NEWS experiment that ammonia is formed by the union of three volumes of hydrogen with one volume of nitrogen. Thus much determined, it remains to ascertain the condensation undergone by these elements in combining to form ammonia. The direct synthesis of ammonia having never yet been accomplished, we must fall back upon analysis to furnish us with this demonstration. We must split up a measured quantity of ammonia into its constituents, and com. pare the space occupied by the ammonia before treatment with the space filled by its separated constituents. This we are enabled to do very easily, by availing ourselves of the tendency of ammonia to break up into its elements under the influence of a moderate heat. The spark-stream supplied by the electric current in traversing the induction-coil may be conveniently used as a source of heat. Among the many forms of apparatus which suggest themselves for this purpose, I find the disposition (Fig. 11) most appropriate. however, be broken by agitating the mercury in the tube until it touches the platinum wires; or its formation may be prevented by reversing the direction of the current from time to time. With these precautions, the experiment affords very closely approximative, though not perfectly exact, results, a slight error arising from a minute proportion of marshgas suffering a different decomposition, so that the volume of the hydrogen obtained is never quite double that of the marsh-gas submitted to the treatment. Nevertheless, the experiment, even in this imperfect form, unequivo cally demonstrates that marsh-gas contains twice its volume of hydrogen. I have made numerous experiments with the view of finding a shorter, simpler, and, more especially, a more accurate method of exhibiting the volume of hydrogen which is present in a given bulk of marsh-gas, but hitherto without result. Eudiometrically, of course, the composition of marsh-gas is given in a single most The sealed limb of a U-tube is filled about one-third elegant experiment, which acquires additional charm full with dry ammonia, over mercury, and the height of when performed at a temperature higher than that of the column of gas is accurately measured, care having been boiling water in an apparatus similar to the one employed taken, as usual, to bring the mercury in each limb of the in determining the ratio of the volume of water-gas to tube to a uniform level. The spark-stream is now set that of its constituents. But at the stage of the course flowing between the platinum points, and the volume of at which I am in the habit of examining the nature of the gas on which it acts is immediately observed to in- marsh-gas, an experiment of this description is unintellicrease. This dilatation continues for some five or tengible to the student, and hence simply out of the question. minutes (according to the quantity of ammonia under treatment); and when it ceases, the level of the mercury (disturbed, of course, by the expansion of the gas) is readjusted to perfect uniformity in both limbs of the tube, when it is immediately perceived that the original volume of gas has become doubled. If a little of the gas (previously so pungent) be allowed to escape from the tube, by a stop-cock provided for that purpose, it is found to have become inodorous, while the presence of hydrogen is indicated by its inflammation on the approach of a light. This experiment proves that hydrogen and nitrogen, as combined in ammonia, occupy only half the space they fill in their free state; or, in other words, that four volumes of the mixed gaseous constituents of ammonia, composed, as we have already ascertained, of three volumes of hydrogen and one volume of nitrogen, condense, during their combination, to form two volumes of ammonia. MARSH-GAS. ACADEMY OF SCIENCES. July 24. M. BECQUEREL presented some "New Observations on Thermo-Electric Piles of Sulphide of Copper." The author first described the way in which he prepared the sulphide of copper. He places a quantity of sulphur in a crucible and heats it to fusion. When this occurs, which is known by the escape of sulphur vapour, he immerses in the melted sulphur a plate of copper previously heated to dull redness, and leaves it in the crucible until all the sulphur is volatilised. He then removes the plate of copper coated with sulphide, cools it rapidly by dipping it into cold water, and finally detaches the coating of sulphide. This is then fused and run into bars or plates for the pile. As a negative element he employs maillechort (a nickel alloy resembling argentine). The author remarks that bars made of the same sulphide show a very unequal action, and that they should be tested before employed for a battery. In a note he mentions that Rhumkorff has found that the addition of th of sulphide of antimony renders the action regular, although it somewhat diminishes the power. The ends of the bars of sulphide must be encased by the metal to prevent reduction when heat is applied direct, as by a gas flame. The author next proves and not by any chemical change in the sulphide, by showing that a battery has kept in action for a month with one extremity near the melting point of lead without loss of weight in the bar of sulphide of copper. M. Becquerel goes on to compare the electro motive force of this battery with other thermo electric piles, and shows that its power is much higher than that of the alloy of antimony and zinc employed by Marcus. It is only available, however, when the effects of tension are required. The only fact connected with the history of this compound which admits of convenient illustration is the existence in a given volume of marsh-gas of its double volume of hydrogen. This demonstration is furnished in very close approximation by the method which served us in the case of ammonia, viz., by splitting it up into its constituents under the influence of heat. This experi-that the current is developed by differences of temperature, ment we perform, as before, in a U-tube fitted up with spark wires, and as source of heat we again employ the spark-current of the induction coil. On transmitting the current the marsh gas expands, and after the lapse of a few minutes a light deposit of carbon is formed in the vicinity of the platinum wires. The decomposition, energetic at the commencement of the experiment, proceeds more slowly as the gas dilates; but if, after fifteen or twenty minutes, the mercury be allowed to run out from the nipper-tap till it has become level in the two M. Isidore Pierre presented a memoir entitled "Analimbs of the U-tube, it is found that the original gas-lytical Researches on the Variations which the Relation of volume has very nearly doubled. This result having been the Potash to the Soda undergoes in Different Parts of a attained, the continued transmission of the spark-current Plant at Various Ages." The author has analysed the produces no further increase in the volume of the gas, nodes, internodes, and leaves of wheat for alkalies at which is now found to consist of hydrogen. various stages of growth, and has come to the following