second method of controlling the explosion of gun-cotton consists in consolidating the material by pressure into compact homogeneous masses, and in confining the first ignition of such compressed gun-cotton in the bore of the gun, to certain surfaces. The gun-cotton fibre in the form of yarn or plait may be compressed into very compact masses by being rammed into strong cylinders of pasteboard or other suitable material; but much more perfectly homogeneous and solid masses are produced, independently of cylinders or other cases, by a method which Mr. Abel has recently elaborated, and which consists in reducing the gun-cotton fibre to a fine state of division or pulp, as in the process of paper-making, and in converting this pulp by pressure into solid masses of any suitable form or density. This method of operating affords also special facilities for combining both methods, dilution and compression, of reducing the explosive violence of gun-cotton. The material is, in fact, operated upon by this system, in a manner exactly corresponding to the processes by which the explosive action of gunpowder is regulated to so remarkable an extent. Some results, which are admitted by the most sceptical as encouraging, have already been arrived at, in the systematic course of experiments which are in progress, with the object of applying the methods of regulation, pointed out, to the reduction of gun-cotton to a safe form for artillery purposes. Its arrangement in a form suitable for small arms is a much less difficult problem, which may be considered as approaching a perfect solution. For employment in shells and for military mines, both land and submarine, the compressed or solid form of gun-cotton presents special advantages, on account of the great compactness which may be imparted to it; a given weight arranged so as to ignite instantaneously under pressure (i.e. in strong vessels), may be made to occupy the same space as an equal weight of gunpowder, whereas the forms of gun-cotton hitherto applied to these purposes occupy about three times the space of gunpowder. Beautiful pyrotechnic effects may be readily produced by means of gun-cotton, though the absence of smoke, which, in some of its applidations (especially in mines), would constitute an important advantage, detracts from some of the effects which may be obtained with pyrotechnic compositions. On the other hand, gun-cotton fireworks may be displayed in-doors without inconvenience. There appears at present no reason to doubt that the application of gun-cotton with great advantage to at least some of the more important purposes for which gunpowder is used, will, ere long, be fully established, and that this interesting explosive agent is destined to occupy a permanent and prominent position among the most important products of chemical industry. [F. A. A.] GENERAL MONTHLY MEETING, Monday, May 7, 1866. SIR HENRY HOLLAND, Bart. M.D. D.C.L. F.R.S. President, in the Chair. The following Vice-Presidents were nominated for the ensuing The Earl Stanhope, D.C.L. F.R.S. Lieut.-General Sabine, R.A. Pres. R.S. W. Robert Grove, Esq. Q.C. F.R.S. William Spottiswoode, Esq. M.A. F.R.S. the Treasurer. Samuel Osborne Habershon, M.D. were elected Members of the Royal Institution. The following Professors were re-elected :-- JOHN TYNDALL, Esq. LL.D. F.R.S. as Professor of Natural Philosophy. EDWARD FRANKLAND, Esq. Ph. D. F.R.S. as Professor of Chemistry. The PRESENTS received since the last Meeting were laid on the table, and the thanks of the Members returned for the same, viz. :— FROM Actuaries, Institute of-Journal, No. 63. 8vo. 1866. Agricultural Society of England, Royal-Journal. New Series. No. 3. 8vo. 1866. Asiatic Society of Bengnl--Journal, No. 130. Svo. 1865. Astronomical Society, Royal-Monthly Notices, 1865-6. No. 5. 8vo. British Architects' Institute, Royal-Sessional Papers, 1865-6. Part II. No. 4. 4to. Chambers, George F. Esq. M.R.I. (the Author)—The Church and State Handybook. (K 92) 8vo. 1866. Chemical Society-Journal for May, 1866. 8vo. Clarendon, The Earl of, K.G. &c.-Pitture Murali a fresco e Suppellettili Etrusche scoperte in una necropoli presso Orvieto nel 1863 da D. Golini: publicata da G. Conestabile. 4to. Firenze. 1865. Editors-Artizan for April, 1866. 4to. Athenæum for April, 1866. 4to. British Journal of Photography for April, 1866. 4to. Practical Mechanics' Journal for April, 1866. 4to. Hardwicke, Robert, Esq. (the Publisher)—Skin Diseases. By W. Tilbury Fox. 2 vols. 8vo. 1863-4. Linnean Society-Journal and Proceedings: Zoology: No. 33. 8vo. 1866. Medico-Chirurgical Society, Royal-Proceedings, Vol. V. No. 4. 8vo. 1866. Philadelphia Academy of Natural Sciences—Proceedings. 8vo. 1865. Squire, Peter, Esq. F.L.S. M.R.I. (the Author)-Companion to the British Pharmacopoeia. 3rd edition. 8vo. 1866. Statistical Society of London-Journal, Vol. XXIX. Part 1. 8vo. 1866. WEEKLY EVENING MEETING, Friday, May 11, 1866. Colonel PHILIP JAMES YORKE, F.R.S. in the Chair. Professor D. T. ANSTED, M.A. F.R.S. On Mud Volcanoes of the Crimea, and on the relation of these and similar phenomena to deposits of Petroleum. In this communication I propose to direct attention to the following subjects, namely: First.-Mud volcanoes generally, and especially those of the Crimea and Sicily, as phenomena of subdued volcanic action. Secondly. The frequent occurrence of petroleum, naphtha, and other hydro-carbons in the vicinity of mud volcanoes. Thirdly. The existence of lignites, coal, or other deposits of vegetable or animal organic matter near mud volcanoes. Fourthly.