59- 



NATURE 



[April 23, 1885 



with many cuts.— C. E. Fritts, on the Fritts selenium cells and 

 batteries. These cells, in which the light enters through a film 

 of gold-leaf appear to have a much lower resistance than any 

 other selenium cell.— Prof. E. J. Houston, on Delaney's lac- 

 simile telegraphic transmission. This number of the journal is 

 also accompanied by reports of the Examiners of certain Sec- 

 tions of the late Philadelphia Exhibition, including electric 

 telegraphs, dental appliances, and applications of electricity to 

 warfare. 



Bulletin de V Academie Royale de Belgique, February 7. — 

 Experimental and analytical researches on the action and con- 

 cussion of gases at various temperatures, by M. Hirn. — A study 

 of the physical aspect of the planet Jupiter, by F. Terby.— Re- 

 searches on the spectrum of carbon in the electric arc in connec- 

 tion with the spectra of the comets and the sun, by Ch. Fievez. 

 — Remarks on the application of electricity to aerial navigation, 

 by MM. Gerard, Van Weddingen and Jacquet.— On the agree- 

 ment between atmospheric variations and the indications of 

 colours in stellar scintillations, by Ch. Montigny. — On the 

 presence of chiastolite rocks in the Lower Devonian formation 

 of the Belgian Ardennes, by E. Dupont.— A new formula 

 applicable to the development of functions, and especially of 

 integers, by Ch. Lagrange.— Remarks on Massy 's Glossary of 

 the Egyptian novel of Setna, by M. Wagener.— The death of 

 Don Juan of Austria, by Baron Kervyn de Lettenhove. 



Engler 1 's Botauische J 'ahrbiichcr, Sechster Band (1885), Heft I. 

 — CEmilius Koehne, Lythraceae, der Bau der Bliithen. Though 

 the majority of the plants of this order are clearly entomophilous, 

 the author is compelled to regard certain species as cleistogamic, 

 e.g. species of Ammaunia and Rotala. — A. Engler, Beitrage zur 

 Flora des siidlichen Japan und der Liu-kiu-Inseln. — J. C. 

 Maximowicz, Amaryllidacea sinico-japonics. — A. G. Nathorst, 

 Notizen iiber die Phanerogamenflora Gronlands im Norden von 

 Melville Bay. — Litteraturbericht. 



Heft 2. — T. F. Cheeseman, Die naturalisirten Pflanzen des Pro- 

 vincial-Districts Auckland. The author is inclined to conclude 

 that the struggle between the naturalised and the indigenous 

 flora will result in a limitation of the distribution of the indige- 

 nous species, rather than in their actual extinction. It must be 

 confessed, however, that some few indigenous species appear to 

 have already become extinct.— A. Peter, Ueber spDntane und 

 kiinstliche Gartenbastarde der Gattung Hieracium, sect. Pilosell- 

 oidea.—Y. Hildebrand, Ueber Heteranthera zosterifolia. The 

 plant develops differently according as it grows in shallower or 

 in deeper water ; in the latter case float-leaves are formed, which 

 differ widely in form from the ordinary leaves of the plant (one 

 plate). — Lad. Celakovsky, Linne's Antheil an der Lehre von der 

 Metamorphose der Pflanze. The author concludes, from careful 

 study of the writings of Linnaeus and his pupils, that Linnaeus 

 definitely laid down the fundamental principle of metamorphosis 

 before Wolff and Goethe. — Litteraturbericht. 



Heft 3. — Franz Buchenau, Die Tuncaceen auslndien (plates 2 

 and 3).— E. Hackel, Die auf der Expedition S.M.S. Gazelle von 

 Dr. Naumann gesammeltenGramineen. — H. Dingier, Der Auf- 

 bau des Weinstcckes (plate 4).— A. Engler, Beitrage zur Kennt- 

 niss der Araceae, vi. —A. Engler, Eine neue Schinopsis.— Beiblatt, 

 short notice of Apospory, and of Treub's discoveries on the sexual 

 reproduction of Lycopodium .— Litteraturbericht. 



Journal de Physique, March. — Prof. Mascart, on the employ- 

 ment of the method, of damping for determining the value of the 

 ohm. — L. Bleekrode, experimental researches on the refraction of 

 liquefied gases. These are determined by the method of De 

 Chaulnes. — L. Cailletet, new apparatus for preparing solid car- 

 bonic acid. — M. Vaschy, note on the theory of telephonic ap- 

 paratus.— G. Meslin, on the definition of perfect gases, and on 

 the resulting properties. The author objects to the usual state- 

 ment of the combined laws, because it rests upon the definition 

 of temperature, which again rests upon the properties of perfect 

 gases. He proposes to deduce all gaseous laws from the follow- 

 ing definitions : — " A perfect gas is one which perfectly obeys 

 the law of Mariotte at all temperatures, and for which there is 

 no change in the (true) specific heat when the volume changes.'' 

