the cell with the copper plate, the specific gravity of the liquid having risen from 1.015 to 1.047. A similar experiment was tried with plates of copper and zinc in sulphate of copper and sulphate of zinc respectively. The result was as before, metallic copper being deposited on the copper plate, and the sulphate of zinc rising in specific gravity from 1.123 to 1.139. In order to determine whether the amount of silver deposited depended, not merely on the amount of the silver in solution, but also on the amount of copper salt that bridged over the intervening space, similar experiments were made in which the nitrate of silver was kept constant, but the nitrate of copper was increased by equivalent multiples. It was found that the silver deposited increased with the increase of the copper salt, being about double when the copper salt was seven times as strong, and that the effect of successive additions gradually diminished. This is in strict accordance with other experiments, showing that, when the copper plate is immersed in a mixture of the nitrates of copper and silver, the amount of silver deposited is increased, and increases with each successive addition of copper salt, though in a diminishing ratio. That this acceleration is not produced by a copper salt only was proved by repeating the experiment with a variety of other nitrates. The subjoined Table shows the results, and indicates, at the same time, that the increased effect does not depend simply upon the nitric element, which was present in the same quantity in all, but likewise on the nature of the salt. Size of plate 3230 sq. millims.; volume of solution 72 cub. centims., containing 2.8 per cent. of nitrate of silver; temperature 18° C.; time 5 minutes. On Crystals of Silver. By J. H. GLADSTONE, F.R.S. The crystalline deposit on copper or zinc immersed in silver nitrate forms a very beautiful object when viewed under the microscope. The form, colour, and general character of it depend very much on the strength of the solution; if weak, say 1 per cent., the red metal is presently covered with a growth of small crystals, which are quite black; but as the action proceeds some of these crystals grow more rapidly than others, especially at the angles of the plate, and the new growth is white. If the solution be stronger, say 3 per cent., there is no black deposit, but the white silver simulates the appearance of furze-bushes or fern-leaves of varied structure. In much stronger solutions, say 12 per cent., the crystals reminded the author of juniper-branches, and in stronger still they had rather the outward form of moss. In nearly saturated solutions the crystals of silver end in thick knobs. The crystals at first advance pretty uniformly into the liquid, but when they have considerably reduced its strength, there usually happens a stoppage of the general advance, and a special growth from one or two points, forming long feathery crystals, that sweep rapidly through the lower part of the solution. In a 1 per cent. solution these are long meandering threads, with tufts like the dendritic appearances in minerals. The crystals are peculiarly beautiful when nitrate of copper or of potassium has been previously added to the nitrate of silver, Some other forms were described as produced under peculiar circumstances, such as long straight threads, of extreme tenuity, often changing their direction at a sharp angle. Note on Fibrin. By Dr. JOHN GOODMAN. The author having read a paper on the above subject at the Meeting of the Association in Liverpool last year, has been since that period constantly engaged in a long series of experiments establishing the truth of the statements there set forth. The following is an epitome of the results obtained. The experiments were performed under the microscope : 1. Albumen immersed for some short time in cold water loses its characters as albumen, and becomes transformed into a substance which the author asserts exactly resembles blood-fibrin under the microscope. 2. This substance exhibits intense attractive powers. 3. It decomposes peroxide of hydrogen with effervescence. According to the author's views, all these experiments showed that water is the primary source of this change, and that until albumen is in some way subjected to the influence of water, oxygen can exert no influence in producing this change. 4. The rapidity or intensity of the transformation was not increased by raising the temperature of the water. 5. Ovalbumen does not per se become transformed into fibrin by the voltaic currents, only to such an extent as its water of fluidity is available for this pur pose. 6. But when diluted with water the entire mass of albumen submitted to the current was rapidly transformed into fibrin. 7. When this substance was submitted to potash it dissolved in three minutes, whilst blood-fibrin required twelve hours and ovalbumen twenty-four hours for solution. 