426 



NATURE 



{March 4, 1880 



duct. Its theoretical com position he gives as— titanic acid, 74'S5 ; 

 lime, 25-45 ; or CaO, 2TiO. : . 



In his recent annual address to the " Geologische Reichs- 

 anstalt " at Vienna, Kitter von Hauer gives some interesting 

 particulars regarding the steps that have been taken to investi- 

 gate the geological structure of Austria's last territorial acquisi- 

 tion. On the occupation of Bosnia and Herzegovina, the 

 Government requested the director of the Reiehsanstalt to make 

 a geological reconnaissance of these provinces, which had formed 

 until that time an almost totally unknown tract of Europe, 

 though their area at least equalled that of Bohemia and Saxony 

 combined. Their rough mountainous character and want ol 

 means of communication and transit made the task by no means 

 a light one. An original plan of co-operation with the Geolo- 

 gical Survey of Hungary had to be abandoned on account of 

 the want of disposable force in that service, and the work was 

 accordingly undertaken by three members of the Austrian Sur- 

 vey, Messrs. Mojsisovics, Tietze, and Bittner, with some assist- 

 ance from Prof. Pilar of Agram, and from previous labours of 

 M. Paul in the saliferous region of Tuzla. As the result of this 

 reconnaissance, an outline geological map of Bosnia and Herze- 

 govina has been prepared on the basis of the sheets of the map 

 of Central Europe issued by the Austrian Military Geographical 

 Institute on the scale of sWatn!- Eighteen tints of colour are 

 employed, and with these are shown Alluvium and Diluvium, 

 Calcareous tuff, Sarmatian, Marine and Freshwater Neogene, 

 Trachyte, Flysch (Younger Flyschsandstone, Nummulite-lime- 

 stone, and li nestone of the Flysch zone), Eruptive rocks of the 

 Flysch-zone (Serpentine and Gabbro), Chalk-limestone, Jurassic 

 Aptychus-limestone, Jura-limestone, Triassic (principally lime- 

 stone and dolomite), Werfen shales, Red sandstones and quartz- 

 ites, Palaeozoic shales, sandstones, and limestones, and granite. 

 The map is being reduced to the same scale as von Hauer's 

 well-known and most useful general geological map of the 

 Austrian- Hungarian Monarchy, and will soon be published by 

 Holder of Vienna, as a supplement to that work. 



PHYSICAL NOTES 



Prof. O. N. Rood communicates to the current number of 

 the American Journal of Science a new method of studying the 

 reflexion of sound waves. The "tremolo" effect in some 

 American organs is obtained by a revolving fan. Prof. Rood 

 conceives that the alternations of loudness iu the sound produced 

 by this fan are not due, as is commonly supposed, to the 

 fluctuations of air-currents which it produces, but to the rapid 

 alternations of reflexion and non-reflexion at its surface. A disk 

 of zinc having sectors cut out of it, rotating in its own plane, 

 yielded similar results. Using such disk as a reflector, when 

 rotating at from two to four revolutions per second, and observing 

 the intensity with which these alternations are produced, Prof. Rood 

 obtains some interesting results. At a perpendicular incidence 

 the short sound-waves are more copiously reflee'ed than those 

 that are longer, and the regular reflexion is more copious from 

 large than from small surfaces. When the sound-waves fall 

 upon small plane surfaces at an acute angle, the reflection is 

 most copious in the same direction as with a ray of light, but 

 (he reflected and inflected waves can be traced all around the 

 semicircle. The reflexion being more intense for waves of short 

 wave-length, the components of a composite sound-wave are not 

 all equally co piously reflected at the same angle. The reflexion 

 of sound from very small surfaces is easily demonstrated by this 

 method. Qualitative comparisons between the power of different 

 substances to reflect sound can easily be made by this method. 

 Thus a disk of cardboard in which the open sectors are covered 

 with filter-paper gives alternations owing to the difference in 

 reflective power between the zinc and the filter paper. 



Quicksilver may be readily frozen by placing a small 

 quantity of it along with anhydrous ether in the decanter used for 

 freezing water of a Carre's freezing-machine, and exhausting in 

 the usual manner. This experiment is due to M. de Waha. 



