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the Giessen laboratory. This position he resigned after the first year, leaving Will the sole control of the laboratory. Kopp remained at Giessen nearly a quarter of a century, and all his most im- portant experimental work was done there. In 1863 he received a call from Heidelberg, which he accepted, and here he stayed until his death, occupying himself with lectures on the history of che- mistry and on chemical crystallography. He was repeatedly solicited to accept a position in one of the larger Universities, notably in Leipsig and in Berlin, but all attempts to draw him from his dear Ruperto-Carolina were fruitless. "Even Bunsen alone," he was wont to say, "keeps me fast in Heidelberg."
Kopp's History of Chemistry' is his greatest literary effort. The first volume of it appeared in 1843, and the fourth and final volume in 1847. By the publication of this classical work, Kopp, when barely thirty years of age, suddenly found himself famous His life-long friend, von Hofmann, who was theu at Giessen, has left us the following accouut of the sensation which the work made on its appearance:
"With one accord his contemporaries recognised that here was a production which, whether they regarded the thoroughness of re- search that it displayed, or the manner in which the material resultiug from that research was sifted and arranged, was without a parallel. in the literature of any other country. And even to-day, after the lapse of nearly half a century, there is no historical work on chemistry that can be even remotely compared with it. Numbers of books relating to the same subject, some of considerable merit, have since been published in Germany and France, but it is not difficult to perceive that they are all grounded on Kopp's great work."
For upwards of forty years Kopp had it in contemplation to bring ont a new edition, and much of the later historical work he published, such as his 'Beiträge zur Geschichte der Chemie,' which appeared between 1869 and 1875, and the 'Entwicklung der Chemie in der neueren Zeit,' printed under the auspices of the Historical Commis sion of the Bavarian Academy in 1873, together with the two volumes on Die Alchemie in älterer und neuerer Zeit,' grew out of the materials he had gathered together. "But," again to quote Hofmann, "the better is here the enemy of the good. Kopp postponed the ' ver- mehrte und verbesserte Auflage' year after year, in the hope of being able to make a fnller study of certain special periods. Who- ever is familiar with the mass of profoundly interesting matter he had accumulated, or who has had the opportnnity of seeing the bulky note-books in which it was stored, must deeply lament that the hand which could alone arrange these treasures is now stiffened in death."
The literature of chemistry is further indebted to Kopp for the
