Chemistry in America : chapters from the history of the science in the United States

Front matter

CORNELL

UNIVERSITY

LIBRARY

Preface

The writer has lectured for several years to his graduate students on the development of Chemistry in the United States. A mass of material has been collected, most of which is not only interesting but valuable. Repeated requests have been made for the publication of these facts as a history of chemistry in the United States. To the writer's mind the information in his possession is not sufficiently complete to warrant such an important undertaking. The earliest endeavors of our country's scientists require even more careful and extended searching out.

Three addresses, delivered before the Chemical Society of Philadelphia, are included in the material collected by the author. These exhibit an earnest interest in chemistry in the early days of the Republic, and show, also, that despite unfavorable conditions our forefathers were eager to cultivate the science that promised so much for their country. Another proof of the genuine appreciation of the value of chemistry is evidenced by the founding of two Chemical Societies before a similar movement had been initiated anywhere else in the world. Minutes of these organizations have not been discovered. If found, they would surely contain most valuable information. Other papers, written during these early years, are even

vji

PREFACE

now most difficult to procure, and as time passes will become more inaccessible.

These "Chapters" are submitted, then, that chemists of to-day may have, in easily accessible form, copies, at least, of some of the real treasures of our science, and with the hope that through them they may be stimulated to search for other, still hidden, documents of equal or of greater value. And, as incentives to the highest endeavors, there have been included brief sketches of the life histories of such men as "Wolcott Gibbs, F. A. Genth, J. Lawrence Smith, Lea, Cooke, TVillard Gibbs and others who have enriched the science of chemistry in this country, and whose names are still familiar to the student.

This compilation of chemical achievement in the United States has brought to the writer great joy, and a fund of helpful information, which he earnestly wishes may be shared by all who chance to read these pages.

In conclusion, the author's sincere thanks are extended to all persons and societies whose letters, books and documents have been drawn upon and used in this labor of love. He also gratefully acknowledges his indebtedness to his colleague — ^Professor Walter T. Taggart — for preparing the illustrations, which have been so successfully copied from old prints and photographs.

vin

Chapter I Pages

Contributions of Americans to Chemistry. — Early Papers by de Normandie; by J. Madison; by M'Causlin 1-11

Chapter II

The Chemical Society op Philadelphia. — Its Formation. — Thomas P. Smith's Oration before the Society in 1798: "A Sketch of the Revolutions in Chemistry." — Women Participators in Chemistry. — Columbian Mineral. — Obituary of Thomas P. Smith 12-43

Chapter III

The Chemical Society op Philadelphia, Continued. — Officers of the Society. — Advertisements of the Society. — Oration by Pascalis in 1802 44-75

Chapter IV

James Woodhouse. — Woodhouse's "Chemical Catechism." — "The Young Chemist's Pocket Companion" (1797). — Pages from the Same. — Woodhouse's Answer to Priestley's Arguments against the Antiphlogistic System of Chemistry: Calcination of Metals in Air; Fixed Air; ix

PAGES

Finery Cinder; Precipitation of One Metal by Another; Air in Charcoal. — Woodhouse's Letter to Maclean. — Methods of Obtaining Oxygenous Gas. — Silliman's Word-Picture of Woodhouse. — Rush on Woodhouse. — Caldwell on Woodhouse 76-108

Chapter V

Joseph Priestley. — Priestley's Arrival in America. — His Letters to Rush. — Minute of the Trustees of the University of Pennsylvania. — Priestley's Unpublished Letter to Dr. Mitchill (facsimile). — Description of Priestley by Silliman. — Sketch of Priestley by Caldwell. — Obituaries of Priestley 109-127

Chapter VI

Thomas Cooper. — His Professorship in Dickinson College and in the University of Pennsylvania. — Decomposition of Potash with the Discovery of Potassium. — Cooj>er's Letter to Dr. Manners. — Sketch of the Apparatus Used in Isolating Potassium. — Woodhouse and Potassium. — Cooper and Hare. — Cooper and the Possible Origin of a Lincoln Phrase. — Caldwell's Estimate of Cooper. — Comparison of Priestley with Cooper. — "The Emporium of Arts and Sciences" 128-146

Chapter VII

John Maclean at Princeton. — Silliman's Estimate of Maclean. — Contemporaries of Maclean : Hutchinson, Dexter, Mitchill, Adam Seybert, Henry Seybert . 147-151