8. In strong hydrochloric acid both this substance and blood-fibrin dissolved in twenty-four hours, whilst ovalbumen was not completely dissolved in sixteen days. 9. In all acid solutions of this substance, and of blood-fibrin precipitated by alkalies, and of alkaline solutions precipitated by acids, the author asserts that he invariably finds fibrinous rods and formations perfectly identical in their appearance one with the other, and without any coagulum peculiar to albuminous precipitations; whilst on the other hand in similar solutions of albumen similarly precipitated, he finds as invariably a dense flocculent coagulum, without the presence of fibrinous rods or other formations. Alkaline solutions, moreover, of albumen precipitated by acetic acid gave always a dense white and flocculent coagulum, and those precipitated by nitric acid gave a lemon-yellow precipitate, whilst neither white nor lemon-yellow coagula occurred in similar precipitations from like solutions of fibrin thus produced as blood-fibrin. The author maintains that these experiments show that the substance thus produced by the agency of water is genuine fibrin. Preliminary Notice on a New Method of Testing Samples of Wood-Naphtha. By WILLIAM HARKNESS, F.R.M.S. The detection of wood-naphtha, when present in alcohol, is now comparatively easy, but the converse problem, viz. the detection of alcohol in wood-naphtha, does not seem to have occupied the attention of chemists generally. Methylated spirit, which is cheaper than wood-naphtha, is the only adulterant likely to be used, and any simple mode of determining its presence must be of some value to the chemist. One of the most common methods of examining a sample of naphtha is to ascertain its boiling-point; but this is not reliable, as different samples, even of the same specific gravity, may boil at different temperatures, varying from 138° F. to 156° F., and yet be free from ethylic alcohol. The following method of testing samples was discovered by the author whilst engaged in the preparation of oxalate of methyl. It was noticed that different samples of naphtha gave different quantities of this crystalline body. Further investigations showed that the presence even of a small quantity of methylated spirit or alcohol in the wood-naphtha from which the oxalate was prepared, altered in the most striking manner the temperature at which solidification took place. Thus, oxalate of methyl prepared from pure wood-naphtha is always solid at a temperature exceeding 100° F. This has been confirmed by experiments on all kinds of naphtha, English and foreign. In samples containing methylated spirit or alcohol, crystallization always takes place at a temperature less than 100° F., such temperature depending on the percentage of alcohol present. The following are the averages of many experiments: 0 The test is easily applied. Distil at a moderate heat 1 oz. of the suspected spirit, 7 drs. oxalic acid, and 1 oz. sulphuric acid; collect the crystals, if any, in a small beaker, and heat until the crystals melt, then with a thermometer watch the temperature at which crystallization again takes place. One precaution is necessary: the sample examined, if not miscible with water, must be rendered so by filtration through charcoal previous to testing. A Method of Preserving Food by Muriatic Acid. As the great objection to preserving articles of food by chemical compounds is that it imparts a flavour to them more or less unpleasant, it occurred to the author to try whether they could not be preserved in the first instance by muriatic acid, and then before use be deprived of their acidity by means of soda or its carbonates. The author tried many experiments, and found that in many cases the plan might be employed with very good results, the muriatic acid not affecting the most delicate flavours, but leaving the article just as it was before, with only a slight not objectionable taste of common salt. There are two principal ways of effecting the object: 1. To dip the meat, fish, or other substance at intervals, if necessary, and expose it freely to the air to dry. During this process of drying the coating of muriatic acid prevented the approach of decomposition. Meat and fish thus prepared remained perfectly sweet for many months. The only thing necessary before using them was to steep them in a very dilute solution of carbonate of soda till any slight traces of the acid were neutralized. 2. The other plan is to enclose the substance in a close vessel with a small quantity of muriatic acid, so as to prevent evaporation. A very small quantity of muriatic acid seems to be sufficient to destroy the germs of decomposition-a quantity which, when ultimately neutralized by soda, gives a scarcely perceptible flavour of salt. A too large quantity of muriatic acid tends itself to decompose the substance submitted to its action. One application of the plan was described. If meat be cut up small and steeped in weak muriatic acid, and when it is thoroughly penetrated boiled in a very dilute solution of carbonate of soda, carbonic acid is evolved in the pores of the meat, and splits it up into such minute fragments as to produce virtually a solution of the meat. On the Aluminous Iron-ores of Co. Antrim. By Dr. J. SINCLAIR HOLDEN, of Larne. These ores have only been discovered within the last few years, and exhibit a seam both extensive and rich. It lies continuously for about seventy miles along the coast and mountain-glens of Antrim, being nearly horizontally interspread throughout the basaltic rocks which form the floor of the county, and at an average height of 300 feet above the white limestone. The elevation above sea-level varies considerably, as among the highest mountains it is found at a height of over 1000 feet, from which it gradually falls north and south as low as 200 feet. The general dip of the beds is south-west. Dr. Holden gave analyses of the ore, and adds that it is not analogous to any known iron deposit in England, and that basaltic rocks, though containing some iron in their composition, are not generally associated with large deposits of ironThe ferruginous stratum consists of three qualities of ore, which, in descending order, are: ore. Pisolite Lithomarge Total thickness ft. Average Metallic Iron per cent. These graduate into each other. The upper bed, or pisolite, is the