NATURE 



[August 31, 191 1 



ions are and how great is the degree of iomsation. It is 

 only for aqueous solutions that Arrhenius was able to give 

 a practically realisable definition of degree of ionisation, 

 and it is on this definition that the whole effective work on 

 aqueous electrolytes is based ; and until some general 

 practically applicable principle of a similar character is 

 attained for hydrates, the work done on that subject, how- 

 ever interesting and important it may be in itself, must 

 necessarily be of an isolated character. 



Arrhenius did not originate the doctrine of electrolytic 

 dissociation or free ions : that was enunciated in 1857 by 

 Clausius, and remained relatively barren. What he did 

 was to introduce measurable quantities into the doctrine, and 

 to show its simple quantitative applicability to aqueous 

 solutions ; immediately it became fertile. And as soon as a 

 simple quantitative principle is developed for hvdrates in 

 solution, that doctrine will become fertile also.' 



It is surely now time that all the irrelevant and intem- 

 perate things that have been said and written bv supporters 

 of the osmotic pressure and electrolytic dissociation theories 

 on the one hand, and by those of the hydrate theory on the 

 other, should be forgotten. Far from "being irreconcilable, 

 the theories are complementary, and workers may, eacli 

 according to his proclivity, pursue a useful course in' follow- 

 ing either. One type of mind finds satisfaction in using a 

 handy tool to obtain practical results ; another delights only 

 in probing the ultimate nature of the material with which 

 he works. For the progress of science both types are 

 necessary — the man who determines exact atomic weights as 

 well as the man who speculates upon the nature of the 

 atoms. That the want of knowledge as to what the exact 

 nature and mechanism of osmotic pressure is, should prevent 

 accurate experimental work being done on it, or interfere 

 with its use in theoretical reasoning, is equally ridiculous 

 with the proposition that because in the theory of osmotic 

 pressure we have a good quantitative tool for the inves- 

 tigation of solutions, therefore we should abandon altogether 

 the problem of its nature. 



The fundamental ideas of a science are the gift to that 

 science of the few great masters ; the manv journeymen in- 

 vestigators may be trusted to utilise them according to their 

 abilities. Having once given his great principles to the 

 world, van 't Hoff remained practically a spectator of their 

 development ; but by his single act he provided generations 

 of chemists with useful and profitable fields for their labour. 



NOTES. 

 Sir Archibald Geikie, K.C.B., president of the Royal 

 Society, Prof. Svante A. Arrhenius, and Prof. Elias 

 Metchnikoff have been elected honorary members of the 

 Vienna Academy of Sciences. 



We regret to announce the death, on August 23, at 

 sixty-three years of age, of the Rev. F. J. Jervis-Smith, 

 F.R.S., late university lecturer in mechanics and Millard 

 lecturer in experimental mechanics and engineering, 

 Trinity College, Oxford. 



The death is announced, at the age of eighty-two years, 

 of Dr. G. F. Blandford. Dr. Blandford earlv devoted 

 himself to the study of insanity, and was for manv vems 

 lecturer on psychological medicine at St. George's Hospital. 

 His chief work, "Insanity and its Treatment," was pub- 

 lished first in 1871, and passed through several editions. In 

 1895 he delivered the Lumleian lectures on " The Diag- 

 nosis, Prognosis, and Prophylaxis of Insanity" before the 

 Royal Colleg,. of Physicians. In ,s 77 he was president of 

 the Medico-psychological Association, and his address for 

 the year was on "Lunacy Legislation." In 1887 he 

 delivered an address before the International Congress of 

 Medicine at Washington on " The Treatment of Recent 

 Cases of Insanity in Private and in Asylums." 



The death is announced of Prof. Georges Dieulafoy, in 

 his seventy-second year. Prof. Dieulafoy was well known 

 in French medical circles, and was professor of clinics in 



no. 2183, vol. 8;] 



the Necker Hospital, succeeding Prof. Trousseau in 1896. 

 He was known as an author by the six volumes of his 

 " Lecons cliniques de l'H6tel-Dieu " and his " Manuel de 

 pathologie interne," which has reached a seventeenth 

 edition. He was a member of the Paris Academy of 

 Medicine and a Commander of the Legion of Honour. 



We regret to record the death of Mr. J. R. Mortimer, 

 of Driffield, on August 20, in his eighty-seventh year. Mr. 

 Mortimer was one of the few remaining antiquaries of the 

 old type, and during the past half-century he thoroughly 

 investigated the archaeological treasures of the East Riding 

 of Yorkshire, in an area adjoining the field of Canon 

 Greenwell's investigations. Mr. Mortimer excavated more 

 than 300 Bronze-age burial mounds, and a number of 

 Anglo-Saxon cemeteries, and also carefully mapped the 

 elaborate series of prehistoric earthworks which occur on 

 the Yorkshire Wolds in all directions. To a smaller extent 

 he excavated Roman and later sites, and also made 

 extensive collections from the chalk and other secondary 

 formations in his district. These he transferred to a 

 special building at Driffield, which has long been the 

 rendezvous of antiquaries and geologists interested in East 

 Yorkshire. This museum also contains a very large collec- 

 tion of stone and bronze axes, flint arrows, spears, &c, 

 which number tens of thousands, all of which have been 

 obtained in the vicinity. Mr. Mortimer was the author of 

 numerous papers and memoirs, a complete list of which 

 will be found in The Naturalist for May last. His prin- 

 cipal work, however, is the massive volume " Forty Years' 

 Researches in the British and Saxon Burial Mounds of 

 East Yorkshire," which was published a few years ago 

 by Browns. Besides elaborate tables of measurements of 

 crania, &c, and hundreds of plans and sections of the 

 barrows and earthworks, this volume has illustrations of 

 more than a thousand Bronze-age drinking cups, food 

 vessels, cinerary urns, and bronze and stone implements, 

 from beautiful drawings made by his daughter, Miss Agnes 

 Mortimer. This book, and his magnificent museum, will 

 ever remain monuments to his memory. 



The death is announced of Mr. John Griffiths, the well- 

 known fossil collector of Folkestone. He rendered 

 important service to Mr. F. H. Hilton Price and Mr. J. 

 Starkie Gardner in their researches on the Gault and 

 associated formations, and he discovered a large propor- 

 tion of the most important Gault fossils now in the British 

 Museum and the Museum of Practical Geology. 



The Scunthorpe Urban District Council has appointed 

 Mr. T. Sheppard, of the Hull Municipal Museums, as 

 expert adviser to the new public museum at Scunthorpe. 



It is announced that on Saturday. September 0. an aerial 

 postal service will be started between Hendon and Windsor. 

 This scheme, which has the sanction of the Postmaster- 

 General, was conceived by Mr. D. Lewis Poole and 

 Captain W. G. Windham, and a contract has now been 

 made with the Grahame-White Company for the carriage 

 of mails by suitable pilots. Post-cards and envelopes, 

 bearing a design of Windsor Castle, have been prepared, 

 and will be on sale, at the price of (>.'if. and is. id. 

 respectively, in the establishments of a number of large 

 firms in London. The letters must be posted in special 

 boxes provided in these establishments, from which they 

 will be collected and conveyed daily to Hendon by motor- 

 van. The mail-bags will be also flown daily, weather 

 permitting, to Windsor from the Hendon ground, and the 

 correspondence distributed from there through the ordinary 

 postal channels. All proceeds from the sale of the post- 



