Providence made the beginning of his future distinguished course in life, seemed likely at the time of its occurrence to have placed him in a sphere inferior to that of his brother. It was his first intention, as it was also that of his elder brother, to have studied theology, but an unmerited hard treatment which he met with at school, so disinclined him to study, that he determined, in his 16th year, to learn the trade of an Apothecary. Five years which he was forced to spend as an apprentice, and two which he passed as an assistant, in the public laboratory at Quedlinburg, do not seem to have furnished the best education for a great chemist; for they placed him out of the reach of scientific study, and instead of that, secured nothing for him but a certain mechanical adroitness in the most common pharmaceutical preparations. In a paper which was found amongst those that he has left behind him, he thus expresses himself: "I cannot boast of the instruction which I have received from my teachers. On the contrary, I was obliged to content myself with such information as I could gain, in those times, from the mechanical operations of my elder companions, and with the perusal of a few old Apothecary books, for the study of which, too, I had but little leisure."

He always regarded, as the epoch of his scientific instruction, the time when he first entered the public laboratory at Hanover, in which he spent two years, namely, from Easter 1766 till the same time in 1768. It was there that he first met with some chemical works of merit, especially those of Spielman and Cartheuser, in which a higher scientific spirit already breathed.

The love of science thus awakened, naturally aimed at a more complete developement. He was anxious to go to Berlin, of which he had formed a high idea from the chemical works of Pott, Henkel, Rose the elder, and Markgraf. An opportunity presented itself, and, about Easter 1768, he was placed as assistant in the laboratory of Wendland, at the sign of the Golden Angel, in the Street of the Moors. Here he employed all the leisure which a conscientious discharge of the duties of his station left him, in completing his own scientific education. And as he judged very correctly, that a profounder acquaintance with the ancient languages, than he had been able to bring with him from the Latin school at Wernigerode, was indispensable for a complete scientific education, he applied himself with great zeal to the study of the Greek and Latin languages, and had the good fortune to enjoy in this study, the assistance of a worthy

and learned Preacher and Doctor of Theology, who is still alive, I mean Mr Popplebaum.

After two years and a half, that is, about Michaelmas 1770, he was permitted, by fortunate circumstances, to go to Dantzig, as assistant in the public laboratory. But in march of the following year, he returned to Berlin, as assistant in the office of the elder Valentine Rose, who at that time was known as one of the most distinguished chemists of his day. But this connexion did not continue long, for Rose died in 1771. On his death-bed he requested Klaproth to undertake the superintendence of his office. He thus, after a most honourable and long continued trial, became superintendant of the office of Rose, in which a greater number of distin guished chemists were formed than in any other, since, beside the elder Rose and Klaproth, this office afforded a larger or smaller portion of their education to Hermbstadt, Gehlen, Valentine, the younger Rose, and several other excellent pharmacopolists. Klaproth not only superintended this office for nine years, with the most exemplary fidelity and conscientiousness, but, what particularly displayed his honourable character as a man, he himself undertook the education of the two sons of Rose, as if he had been a second father to them. The younger of the two died when he had scarcely reached the age of manhood. The elder, whom, after his own example, he permitted to pass from the study of theology to that of medicine, became in after life his most intimate friend, and the associate of all his scientific researches. Several years before the death of Rose, which happened in 1808, much too soon for science, they wrought together, and Klaproth was seldom satisfied with the results of his experiments, till they were repeated by Rose. Klaproth often asserted to the author of this memoir, that, in regard to many of his discoveries, as, for instance, with respect to the important method of analyzing by means of barytes, he scarcely knew whether the merit of the discovery was more to be ascribed to himself or to Rose. Like Valentine Rose, all the other members of the worthy family of Rose honoured Klaproth with the attention of children till his death.

In the year 1780, when Klaproth was thirty-seven years of age, he went through his trials for the office of Apothecary, with distinguished applause. His Thesis, "On Phosphorus and Distilled Waters," was printed in the Berlin Miscellanies for 1782. Soon after this, Klaproth bought what had formerly been the Fleming Laboratory in the Spandau Street, and he married Sophia Christiana Lehman, with whom he

lived till 1803 (when she was taken from him by death,) in a happy state of marriage, the fruits of which, three daughters and one son, now survive their parents. He continued in possession of this laboratory, in which he had arranged, for his scientific labours, a small work-room of his own, till the year 1800, when he purchased the room of the academical chemists, in which he was enabled, at the expense of the academy, to furnish a better and more spacious apartment for his labours, for his extremely valuable mineralogical and chemical collection, and for his lectures.

