NEWS 1833. H. A. Dufrené, Rue de la Fidélité, Paris, "An improved process for obtaining oxygen."-A communication from C. Tellier, Passy, Paris.-July 11, 1865. 1841. H. Blair, Kearsley, Lancashire, "Improvements in the production of gases from aqueous vapour and in the application thereof to heating purposes."-July 12, 1865. NOTICES TO PROCEED. 657. R. Mushet, Belgrave House, Cheltenham, "Improvements in the manufacture of steel and homogeneous iron."-March 9, 1865. 806. M. Morgans, Brendon Hills, Somersetshire, "Im provements in the manufacture and refining of iron and steel."-March 22, 1865. 871. J. C. C. Halkett, Cranwood House, Mid Lothian, N.B., "An improvement in paints or compositions used for coating iron or wooden vessels, and other structures exposed to the action of sea-water."-March 28, 1865. 1560. J. Ferguson and R. Miller, Glasgow, N.B., "Improvements in the manufacture of steel."-June 7, 1865. 670. J. Freeman, E. G. Freeman, and C. H. Freeman, Battersea, "Improvements in the preparation of turpentines and varnishes."-Petition recorded March 10, 1865. 692. E. B. Wilson, Glasgow, N.B., "Improvements in furnaces and fire-places."-March 11, 1865. 44 712. R. A. Brooman, Fleet Street, Improved processes for the production of photographic images capable of being inked with fatty inks."-A communication from C. M. T. du Motay and Č. R. Maréchal, Metz, France.-March 14, 1865. 729. A. P. Price, Lincoln's Inn Fields, Middlesex, "Improvements in obtaining sulphurous acids."-March 15, 1865. 855. W. Clark, Chancery Lane, "Improvements in the manufacture or preparation of materials for, and in their application to, lighting and heating purposes; also in apparatus used for the same." A communication from A. de Peyrouny, Boulevart St. Martin, Paris.-March 25, 1865. 1456. R. A. Brooman, Fleet Street, "A new method of manufacturing oil from fatty matters, or the residuum arising from the distillation of fatty matters, the manufacture of stearic acid, soap, and purification of oils." A communication from P. R. Beaumont, Paris.-May 27, 1865. 1719. W. E. Newton, Chancery Lane, "Improvements in the preparation of amalgams of quicksilver or mercury, and in the application of such amalgams to various purposes in the arts." A communication from H. Wurtz, New York, U.S.A.-June 28, 1865. CORRESPONDENCE. Continental Science. PARIS, July 24. Ir is now settled definitely that the Great Exhibition of 1867 will be held in a temporary building to be erected on the Champ de Mars. This being decided, it is unnecessary to refer to a scheme emanating, I believe, from M. Silbermann, who proposed to exhibit the different classes of manufacture in separate buildings, to be erected at intervals along the Boulevards, and so bring the Exhibition nearer the homes and within the means of the working classes of Paris. This plan is not without its recommendations, but here as in London people will have a grand show, and, moreover, we have an architect who wishes to give us a glass dome which will reduce those of Captain Fowke to insignificance. A vinegar-making polyp from China has just been added to the collection of objects at the Jardin d'Acclimatation. This animal is described by Father Huc in his work on China. It is placed by the Chinese in weak spirit and water, which in the course of a month or so it transforms into vinegar. No experiment has yet been made here to test the truth of this story, the polyp being still in the water in which it arrived. At the last meeting of the Photographic Society M. Couvreux recommended the use of chloride of calcium for salting paper, the excess of which, he says, is very easily got rid of after the paper has been in the silver bath. M. Meynier read a paper strongly recommending the use of sulphocyanide of ammonium in place of hyposulphite of soda. The sulphocyanide, he affirms, leaves no objectionable sulphur compound in the paper. The same gentleman recommended the use of a double nitrate of silver and ammonia, instead of adding ammonia to a nitrate bath. M. Leon Vidal has published a set of photometric tables, and what he calls a photometer. The object of these is to tell inexperienced photographers how long to expose. In order to do this the experimenter has first to expose a strip of sensitised paper for one minute, and then compare the colour with the "photometer," which is a card having fixed upon it the ten graduated shades through which chloride of silver passes in the course of one minute's exposure to full sunlight. And now knowing the number of the shade of colour on the photometer, the focal distance of the objective, and the size of the diaphragm, the operator on referring to the tables will be told the exact time necessary for the exposure. Skeleton Leaves. To the Editor of the CHEMICAL NEWS. SIR,-A "Constant Reader," who in a late number of the method of obtaining "skeleton leaves," may try my plan: CHEMICAL NEWS