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Of the ART of

ASSAYING METALS.

In TWO PARTS.

The Firft containing

THE THEORY,

The Second

THE PRACTICE
of the faid ART.

THE WHOLE

Deduced from the true Properties and Nature of
FOSSILS; Confirmed by the most accurate and
unquestionable Experiments, explained in a na-
tural Order, and with the utmost Clearness,

Written originally in Latin, by

JOHN ANDREW CRAMER, M.D.

WITH

NOTES and OBSERVATIONS not in the ORIGINAL,
particularly Useful to the English Reader.

By CROMWELL MORTIMER, M.D..
Secretary to the ROYAL SOCIETY,

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To which is prefixed

A LIST of the Chief English Authors who have written
upon Minerals and Metals.

THE SECOND EDITION, corrected.

LONDON,

Printed for L. DAVIS and C. REYMERS, against Grays Inn Gate,
Holborn: Printers to the ROYAL SOCIETY,

MDCCLXIV.

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ADVERTISEMENT

TO THE

SECOND EDITION.

T

HE principal Parts of this Treatise were first difpofed into Order, to ferve as Materials for a Course of Lectures and Experiments; which, in the Year 1737, were given at Leyden, to a Society of Gentlemen, moft eminently diftinguished for their Skill, in all Branches of Natural knowledge. This will be readily allowed, when it is known, that Van Swieten and Gronovius were of the Number. Cramer, who had collected the Chief of these Materials, and made the Experiments, had been inftructed in Mineralogy, and in the Practice of Metallurgy, by the greatest Masters in Germany; and at the time above-mentioned, and for fome Years before, was employed by Doctor Ifaac Lawfon, as his Operator in Chemistry. This laft named Gentleman, had refided much longer at Leyden, than those Foreigners ufually do, who go there to qualify themfelves for the Practice of Phyfick. He then employed himself in the Cultivation of thofe Arts which he had there been taught; particularly, of Chemistry; and was highly efteemed for his Skill therein; and lived in great Intimacy, with Boerbave, Van Swieten, Gaubius, Gronovius, s'Gravefand, Albinus, and with feveral other Men of great Learning, who refided in that University, and which was then in its most flourishing State; as alfo with Linnæus, who was occafionally there. Doctor Lawson afterwards ferved as Phylician to the British Army in Flanders; where, by his Death, in A 2 the

the Year 1745, the World was deprived of the Advantage of many ufeful Difcoveries. To him we owe feveral of the Obfervations contained in this Work, to which Van Swieten, Gronovius, and others of the learned Gentlemen before mentioned alfo contributed. But the Care and Trouble of reducing the Materials into Order, and writing them out fair for the Prefs, devolved entirely on Doctor Lawfon, as fully appears from his Letters to the + Gentleman who hath fupplied us with these anecdotes, and who, in Juftice to the Memory of fo worthy a Man, thought proper to make known how much he had contributed, to this Performance. If any Thing can add to the high Reputation of this Work, it must be the Knowledge of its having been compofed under the Direction and Patronage of Men fo diftinguished for their Knowledge in Natural History, and in every Branch of the Chemical

Art.

In this SECOND Edition, the Lift of English Authors has been enlarged; and the References to the Philofophical Tranfactions of the Royal Society, brought down to the Year 1764.

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PREFACE

TO THE

FIRST EDITION

In 1741.

SHALL, in this compendious Work, give the Reader the Elements of the Art of Affaying, that is, that Part of Chemistry, which confifts in a ftrict Examination of Minerals, by Means of a proper Apparatus. I have written this chiefly, that it may be of use to fuch Lovers of Chemistry as apply themselves to the Study of mineral Matters. For this Reason, fuppofing that fome of the flighteft and most common Chemical Preparations were in some measure known to the Reader, I have been very fhort about them, when I have had Recourfe to them in the Practical Part of the docimaftical Art, except perhaps in fome Places, that required a more particular Defcription, as being little taken Notice of in the common Chemical Proceffes. Therefore I thought it proper, previously to give a fhort and fpecial Theory of this Art, that those who fhould come to the Proceffes, might already be acquainted with certain Things neceffary to be known; that by this Means the Mind might be more compleatly Inftructed in the making of the Apparatus, and the different Manners of proceeding be more eafily understood. I have begun this Theory by an Explication of the lefs compound Objects of the Art, that thefe being found pure, might be diftinguished by their outward Form, or by the flightest Trial, especially in the Fire. The fimple Stones have rendered this Matter the most difficult: For A 3 almost

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