-The geological relation probably existing between mud volcanoes, recognized lines of volcanic energy, main lines of elevation affecting great tracts of land, and the metamorphoses that have produced the hydro-carbons in the form of petroleum, naphtha, bitumen, and bituminous shales. I. MUD VOLCANOES. The phenomena of mud volcanoes are illustrated on a grand scale in the eastern part of the Crimea, near Kertch, and on the adjacent peninsula of Taman. The eastern shore of the Cimmerian Bosphorus is nearly level, but in certain places presents a multitude of hillocks and some considerable hills. These hills are due to eruptions of mud. Some are large and lofty, and do not now erupt mud. Others are also of large dimensions, but are continually or occasionally active. I visited the Crimea in the course of last summer, and although for some months previously none of the older and larger mud volcanoes had broken out afresh, and no new ones had appeared, it was not difficult from the number of examples in different states of activity to make out the principal varieties of appearance. Before describing them, however, I think it will be better to give a brief account of an eruption of the same nature that occurred in Sicily during my stay in the island. I was on that occasion fortunate enough to be able to visit a mud volcano from its commencement, and thus, combining the observations in Sicily and the Crimea, I have been able to judge of and describe from my own observation the whole history of one of these curious phenomena. The Sicilian eruption commenced seven days only before the commencement of the eruption in the island of Santorin. It should be borne in mind that the eruption of Etna of last year was accompanied by subterranean action in the Ægean sea, both near the extremity of the Morea and also in Santorin itself; and although the distance is five hundred miles, a subterranean communication must be considered proved. At Paternó, close to the south-western extremity of the Etna lavas, a mud eruption took place on the 23rd of last January, in a flat plain below the steep hill on which Paternó is built, and not far from the bed of the Simeto. It commenced by the outburst of a strong jet of water, which must have issued through a crevice in underlying lava. The crack is not traceable in the conglomerate and sandy gravel of the surface, except from the indications afforded by the eruptions. The water at first rose about six feet in a strong jet, at boiling temperature, from only one point. Several such jets followed from other places a few yards off, the volume of the first jet diminishing though the total quantity of water erupted was increased. The temperature of the erupted water diminished slowly from the commencement. There was no noise, no flame, and no visible vapour, but much gas bubbling through the water, and some naphtha. The water issuing was muddy from the commencement, but no stones or lumps of solid matter were erupted. The level of the point of eruption was about 600 feet above the sea, as determined by an aneroid. The water erupted ran off into the Simeto, leaving behind a thin coating of tenacious mud, which covered the ground for some distance. I visited the spot on the eighth day from the commencement. From the principal jet there then issued a large column of dirty water, with much gas. A considerable quantity of petroleum of dark-green colour floated on the surface of the water, but had not been collected. The temperature of the water was above 110° Fah., but observations were difficult to make and uncertain, owing to the absence of a maximum thermometer. The heat was certainly much greater than was recorded, as the water scalded the hand. The gas bubbles were large, and issued at intervals by puffs, of which forty per minute were counted. The gas was chiefly carbonic acid gas. There were four other considerable jets of warm but not hot water all in a line, and all in the direction of a line joining the original point of eruption with the principal cone of Etna. They were about four yards apart. A multitude of much smaller jets of cold muddy water came out from cracks in the ground at various points within an area of about twenty acres. None of the issuing fluid could be called thick mud, but on exposure to the air and evaporation it left a tenacious paste. About 300 yards beyond, in the direction of the great cone of Etna, there is a remarkable spring of water loaded with carbonic acid gas, rising at a temperature of 64° Fah. Though well known and used this spring does not seem to have been affected by the eruption. Except at Pyrmont, I have never seen water so charged with gas. A short distance beyond this spring is another of subacid water issuing from beneath old lava, at a temperature of 60° Fah. About a mile from the mud volcano, and in the direction opposite to the springs, are blocks of very tough basaltic lava, on a natural slope. They had apparently fallen from a basaltic cliff above. These blocks, when struck with a hammer, give out a strong bituminous odour, and when a fragment is broken off, innumerable small cavities full of naphtha may be observed on examining the broken surface. The mud volcanoes of the Crimea and Taman are very numerous, and all within a belt of country nearly parallel with the axis of the Caucasus. It is known that similar phenomena exist near Teflis, halfway between the Black Sea and the Caspian, at Baku, on the western shore of the Caspian, and in islands near the eastern shores of the Caspian. The district I chiefly examined reached about fifty miles from the straits of Kertch, towards the east, and about twenty miles towards the west. Near Enikale are several distinct cones. Of these some are moderately active, many quite inactive. The date of activity can often be guessed at by the state of the slopes; for the mud as it first issues, and for some time afterwards, is perfectly unfit for vegetation, but after about two years' exposure it begins to acquire properties and materials allowing vegetable growth. By noticing the state of vegetation, I was thus able to make out that many of the hills had been very recently subject to a flow of mud, though quite dry at the time of my visit. The erupting cones are all of the same general character. The mud is poured out very slowly from the top, and is tenacious and often as thick as treacle. Bubbles of gas accompany the mud. In one case I counted fifteen large bubbles per minute, in another thirty. The temperature of the issuing mud was in one case 56° Fah., in another close by as much as 66° Fah. I measured the length of one coulée of mud, and found it to be about 60 yards from the outlet before it was completely checked. The various cones are accumulated from the material erupted, and in no other way. In the cone I measured I found the fall to be 20 feet, the slope therefore being one in nine, Other cones, and the upper part of all the cones, are much steeper than this. In all this group a north wind is universally understood to increase the flow of mud, and the quantity of mud issuing varies from month to month and at different seasons. It not unfrequently stops altogether for some time. A short distance to the west of Enikale is another tract of considerable area completely covered with recently erupted mud. The |