[ 42 ] TRANSACTIONS OF PUBLIC SOCIETIES. ROYAL SOCIETY. [Aug. 1, to a certain configuration of the surface, which cannot be removed by the finest polishing. By examining the surface of mother-of-pearl by means of microscopes, he found that it was composed of grooves similar to the skin at the point of an infaut's finger. These grooves are very fine. The distance between them varies. Sometimes they may be seen with the naked eye; sometimes there are about 3000 in the inch. It is to this grooved structure that mother-of-pearl is indebted for its optical properties. MARCH 25. A paper by Thomas Young, M. D. foreign secretary to the Royal society, on the new structure of ships proposed by Mr. Seppings, was read. Dr. Y. began by observing, that the advantage of the oblique position of the bea.us and riders had been long known to men of science, and that various unsuccessful attempts had been made to introduce that position into ship building. He then calculates the strain upon ships of war from the length and weight, and the action of the waves. He shows that the oblique position of the beams and riders does not add to the total strength; but that it is an improvement, on account of the additional stiff-larizing light in a way different from all ness and inflexibility which it affords. He examines the different alterations made by Mr. Seppings, and points out those which he considers as improvements, and those respecting the advantage of which he is doubtful. March 31, a paper by Mr. Groombridge was read, contring additional observations on atinospherical refraction. In his former paper he had confined his observations to stars not more than 70° from the zenith. He has since gone a good deal farther. The result is, that Bradley's formula, with certain alterations in the value of some of the quantities, will apply to all stars not more than 85° from the zenith, but beyond that distance a new formula is necessary. At the same meeting a paper by Mr. Hay was read, on certain properties of tangents, of circles, and of trapeziums inscribed in circles. April 21, a paper by Dr. Brews'er, on the optical properties of mother-of-pearl, was read. When we look at the image of a candle reflected from the surface of a piece of regular mother-of-pearl, ground but not polished, we perceive at the distance of four or five degrees from the common image a highly coloured image, the distance of which from the common image increases with the angle of incidence. By polishing the mother-of-pearl a new image exactly like the first, and obedient to the same laws, is developed on the other side of the common image. These optical properties inay be communicated by pressure to wax, cement, gum arabic, balsam of Tolu, realgar, tin-foil, the amalgam of bismuth, and even to lead. Hence it follows that the optical properties of mother-of-pearl are owing April 28. The remainder of Dr. Brewster's paper on the optical properties of mother-of-pearl was read. Thus substance possesses the property of pc other bodies. In crystallized bodies the opposite polarization of the two images is always related to some axis or fixed line in the primitive form; but no such relation exists in mother-of-pearl. In uncrystallized bodies the reflected pencil is always polarized in an opposite maaner to the refracted pencil; but in mother-of-pearl a single plate possesses the property of polarizing the whole of the transmitted light at an angle of incidence of 60°; and the transmitted pencil is polarized in the same manner as the reflected pencil. At the same meeting part of a paper by Captain Henry Kater was read, descrit ing a new method of dividing circles, and other astronomical instruments. The method of Bird was used in dividing astronomical instruments till it was superseded by the new method of Troughton, of the perfection of which the mural circle at the Greenwich Observatory exhibits an admirable proof. Captain Kater conceives that the method of Troughton admits of simplification. He considers his own method as possessed of the greatest possible simplicity, and as very accurate. The remainder of Captain Kater's paper was read on the 5th May. May 12. A paper by Dr. Benjamin Heyne on the Indian method of oxy dizing silver by means of the juice of jatropha cureas, and on the milk of plants, was read. A piece of silver is heated to redness, wrapped in the leaves of any kind of tree, and then quenched in the juice of the jatropha moluccana. This process is repeated about twenty times, taking care never to fuse the silver. The metal becomes quite brittle. and crumbles to powder between the 1814.] Sir Everard Home on Injuries of the Brain. fingers. Dr. Heyne tried the same process, substituting