Entered according to Act of Congress, in the year 1852, by

HENRY CAREY BAIRD,

In the Clerk's Office of the District Court of the United States in and for the Eastern District of Pennsylvania.

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PREFACE.

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In presenting this little volume to the public, I trust that I am filling a void in our chemical literature. I believe there is no work in the English language on assaying which combines with practical usefulness a sufficiently popular character for those readers who have not made metallurgy, and its kindred sciences, objects of their especial study. My desire is, to offer a book which fully treats of all the subjects of assaying, and whose price will yet place it within the reach of all persons professionally interested in this important branch of knowledge.

The more compendious works on chemistry, if they allude to assaying at all, give so sparing and incidental remarks, that they do not throw any light upon it for technical

purposes, as indeed it does not fall within their province to do.

The immense mineral wealth of the United States, to which the discoveries in California have so largely added, makes this art a very desirable acquirement for every one engaged in any business connected with the metals; and it would appear indispensable to those desirous of deriving the greatest advantage from a residence in that promising and alluring part of our country.

Although these pages principally treat of the processes by heat, I have thought it proper to describe also some wet processes, either where they serve as methods to rectify the former, or where no others exist; as, for instance, is the case with platinum. For the coins, I have selected those employed at mints, and which are therefore generally considered the most serviceable for the analysis of those alloys.

I feel induced here to recommend at least · a partial study of blowpipe assaying, to those who may wish to make use of the

instructions given in this treatise. This infant branch of chemistry was first created, I may say, in Sweden by Cromsted, and established more firmly by Gahn and Berzelius, both his countrymen; and has of late been made by Plattner a method even for quantitatively ascertaining the contents of most minerals.

The requisite blowpipe utensils for the mere detection of the principal components of ores are so few, can so easily be commanded, and may be so readily carried about one's person, that, at least for the purpose of a prior test, it is very advisable to possess some knowledge of their application, which can be acquired with great facility.

I beg to refer those readers who may be desirous of pursuing assaying more scientifically, in particular to two works of merit, neither of which is written in our language. The one is the Traité des Essais par la Voie séche, by Berthier, Paris, 1834; the other is in German,-Instructions on Assaying, for Miners and Smelters, by

Bodeman, Clausthal, 1845. The last mentioned work has been of much use to me in writing this volume.

I cannot conclude these brief remarks without seizing upon the opportunity of acknowledging the liberality of a distinguished officer at Freiberg in Saxony, Mr. Fritzsche, chief assayer of that mining district. I have made frequent use of his notes and hints, given me while I had the advantage of a personal intercourse with him.

COLUMBIA, S. C., 10th April, 1851.

O. M. L.