494 



NATURE 



[March 24, 1892 



Darmstadt, where his father spent his enforced leisure. 

 He was apprenticed to the Hof-Apotheker in Darmstadt, 

 and in due time passed his " Gehiiife Examen" with dis- 

 tmction. He had access to a good collection of books on 

 chemistry and physics, which he eagerly read. He went 

 as Gehiiife to Miihlhausen in Alsace, where he spent 

 several years, and returning to Darmstadt passed the 

 " Staats Examen " in pharmacy, passing in the first class. 

 But the attraction of pure chemistry prevailed, and in 

 1857 he went to Heidelberg. Bunsen soon saw what 

 kind of student he had got, and appointed him assistant 

 m the laboratory. There he met Sir Henry Roscoe, who 

 invited him to Manchester as his private assistant. On 

 Roscoe's appointment as Professor of Chemistry in the 

 Owens College, Dittmar went with him as assistant. In 

 1861 he became chief assistant in the Edinburgh Uni- 

 versity Chemical Laboratory under Prof. Sir Lyon Play- 

 fair. In 1869 he went to Bonn, where he acted first as 

 Privatdocent and afterwards as Lecturer on Meteorology 

 at the .Agricultural College at Poppelsdorf. In 1872 he 

 declined the Chair of Chemistry in the Polytechnic 

 School at Cassel, preferring to return to Edinburgh to his 

 old post in the University. Here he remained only a 

 few months, accepting in 1873 the Lectureship on 

 Practical and Technical Chemistry in the Owens College. 

 Thence he removed to Glasgow to succeed Prof. Thorpe 

 in the Chair of Chemistry in the Andersonian College. 

 This office he held till his death, February 9, 1892. He 

 died literally in harness. He lectured in the morning, 

 but not feeling very well, went home in the middle of the 

 day, and after a few hours' illness died at 11.30. 



He was a Fellow of the Royal Society and of the Royal 

 Society of Edinburgh. In 1887 the University of Edin- 

 burgh conferred on him the degree of Doctor of Laws. 

 The Philosophical Society of Glasgow awarded him last 

 year the Graham Medal for his investigation into the 

 composition of water. 



Dittmar was a man of great intellectual energy, which 

 always took a practical turn, indeed it is rare to see a 

 man so truly scientific in all the operations of his mind 

 so free from speculation. Not that his imagination was 

 unused, but so prominent before him was the practical 

 result to be obtained, that it gave a character of reality 

 to the whole process by which he sought to reach it. 



His most important work was analytical. His great 

 investigation into the composition of the specimens of 

 sea-water collected by the Challe7iger Expedition is a 

 masterpiece of judgment and skill, important not only for 

 Its results, but perhaps even more for its methods. We 

 may mention also his determination of the atomic weight 

 of platinum, his method for the analysis of chrome iron 

 ore, his examination of the alkaline hydrates and car- 

 bonates, and the gravimetric determination of the com- 

 position of water. But he did not confine himself to 

 analytical work. He published along with Kekule' a 

 paper on oxymethylbenzoic acid, the first aromatic 

 alcohol acid ; and also while at Bonn obtained glutaric 

 acid by the reduction of Ritthausen'.s glutanic acid. He 

 did much excellent work in physical chemistry. We may 

 mention the determination of the vapour-pressures of 

 formate of ethyl and acetate of methyl, his work on the 

 dissociation of sulphuric acid and on the relation of the 

 composition of acids of constant boiling-point to the 

 pressure under which they are distilled. He made the 

 construction of the balance a subject of special study, 

 and the balances constructed for him by Oertling and by 

 Staudinger are models of convenience and accuracy. 



But Dittmar was greatest as a teacher. Patient and 

 careful, he helped his students where they needed help, 

 and led them to think and work for themselves. He had' 

 no ambition to make his pupils analyzing machines ; they 

 had to understand all that they did. Gradually his great 

 power as a teacher came to be appreciated, and latterly 

 his laboratory was filled with enthusiastic pupils. Those 

 x\0. I 169, VOL. 45] 



whom he has trained are his real works on analytical 

 chemistry; but others can learn much of his method from 

 his admirable treatise on qualitative analysis. 



A. C. B. 



SERE NO WATSON. 

 T^HE last American mail brought the sad intelligence 

 •*• of the death of this indefatigable botanist, upon 

 whom, in one sense, the mantle of Asa Gray fell barely 

 ^four years ago. Early in the year he was seized with a 

 bad attack of grippe, and although he rallied and was 

 better for a time, he never recovered strength, and finally 

 succumbed on the 9th inst., in the sixty-sixth year of his 

 age. Of his early life we know nothing, but he appears 

 to have published no botanical work previous to 1873, 

 about the period that he was appointed Herbarium 

 Assistant to Dr. A. Gray at Harvard. From that date, 

 however, onward until within a few months of his death, 

 he was, next to Gray, the most active writer on North 

 American Phanerogams. Much of his work appeared 

 originally in the Proceedings of the American Academy 

 of Arts and Sciences, under the title of "Contributions 

 to American Botany," numbered consecutively, the last 

 being the eighteenth. These consist principally of 

 monographs of North American genera and descriptions 

 of novelties. He was also the principal author of 

 the " Botany of California," the last volume of which 

 appeared in 1880; and since the death of Dr. A. 

 Gray, he in conjunction with Prof J. M. Coulter 

 has edited the sixth edition of the deceased author's 

 valuable " Manual of the Northern United States." 

 This work has been considerably decried by contem- 

 porary American botanists, because Watson did not in- 

 troduce the changes in nomenclature consequent on a 

 strict and unqualified observance of the law of priority. 

 But in this conservatism he doubtless followed the wishes 

 of his former master, and enjoyed the sympathies of 

 those whose experience teaches them that it is much 

 easier to make these changes in books than to carry 

 them into practice. Watson had a still more important 

 work in hand, for he had undertaken the continuation of 

 Gray's " Synoptical Flora of North America." How far 

 this is advanced we do not know, but it is not probable 

 that it will see the light on the same lines as the pub- 

 lished volumes, or as he would have continued it. Un- 

 fortunately, an exceedingly useful work, commenced 

 during the early part of Watson's engagement at Har- 

 vard, was never completed. We allude to his " Biblio- 

 graphical Index to North American Botany," which was 

 only carried to the end of the Polypetate. To a great 

 extent, Gray's " Synoptical Flora " takes its place, so far 

 as the Gamopetate are concerned ; but it is difficult to 

 find one's way in the remaining groups. Though Sereno 

 Watson was of a retiring disposition, and did not belong 

 to the teaching body, nor take a prominent part in the 

 gatherings of scientific men, yet the loss of him will be 

 widely felt and deplored. He was elected a Foreign 

 Member of the Linnean Society of London in 1890, but he 

 was not a man who craved after honours and distinctions. 



NOTES. 

 It seems almost incredible that the Treasury should think of 

 stopping the publication of the Kcw Bulletin simply because it 

 does not quite pay its own expenses. The periodical, as our 

 readers know, is one of high value, both from the scientific 

 and the industrial point of view, and, if the Treasury persists in 

 the design attributed to it, something ought soon to be said on 

 the subject in Parliament by the scientific members. The Times 

 has argued strongly against the proposed step, and the view it 

 has expressed will be shared by all who are capable of forming 



