FIG. 40. Representing the Cylinder and the Pipes connected with the Steam Box upon an enlarged scale. Z.Z The Cylinder in which the Piston moves. E.E Steam Pipe to convey steam to force down the Piston. Y.Y Piston fitted to work in the Cylinder. G Pipe from Steam Box to Condenser. I.I A hollow Sliding Valve. C Steam Pipe from the Boiler. 6 Valve. ON CHEMISTRY; IN WHICH THE ELEMENTS OF THAT SCIENCE ARE FAMILIARLY EXPLAINED, AND Ellustrated by Experiments, AND 38 ENGRAVINGS ON WOOD. THE TWELFTH AMERICAN, FROM THE LAST LONDON EDITION, WITH TO WHICH ARE NOW ADDED, EXPLANATIONS OF THE TEXT-DIRECTIONS FOR SIMPLIFYING THE BY J. L. COMSTOCK, M. D. TOGETHER WITH A NEW AND EXTENSIVE Series of Questions, BY REV. J. L. BLAKE, A. M. HARTFORD : PUBLISHED BY COOKE AND CO. PACKARD AND BUTLER. COMVATO 46*130 L. S. District of Connecticut, ss. BE IT REMEMBERED, That on the second day of October, in the fifty-first year of the Independence of the United States of America, Oliver D. Cooke, & Co. of the said District, have deposited in this office the title of a Book, the right whereof they claim as proprietors, in the words following, to wit, "Conversations on Chemistry; in which the elements of that science are familiarly explained and illustrated by experiments, and thirty-eight engravings on wood. The tenth American from the eighth London edition, revised, corrected, and enlarged. To which are now added, explanations of the text, directions for simplifying the apparatus, and a vocabulary of terms; together with a list of interesting experiments. By J. L. Comstock, M. D. Together with a new and extensive Series of Questions, by Rev. J. L. Blake, A. M. In conformity to the act of the Congress of the United States, entitled, "An act for the encouragement of learning, by securing the copies of Maps, Charts and Books, to the authors and proprietors of such copies, during the times therein mentioned." CHAS. A. INGERSOLL, Clerk of the District of Connecticut. A true copy of record, examined and sealed by me, CHAS. A. INGERSOLL, Clerk of the District of Connecticut. ADVERTISEMENT OF THE AMERICAN EDITOR. THE familiar and agreeable manner in which the "Conversations on Chemistry" are written, renders this one of the most popular treatises on the subject which has ever appeared. The elegant and easy style also, in which the authoress has managed to convey scientific instruction is peculiarly adapted to the object of the work. In some respects, however, the English edition may be considered as objectionable. A book designed for the instruction of youth, ought, if possi ble, to contain none but established principles. Known and allowed facts are always of much higher consequence than theoretical opinions. To youth, particularly, by advancing as truths, doctrines which have arisen out of a theory not founded on demonstration, we run a chance of inculcating permanent error. Inthese respects we think that Mrs. Bryant has not been sufficiently guarded. The brilliant discoveries of Sir Humphrey Davy, and his known eminence as a Chemical Philosopher, seem in many instances to have given his opinions an authority, which, in the mind of the writer, superseded further investigation. Indeed, inferences are sometimes drawn from these opinions which they hardly warrant. Under this view of the subject, a part of the notes is designed to guard the pupil against adopting opinions which he will find either contradicted, or merely examined by most chemical writers. In addition to this, I have made such explanations of the text as I thought would assist the pupil in understanding what he reads. In attempting to make this science popular, and of general utility, it is of great importance that the experiments come within the use of such instruments as are easily obtained. I have therefore given such directions on this subject, as my former experience as a lecturer, with a small apparatus, taught me to believe would be of service. The list of experiments was chiefly made up without referring to books; some few of them, however, are copied from Parke, Accum, &c. REMARKS BY THE REV. MR. BLAKE. The questions, in the present edition, are placed at the bottom of the several pages to which they relate. This plan has been adopted in the Boston edition of Conversations on Natural Philosophy, and is become very popular. The advantages of it are too obvious to escape observation, and, of course, to need being particularized. It will be seen that the questions are more numerous than they were in the two first impressions from this copy. It may be supposed by persons not acquainted with teaching, that they are too numerous, as some of them are repeated in various forms, and others are seemingly unimportant. But it is found necessary that scholars should be examined on every page, and upon nearly every paragraph, whether there is any thing very important or not. No small portion of learners will pass over without study, all in which they are not to be questioned. Hence what might be called a system of questions would be quite insufficient. PREFACE. IN venturing to offer to the public, and more particularly to the female sex, an Introduction to Chemistry, the author, herself a woman, conceives that some explanation may be required; and she feels it the more necessary to apologize for the present undertaking, as her knowledge of the subject is but recent, and as she can have no real claims to the title of chemist. On attending for the first time experimental lectures, the author found it almost impossible to derive any clear or satisfactory information from the rapid demonstrations which are usually, and perhaps necessarily, crowded into popular courses of this kind. But frequent opportunities having afterwards occurred of conversing with a friend on the subject of chemistry, and of repeating a variety of experiments, she became better acquainted with the principles of that science, and began to feel highly interested in its pursuits. It was then that she perceived, in attending to the excellent lectures delivered at the Royal Institution, by the present Professor of Chemistry, the great advantage which her previous knowledge of the subject, slight as it was, gave her over others who had not enjoyed the same means of private instruction. Every fact or experiment attracted her attention, and served to explain some theory to which she was not a total stranger; and she had the gratification to find that the numerous and elegant illustrations, for which that school is so much distinguished, seldom failed to produce on her mind the effect for which they were intended. in Hence it was natural to infer, that familiar conversation was, studies of this kind, a most useful auxiliary source of information; and more especially to the female sex, whose education is seldom calculated to prepare their minds for abstract ideas, or scientific language. As, however, there are but few women who have access to this mode of instruction; and as the author was not acquainted with any book that could prove a substitute for it, she thought it might be useful for beginners, as well as satisfactory to herself, to trace the steps by which she had acquired her little stock of chemical knowledge, and to record, in the form of dialogue, those ideas which she had first derived from conversation. But to do this with sufficient method, and to fix upon a mode of arrangement was an object of some difficulty. After much hesitation, and a degree of embarrassment, which, probably, the most competent chemical writers have often felt in common with the most superficial, a mode of division was adopted, which, though the most natural, does not always admit of being strictly pursued-it is that of treating first the simplest bodies, and then gradually rising to the most intricate compounds. It is not the author's intention to enter into a minute vindication of this plan. But whatever may be its advantages or inconveniences, the method adopted in this work is such, that a young pupil, who should only recur to it occasionally with a view to procure in |