expressed a wish to hear of a ready them in dilute sulphuric acid containing from 10 to 30 First dip the leaves in boiling water, and then immerse per cent. of the acid, according to the delicacy or coarseness of the leaf-structure. In a day or two use a pretty stiff bristle brush to the leaves, adding drop by drop a little saturated solution of bichromate of potassium. When the operation seems complete, wash the leaves carefully in ammoniated water, and finish with a little weak hypochlorite of calcium or chlorine water. The "skeletons" may be plated by being dipped into a very weak solution of phosphorus in bisulphide of carbon, dried, placed in a neutral solution of nitrate of silver for fifteen minutes, dried again, and lastly covered with dead silver in a small electro-plating apparatus. An almost equally beautiful result is produced if the "skeletons" are dipped into a clear boiling saturated solution of iodide of lead. When dry they appear as if frosted with gold. If cautiously painted with a very concentrated alcoholic solution of mauve, skeleton leaves present the appearance of a magnificent and delicate casting in bronze. I am, &c., WENTWORTH E. SCOTT, F.C.S. On the Estimation of Uric Aoid. To the Editor of the CHEMICAL NEWS. SIR,-Since the publication of my paper on uric acid in the Lancet, and of which you were good enough to give an abstract in the CHEMICAL NEWS of July 22nd, I have made some further observations, the purport of which I desire should be known. Dr. Odling, a short time since, suggested to me that it would be desirable that the precipitates obtained by me should be dissolved in alkali and the uric acid reprecipitated with hydrochloric acid, in order that it might be procured in a purer condition. This proceeding I have adopted in several cases, and with the following results; it being remembered, however, that my precipitates were treated with boiling alcohol of specific gravity 8105, in order to free them from various impurities, and that the amount of mineral matter contained in them was ascertained in all cases and deducted. The urine of twenty-four hours, obtained from the same case on two consecutive days, yielded deposits which, after treatment with alcohol and deduction of mineral matter, amounted to 2160 and 2065 grains, and these furnished on reprecipitation 16:36 and 16.51 grains respectively of uric acid, which, on examination with the microscope, was ascertained to be in its usual exceedingly characteristic crystalline condition. In another case, the precipitates similarly treated amounted to 14'97 and 13.97 grains, which furnished on reprecipitation 11.85 and 12.50 grains of uric acid in crystals. Lastly, a deposit obtained by the evaporation of nine different urines, weighing after the usual treatment 30°15 grains, gave on reprecipitation 24'36 grains. These results are important in two respects; they show, first, that a reduction must be made from the amounts obtained after treatment with alcohol and deduction of the ash, but they also prove conclusively, when considered in connection with the quantities given in my paper already referred to, that the amount of uric acid contained in human urine is greatly in excess of that hitherto obtained, being, in fact, about double. In addition, therefore, to the recommendations already given for the estimation of uric acid, I would advise that | the precipitate should in all cases, after treatment with alcohol, be dissolved in as small a quantity as possible of a solution of potash, filtered to separate the insoluble matter, and the uric acid reprecipitated with a slight excess of hydrochloric acid. The boiling with alcohol must be effectual, otherwise some hippuric acid may remain behind on the filter, when there will be danger of its precipitation on the addition of the hydrochloric acid. I am, &c. - Poisoning by Atropine. A surgeon named Sprague, at Ashburton, is in custody on the charge of attempting to poison his wife and several other persons by placing atropine in a rabbit-pie. The presence of atropine in the pie was proved by Mr. Herapath, and the evidence of the medical man called to attend the sufferers described the symptoms of poisoning by belladonna. Processes of Disinfection.