water instead of the vegetable juice, and a similar efect was produced. From Dr. Heyne's account of the above process, it seems probable that the silver is not oxidized, but merely rendered brittle, and reduced to a fine powder; probably by combining wit i Something which exists in the veget; bie juice employed, or rather in the cowdung in which the silver is heated. The only known oxide of silver is a dark greenish brown powder, which is reduced to the metallic state by a very moderate heat. If the vegetable juice merely communicated oxygen, it is obvious that that principle would be driven off every time the metal was heated to redness; so that the process would never advance: but if the vegetable juice or cow-dung employed supplied sulphur, or any analogous principle, we can see how the repeated heatings would facilitate the combination, and how fusion would retard it. Dr. Heyne's observations on the milk of plants were curious and valuable. May 19. A paper by Dr. Brewster was read on the optical properties of hot glass. The author discovered that glass, when heated nearly to redness, polarises and depolarises light, and forms two mages, one of which coincides with the other. Hence it is analogous to doubly refracting crystals. The beautiful coloured rings produced by topaz were not perceptible in this case; but it occurred to Dr. Brewster that glass, in order to produce them, must be in a state of fuSton. As it was not possible to examine its optical properties in that state, Dr. Brewster had recourse to the glass tears formed by dropping melted glass into cold water, on the supposition that from the sudden cooling of the outer coat the interior part of these tears would be in the same state as melted glass, or at least their ultimate particles at the same distance from one another as in melted glass. He found accordingly that these tears produced the coloured rings in question. He found that this tear has regular axes of crystallization, the axis of the conical tail, and a line perpendicular to it, corresponding with the short and the long diagonals of a rhomboid of cal careous spar. At the same meeting a paper by Cap. tain Kater was read, containing farther experiments on the light of the Gregorian and the Cassegrainian telescopes. He examined the quantity of light passing through a glass lens before and behind the focus. He found the light be 43 hind the focus to that before as 1000 to about 650, or somewhat less in the greater number of experiments. These results approach to the degree of light observed in the Cass graiman and Gregorian telescopes, and therefore serve to confirm Captain Kater's preceding ob servations. May 26. A paper by Sir Everard Ho ne, Bart., On the Effect of different injuries in the Brain upon Sensation, was read. The attempts to determine the functions of the different parts of the brain not having been attended with success, Sir Everard conceives that it would promote the advancement of phystology if medical men were to collect together, and arrange the effects produced by different diseases or injuries of the brain The present paper contains the result of his own practice. It is divided into ten sections 1. On the effect of water accumulated in the ventricles. Water accumulated in the ventricles, even to the amount of 64 ale pints, does not destroy the faculties, provided the hones of the era um be not united, and the head enge according to the accumulation A curious case was relaed of a young man whose had had increased enormously, and who retained his faculties entire, except some inconvemences from the size and weight of the head. He was in his nineteenth year, and the head was 33 inches in circumference. When the bones of the cranium, being united, prevent the head from enlarging, the accumulation of wa ter in the ventricles destroys the faculties, and produces idiotism and death.' 2. On the effects of concussion. It occasions nausea and vomiting, giddiness, and apoplectic fits, which return at intervals for some time. S. On the enlargement of the blood-vess is of the brain. It occasions violent headaches, watchfulness, and disorders of the bowels. The beating of the arteries of the brain has been supposed essential to the exertion of the senses; but John Hunter retained his senses after the heart had apparently ceased to beat. 4. On the extravasation of blood. It produces similar effects to the accumulation of water; cona, nausea, apoplexy. 5. On the effects of the formation of pus. It occasions melancholy, lowness of spirits, and mania, with incessant talking. 6. On the effects of external pressure. The depression of the skull occasions loss of memory, the incapacity of using the proper conversation, &c. all which disappear when the cause is re 44 ties. Sir H. Davy on Iodine. moved. 