Volume 1

The chemical works of Caspar Neumann ... / abridged and methodized. With large additions, containing the later discoveries and improvements made in chemistry and the arts depending thereon by William Lewis.

  • Caspar Neumann
Date:
1773
Catalogue details

Licence: Public Domain Mark

Credit: The chemical works of Caspar Neumann ... / abridged and methodized. With large additions, containing the later discoveries and improvements made in chemistry and the arts depending thereon by William Lewis. Source: Wellcome Collection.

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    j6 Chalk. Stones in Chalk-pits A K T H S St o n&s in the firft paifages ; and fometimes as a deiiccative for running fores and ulcers. It is the balls of the car- dialgic troches of the Ihops: to which foine prefer Chalk itfelf in powder, the Sugar, which enters in large quantity in the troches, being often found to aggravate thofe complaints. Chalk is more ftyptic than moil of the other abforbent Earths, and there¬ fore to be ufed with caution. Some have taken it freely, for procuring a white complexion *, but its more certain eifeds are gripes and obftruhlions. It is fometimes employed for curing Wines or Malt Li- quors on the fret; it takes off their acidity, but ren¬ ders them very apt to grow vapid. In the Chalk-pits are found black or blackifti brown femkranfparent Stones, fo hard as to ftrike fire with Steel. Many of thefe appear externally whitifh and corroded as it were; and on being broke, prove gradually more compadt, and darker coloured, from the furface to the center ; as if the Chalk was produced from a corrofion and refolution of the Stone by mi¬ neral vapours. On this prefumption, fundry trials ■were made for obtaining a like refolution by art. The Stones were calcined by the greateft heat procu¬ rable in a potter’s furnace : but they remained as com¬ pact and folid as at firft, and, what is remarkable, loft nothing of their weight. Calcination in mixture with Pit-coal fucceeded no better ; nor did expofure to the fumes of Pit-coal, or of Sulphur, make any change in the Stone. The pulveriled Stone, mixed with Sulphur, and calcined, inhered no dimi¬ nution, nor any other alteration than becoming darker coloured. The Powder, both calcined and uncal¬ cined, was examined alfo with Acids ^ but none of them had any adtien on it, except that oil of Vitriol acquired from the crude Stone a red tinge; which that Acid readily does from any thing impregnated, however (lightly, with inflammable matter. Thefe Stones appear therefore to be of a different nature from Chalk, and to belong to another dais [the Cryftalline].
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