As soon as Klaproth had brought the first arrangement of his office to perfection,-an office which, under his inspection and management, has always been a model of a laboratory, conducted upon the most excellent principles, and governed with exact conscientiousness, there appeared in Crell's Chemical Annals, in the Writings of the Society for the Promotion of Natural Knowledge,-in Selle's Contributions to the Science of Nature and of Medicine,—in Köhler's Journal, and in other periodical works,-a multitude of essays by him, which drew the attention of all- chemists, and afterwards gained for him the rank of the first analytical chemist in Europe. Of these labours, we may mention only an Essay on Copal,-on the Elastic Stone,-on the Pearl-Salt of Proust, -on the Green Lead-Spar of Tschoppau, on the best Method of preparing Ammonia,-on the Carbonate of Barytes, on the Wolfram of Cornwall,-on the Wood TinÖre, on the Violet Schorl,-on the celebrated Aerial Gold, -on Apatite, and so forth. All these labours, by means of which scientific chemistry was illustrated and enriched, were gone through before the year 1788, when he was adopted as an ordinary member of the physical class of the Royal Academy of Sciences, the Royal Academy of Arts having elected him one of their members a year before. From this time, not only all the volumes of our academical memoirs, but several of our well known daily papers, contained a multitude of new discoveries by this accomplished chemist; and we must say, that, amidst all this crowd of his works, there is not one by which we have not been led to a more exact knowledge of some one or other of the productions of nature or of art, since in these works he has either corrected false representations, or extended views that were before partially known, or has revealed the internal and formerly unknown composition and mixture of the parts of bodies, and has made us acquainted with a multitude of new elementary substances. Amidst all these labours, it is diffi

cult to say, whether we should most admire the fortunate genius, which in all cases readily and easily divined the point where any thing of importance lay concealed; or the acuteness which enabled him to find out the best means of obtaining his object, or the unceasing labour, and the incomparable exactness with which he developed it,-or, lastly, the pure scientific feeling under which he acted, and which was removed at the utmost possible distance from every selfish, every avaricious, and every contentious purpose.

He very properly began in 1795 to collect his works, which were dispersed among so many periodical publications, and to edite them under the title of Contributions to the Chemical Knowledge of Mineral Bodies. Of this work, which must always be a classical production in chemical literature, six volumes had appeared by the year 1815. It contains,

in no fewer than 207 treatises, the most valuable part of all that Klaproth had done for Chemistry and Mineralogy; and it is to be wished that the profits may so turn out as to lead to the collection of a few essays which still remain dispersed, into a seventh volume, and to the furnishing of the whole with a good index; an undertaking which, to a young chemist, anxious to perfect his knowledge, would be as full of instruction as of pleasure.

Beside Klaproth's own printed works, the interest which he took in several important labours of others, ought not to pass unnoticed. He superintended a new edition of Gren's Manual of Chemistry, with respect to which, however, he did not seek to earn so much merit by what he added, as by what he took away and corrected. But the part which he took in the Chemical Vocabulary, which was edited under his own name, and that of Wolff, was of great importance. For although the composition of every particular article was the labour of the learned Professor Wolff, yet Klaproth took such an active interest in the work, that he read through every important article before it was printed, and assisted the editor, on all occasions, with the treasures of his experience and knowledge. In the German translation, too, of Berthollet on Affinity and on Chemical Statics, the author of the present memoir was much indebted to the revisal of Klaproth.

If the author of this memoir were to collect the merit of Klaproth as a chemist into one great feature, he would place · it not so much in the discovery of new metals and earths, as in the invention of more exact and more perfect methods of analysis, than were known before his time. The former

kind of merit is more adapted to draw the attention of the public at large; but the latter is of infinitely greater consequence to science. Passing by the numberless small expedients which Klaproth devised for procuring a more unmixed deposition and separation of all kinds of matters, we only notice at present that he enriched experimental chemistry with two new methods of analysis, which are unlimited in their applications.

The first of these was the complete resolution of the hardest minerals, by means of fluid caustic alkali, instead of the former treatment with dry caustic alkali, which had introduced the use of silver crucibles and saucers into experimental chemistry. The complete resolution of the hardest stones, by this method of analysis, has enabled us to ascertain, with extreme accuracy, the quantity of earths, oxydes, metals, and even of acids, which minerals contain. Exact analyses of this kind remain sure for ever, and are of importance to the science, independent of any discoveries which may be made, respecting the particular nature of the substances mentioned. As, for instance, the capability of being decomposed, which was afterwards discovered to belong to the earths, makes not one cypher incorrect or superfluous in such analysis. The advantage of this method is particularly evident in the decomposition of corundum or diamond-spar. As Klaproth first attempted the analysis of these bodies, by the former method of decomposition, he found a considerable remainder of matter unaccounted for. On the suspicion, which he then expressed, that this remainder might perhaps be a new, and yet undiscovered earth, many compilers of school books were in a hurry to admit the earth of corundum into the list of the simple earths. But when Klaproth repeated the analysis, by means of the liquid alkali, he found that this substance was one of the many compositions of sili ceous and argillaceous earths, which had not previously been known, and which in former analyses had sometimes been referred to the one kind of earth, and at other times to the other. In the same manner, the chemists of England gave an account of a species of sand, which had been brought from New Holland, as a new earth; but Klaproth shewed, by his new method of analysis, that this body also, which had already been introduced into introductory treatises, under the name of "the Austral Earth," was nothing but an intimate mixture of siliceous and argillaceous earth. Indeed, the first analyses that can be considered as certain, are those which have been undertaken on this plan. Hence, by this