7. Iaternal pressure from tubercles produces similar effects. 8. Hydatids in the brain occasion bowel complaints, and a comatose state of the rectum and bladder. 9. Wounds in the brain occasion no symptom whatever, nor the destruction of any of the faculWhen a fungous excrescence of the brain takes place through a hole in the skull, the esophagus becomes so sensible as to prevent swallowing solids, from the pain which they occasion. Injuries of the spinal marrow in the neck occasion paralysis of all the parts of the body below the injury. 10. June 9. A paper by Sir Humphry Davy was read, containing additional observations on iodine. The paper consisted of five parts. Part first contained additional observations on the triple compounds formed by dissolving iodine in solutions of alkalies and alkaline earths. The author had already ascer tained that when iodine is dissolved in a solution of potash two different sub stances are formed; the first a coinpound of oxygen, iodine, and potassium; the second a compound of iodine and potassium. The first of these compounds, which is analagous to hyperoxymuriate of potash, is nearly insoluble in water. To obtain it pure, it must be boiled repeatedly in alcohol, which dissolves the iodine of potassium, but leaves the triple compound, to which Davy gives the name of oriode of potassium. This substance dissolves in sulphuric, phosphoric, acetic, oxalic, and indeed in all the acids tried, without undergoing decomposition. At a red heat it gives out oxygen gas, and sulphuric acid poured upon the remainde. expels iodine, while sulphate of potash is formed. From two analyses, but both upon a very small scale, Davy concludes that this salt is precisely similar in its composition to hyperoxymuriate of potash, only that iodine comes in place of chlorine Oxiode of sodium is analogous in its properties to oxiode of potassium. Oxiode of barium is nearly insoluble in water, The author did not succeed in his attempts to obtain a separate compound of iodine and oxygen. Part second consisted in experiments on hydr.onic acid, This acid dissolves iodine, and forms an orange coloured solution. It absorbs oxygen from the atmosphere. The com. pounds which it forms with bases are very similar to the analogous muriates. When oxygen is present they are decom posed by heat, iodine being disengaged; [Aug. 1, and potash, lime, or whatever constituted the basis, left behind. On Thursday, the 16th of June, the remainder of Sir Humphry Davy's paper on iodine was read. In the third part, the author gave an account of his experiments on the combination of iodine and chlorine. When iodine is heated in a dry vessel filled with chlorine gas, it absorbs about one third of its weight of that gas. The compound formed dis solves in water, forming a very acid liquid, which, in the author's opinion, owes its acidity to the properties of this chlo ride of iodine, which of course he considers as an acid. When agitated in chlorine gas, this substance becomes colourless. It has the property of dissolving a good deal of iodine, and acquires in consequence a dark colour. The author conceives this chloride to be a compound of one atom of chlorine and one atom of iodine. In the fourth part, the author gave an account of the action of iodine and several of the compound gases. When sublimed repeatedly in sulphurated hydrogen gas, a red liquid is formed, which is a compound of the gas and iodine. When dissolved in water, sulphur is deposited, and hydrionic acid formed. When iodine is heated in olefiant gas, a very small quantity of a colourless liquid, having an acrid taste, is formed. On nitrous gas and carbonic oxide it produces no change. The fifth part of the paper consisted in experiments on different marine productions, to determine whether they contain iodine. In the sea water of the Mediterranean, he did not find any traces of it. He found traces of it, but in very minute quantity, in some fuci and ulvæ, but not in any of the confervæ or spon ges which he examined. In the author's opinion, it exists in the ashes of these plants, in the state of oxiode of sonium. The most delicate test of iodine he found the property which its salts had of discolouring polished silver. A very minute quantity of it in a salt makes the salt capable of forming a red solution in sulphuric acid. At the same meeting, a paper by Dr. Kidd, professor of chemistry at Oxford, on the formation of nitre on walls, was read. This salt appears spontaneously on the walls of the Laboratory at Oxford; and Dr. Kidd relates the result of his obser vations on its appearance, continued