Feb. 20, 1890] 



NATURE 



l^l 



by M. A. Mannheim. In a preceding communication the author 

 has shown how t o transform the properties relating to the dis- 

 placement of a straight line, of which the points describe tra- 

 jectory surfaces ; he now extends his method to the case 

 where the points of the movable line describe trajectory 

 lines only, and taking as examples several theorems relating 

 to the former case, derives therefrom corresponding theorems in 

 the latter. — On a generalization of Euler's theorem relating to 

 polyhedrons, by M. R. Perrin. Attention is drawn to some 

 relations bearing upon Euler's formula, published by the author 

 in 1882 {BtiUetin de la Societe Mathematique de France, t. x. ).— 

 On bodies which give a tension of dissociation equal to the 

 tension of the vapour of their saturated solutions, by M. H. Les- 

 cceur. Experiments are referred to which are antagonistic to 

 the theory of M. Bakhuis-Roozeboom. According to experi- 

 ment, the curves representing the tensions referred to as func- 

 tions of the temperature are tangential, and do not intersect at 

 an acute angle as required by the theory. — Action of fluorine 

 upon different varieties of carbon, by M. Henri Moissan. — A 

 general method for the preparation of fluorides of carbon, by M. 

 C. Cbabrie. — On the blue flame of common salt and the 

 spectroscopic reaction of copper chloride, by M. G. Salet. The 

 author finds that the bands seen in the spectrum of salt burning 

 in a common fire, and of which the strongest are situated in the 

 indigo and blue-green, are due to copper chloride, and coincide 

 with bands given by Lecoq de Boisbaudran in his " Spectres 

 Lumineux." — On the electrical resistance of iron and its alloys 

 at high temperatures, by M. H. Le Chatelier. The electrical 

 resistances for a considerable range of temperature of a number 

 of iron alloys have been examined. When the results are 

 graphically shown, the curve for ferro-manganese (13 per cent. 

 Mn) is found to be regular, just as is the case with platinum or 

 platinum-rhodium alloy, while the curves for mild and hard 

 steels show distinctly two singular points at 820° and 710°, and a 

 silicon steel (Si = 3 per cent.) shows the former only. Ferro- 

 nickel (25 per cent. Ni) behaves very peculiarly, as below 550° 

 two modifications having quite distinct properties exist, and 

 nickel itself shows a sudden change of curvature at 340°. — 

 Thermochemical researches upon silk, by M. Leo Vignon. In- 

 vestigations have been made to determine the heat disengaged 

 when various reagents are absorbed by raw and prepared silk. 

 A discussion of the results seems to indicate that the method 

 may be employed to elucidate the theory of dyeing. — -Estimation 

 of potassium and humus in soil, by M. J. Raulin. A method 

 of estimating potassium by weighing it on a tared filter as phos- 

 phomolybdate is described, together with the application of the 

 modified permanganate process of J. II. Schmidt to the deter- 

 mination of humus. — On a colouring-matter from Diaptomus, 

 analogous to the carotin of vegetables, by W. Raphael Blanchard. 

 The colouring-matter, isolated from these animal organisms, is 

 shown to differ considerably in spectroscopic properties and in 

 its solubility in alcohol from the lipochromes, and it does not 

 prove to be identical with any of the red pigments from the 

 Coelenterata, Echinodermata, Bryozoa, or.Mollusca; while on 

 the contrary it is found to show many analogies to carotins 

 (CjfiHsg), which are so marked as to lead to the conclusion that 

 it is itself a carotin and so possesses great interest as a colouring 

 substance common to both the animal and vegetable kingdoms, 

 and as an instance of the production of a hydrocarbon by animal 

 agency. — On the intercellular substance, by M. Louis Mangin. It 

 is shown that among Phanerogams and Cryptogams (with the 

 exception of Fungi and many Algae) the tissues of the softer parts 

 are composed of cells cemented together by an intercellular sub- 

 stance composed of insoluble pectates. — On the localization of 

 colouring-matters in the seminal integuments, by M. Louis 

 Claudel. — Formation of quartz at the spring of Maubourot at 

 Cauterets, by M. Beaugey. — On the existence of leucite rocks 

 in Asia Minor, and on some hypersthene rocks from the 

 Caucasus, by M. A. Lacroix. It is found that the leucitic rocks 

 from near Trebizonde fall under two main types, leucitite and 

 leucotiphrite. — Upon the composition of some pseudo-dolomitic 

 chalks from the north of France, by M. L. Cayeux. 



Berlin. 

