398 



NATURE 



[February 23, 1893 



poured into a flask of 500 c.c. capacity, filling up with water. 

 400 C.C. are filtered through a dry filter, acidified with sulphuric 

 acid, reduced by SOg, and concentrated to 200 or 100 c.c, 

 according to the quantity of chromium probably present. 

 Donath's method may then be employed, consisting in the 

 addition of the chromium salt prepared as above described, to 

 a measured quantity of a standard permanganate solution, and 

 watching for the golden yellow colour assumed by the mixture 

 when the permanganate is all dissolved, i.e. when all the 

 chromium exists in the form of a chromate, from which the 

 amount of chromium is easily calculated. It is said that this 

 process is extremely accurate, and requires only a small fraction 

 of the time required by gravimetric methods. 



The subject of dew appears to be still involved in some con- 

 troversy. An experimental contribution to it has been recently 

 made by Herr Wollny {Forschungen, <&c.), who used plants in 

 glazed pots with earth of varying moisture, some of these being 

 allowed to radiate freely on favourable nights, while others were 

 screened. The following is a brief outline of Herr Wollny's 

 views : — Dew depends partly on evaporation from the ground, 

 partly on transpiration. It is at present doubtful whether pre- 

 cipitates from the air share in it or not. A cloudy sky weakens 

 the cooling process without stopping it wholly. With copious 

 radiation, the temperature minimum is at the surface of the plant- 

 covering (of the ground), and here the aqueous vapour rising 

 from the warm ground is partly precipitated. With increase of 

 the ground-heat downward there is increase of the water brought 

 up by the plants, which is given up as vapour and condensed. 

 The more moisture there is in the ground, the more water is 

 evaporated from the ground and the plants. Dew formation is 

 usually favoured by the larger number of stomata on the under 

 surface of leaves than on the upper. On a given surface of 

 ground the dew is more plentiful the stronger the plant organs 

 above ground, and the closer the plant growth. The temper- 

 ature of still air increases from the surface to a certain limit (at 

 about 5 feet over grass it was sometimes 4° or 5° C. warmer than 

 on the ground). In experiments with blotting paper, cotton wool, 

 feathers, and asbestos, the first was much moistened, while 

 the others showed dew in drops. Bodies of organic origin at- 

 tract more moisture than those of mineral (a case of hygroscopic 

 absorption). For vegetation, the author considers the benefit of 

 dew but trifling. Of the whole annual precipitation at Munich 

 dew only gave 3*23 per cent. 



With the present year the weekly Botanische Zeitung enters 

 on the fifty-first year of its existence, and Grafzu Solms-Laubach 

 gives with the first number of the year an interesting sketch of 

 its history, uninterrupted for half a century, even during the 

 stormy period of 1847-1849. The inception of the undertaking 

 was due to the suggestion of a botanist still living, Dr. Carl 

 Muller, of Halle. The first number of the Botanische Zeitung 

 appeared on January 9, 1843, under the editorship of Von 

 Mohl and Schlechtendal. The editorial chair has been occupied 

 since then by some of the most distinguished German botanists, 

 De Bary, Hallier, Kraus, Jost, and the present editors, Solms- 

 Laubach and Wortmann. 



Dr. Vines, the Professor of Botany in the University of 

 Oxford, has for some time past had in preparation a " Student's 

 Text- book of Botany," which will be more comprehensive than 

 his edition of Prantl's well-known " Elementary Text-book." 

 It is to be fully illustrated, and is expected to be ready early in 

 the autumn of this year. It will be published by Messrs. Swan 

 Sonnenschein and Co. 



Messrs. Gauthier-Villars et Fils, Paris, continue 

 to issue the useful series of small volumes called "En- 

 cyclopedic Scientifique des Aide-Memoire." The follow- 

 NO. 1217, VOL. 47] 



ing volumes have lately been added: " Corderie," by M. 