-The following memoranda on disinfection have just been issued by the Privy Council; and, considering the circumstances under which they are published, we feel bound to assist in giving them all publicity: "1. For purposes of artificial disinfection, the agents which most commonly prove useful are-chloride of lime, quicklime, and Condy's manganic compounds. Metallic salts-especially perchloride of iron, sulphate of iron, and chloride of zinc, are, under some circumstances, applicable. In certain cases chlorine gas or sulphurous acid gas may advantageously be used; and, in certain other cases, dered charcoal or fresh earth. "3. In the ordinary emptying of privies or cesspools, use may be made of perchloride of iron or chloride of zine, or of sulphate of iron. But where disease is present, it is best to use chloride of lime or Condy's fluid. Where it is desirable to disinfect, before throwing away, the evacuations from the bowels of persons suffering from certain diseases, the disinfectant should be put into the night-stool or bed-pan when about to be used by the patient. "4. Heaps of manure or of other filth, if it be impossible or inexpedient to remove them, should be covered to the depth of two or three inches with a layer of freshly burnt vegetable charcoal in powder. Freshly burnt lime may be used in the same way, but is less effectual than charcoal. If neither charcoal nor lime be at hand, the filth should be covered with a layer some inches thick of clean dry earth. 86 5. Earth, near dwellings, if it has become offensive or foul by the soakage of decaying animal or vegetable matter, should be treated on the same plan. "6. Drains and ditches are best treated with chloride of lime, or with Condy's fluid, or with perchloride of iron, A pound of good chloride of lime will generally well suffice to disinfect 1000 gallons of running sewage; but, of course, the quantity of disinfectant required will depend upon the amount of filth in the fluid to be disinfected. "7. Linen and washing apparel requiring to be disinfected should without delay be set to soak in water containing per gallon about an ounce either of chloride of lime or of Condy's red fluid. The latter, as not being corrosive, is preferable. Or the articles in question may be plunged at once into boiling water, and afterwards when at wash be actually boiled in the washing water. "8. Woollens, bedding, or clothing, which cannot be washed, may be disinfected by exposure for two or more hours in chambers constructed for the purpose to a temperature of 210 to 250 degs. Fahrenheit. "9. For the disinfection of interiors of houses, the ceilings and walls should be washed with quick-lime water. The wood-work should be well cleansed with soap and water, and subsequently washed with a solution of chloride of lime, about two ounces to the gallon. "10. A room, no longer occupied, may be disinfected by sulphurous acid gas, or chlorine gas-the first by burning in the room an ounce or two of flowers of sulphur in a pipkin; the second, by setting in the room a dish containing a quarter of a pound of finely-powdered black oxide of manganese, over which is poured half-a-pint of muriatic acid, previously mixed with a quarter of a pint of water. In either case the doors, chinney, and windows of the room must be kept carefully closed during the process, which lasts for several hours.' Vol. XI. of the CHEMICAL NEWS, containing a copious Index, is now pow-ready, price 11s, ed., by 1 ost, 118. 6d., handsomely bound in cloth, "2. If perchloride of iron or chloride of zinc be used the common concentrated solution may be diluted with eight or ten times its bulk of water. Sulphate of iron or chloride of lime may be used in the proportion of a pound to a gallon of water, taking care that the water completely dissolves the sulphate of iron, or has the chloride of lime thoroughly mixed with it. Condy's stronger fluid (red) may be diluted with fifty times its bulk of water; his weal er fluid (green) with thirty times its bulk of water. Where the matters requiring to be disinfected are matters having an offensive smell the disinfectant should be used till this smell has entirely ceased, gold-lettered. The cases for binding may be obtained at our Office, price 18. 6d. Subscribers may have their copies bound for 28. 6d. if sent to our Office, or, if accompanied by a cloth case, for Is. Vols. I. and II. are out of print. All the others are kept in stock. Vol. XII. commenced on July 7, 1865, and will be complete in 26 numbers. J. D. O. We gave our correspondent the best information in our and small experiments are of no value in determining such questions. power. Manufacturers, of course, keep their results to themselves, Twaddell is not used in France. Inquir.r.-Iwenty degrees Baumé corresponds to the density 1-161, A Simple Molecule.-The first week in November. Send your name, and give your subjects to the Secretary of Science and Art Department, South Kensington, be'ore October 15. Received.-Chen istry as a Branch of General and Practical Educa tion. By Dr. T. Wood, F.C.S. Received with thanks.