. II, p. 482) since acids calcine metals, and hence acids are not elements. Fixed fire (phlogiston) and fixed air mutually exchange the metallic earths by their attraction. These views had little influence. 

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