Chapter VIII Pages

Robert Hare. — The Invention of the Oxy-hydrogen Blow- Pipe. — Memoir on the Blow-Pipe before the Chemical Society in 1802 : Application of the Blow-Pipe ; Account of the Manner and Principle of Its Action; Heat of Oxy-hydrogen Flame and Its Effect on Refractory Substances. — Silliman and Hare's Blow-Pipe. — Silliman's Description of Life in Philadelphia. — Silliman's Account of Hare. — Dr. Clarke and Hare's Blow-Pipe. — Hare's Deflagrator. — Hare's Calorimotor. — A Letter from Hare to Silliman. — Hare and Galvanism. — Amalgams. — Mercury as Cathode. — Electrolytic Process. — Deflagrating of Carburets 152-205

Chapter IX

Silliman's Second Visit to Philadelphia. — Columbian Chemical Society Founded in 1811. — Memoirs of the Society, Volume I : Preface ; Papers before the Society; Officers and Members 206-218

Chapter X

Leading Chemists as Mineralogists. — Archibald Bruce. — Clemson. — Vanuxem. — Ton-ey. — Cloud. — Cleaveland. — Gorham. — James F. Dana. — Samuel L. Dana. — Bowen. — Troost. — Olmsted. — J. Redman Coxe and Electric Telegraphy. — Cutbush. — Emmett. — Griscom. — McNevin and the Atomic Theory. — W. W. Mather and the First Atomic Weight Determination Made in the United States. — Lewis C. Beck. — J. W. Bailey and the Common Blow-Pipe. — Samuel Guthrie and the Discovery of Chloroform. — Alexander Dallas Bache and the Specific xi

PAGES

Heat of the Atoms of Bodies. — John P. Norton and Agricultural Chemistry. — Evan Pugh and the Assimilation of Free or Uncombined Oxygen; His Presidency of the Pennsylvania State College. — Charles M. Wetherill. — The Rogers Brothers; Eobert E. Rogers and Gas Diffusion; the Rogers' Wet Method for the Determination of Cai'bon. — Wormley's "Micro-Chemistry of Poisons" 219-244

Chapter XI

Other Eminent Chemists. — James C. Booth's Laboratory. — T. Sterry Hunt's Chemical, Mineralogical and Geological Investigations. — J. Lawrence Smith's Contributions to the Chemistry of Minerals and Meteorites. — Gibbs, Genth and J. Lawrence Smith. — The Cobaltamines. — Mineral Alterations 245-263

Chapter XII

Eminent Chemists, Continued. — Wolcott Gibbs; the Ammonia Cobalt Bases; Platinum Metals. — Complex Inorganic Acids; Electro-Analysis. — Prescott and Pharmaceutical Chemistry. — Johnson and Agricultural Chemistrj'. — ^Mallett and Atomic Weight Determinations. — M. Carey Lea and Photo-Chemistry. — Josiah P. Cooke and Atomic Weight Determinations; "The Numerical Relation Between the Atomic Weights." — J. Willard Gibbs and Physical Chemistry; the "Phase Rule"; Thermodynamics; Geometrical Methods; Chemically Homogeneous Substances. — Chemical Publications in the United States 264-353