-L. R. Dar'ing. SCIENTIFIC AND ANALYTICAL CHEMISTRY. Chlorides of Tungsten,* by M. H. DEBRAY. I. By passing a current of dry chlorine on tungsten heated to dull redness in a hard glass tube, intensely red vapours are obtained, which condense into a dark grey liquid mass. This product is a mixture of perchloride of tungsten, WC, and of subchloride, W2Cl, (W92, Cl = 35'5). It must be distilled in a current of chlorine to produce perchloride of tungsten as pure as possible; but, however obtained, this product is never wholly free from subchloride. It is, however, present in such small quantities as not sensibly to alter the composition of the perchloride. By dissolving this body in potash hydrogen is disengaged (2 to 3 cubic centimetres from 4 to 5 grammes of material). Ammonia also dissolves perchloride, giving a yellow liquid, which soon becomes turbid and decolourises, depositing brown oxide of tungsten. With ammonia only a trace of gas is disengaged. In contact with water, the perchloride, distilled in chlorine, alters slightly and is transformed, first into a white substance, then into yellow tungstic acid, without producing at all the blue oxide of tungsten, corresponding to the chloride W,C,. This is because the smallest quantity of oxygen dissolved in water suffices to transform the oxide into tungstic acid. When, on the contrary, chloride, not distilled in chlorine, is placed in contact with water, the decomposition may be instantaneous, and in every case blue oxide of tungsten, mixed with a more or less considerable quantity of tungstic acid, is obtained. Perchloride of tungsten offers, then, like monohydrated sulphuric acid, an instance of a body sensibly decomposing at its boiling point, giving a product the composition of which, though constant under fixed pressure,† can be expressed by no simple equivalent formula. II. There are two oxychlorides of tungsten corresponding to tungstic acid. One, which is red, has for formula WOC; the other, yellowish white, has WO,Cl. A mixture of these two is generally obtained at the same time as tungstic acid by passing a current of chlorine on the anhydrous oxide WO. They are then separated by distillation, the red chloride being more volatile than the white. I easily obtain these two oxychlorides by distilling perchloride of tungsten with a sufficient weight of dry or ordinary oxalic acid. This, it will be seen, is the process formerly used by Gerhardt for quickly preparing oxychloride of phosphorus with perchloride. Pure red oxychloride may be obtained, but whatever the method employed yellow oxychloride will always be mixed with tungstic acid or red oxychloride, because a large portion of the oxychloride WO,CI decomposes when it is distilled into tungstic acid and red oxychloride, as represented by the equation, 2 WO,CI WOCI2+ WO3. It was this decomposition which, when observed by H. Rose, caused him to discover the true nature of the * Comptes Rendus, lx., 820. + It is certain that were sulphuric acid or chloride of tungsten disfilled under variable degrees of pressure, products of equally variable composition would be obtained, as M. Roscoe has proved to be the case with the hydrates of nitric and hydrochloric acids. VOL. XII. No. 296.—AUGUST 4, 1865. yellow oxychloride, which had till then been regarded as perchloride of tungsten, because water transformed it into tungstic acid. It is equally on account of this property that the mixture of oxychlorides and tungstic acid is obtained by the action of chlorine on oxide of tungsten WO2. It was of importance to decide whether it were possible to obtain oxychlorides by treating perchloride of tungsten WCl, with anhydrous tungstic acid. Experiment shows that the combination of the two bodies for instance, WO, + 2WCI, 3 WOCI is effected with disengagement of heat. There is, = From a theoretical point of view, this reaction has a peculiar interest,§ on which it is not here necessary to enlarge. III. I have not hitherto been able to obtain, even approximately, the density of yellow oxychloride; its easy decomposition has rendered all my determinations so uncertain, that it has been impossible to arrive at any conclusion. It is, on the contrary, very easy to determine that of the other two chlorides, in the vapour of mercury or sulphur, for the least volatile of the two, the perchloride, distils towards 300 degrees. Perchloride WCl, in vapour WCl, in vapour of sulphur. The following are the results of my experiments :1st experiment D=11'89. of mercury. D = = 11'50. Oxychloride WOCl, in mercury. 1st experiment D= 10'87. 2nd D= 10'70. 2nd 3rd D= 11.80. D= 11'69. WOCl, in vapour of sulphur. D = 10'27. If it be desired to make the formula correspond to 2 or 4 volumes of vapour, it is found by a very simple calculation-1st, that the theoretical density of the chloride vapour WCl, is D=13'75, supposing the symbol WCl, corresponds to 2 volumes, and 1) = 6.875 supposing it to correspond to 4 volumes; and, that the theoretical density of chloride WOC is D the case of 2 volumes, and 5'93 in that of 4 volumes. These numbers, it will be observed, are very different from those furnished by experiment. = 11.86 in If, with M. Persoz, we assign to tungsten the formula W'Cl, (granting W' = { W 92), the equivalent of the chloride becomes grds of the old equivalent; were W'Cl, supposed to correspond to 4 volumes of vapour, the theoretical density