 Meteorological Society, January 7.— Dr. Vettin, Presi- 

 dent, in the chair. — Dr. Wagner spoke on the behaviour of 

 water in the soil. The relationships between surface water and 

 springs and deposits, possessing as they do a distinct meteoro- 

 logical interest, have as yet been but slightly investigated, probably 

 because the behaviour of water in soil occupies the border-land 



between the subjects of meteorology, geology, agriculture, antf 

 hygiene. A review of scientific investigations which have so 

 far been made on the subject of surface water and the formation- 

 of springs, shows that the problems of most importance are still 

 awaiting their solution. In the speaker's opinion the task to 

 be undertaken in the interests of meteorology is the establishing 

 of as many lysimeters as possible, so that by keeping a con- 

 tinuous record of their indications a continued set of observations 

 on surface water would be provided. He further considered it 

 to be essential that the relationship of water to the soil should be 

 investigated at depths far greater than has as yet been the case. 

 A lengthy discussion followed the above communication, which 

 turned chiefly upon a consideration of the forces, as yet but little 

 known, which determine the collecting of water on internal im- 

 pervious layers of the earth.— Prof. Sporer gave a short 

 statistical statement on sun-spots during 1889. The chief point 

 of interest was that the spots appeared during the first half of 

 the year in the lower latitudes and in the second half in the higher. 

 Taking the year as a whole, there were considerably more spots 

 in the southern than in the northern hemisphere ; this has been 

 the case in each year since 1883. — The Secretary then handed 

 in his annual report, and the Society proceeded to elect its 

 officers for the year 1890. Prof. Schwalbe was elected President. 



Physical Society, January 27. — Prof. Kundt, President, in 

 the chair. — The President opened the meeting by a short address 

 in memory of civil engineer G. A. Him, who died recently at 

 Logelbach in Alsace. — Dr. Lehmann spoke on the testing of 

 tuning-forks. After the International Congress met for the 

 establishing of a uniform standard of tone, and selected for this 

 purpose a vibration frequency of 435, it devolved upon Govern- 

 ment to construct a standard fork, and to devise some ready 

 method for testing ordinary forks to an accuracy within half a 

 vibration per second, and standard forks within o'l of a vibra- 

 tion. The speaker discussed the various methods in use for 

 comparing two forks and for counting the number of vibrations 

 per second which they yield. For the first purpose the vibra- 

 tions of the respective forks are employed, these being observed 

 either acoustically or optically ; a further means of effecting the 

 comparison is by the stroboscopic method or by the acoustic 

 wheel. The vibration frequency of a fork is determined either 

 graphically or by means of a tuning-fork clock, or by means of 

 the undulations obtained by oscillating or rotating acoustical 

 instruments. An important factor in all these methods is the 

 temperature of the fork. To determine this a special thermostat 

 is employed, by means of which the fork can be set in vibration 

 in an air-bath whose temperature is constant and accurately 

 known. The standard fork for reference is one of Konig's, 

 whose vibration-frequency has been accurately determined by 

 several methods. The comparison of any new fork with the 

 standard is made by means of the acoustic wheel, and by a 

 simultaneous graphic recording of the movements of the fork 

 which is vibrating inside the thermostat, and of the magnetic 

 interrupter; the latter consists of a tuning-fork vibrating to 

 the octave below the note yielded by the standard fork. — Dr. 

 Eschenhagen exhibited curves of the three elements of terrestrial 

 magnetism recorded by the new instruments in the Observatory 

 of Potsdam, and gave a short description of the an-angement of 

 the apparatus. The curves were taken on white photographic 

 paper, and were of such dimensions that the greatest variations 

 which have as yet been observed were completely recorded. 

 — Prof. Kundt exhibited some quartz-fibres which he had re- 

 ceived from Prof. Weinhold. He made, in addition, some 

 remarks on the preparation of these fibres by Boys's method, 

 and gave some data as to the dimensions of an apparatus which 

 Prof. Weinhold had constructed for the measurement of gravita- 

 tion constants, and had employed in several determinations. 



Amsterdam. 



Royal Academy of Sciences, Dec. 28, 1889. — Prof, van 

 de Sande Bakhuyzen in the chair. — M. Hugo de Vries related 

 the results of the scientific researches made by the Committee of 

 Advice, appointed in July 1887 at Rotterdam, to report on the 

 appearance of Crenothrix in the drinking-water of the Rotterdam 

 water-supply. He gave an account of the organisms met with 

 in the mains and basins before and after the filtration of the 

 water, and of the degree of the pollution caused by these 

 creatures in the colder and warmer months of the year. He 

 spoke also of the influence of darkness on the water-organisms, 

 which, under ordinary circumstances, live in the sunlight ; of the 