INDEX 351

xii

LIST OF ILLUSTEATIONS

PAQG

Robert Hare Frontispiece

James Woodhouse 76

Joseph Priestley 110

Priestley's Home and Laboratory .... 116

Thomas Cooper 128

Apparatus for the Decomposition op Potash . . 135

John Maclean 148

Samuel Latham Mitchill 150

Hare's Chemical Laboratory 158

Hare's Hydrostatic Balance 164

Hare's Deplagrator 188

Hare's Calorimotor 189

Hare's Apparatus for Obtaining Amalgams . . . 194

A Section op Hare's Amalgam Crucible . . . 198

Hare's Distillatory Apparatus 199

Hare's Apparatus for Deflagrating Carburets . . 202

Benjamin Silliman 206

James C. Booth 246

T. Sterry Hunt 252

J. Lawrence Smith 258

Wolcott Gibbs 264

M. Carey Lea 278

Josiah Parsons Cooke 302

J. WiLLARD Gibbs 344 xui

Chapter I

AEEVIEW of the contributions of Americans to the Science of Chemistry would be incomplete without a consideration of the publications made in the earliest days in which scientific matters began to interest the people of our country. Before the United States became a republic, interest in such matters was manifested. The members of the venerable American Philosophical Society were most anxious to foster investigations along all lines of scientific endeavor. This is evidenced in a preface to the first volume of the Transactions of that Society, published in 1789, in which the aims of the Society were set forth — to seek the best methods of promoting the fertility of land and of protecting trees and plants from worms and insects, to improve useful animals, to preserve timber, and to ascertain the virtues and use of many plants; and, further, the Society expressly states that it will not confine its efforts wholly to these things, nor will it exclude other useful subjects such as Physics and Chemistry. "It is believed that the study of natural objects would have a tendency to inspire our youth with a love of knowledge, draw them gently from scenes of dissipation, and animate them with a laudable desire of distinguishing themselves in the arts and sciences, hy making useful discoveries that would honor them and promote the interests of the country. " It is not surprising, then, that the earliest chemical contribution from this country, bearing the date September 10, 1768, appears on the pages of the Transactions of this Society under the title, "An Analysis of the Chalybeate "Waters of Bristol in Pennsylvania," by Dr. John de Normandie, in which the author remarks that ' ' although it must be confessed that a chymical analysis is, in some measure, an uncertain test of the medical virtues of any compound; and that the qualities of its constituent parts, when separated, may not only differ from, but are sometimes opposite to, those of the mixture; yet, when we want the testimony of experience, a chymical analysis is the best means of investigating the truth." He then proceeds to describe his experiences in the analysis of the water :

Experiment I. A small portion of white oak bark, infused in the waters, induced an immediate change from transparency to a dark purple colour, which it retained twenty-four hours, without depositing any sediment.

II. Some of the same water, after being made hot, or exposed for a few hours to the open air, in a great measure lost its irony taste, and received no other colour than a common tincture from the white oak bark.

III. One drop of strong oil of vitriol, in two ounces of the water, produced no sensible alteration ; and the water after standing some time continues transparent, without depositing any okerish or other sediment to the sides or bottom.

IV. 01. tart. pr. deliq. dropt in some of the same water induced a change in the colour, rendering it somewhat yellow ; and in time precipitated to the bottom of the eup a fine gold coloured oker.

V. Sixteen ounces avoirdupois, carefully evaporated to a dryness in a China bowl in B. M. left one grain of a yellowish brown powder of the taste of tart, tartariz.

VI. Linen, moistened with the scum floating on the top of the spring, is tinged with a strong iron mold.

VII. This water ia weight is exactly the same as that of rain water.

It is evident from these experiments that Dr. de Normandie had recourse to the use of the balance. What conclusion did the author draw from his investigations? He writes: "It is sufficiently evident that this water, in its natural state, contains a large portion of iron dissolved in pure water by means of an acid, which acid is extremely volatile, and probably of the vitriolic kind. ' '

In a communication bearing a later date than the preceding, but published in the same Transactions, he adds some additional facts concerning the same water:

I. Upon the addition of Sp. Sal. Arom. to the water a slight effervescence ensued, and upon standing about an hour, a light yellow matter was separated and floated upon the top of the liquor.

II. From a mixture of lime water, the same separation was made, but fell to the bottom of the liquor.

III. Powder 'd chalk added to the water produced the same separation, but not in so short a time as in the preceding experiments.

IV. The residuum, after a slight calcination, was strongly attracted by the magnet.

V. A solution of crude Sal. Ammon. being mixed with the water, was succeeded by the same appearance as the addition of lime water.

VI. The residuum after evaporation in Bain. Mar. before calcination, discovered to the taste a considerable portion of salt, which left a coldness on the tongue, and when separated by solution, filtration and evaporation, appeared of the colour of salt of amber, and shot into right angled crystals, which through a microscope appeared beautifully feathered; and from every experiment was found perfectly neutral.

VII. Silver immersed for some time in the water acquired a slight yellow colour.

VIII. The residuum thrown on a red hot iron sparkled very much, and emitted a sulphureous smell, what remained on the iron had not the least perceptible taste of salt.

IX. The waters, and the solution of the crystallized salt, changed sj^rup of violets to a fine light green.

The first four of these experiments, in which the waters were decomposed as well by a volatile alkali, as by lime water, and an absorbent earth, and the residuum (after a slight calcination) being attracted by the magnet, evidently prove that they are impregnated with a considerable portion of iron.

The fifth experiment (in which a decomposition takes place by means of a double elective attraction) shews that the acid in these waters has a stronger affinity with alkalies than that which is the basis of Sal. Ammoniac (which is the marine acid), and must be either the nitrous or vitriolic. And from a decomposition taking place, on the addition of common nitre with the Chalybeate waters, in about the same time as when left exposed in the open air, we may rationally conclude the acid to be of the vitriolic kind.