of this chloride would be D=11'46 -a number very near those given by experiment. But then W'O, Cl, must be admitted as the formula of red oxychloride; its theoretical vapour density, supposing this formiate to correspond to 4 volumes, would be D=987, which agrees very well with the numbers given above for this chloride. But such a formula is contrary to the generally-received ideas, and it is better to do away with fractional exponents; the formula of red oxychloride must then be given as W',O,Clo; or, there exist bodies the vapour-density of which correW'O,+2W'Cls, which is tantamount to admitting that sponds to 12 volumes. I mention this difficulty without attempting to grapple with it. I hope to continue my researches, which I propose extending to chlorides of molybdenum, and to have the honour of laying the results before the Academy. Annales de Chimie et de Physique, lxvi., 213. $ According to M. Persoz, anhydrous phosphoric acid and perchloride of phosphorus also combine directly, giving oxychloride.➡ (Annales de Chemie et de Physique, i., 109.) 50 PHOTOGRAPHY. Astronomical Photography, by LEWIS M. RUTHERFURD. My present observatory is a circular brick building of twenty feet internal diameter, with a light revolving roof supported on twelve wheels which are fixed to the stone coping of the walls. The opening, two feet wide, extends from side to side with simple shutters, which, when elevated on the weather side, serve to prevent the wind from blowing into the observatory and shaking the telescope. Opening from the west side of the equatorial dome is a small transit apartment with computing room attached. This observatory is in the garden of the house where I reside. The transit is 189 feet N.W. from the Second Avenue, It was and 76.3 feet N.E. from Eleventh Street. erected in the summer and autumn of the year 1856. The equatorial, by Fitz, is a very substantial instrument, having circles divided on silver 18 and 20 inches in diameter. The objective is of 11 inches aperture, and 14 feet focal length, and was corrected for figure by myself after the methods and directions of Mr. Fitz. It is a fine glass, capable of showing any object which should be seen by a well corrected objective of those dimensions. The observatory is low, and therefore cannot reach any object near the horizon, but I prefer losing such observations to the tremors and expense of a high structure. The transit room has been used on several occasions by the U.S. Coast Snrvey in their telegraphic operations for longitude. It is oh. 12m. 15'47s. E. of Washington, and in latitude 40°, 43′, 48" 53; the latitude being the result of observations with the zenith telescope upon twenty-four pairs of stars by the observers of the Coast Survey. During the winter of 1857-58, Messrs. Alvan Clark and Sons constructed, and in the spring attached to the equatorial, a driving clock of the highest merit. It has a remontoir escapement similar to that of Bond's spring governor. Having seen with great interest the photographic experiments conducted at the observatory of Harvard College, I determined, as soon as the clock should be in working order, to prosecute the subject of celestial photography. After many experiments it was ascertained that the best photographic focus of the objective was about ths of an inch outside the visual focus. I continued making photographs of the moon and such stars as could be obtained, and although when compared with what had been done by others the results gave reason for satisfaction, yet in view of what was desirable and apparently attainable, astronomical photography with me was a failure. By reducing the aperture of the telescope to five inches for the full moon, I was enabled to produce negatives which would bear an enlargement to five inches or fifty diameters. An impression of a sixth magnitude star was never obtained, y Virginis, then 3" distant, was the closest pair, the duplicity of which could be measured on the collodion plate. The ring of Saturn and the belts of Jupiter were plainly visible, but entirely unsatisfactory. An image of Jupiter could be obtained in from five to ten seconds' exposure, but the satellites failed to impress the plate in any length of time. This was due to the uncorrected condition of the objective which diffused the violet rays over a large space, so that in the case of the planet each point of the picture was influenced not only by the ray due NEW to that point, but by the stray beams from adjoining During the summer of 1858 I combined my first stereograph of the moon, producing quite a satisfactory result with the low power of the stereoscope. I do not know when this was first done in England by Mr. De La Rue, but with me the idea was an original one. My greatest success with an uncorrected objective was in the pictures of the sun taken with about one-fiftieth of a second exposure, with the aperture reduced to