Prof. Colladon of Geneva, has been studying the instrument 

 invented by Rhodes, of Chicago, and named the audiphone, whose 

 purpose is to aid the deaf in hearing. The newest form of this 

 instrument, as imported from America, consists of a thin flexible 

 sheet of hard ebonite rubber, provided with a handle like a 

 palm-leaf fan, and with a cord which . can be tightened at 

 pleasure to curve it into the form of a semi-cylinder. The 

 edge of the sheet is pressed against the upper set of teeth, as 



described in a recent "Note," the convex surface being out- 

 wards, and so the vibrations impinging upon the sheet are trans- 

 mitted through the teeth and bones of the skull to the auditory 

 nerve. Prof. Colladon finds that the sheet of ebonite may be 

 advantageously replaced by a sheet of fine ela-tic cardboard, the 

 best kind being that smooth, dense variety known to the trade 

 as shalloon board or satin board (carton d'orties). This card 

 audiphone costs but a trifling fraction of the ebonite article, and 

 is on all hands admitted to yield a better result. Some experi- 

 ments conducted in January by M. Colladon and by M. Louis 

 Sager upon deaf-mutes leave no doubt of the existence of cases 

 in which, while the ordinary hearing-trumpet fails, the audiphone 

 is successful. M. Colladon mentions the case of a professional 

 singer who had been deaf for fourteen years, to whom the audi- 

 phone of cardboard brought back once more the power of hearing 

 the music of a piano. It is an interesting point in M. Colladon's 

 observations that persons deaf-mute from birth evinced emotions 

 of a pleasurable nature on thus hearing music for the first time. 



There appears to be no doubt as to the reality of the gems 

 produced by Mr. Hannay being diamonds. It is now understood 

 that the process by which they are obtained is one suggested by 

 Mr. Hannay's recent research on the solubility of solids in gases, 

 of which an account was given in a recent number of Nature. 

 Mr. Hannay observed that when a gaseous solution of a solid is 

 allowed to expand, some of the solid is usually deposited, and is 

 deposited in crystalline forms. Acting on this hint, it was 

 attempted, though in vain, to procure the gaseous solution of 

 graphite and other forms of carbon. However, it had been 

 observed by Mr. Hannay — if we are rightly informed — that 

 certain metals act upon hydrocarbon gises at considerable pres- 

 sures, abstracting from them the hydrogen. Such a gas, on 

 being cooled and allowed to expand, deposits its carbon. Per- 

 forming this operation in the presence of nitrogen, at a pressure 

 of some thousands of atmospheres, and at a temperature not far 

 from a red heat, crystals of carbon w ere obtained. These proved 

 to be good octohedra, some of them having the property of 

 showing curved edges, which is unique to the diamond. Their 

 angles, when mea ured by Prof. Maskelyne, gave the true value 

 for octohedra. The crystalline fragments di-appeared when 

 heated upon platinum-foil in oxygen. A portion weighing 14 

 milligrams, when duly " combusted " as for an organic analysis, 

 showed 97 - S5 per cent, of carbon. Mr. Hannay employed 

 digesters resembling gun-barrels, with wrought-iron coils having 

 an internal diameter of one inch and an external diameter of 

 four inches. Even these strong tubes repeatedly gave way under 

 the enormous pressure required. 



O. E. Meyer has recently shown, by careful measurement of 

 the intensity for different groups of rays of the spectrum, that 

 ordinary daylight contains relatively a greater proportion of red 

 and yellow rays, and a less proportion of blue and violet rays 

 than the direct light of the sun. 



Newton denoted by the name of " indigo " the tint of the 

 spectrum lying between "blue" and "violet." Von Bezold, in 

 his work on colour, rejects the term, justifying his objection by 

 observing that the pigment indigo is a much darker hue than the 

 spectrum tint. Prof. O. N. Rood, who follows von Bezold in 

 rejecting the term, brings forward the further objection that the 

 tint of the pigment incligo more nearly corresponds in hue 

 (though it is darker) with the cyan-blue region lying between 

 green and blue. By comp.iring the tints of indigo pigment, both 

 dry and wet, with the specrum, and by means of Maxwell s 

 disks, it appears that the hue of indigo is almo-t identical with 

 that of Prussian blue, and certainly does not lie on the violet 

 side of " blue." Indigo in the dry lump, if scraped, has, how- 

 ever, a more violet tint ; but if fractured or powdered, or dis- 

 solved, its tint is distinctly greenish. Prof. Rood considers that 

 artificial ultramarine corresponds much more nearly to the true 

 tint of the spectrum at the point usually termed "indigo, and 

 he therefore proposes to substitute the term "ultramarine in 

 its place, the colour of the artificial pigment being thereby 

 intended. 



Prof. W. F. Barrett has recently come to the conclusion 

 that the phenomenon of the Trevelyan "rocker," which has 

 been hitherto regarded as produced by the rapid expansion and 

 contraction of the metals in contact, is due rather to the action 

 of a polarised layer of gas between the hot and cold surfaces 

 like that existing between the hot and cold surfaces of the layer 

 of vapour supporting a drop of liquid in the spheroidal state, 