The sixth experiment shews that there is a small portion of neutral salts in these waters, which from the coldness with which they affect the tongue, and the appearance of the crystals, are probably of the ammoniacal kind.

The seventh and eighth experiments together with the smell of the hath and the considerable odour which the waters acquire when kept for any time, evidently shew that they contain a third principle, which is sulphur. This, indeed (as well as the salt), is in a small quantity, yet it may contribute somewhat to the medicinal virtues of these springs.

The ninth experiment seems to prove them to tend rather to an alkaline nature, but as this was in a very trifling degree, it may be accounted for from the escape of the acid which is extremely volatile.

These experiments compared with those I have already communicated to you sufficiently discover the constituent parts of these waters.

Somewhat later, in the second volume of the Transactions of the Philosophical Society, appeared a letter from J. Madison, Esq., to the astronomer, Rittenhouse, recording certain experiments "upon what are commonly called the Sweet Springs."

Experiment I. Having plunged a very sensible mercurial thermometer in the spring, it stood at 73°. The temperature of the air was about 69°.

II. A good hydrometer sunk one-twentieth of an inch deeper in common mountain water than in the spring.

III. Nut-galls mixed with the water in a wine glass struck a palish brown, which shewed that there was little or no iron in it.

IV. Violets, mixed with the water in a wine glass, turned it in a short time of a reddish colour. This was a proof that the waters contained some kind of an acid.

V. Having made a solution of silver in the nitrous acid, and mixed a little of it with the water, it immediately became milky, and a white pulverulent precipitate ensued.

The experiment shewed, by the whiteness of the precipitate, that the waters contained nothing sulphureous, and by the pulverulencj- of the precipitate that the acid contained in the waters was vitriolic.

VI. A solution of lead in the nitrous acid being mixed with the water, it becomes somewhat milky, and a white precipitate was observed. This experiment also shews that the waters contain an acid, most probably the vitriolic, and also that they contain calcareous earth. Soap is not readily miscible with them.

VII. A solution of saccharum saturni in the nitrous acid being made, and lines marked upon paper with it, and placed over the water, the lines retained their former colour. This experiment also shews that the water contains nothing sulphureous.

VIII. Having poured a little of the spirit of salt into the water, after some time a coloured precipitate was observed, but as the waters did not strike a green or blue colour, it shewed that there was no copper in them.

IX. A solution of vitriol of copper mixed with the water produced a thick, green, curdly appearance, but did not become bluer. This experiment shewed that there was no vol. alkali contained in them.

X. The vitriolic acid mixed with the water suddenly effervesced, and produced a heat which raised the thermometer from 75° to 83°, by applying the bulb to the outside of the glass.

As the spring is continually discharging large bubbles of air, which rising from the bottom break upon the surface of the water, I was desirous of making some experiments upon the air, in order to determine whether the acidity of the water might not be owing to it ; and also to determine the nature of the air, whether fixed or not. Having therefore caught a quantity of the air in a decanter, I communicated a part of it to an equal bulk of pure mountain water, and after agitating them for some time, gave it to several to taste; who agreed that it had the taste of the spring water. Upon a second trial this experiment did not succeed. I had not an opportunity of trying the nature of the air by means of chalk-water, and was prevented from prosecuting any farther inquiries into the nature of these celebrated waters by a sudden alarm, to which the frontiers were then continually exposed.

These waters have been falsely called sweet, for theirtaste is evidently acidulous. The experiments also shew that they contain an acid. Their taste resembles exactly that of waters artificially impregnated with fixed air, extricated from chalk, by means of the vitriolic acid, and I conceive must be nearly the same with the true Pyrmont water. They have little or no smell, do not form an incrustation, nor do they leave a deposit upon standing many hours. Upon bathing in the morning, the skin has a soapy kind of feel. This was not observed in the evening.

There is near this spring another, a very strong chalybeate.

In 1789, Dr. Robert M'Causlin communicated "An Account of an Earthy Substance found near the Falls of Niagara and vulgarly called the Spray of the Palls, ' ' which contains the following record of experiments:

Experiment 1. I put an opaque piece, weighing. 14 grains, into the vitriolic acid diluted with three times its quantity of water; and let it remain there twenty-four hours, shaking it now and then. Not the least effervescence ensued, and on taking out the piece it weighed near one grain more than when it was put in, although care was taken to absorb the moisture which was upon its surface. This experiment was repeated with a shining piece, and with exactly the same results.