one inch. The negatives were four inches in diameter and exhibited the spots with reasonable sharpness, the manifest difference in light between the centre and the edge, and under favourable circumstances the faculæ. Some of the negatives verify the observation of M. Dawes, that the faculæ are elevations. In June, 1860, the sun's disk was remarkably rich in spots, and I combined the pictures of two days to produce a stereograph, but the result was a failure and did not give the impression of a sphere, but presented the appearance of a flat uniform disk spanned by a spherical net-work which seemed entirely detached from the disk. This is attributable to a want of sufficient detail on the surface of the sun. During the year 1859 and for a long time I worked with combinations of lenses to be inserted in the tube between the objective and the plate with the view of correcting the photographic ray. This attempt succeeded well so far as the centre of the field was concerned, but it was impossible to produce a good correction over a space equal to the area of the image of the moon, without using a corrector of inconvenient size. In 1860 I prepared a telescope with camera and instantaneous apparatus mounted equatorially to send by the U.S. Coast Survey Expedition to Labrador for the observation of the eclipse. The objective in this case was a fine one, by Alvan Clark, of 44 inches aperture. A ring was placed between the crown and flint lenses of such a width that the best visual and photographic foci were united. For this purpose it was necessary to shorten the combined focus about one-twentieth of its former value. The pictures of the sun taken with this instrument were better than those made by my large telescope, in which no attempt had been made to correct the photographic rays. Being unable to accompany the expedition, I made a series of pictures of the eclipse at home, upon which are seen the nuclei and penumbra of the spots, the gradation of light of the sun's disk, and the serrated edge of the moon projected upon the sun. They show, however, none of the fogging of the moon's surface commented upon by other observers, nor a greater intensity of light at the points of contact between the sun and the moon ; due, in my both these results are, when they occur, opinion, to photographic or optical causes, and not to any true astronomical phenomena of that nature. On examining the first negative of the eclipse I was struck by the difference of sharpness between the edge of the sun and that of the moon projected upon its disk. At first I was inclined to think that it was caused by a falling off in definition near the edge of the eyepiece used. In the next picture the edge of the sun was placed near the centre of the field and the moon removed to a remote part of the plate, yet still the result was the same; the sun's edge was soft and indefinite, while that of the moon was hard and sharp, showing that the light from the two objects comes to us under different conditions; in one case traversing the sun's atmosphere, in the other unaffected by this disturb ing cause. (To be continued.) THE DUBLIN INTERNATIONAL EXHIBITION. By CHAS. R. C. TICHBORNE, F.C.S., F.R.G.S.I., &c. (Specially Reported for the CHEMICAL NEWS.) (Continued from page 39.) IN the French Department, Baudesson and Hauzeau show a novel application of photography-viz., photographs printed upon calico, in black, blue, magenta, and sepia; but they give no details of their process. Dubosc and Co. exhibit extracts in the liquid and solid form for dyeing purposes. We believe that no mention of their preparations was given in any of the reports yet published, but they have been used with some considerable success in the Manchester houses. The liquid extracts would, in the writer's opinion, be open to the objection that the actual amount of tinctural value will probably vary very much in different samples. This will not apply so much to the solid extracts. The one examined by the author (Persian berries) gave a bright solution and left no residue. The value of these preparations will, of course, depend upon the prices, taken in connection with their dyeing strength. The celebrated firm Tissier and Sons show bromine and iodine, and bromides and iodides. There is a remarkably fine specimen of bromide of potassium, if it is pure. But these specimens are shown as commercial ones, and, therefore, probably the bromide contains a little iodine. At least, it is a fact that a small quantity of iodide of potassium makes the bromide crystallise in much larger crystals. Italy shows some beautiful crystals of native sulphur exhibited by Federico Lancia, Duke of Brolo; also some very fine specimens of worked sulphur are exhibited in Section 1. The rolls of sulphur differ in form, being more conical than those found in our commerce. There is also in this Section a very interesting series sent by the directors