for about a year. The wall is composed of lime-stone, containing 96 per cent. of carbonate of lime, and 4 per cent. of 1814.] Sir H. Davy on the Combustion of Diamond, &c. oxide of iron, clay, sand, and a trace of magnesia. The nitre only appears on this lime-stone. Frost encreased the rapidity of the formation; but an intense cold seemed to put a stop to the process, to which moisture also seemed injurious to the process. The free access of air was requisite for the formation of the salt in the usual quantity; though a portion was formed on a part of the wall separated from the external air by means of a glass-case; but after a certain time this formation ceased. Pure carbonate of lime, spread upon the glass-case, did not yield any saline efflorescence. The saltpetre was nearly pure. It did not contain above half per cent. of lime, and gave very minute traces of sulphuric and inuriatic acids. 45 residue, and produced a greater quantity of water, and a greater diminution of the gas than plumbago. Charcoal from alcohol, formed during the making of either, left a small white residue, owing probably to the impurity of the sulphuric acid employed in the process. It formed more water, and occasioned a greater absorption. Charcoal from oak left a white ash, consisting chiefly of carbonate of lime. It formed the greatest quantity of water, and occasioned the greatest absorption. These experiments led to the conclusion that diamond is pure carbon, and that the other substances contain a little hydrogen in a state of chemical combination. Sir H. Davy conceives, with Mr. Tennant, that the dif ference between charcoal and diamond depends chiefly on the crystallized state of the latter. June 23d, a paper by Sir Humphry Davy was read, on the combustion of diamond in oxygen gas. These experiments were made at Florence by means of the large burning-glass, which was used in the first combustions of diamond, at the expense of the Archduke Leopold. They were afterwards continued at Rome. The oxygen gas was prepared from hyperoxymunate of potash, and introduced into dry glass globes, fitted with stop-cocks, and capable of holding from 14 to 40 cubic inches of gas. The diamond was put into a small platinum capsule full of holes, and attached to the stop-cock. The absorption of gas was determined by means of a small glass tube, properly fitted to the stop-cock, graduated, and plunged in mercury. When the diamond was once kindled by the burning-glass, it continued to burn for some time, though the burning-glass was withdrawn, and even melted a platinum wire by which it was attached to the tray. No moisture was produced by the combustion, and the diminution of the bulk of gas was scarcely sensible. Nothing was produced but carbonic acid gas, possessing all the properties of common carbonic acid gas. When plumbago was burned, some moisture was produced, and the bulk of the gas was sensibly diminished, indicating the presence of a small portion of hydrogen as a constituent of this substance. When two grains of plumbago were burnt, the absorption amounted to the bulk of 96 grains of mercury; but as some oxide of iron was left, the whole of this absorption cannot be ascribed to the formation of water. Charcoal from turpentine burnt all away, without leaving any At the same meeting, a paper by Smithson Tennant, esq. was read, on an easier mode of procuring potassium than the process of Gay-Lussac and Thenard. The method is this:-A piece of gunbarrel, about 18 inches long, shut at one end, is covered with a lute composed of raw and baked Stourbridge clay. A piece of gun-barrel, about 9 inches long, open at both ends, is made to slip into the upper end of the first gun-barrel. The lower end of this piece has a narrow opening. It may be fixed on with sealing-wax or any common lute. Over the open end a third tube, or cap of tin plate, is luted, having a perforated cork, through which passes a bent tube of safety. A mixture of caustic potash and iron turnings is put into the bottom of this gun-barrel, and it is then heated violently, for about an hour, in a common smith's forge. The potassium is found sublimed pure in the interior iron tube. At the same meeting, a paper by Sir Everard Home, Bart, was read, giving an account of the skeleton of a fossil animal related to the class of fishes lately dis◄ covered on the south coast of England, This specimen is in Mr. Bullock's mus seum. It was discovered in a limestone rock, situated on the west of Lyme, The scull was found in 1812, and the other parts some months after. The author shows that it must have been a swimming animal, from the articulations of the vertebræ. But it differs in its structure from all known gencra of fishes, and the author conceives that it is related to some of those intermediate animais found upon the coast of New South Wales. [ 46 ] NEW PATENTS. The Repertory of Arts, No. 146, contains the following specifications: JOHN HANCOCK's, Reading, Gentle man, for an Impro,enent in the Construction of Carriages, and in the Application of a Material hitherto unused n heir Construction.