Exp. 2nd. When put into vinegar it did not produce the least eifervescence. The vinegar having stood upon it some time was then poured off and spirit of vitriol dropped into it, yet not the least precipitation ensued.

That I might not be led into error by the viaegar not being good of its kind, I repeated these experiments with chalk; and as both effervescence and precipitation took place it was evident that there was no defect in the vinegar.

Exp. 3rd. A small piece was exposed to the heat of a blacksmith's forge during fifteen hours. Upon taking it out and pouring water upon it, no ebullition ensued : nevertheless it tasted like weak lime water ; being then divided into two portions, a solution of mild fixed alkali was dropped into the first, and immediately a precipitation ensued. The second portion being exposed to the air in a tea-cup soon contracted a changeable coloured film, which next morning was become very thick, resembling in. every respect that of lime water.

Exp. 4th. Hot water being poured upon some of these substances, reduced to powder and the whole suffered to settle, the clear liquor had not the taste of lime water as in the third experiment ; nevertheless a solution of mild fixed alkali being dropped into it as copious a precipitation ensued as when the earth had undergone calcination.

As I had neither the nitrous nor muriatic acids, nor even caustic fixed alkali, I had it not in my power to make any trials with them.

From these experiments we may, perhaps, be authorized to draw the following conclusions:

I. That this concrete is not an alkaline earth, as it is not affected either by the vitriolic or vegetable acids.

II. We may, with more probability, say that it is a combination of an acid with a calcareous earth, and that it might with propriety be ranked amongst the selenites. This supposition is founded upon the following reasons: 1st, it appears from the fourth experiment that it is partially soluble in water, and that its earth can be precipitated by a mild fixed alkali: 2ndly, the third experiment shews evidently that its earth is of the calcareous kind, as appears by the styptic taste and changeable coloured film, agreeing exactly with common lime water. It seems probable that the vehemence of the fire had in part expelled the acid, leaving a portion of the mass in the state of quicklime. — It is well known that most waters are more or less impregnated with a selenitic matter. It is said that agitation disposes water to deposit a part of its earth.

It is also agreed that water becomes more pure by being freed from its earthy parts.

These three considerations, together with the result of the above experiment, inclined me much to favour an opinion which universally prevails in this part of the world, viz. : That the water is purified in coming down the Falls. They also suggested a thought to me, that this purification might depend upon the latter depositing part of its earth in consequence of the violent agitation it had received in passing over rapids upwards of a mile in length, and the tumbling down the falls. Such a supposition received great support from the substance called the Spray being only found at the bottom of the Falls, which seemed to show that a deposition did actually take place. This theory was very plausible, and gave me, at first, much pleasure in contemplating it: Nevertheless succeeding observations and more strict inquiries have led me to entertain many doubts upon the subject. — That the water is much better at Niagara, which is about thirteen or fourteen miles below the Falls, than it is at Fort Schlosser, which is about a mile and a half above them, is an unquestionable fact : Nevertheless, I do not think that this can with strict justice be alone attributed to the deposition of the earthy parts. There are several low marshy grounds which empty themselves by small creeks into the river immediately above the Falls, and it is reasonable to suppose that such an impregnation would be more sensibly perceived at its source than afterwards, when it is mixed and diluted with the water of the river.

To this may be added that at Fort Erie, about twenty miles above the Falls, the water is thought not to be inferior to that of Niagara. In the second place, it occurred to me, that if any considerable deposition of earth took place, as I had supposed, the specific gravity of the water below the Falls must be less than that of the water above. To determine this point, I weighed a quantity of water at Niagara with all the care and exactness I was master of, and the very same day made a journey up to Fort Schlosser, and weighed the water immediately above the Falls. The specific gravity was found to be exactly the same. As I conducted this experiment with all possible caution, measuring the temperature of the water and also that of the room, in which it was weighed, each time by Fahrenheit's thermometer, I think I can depend upon its being pretty accurate. In inquiring into the formation of this substance called the Spray, it must be observed: 1st, that the rocks near the Falls are kept constantly wet by the vapour which rises in form of a thick mist ; and even those at a distance of a quarter of a mile, or more, are affected by it, when the wind blows down the river ; 2ndly, that these rocks, either from the nature of their structure, or from the circumstance of their being kept constantly wet ; or perhaps from the Spray accumulating between their layers, and acting as a wedge, are very apt to crack and split; and hence are almost constantly tumbling down in larger or smaller pieces; 3rdly, that upon separating the layers of these rocks there is generally more or less of this substance called Spray found between them and almost universally in a soft state. From the best inquiries I have been able to make, during a residence of many years, this substance is never found above the Falls, perhaps never at a much greater distance than one mile below them. Close to the