of the Mont Cenis railway tunnel through the Alps. These are a series of specimens of the rock met with in the Mont Cenis tunnel taken at equal distances apart both on the Bardonnêche and Modane entrances; they are taken at a distance of 200 metres apart. They therefore serve to illustrate the internal geological structure of the Alps in the province of Turin. Mannite, or sugar of mushrooms (CHO), occurs very generally diffused through the vegetable kingdom. Professor de Luca, of the Royal University of Naples, has shown that mannite is present in all parts of the olive tree, and sends some beautiful specimens crystallising in prisms from all parts of the tree. Thus we have specimens from the green leaves, from the yellow leaves, from the flowers, from the unripe olive, and from the olive just commencing to ripen. Professor Luca says that mannite exists in every part of the olive tree-the leaves, flowers, and fruit containing the greatest quantity; the roots, wood, bark, and branches rather less. This saccharine principle is not always found in the same quantity at all stages of vegetation. At the period of blossoming it accumulates in the flowers and diminished in the leaves; the fallen flowers having once completes the phenomenon of fecungation, no longer contain any mannite. It has likewise been found, says De Luca, impossible to obtain the slightest traces of it in the yellow, fallen leaves. Mannite exists in the fruit as long as it continues green, diminishing in proportion as it ripens, and disappears entirely when it becomes perfectly ripe, and contains the greatest quantity of oil. The chlorophyle which accompanies the mannite seems to follow its changes; the leaves are never devoid of more or less mannite as long as they continue green, but the mannite diminishes as it turns yellow. De Luca has published a table showing the analysis of the olive leaves during six months in the year. No. 28 in Section 2 is a curious and interesting product. It is exhibited by Ciaranfi, of Florence, and the Convent of the Servite Friars. It is crystallised bicarbonate of potassium, obtained by submitting a solution of commercial potash to the action of the carbonic anhydride evolved spontaneously and in great abundance from the mineral spring of Chianciano, near Poggibonsi (Senna), and belonging to the convent. Bicarbonato of sodium, obtained by the same method, is also exhibited. They also show protocarbonate of iron obtained by the double decomposition of solutions of sulphate of iron and an alkaline carbonate, subsequently washed with distilled water, and dried in an atmosphere of the pure dry carbonic acid gas evolved from the spring of Chianciano-a process which, as the label states, could not be followed in an ordinary manufactory. The Netherlands would hardly be well represented if they did not exhibit some madder products. The garancine and madder factory of Tiel produces a very complete collection of madder products, including alcohol procured as a bye product of the garancine process, the specific gravity being 828. The latter article may be the cause of the compiler of the official catalogue placing this collection in Section 3 (substances used as food); otherwise we do not see the connection of this display with the said section. In the Siam and many other departments Mr. Simmonds (well known in connection with the Technologist) exhibits many substances which would be of interest to the chemist, but they are so numerous that we could not even attempt to pick them out of the catalogue. This gentleman seems to have succeeded in making an extraordinary collection from all parts of the world. In Switzerland there is a splendid case by Henner and Co. containing some rare organic and other chemicals. To look at such a recherché collection of out of the way products as are found in this case would warm the heart of a Hofmann. The Zollverein department, as might be imagined, is particularly rich in geological and chemical specimens. The maps displayed by the Government Boards of Mines in Bonn, Breslau, and Halle are colossal in the extreme, and are some of the finest things in this way that we have seen; but the chemical interest is brought to a focus upon viewing a case exhibited by Th. Schuchardt, which is one of the most unique things in the whole Exhibition. It consists of a collection of chemical products used in glass staining and porcelain works. Many of these specimens, we are told, are the same as are supplied to the imperial potteries at Sévres. M. Schuchardt also exhibits some vanadiates, and a very fine specimen of red chromate of lead of a most brilliant hue. Thus a fine painter's colour may be procured for about 2s. Also a specimen of borate of manganese; this is more extensively used as a siccative, two ounces being sufficient to make cwt. of linseed oil drying. A very pretty scries of nickel salts is displayed in this I |