-Dated Aug. 25, 1813. The new material employed by Mr. Hancock is whalebone, which being ferriled at certain distances to counteract its tendency to split longitudinally, and inserted in the parts to which it is attached, prevents their sustaining any injury from those concussions to which carriages are hable. The spokes of the wheels, for the construction of which he gives particular directions, are of this substance. The carriage itself is made nearly in the usual manner, except that in pigs a piece of whalebone is put between the iron under the sha ts, and it is otherwise introduced to strengthen and brace the vehicle, as may appear necessary in the different forms on which carriages may be constructed. The springs are made of steel, with bone round, under or upon them, or of whalebone only. The body has no other novelty than the occasional introduction of the same material; and the heads, hoods, or roofs are composed of cotton, silk, or leather, with whalebone, iron, steel, cane, or wood, to strain or raise them. The patentee makes his wheels upright, that is, without dishing. According to this mode of construction, the elasticity is much more pleasant than that of steel. Springs of that metal. if made to carry much weight, recover so suddenly after bending as frequently to throw the person riding out of the carriage; and to this recoil, and not to the first shock, many of the fatal accidents which occur are to be attributed. Whalebone being more pliant, does not recoil so speedily, and springs made of it cannot be broken. JOHN KERSHAW'S, Cotton-spinner, and JOHN WOOD's, Gentlemen, of GlossopDale, Derby, for a Mode of preparing Flar for the pur, ose of being spur on the like Machinery as Cotton.Feb. 10, 1814. The object of the patentees in this process is to preclude the necessity handspinning in the higher numbers eithx, by adapting it to the same kind of machinery as cotton; and in acco plishing this object, they hope to have laid the foundation of a manufacture which may [Aug. 1, enable this country, at no distant period, to meet the French in a market hitherto their own, that of lawns, and cambric. The process, claimed as their invention, is that of separating the fibres of the flax from each other by bleaching, and afterwards, either passing it between rollers pressed together with force sufficient to separate such of the fibres as have not been sufficiently separated by bleaching, or beating it with hammers or beatles, or by other modes of percussion sufficient to effect the same purpose. The rollers used for this purpose may be made of any convenient diameter and length, and of any materials sufficiently hard; but the patentees usually have one of close-grained, well-seasoned wood, and the other of iron, about seven inches in diameter and three in length. They press them together by means of a weight of fifty-six pounds at each end of the upper roller, and usually pass the flax twice or oftener through six successive sets of rollers until the fibres are sufficiently separated. WILLIAM PARKER'S, Oil and Colourman, Whitechapel, for an Improvement in making Green Paint.-Aug. 10, 1812. This invention consists in combining fixed alkah with mineral oxyd and precipitate of copper, and thus producing a permanent pea-green colour, for house and ship painting, not liable to decom position by salt water. This is effected in the following manner:-Boil fourteen ounces of crude potash and fourteen drachms of crude white arsenic in two gallons of water till quite dissolved; then put the liquor into a cast-iron vessel to cool and settle: draw off the clear liquor into a vessel that will hold twenty gallons, and add to it six gallons of clear, cold, soft water. Boil one pound of Roiñan vitriol in soft water till dissolved; put the solution into an open vessel till quite cold, then add it gradually to the solution of fixed alkali, stirring all the time, which will produce a genuine green oxyd. A precipitate of copper to be mixed with this oxyd is thus prepared-Boil one pound of Roman vitriol, till dissolved, in two gallons of soft water. Dissolve in another vessel half a pound of the first soft American pearl-ash put the solution of vitriol, boiling hot, into a vessel that will hold ten or twelve gallons: add to it gradually the solution of pearl-ash, |