Falls it is found between the layers of most of the rocks, the quantity lessening in proportion to the distance from the Falls. Upon comparing all these circumstances together, it seems probable that this substance is formed by the moisture arising from the Falls constantly and slowly filtering between the layers of the rocks, and it seems very possible that the violent agitation which the water has undergone may dispose it to part with earth more easily than it otherwise could do. — The circumstance of the Spray not being found above the Falls seems to suggest an opinion that that part of the vapour which hangs upon the surrounding rocks is the heaviest as being most loaded with earthy particles, whilst the remainder which mounts up is the purest and contains little or no earth. The want of proper rocks to filter through and to attract the earthy particles may likewise be a reason why the Spray is not found above the Falls, and the specific gravity of the water which runs down the channel of the river below the Falls being equal to that above them (which seems to argue that from want of some attracting body it had parted with little or none of its earth) favours such a supposition.

These communications testify to a spirit of inquiry, at least, on the part of our early devotees to science. They are, further, interesting in that they show the use of the balance as early as 1768 and indicate the steps of analysis, always regarded as of prime importance.

Chapter II

lyj^ODERN chemistry began when Lavoisier overthrew the views of Stahl and presented his own antiphlogiston theory. It is interesting to note that the thought of the French School reached this country very early and there were here those who defended it.

Chief among these was James Woodhouse, who had founded the Chemical Society of Philadelphia in 1792. This was the first chemical society in the world. As far as can be learned, Woodhouse was its first and only president. This society lived about seventeen years. Its members favored Lavoisier's doctrine of combustion. The minutes of the society have never been found, although diligent search has been made for them. There appear to have been two classes of membership — regular and junior. On the title pages of many of the theses offered by the students of the iledical Department of the University of Pennsylvania will be noticed, after the name of the author, " Jiinior member of the Chemical Society of Philadelphia. ' '

Every year an address was delivered before the Society. If the latter continued seventeen years, there should be that many addresses, but it is doubtful whether any person living at the present time has seen more than three or four of them. As a matter of historical interest, three win be given in full:

ANNUAL ORATION

DELIVERED BEFORE THE

CHEMICAL SOCIETY OF PHILADELPHIA,

A SKETCH OF THE REVOLUTIONS IN CHEMISTRY,

BY THOMAS P. SMITH

PHILADELPHIA:

Printed by Samuel H. Smith, No. 118 Chestnut Street

MDCCXCVm

To ROBERT PATTERSON, A. M.

Professor of Mathematics in the University of Pennsylvania.

Sib:

I KNOW no person to whom my first essay can be DED- ICATED with so much propriety as to the instructor of my early youth. Accept it then as a small, but sincere, tribute of gratitude, from

Tour friend and pupil,

Thomas P. Smith.

PHILADELPHIA LABORATORY.

April 14th, 1798.

In meeting of the Chemical Society of Philadelphia. Resolved — That a copy of Mr. Smith's learned and ingenious Oration be requested for publication. Extract from the minutes,

George Lee,

Junior Secretary.

Introduction

Gentlemen of the Chemical Societt:

Having been honoured by you with the appointment to deliver the Annual Oration, I have, with diffidence, prepared myself to comply with your request. I shall not attempt to apologize for any imperfections it may contain, however numerous they may be, as they are the inevitable effects of your choice. But there is one liberty I have taken, for which I consider myself bound to apologize.

The Besolution, in pursuance of which this oration is delivered, directs that it shall contain all the discoveries made in the science of chemistry during the preceding year. Instead of complying with the letter of this resolution, I have taken the liberty of preparing for you a sketch of the revolutions in chemistry. To this I have been induced from a consideration of the utility and pleasure that always result from a knowledge of the origin of our opinions. He who should take up his abode on the banks of a stream, and quench his thirst from its waters, could not feel uninterested in a knowledge of its source, and the course it has run. Knowing over what substances its waters have passed, he is enabled in some measure to judge of their purity, and is put on his guard against any bad effects that may be produced by them. Thus, by knowing the origin of our opinions and the channels through which they have come to us, we can form a tolerable judgment of what particular prejudices they are most likely to be biassed by, and be thus put on our guard against receiving them without the strictest examination. Such were the reasons which induced me to write, and which I hope will induce you to pardon me for delivering before you, A Sketch of the Revolutions in Chemistry.