 Alheilig ; "Formation des Gites Metalliferes," by L. de 

 Launay ; "Le Grisou," by M. Le Chatelier ; " Moteurs a 

 Vapeur," by M. Dudebout ; "Detente Variable de la Vapeur," 

 by A. Madamet ; "Canons, Torpilles, et Cuirasses," by A. 

 Croneau ; "Textiles Vegetaux," by H. Lecomte ; "Essaisd'Or 

 et d'Argent," by H. Gautier ; " Etat Actuel de la Marine de 

 Guerre," by L. E, Berlin ; " Industrie des Cuirs et des Feaux," 

 by Ferdinand Jean. 



The "Annuaire," for 1893, of the Royal Observatory of 

 Belgium, by F. Folic, has been published. This is t he sixtieth 

 year of issue. 



The Department of Science and Art has issued the volume 

 for 1893 containing its calendar, history, and general summary 

 of regulations. 



In the course of an elaborate investigation recently published 

 in the Zeitschrift fiir Hygiene, December 9, 1892 (" Die Aetio- 

 logie des infectiosen fieberhaften Icterus " (Weil'sche Krank- 

 heit), Jaeger draws attention to the dangers which may arise 

 from bathing in polluted water. Already in 1888 Pfuhl [.Deutsche 

 militdr-drztl. Zeitschrift, i888, Heft 9 and 10) attributed an 

 outbreak of typhoid fever, accompanied by jaundice, which 

 occurred amongst the garrison stationed at Altona to bathing in 

 the Elbe, which at the time was described as more than usually 

 polluted. Hiieber and Globig came to similar conclusions with 

 regard to outbreaks of the above "Weil'sche Krankheit," which 

 appeared at Ulm on the Danube and Lehe respectively. Jaeger 

 has made a special study of the case^ which aro^e amongst the 

 soldiers at Ulm, and has eadeavoured to trace, if possible, the 

 infection to its source. It was found that the military bathing- 

 place was situated below the point where the Danube is joined 

 by the highly-polluted river Blau. This stream is described as 

 being practically an open sewer, and even before it reaches Ulm 

 is stated to be grossly contaminated in its flow through the 

 small village of Soflingen. It was further ascertained that in 

 this village for many years a mysterious disease had been rife 

 amongst the ducks and geese, whilst fowls were also occasionally 

 attacked, and that moreover it was a common custom to throw 

 the dead carcases of these animals into the Blau as the readiest 

 means of getting rid of them. A careful eximination of some 

 of the birds which had succuuibed to this disease revealed the 

 constant presence of a micro-organism, which Jaeger asserts 

 was identical with that found repeatedly and isolated in the 

 cases of icterus investigated by him at Ulm. It is further stated 

 that by mixing some of the highly- polluted Blau water at 

 Soflingen with sterile broth, and inoculating it into white mice, 

 they were killed in sixteen hours, and that the organism, which 

 was found abundantly present in various organs of the body, 

 was in every respect identical with that previously isolated in 

 the cases of icterus at Ulm, and from the carcases of the birds at 

 Soflingen. Taking these various results into consideration 

 Jaeger is of opinion that they afford very strong evidence of the 

 virus of this disease having been introduced into the highly con- 

 taminated stream at Soflingen, and conveyed thence to the 

 military bathing-place, which, as already mentioned, is situated 

 below the junction of the Blau with the Danube. In conse- 

 quence of the appearances in cultivations to which this organism 

 gives rise, the author has suggested for its name Bacillus proteus 

 Jluorescens, and claims in it to have discovered the exciting 

 cause of the so-called " Weil'sche Krankheit," the etiology of 

 which is attracting much attention on the continent. 



Notes from the Marine Biological Station, Plymouth : — 

 Heavy gales have prevailed for many weeks, confining operations 

 to the inshore waters. The week's captures include numbers of the 

 Archiannelid Dinophilus tteniatus, of the Polychseta Marphysa 