 — R. T. Glazebrook, on a method of measuring the electrical 

 capacity of a condenser (abstract from Phil. Mag.).—C. R. 

 Alder- Wright and C. Thompson, on the variation of chemical 

 affinity in terms of electromotive force (from Phil. Mag.). — W. 

 Hankel, on the electricity developed during certain processes 

 evolving gases.— P. Kramer, Descartes and the law of refraction 

 of light. A polemic to show that the accusation made against 



Descartes of having appropriated the discovery of Snell is un- 

 founded. — A. Genocchi, on some writings concerning the devia- 

 tions of the pendulum and the experiment of Foucault. 



Rivista Seientifico-Iniustriale, March 15. — Some experiments 

 made by Prof. Tito Martini with an accumulator of the Plante 

 type modified by Antonio Trevisan.— Influence of the capacity 

 of the condensor on electric sparks, and their duration in con- 

 nection with the hypothesis which considers electricity as an 

 incompressible fluid, by Dr. Pietro Cardani.— Remarks on the 

 Trouve universal incandescent electric lamps (continued ; two 

 illustrations), by the Editor. — Experimental researches on the 

 action of boric acid in the human system in connection with 

 epidemics and contagious diseases, by Prof. Philippo Artimini. 

 —On a method for extracting chlorophyll, by E. Guignet. — On 

 certain so-called "thunderbolts" of volcanic origin recently 

 found on Mount St. Angelo, near Baccano, and in some other 

 places east of Lake Bracciano, by Prof. G. Striiver. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, April 16. — "On the Agency of Water in 

 Volcanic Eruptions, with some Observations on the Thickness 

 of the Earth's Crust from a Geological Point of View, and on 

 the Primary Cause of Volcanic Action." By Joseph Prestwich, 

 F. R. S., Professor of Geology in the University of Oxford. 



That water plays an important part in volcanic eruptions is a 

 well-established fact, but there is a difference of opinion as to 

 whether it should be regarded as a primary or a secondary 

 agent, and as to the time, place, and mode of its intervention. 

 The author gives the opinions of Daubeny, Poulett Scrope, and 

 Mallet, and, dismissing the first and last as not meeting the views 

 of geologists proceeds to examine the grounds of Scrope's hypo- 

 thesis — the one generally accepted in this country — which holds 

 that the rise of lava in a volcanic vent is occasioned by the ex- 

 pansion of volumes of high pressure steam generated in the 

 interior of a mass of liquefied and heated mineral matter within 

 or beneath the eruptive orifice, or that volcanic eruptions are to 

 be attributed to the escape of high pressure steam existing in the 

 interior of the earth. The way in which the water is introduced 

 and where is not explained, but as the expulsion of the lava is 

 considered to be due to the force of the imprisoned vapour, it is, 

 of course, necessary that it should extend to the very base of the 

 volcanic foci, just as it is necessary that the powder must be in 

 the breech of the gun to effect the expulsion of the ball. 



The author then proceeds to state his objections to this hypo- 

 thesis. In the first place he questions whether it is possible for 

 water to penetrate to a heated or nnlten magma underlying the 

 solid cru«t. The stratigraphical difficulties are not insurmount- 

 able, although it is well known that the quantity of water within 

 the depths actually reached in mines decreases, as a rule, with 

 the depth, and is less in the Palaeozoic than in the Mesozoic and 

 Kainozoic strata. 



The main difficulty is thermo-dynamical. As the elastic 

 vapour of water increases with the rise of temperature, and 

 faster at high than at low temperatures, the pressure — which at 

 a depth of about 7500 feet and with a temperature (taking the 

 thermometric gradient at 48 feet per 1° F.) of 212° F., would be 

 equal to that of one atmosphere only — would at a depth of 

 15,000 feet and a temperature of 362 , be equal to loj atmo- 

 ! spheres, and at 20,000 feet and temperature of 467° would 

 exceed 25 atmospheres. Beyond this temperature the pressure 

 has only been determined by empirical formulae, which, as the 

 increase of pressure is nearly proportional to the fifth power of 

 the excess of temperature, would show that the pressure, in 

 presence of the heat at greater depths, becomes excessive. Tims, 

 if the formulae hold good to the critical point of water, or 773°i 

 there would at that temperature be a pressure of about 350 

 atmospheres. 



At temperatures exceeding 1000° F. and depth of about 50,000 

 feet, the experiments of M. H. St. Claire Deville have shown 

 that the vapour of water, under certain conditions, probably 

 undergoes disassociation, and, consequently, a large increase in 

 volume. It would follow also on this that if the water-vapour 

 had been subject to the long-continued action of the high tem- 

 peratures of great depths, we might expect to meet with a less 

 amount of steam and a larger proportion of its constituent gases 

 than occurs in the eruptions. Capillarity will assist the desc nt. 

 and pressure will cause the water to retain its fluidity to con- 



