270 



NATURE 



[May 31, 1917 



artificial kaliophilite is occasionally accompanied by 

 leucite. An orthorhombic form of KAlSiO^ has also 

 arisen during the experiments. Readers of this paper 

 may like to note Dr. A. Scott's references to artificial 

 nephelLne and carnegieite prepared by him (Trans. 

 Geol. Soc. Glasgow, vol. xvi., p. 41, 1916). 



Mr. E. T. Wherry (American Mineralogist, vol, i., 

 P' 37> 1916) shows that crystals of glauberite, 

 NajCa(S04),: were deposited during the drying of 

 fluviatile beds of Triassic age in eastern Pennsylvania, 

 in place of those of rock-salt that are familiar in 

 many areas. The author attributes this occurrence to 

 the composition of the local waters ; it seems possible 

 that glauberite, which has a low solubility, represents 

 a stage antecedent to that of the deposition of gypsum, 

 and that the continued trickle of waters seaward 

 carried off the sodium chloride and many other salts. 



A PROCESS is described in the Scientific American 

 for April 2 1 for coating the end portions of wooden 

 propeller blades for aeroplanes, etc., with a thin layer 

 of copper, by which they are strengthened, given a 

 better cutting edge and surface, and protected from 

 brush, etc., on landing. The details of the process are 

 interesting. First, the wood is rendered impervious 

 by saturating with a wax varnish, which is then coated 

 with a thick linseed-oil varnish. Then a shellac 

 varnish is applied and allowed to dry. A thin deposit 

 of silver sulphide is produced by treatment with a 

 silver nitrate solution made with alcohol and water, 

 the surface being then exposed to sulphuretted 

 hydrogen gas. Copper is electrolytically deposited on 

 this film. 



The Ordnance Survey has published, at the price of 

 35., a geological map of Dublin on the scale of 6 in. 

 to I mile. The topographic basis is identical with 

 sheet 18 of the Ordnance Survey map of the county 

 of Dublin. The map embraces the city, Phoenix 

 Park, and a large outlying residential district. The 

 superficial deposits, boulder clay, glacial gravels, river 

 gravels, alluvium, and materials on the area in-taken 

 from the sea, together with the few patches of under- 

 lying limestone rock which rise to the surface, are 

 indicated by separate colours. The alterations, due 

 partly to human, partly to marine agency, in the coast- 

 line at the west end of Dublin Bay are well shown by 

 the Insertion, in red dotted lines, of the coast as repre- 

 sented in a map by Bernard de Gomme, published in 

 1673. We believe this is the first urban district for 

 which a cheap colour-printed map has been published 

 on the six-inch scale. This excellent example might 

 well be followed In the case of each of our larger town 

 areas. Such maps, particularly if they were accom- 

 panied by a short, clear, explanatory pamphlet, would 

 be invaluable for educational purposes, and copies 

 should be hung in every urban school. They would 

 also be of verv great use to architects, surveyors, and 

 engineers, and to all who are concerned with house- 

 sites or town planning. 



An effort is being made by the American National 

 Advisory Committee for Aeronautics to promote the 

 study of the atmosphere over the United States and 

 the adjacent seas, and have a set of accurate charts 

 made for the benefit of aviators. We wish the com- 

 mittee every success in the endeavour, but there is a 

 proverb "as uncertain as the wind*," and it is diffi- 

 cult to see how so uncertain an element as the wind 

 can be charted at all, much less " accurately charted." 

 No^ doubt the Weather Bureau has a large amount 

 of information as to the strength and direction of the 

 prevailing winds, and In America, as In Europe, the 

 wind at a few thousand feet height will In general 

 agree more or less with the Isobaric charts, but a 



NO. 2483, VOL. 99] 



knowledge of the prevailing wind will not much in- 

 crease the safety of an aviator who has to fly at a 

 definite time and place. It is a correct and definite 

 forecast rather than a chart that he requires, and 

 It has been, as a matter of course, the chief object 

 of the U.S. Weather Bureau to be able to give such 

 forecasts for many years past. Extending the forecast 

 to some 5000 ft. altitude is a comparatively easy 

 matter when the surface conditions can be accurately 

 foretold. 



Some interesting results of a spectroscopic investi- 

 gation of sources of ultra-violet radiation for thera- 

 peutic purposes are given by C, A. Schunck in the 

 Journal of the Rontgon Society for April. Among 

 the sources examined were electrodes of pure metallic 

 tungsten, molybdenum, and iron ; carbon rods im- 

 pregnated by boiling in solutions of sodium tungstate, 

 uranium nitrate, and ammonium molybdenate ; cored 

 carbons filled with uranium oxide or wolfram ; and 

 the Simpson electrodes, which are said to consist of 

 wolfram. The most intense source of ultra-violet 

 radiations was found to be the electric arc with 

 metallic tungsten electrodes, the spectrum being so 

 full of lines as to be almost continuous to the limit 

 of the spectrograph employed, at A 2130. The Simpson 

 arc gives a very similar spectrurh, but the unsteadi- 

 ness of this source is a disadvantage. The impreg- 

 nated carbons give much more intense radiation In 

 the spark than In the arc, a mixture of uranium 

 nitrate and ammonium molybdate being the richest 

 in ultra-violet radiations of any spark source. Ob- 

 servations of the effects of the various sources appear 

 to show that the radiations of greatest therapeutic 

 value lie between A 3000 and Ai85o, and further spec- 

 troscopic observations to ascertain which part of this 

 region has the greatest efficiency are in progress. The 

 paper Is illustrated by an excellent series of photo- 

 graphs of spectra. 



In part 5 of vol. v. of the Science Reports of the 

 Unlversltv of Sendai, Japan, Prof. K. Honda and 

 Mr. J. Okubo apply the theory of ferro- and para- 

 magnetism, published three years ago by Prof. Honda, 

 to the effect of temperature on the magnetism of 

 ferro-magnetic substances, and find a close agreement 

 between their deductions from the theory and the 

 experimental facts. According to Prof. Honda's 

 theory, the molecules of a ferro-magnetic substance 

 are nearly spherical, and the impacts of the molecules 

 on each other due to their thermal motions have only 

 a small effect in rotating the molecules, while the 

 effect of their mutual magnetic action on each other 

 Is considerable. The molecule of a para-magnetic 

 substance has, on the contrary, a more or less elong- 

 ated form, and thermal motions have in consequence 

 a great effect on the molecular rotations. The effect 

 of the rotations in the case of the ferro-magnetic 

 material Is worked out in detail for weak external 

 fields in the present paper, and it is shown that the 

 magnetisation will diminish as the rotation increases, 

 at first slowly, then faster, and that at a given angle the 

 magnetisation will disappear. The effect of tempera- 

 ture on the permeability of ferro-magnetic substances 

 is also investigated, and the curves connecting perme- 

 ability with the angle of rotation are shown to be 

 of the type found by Hopkinson for the relation be- 

 tween permeability and temperature In weak fields. 



In the Bulletin of the Soci^t^ d 'Encouragement 

 pour 1 'Industrie Natlonale for March-April M. Paul 

 Janet gives some Interesting details of the founda- 

 tion and activities of the Laboratoire Central d 'Elec- 

 tricity at Paris, which is administered by the Socidt^ 

 Internationale des Electriciens under an arrangement 



