6 MANUAL OF TECHNICAL ANALYSIS: A GUIDE FOR THE TESTING AND VALUATION OF THE VARIOUS NATURAL AND ARTIFICIAL SUBSTANCES EMPLOYED IN THE ARTS AND IN DOMESTIC ECONOMY. FOUNDED UPON THE HANDBUCH DER TECHNISCH-CHEMISCHEN UNTERSUCHUNGEN OF DR. P. A. BOLLEY, PROFESSOR OF CHEMISTRY AND TECHNOLOGY IN THE UNIVERSITY OF ARAU. BY BENJAMIN H. PAUL, PH.D., F.C.S., LATE PRINCIPAL ASSISTANT IN MR. GRAHAM'S CHEMICAL AND ASSAY LABORATORIES LONDON: HENRY G. BOHN, YORK STREET, COVENT GARDEN. PREFACE. THE preparation of this Manual has been undertaken in the belief, that the increasing recognition of the value of chemical data for commercial and technical purposes, renders it desirable that the capability of executing chemical analyses and examinations of a certain class, should be a more frequent qualification than hitherto. It is believed, too, that there are a great number of questions of considerable technical importance, for the determination of which it.is.not at all necessary that the operator should be possessed of any greater chemical knowledge than may be assumed to belong to the occupation in which he is habitually engage It is not at all my intention, by these remarks, to question the value of sound scientific training, or to imply that a thorough acquaintance with physical science would not be very desirable in many cases where it is commonly wanting. I merely propose to point out, that, even in the absence of such qualifications, there are many well-defined lines of analytical inquiry, which may be advantageously pursued by persons, engaged in business, who may be unable to avail themselves of the very scanty means that exist in this country of acquiring really practical and useful scientific knowledge. It is to serve as a guide in such cases that this Manual is intended. For the general plan of it, I am indebted to the "Handbuch der technisch-chemischen Untersuchungen" by Dr. Bolley of Arau. In the first instance a translation of that work was contemplated, but afterwards it appeared advisable to make very considerable alterations and additions. Chapters I. II. VIII. IX. and X. have been entirely rewritten, and much new matter introduced into the others. It is with great satisfaction in this respect, that I am able to state, that these alterations have met with the entire approval of Dr. Bolley, who in a letter to me says, "The very essential alterations in the arrangement and contents "of the book were soon evident to me. I consider them "much to its advantage, and perceive from the general "treatment of the subject, that the book has fallen into just "the right hands to be presented to English readers in an “appropriate manner.” In conclusion, I may remark that in a work of this kind, which cannot lay claim to originality other than that which may appertain to the adaptation and arrangement of existing material, there will of course be much that is borrowed. Supposing this to be generally understood, I have limited. myself to the endeavour to describe briefly and simply the methods of carrying out different examinations, and have availed myself of what has been published on the subject by various chemists, without especial reference to the authors. I have to express my thanks to Mr. Phillips of the Excise, for tables of the relation between the density of spirit and the per-centage of alcohol, and for a drawing of the apparatus devised by him for estimating original gravities. I trust that the object with which the book has been written, will be borne in mind by those who may give an opinion of its value, and hope that it may be found worthy of approval as well as useful. London, May 1857. BENJ. H. PAUL. |