richest in iron, and working quantities can be mined containing from 30 to 50 per cent. of metallic iron. Large quantities of this ore have now been raised and shipped to England, where it has already made a reputation for itself, in facilitating the production of pure iron from the siliceous hæmatites. The entire absence of phosphorus and sulphur, and the presence of a large percentage of alumina, add much to its value, both as an iron-ore and a flux. When intermixed with the siliceous ores in the smelting-furnace, the effect is to soften the slag, producing a "loose load," which allows the metal to pass through easily, forming a pure "pig," and, from a given quantity of the mixed ores, determining a higher percentage of metallic iron than could be otherwise obtained. It is chiefly used in Lancashire, Cumberland, and South Wales, and is becoming a necessity where good steel-iron is demanded. To show that an extensive source of industry has already been developed, it may be stated that upwards of 50,000 tons were exported last year, and the quantity will be much greater this year. The discovery of this ore has had the effect of stimulating mineral research in the adjoining counties, and Dr. Holden states not in vain, as samples of a good siliceous hæmatite have been shown him, and only wait exploration where they were discovered. If found in quantity, no better outlay of capital could be invested than in the erection of smelting-furnaces on the Antrim coast. As suggested by the President of the Section, there could be utilized in the local smelting of the ores the large quantity of peat available in the north of Ireland. Localities of Dioptase. By Professor N. STORY MASKELYNE, F.R.S. Dioptase has hitherto only been known as a product of the copper-mine at Altyn Tubeh, in the Kirghese steppes of Tartary, if we except certain reputed localities in Germany; it has been recently met with among old specimens that have been traced to localities in Chili. One of these was among the specimens preserved in drawers at the British Museum, which have lately been under careful examination with a view to their identification, and another similar specimen was obtained some years since by W. G. Lettsom, Esq., the well-known mineralogist, from a dealer at Vienna. The crystals on both are minute but distinct, and are those of dioptase. The ! gangue is a compact micaceous hæmatite; the locality, traced to an old sale catalogue of Heuland's, is the Rosario Mine, Chili. It is singular that other specimens of the same mineral should have been found among the specimens preserved in the British Museum. One of these is associated with chrysocolla and ochre on a quartzose veinstone, another occurs as a thin crust on a schorlaceous rock, both being from a Chilian locality. A specimen recently obtained is associated with quartz and eisenkiesel, and is from the Mina del Limbo, Del Salado, Copiapo, Chili. On Andrewsite. By Professor N. STORY MASKELYNE, F.R.S. A somewhat well-marked group of minerals would seem to justify the designation of the Dufrenite group, by reason of their having, as a common constituent (or being capable of being so represented), a compound of which the formula is R2 P2O+R2H, O.; R being Fe in the case of Dufrenite. 8 Dufrenite being Fe, P2O̟ + Fе, H ̧ O ̧, or, in Berzelian symbols, Fe P, Fe H ̧. 2 2 8 Peganite is Al P, Al H ̧ + 3H. Fischerite is Äl P, Al Ik ̧ + 5ik. Cacoxene is Fe P, Fe H2 + 911. Wavellite is 241 P, Al H ̧ + 9H. 2 6 A mineral recently found in Cornwall, and sent to the British Museum by Mr. Talling, may perhaps be referred to this group. It has been analyzed in the Museum Laboratory, and Professor Maskelyne named it Andrewsite, in honour of the distinguished President of the Chemical Section of the British Association, Dr. Andrews, of Belfast. Andrewsite occurs in occasional association with a bright green mineral in brilliant minute crystals, presenting a strongly marked resemblance to those of Dufrenite. This green mineral not having been as yet, from the small amount obtained of it, submitted to an analysis, is only provisionally termed Dufrenite. The Andrewsite which it sometimes thus accompanies presents itself in globular forms or in disks with a radiate structure, and in habit curiously resembles Wavellite. Its colour is a slightly bluish green; its surface is generally formed of a very thin layer of the mineral provisionally termed Dufrenite, crystals of which occasionally stand out of the globules. The interior of the globules is sometimes homogeneous, and consists of radiating crystalline fibres; oftener one perceives an almost sudden transition from an outer shell of some thickness, which consists of Andrewsite, into an inner core, formed of a brown mineral. Seen under the microscope, the two minerals appear to a certain degree to interpenetrate each other, so that the selection of material for analysis is a work of much caution. The spherules usually stand on the projections of a quartzose veinstone, protruding into a hollow, and covered with a mass of limonite, sometimes carrying a drusy crust of Göthite, and studded occasionally with a few brilliant little crystals of cuprite. The spherules are met with in one or two cases on cuprite formed round a nucleus of native copper. Andrewsite, in fact, contains copper, four analyses of separate specimens giving the percentages of 10-651, 10-702, 10-917, and 11.002. The analyses of Andrewsite have proved sufficiently concordant to justify the formula in which, however, a portion of the ferric phosphate is replaced by ferrous phosphate, as in Vivianite is frequently the case with the two phosphates. |