conclusions:-1. That in these various parts of the plant the amount of potash in relation to that of the soda augments as you go from the lower to the upper portion of the stalk; and 2. That in the same parts and in the same order the relation diminishes as the plant advances This experiment presents greater difficulty of manipulation than either of the preceding. The spark-current, when transmitted through marsh-gas, is not unfrequently interrupted by the formation of a conducting-bridge of carbon between the platinum points. This bridge may, towards maturity. Thus, the author argues, the salts of potash play a more important part in the life of the plant than the salts of soda. Potash predominates in the most perfect and last-developed parts of the plant, while soda accumulates in the oldest parts, which only serve a secondary or temporary purpose. He infers the uselessness of common salt as a manure for wheat. The ashes of the nodes, he states, contain 42'5 per cent. of potash. M. Demarquay presented a note " On the Physiological Action of Carbonic Acid." The author states that he has made numerous experiments on animals, on himself, and on several of his pupils, the details of which will be published shortly. He now gives his conclusions, some of which we quote. Carbonic acid exerts some exciting action on the surface of the body, particularly with a fine and very sensitive skin. The regions in which this effect is most marked are those of the penis and perinæum. Insensibility of the skin when obtained is only produced by a continuous jet of the gas thrown on a very limited space of the body. When injected into the veins a large quantity is absorbed and rapidly eliminated without mischief, if the operation be carefully performed. The gas acts as a slight stimulant in the alimentary canal. When breathed, it does not produce the poisonous effects commonly attributed to it. One part of carbonic acid and three parts air produces in man but slight discomfort after being breathed for some time. Most of the accidents caused by the vapour of carbon, confined air, and gases in fermenting vats, the author states, are wrongly ascribed to carbonic acid, and must be attributed to carbonic oxide, sulphuretted hydrogen, alcoholic vapours, or other gases not yet understood, which are generated under the circumstances. Respiration consists essentially of an exchange of gas between the blood and air, and this can only take, according to physical laws, between gases of a different nature. Carbonic acid being the gas to be eliminated, the exchange does not take place when the pure gas is respired, and hence asphyxia and death. From experiments on himself, the author found that the production of anæsthesia by carbonic acid is attended with danger, and, moreover, if produced, the effect is too fugitive to be utilised in surgery. A note, by M. Naquet, "On the Action of Perchloride of Phosphorus on Thymotic Acid," was read. The author's results are of no interest. M. Hiortdahl read a note "On the Action of Zirconia on Alkaline Carbonates." Zirconia at a moderate temperature easily expels carbonic acid from carbonate of soda, and forms the compound NaOZrO2, which decomposes after a time in water, the zirconia separating in an amorphous condition. Heated with an excess of carbonate to a higher temperature, two equivalents of CO, are expelled, and the compound 2NaOŽÃO, is formed. When this is treated with water a crystallised compound of zirconia, and water separates. The author gives tables showing the quantities of carbonic acid expelled at different temperatures and different times; and also the loss experienced when carbonate of soda is heated alone, the latter table serving for corrections. NOTICES OF BOOKS. Zeitschrift für Analytische Chemie. Edited by Dr. C. R. FRESENIUS. No. 4, 1864. THIS journal appears very irregularly, and this number, the last for 1864, has but recently reached us. It contains a few very useful papers which we have not seen before. The first we may notice is one by Dr. Leucanus, "On the Transformation of Alkaline Nitrates into Chlorides." All analysts are aware that to change alkaline nitrates into chlorides by evaporating to dryness with an excess of hydrochloric acid it is necessary to repeat the process once or twice. With this most analysts are content, but the author shows that probably no number of evaporations would effect the complete conversion. Starting with a solution containing o'18930 gramme of nitrate of potash, he found that after one evaporation o'11356 of the nitrate remained undecomposed; after two evaporations, o'05806; after three, 301487; and after nine, o'00130 still remained. The evaporation repeated twelve times still left the same amount. It then became a question how to effect the perfect conversion, and the author found that by igniting the nitrate with four or six times its weight of grape sugar, thus converting the nitrate into carbonate, and then extracting the carbonaceous residue with dilute hydrochloric acid, the whole of the nitrate is found in the form of pure chloride. Another noticeable paper is by Dr. C. Winkler, “ On the Volumetric Estimation of Cobalt." It contains an account of some precautions necessary to observe in making use of the author's process (C. N. vol. x., p. 215). Dr. Hoppe-Seyler publishes "A Contribution to the Knowledge of Albumens." The author describes the various forms of albumenoid matters, with their principal chemical properties. Among the albumens he classes the "amyloid substance,' -a body which Pelouze and Apjohn have found to be identical in composition with dextrine and glucose. Apjohn did find nitrogen in a specimen, but so little that he considered it an accidental impurity. The author of this paper calls it a "pathological product," and would appear to be unacquainted with the most recent researches on the nature and history of the substance. Another paper by the same author is "On the Optical and Chemical Properties of the Colouring Matter of the Blood," to which we need only call attention. A method of "Recognising Foisoning by Carbonic Oxide," also by HoppeSeyler, deserves more notice. The method is founded on the following observation :-Blood treated with carbonic oxide alone shows the same spectrum as blood containing oxygen, and, if sulphide of ammonium be added, no change will take place even after several days; but if blood which contains only oxygen in solution is treated with sulphide of ammonium, an almost immediate change takes place, and only one band is seen about midway between D and E. By this unchangeability of blood holding carbonic oxide in solution on the addition of sulphide of ammonium, the author detects the presence of the poisonous gas. It is worth quoting that the author has found that, by continuing artificial respiration for a time, animals poisoned by carbonic oxide have been restored to life, the gas being expired as carbonic acid. Another paper by the same author, "On the Decomposition Products of Blood Globules, deserves the attention of physiological chemists. A paper by Fresenius," Experiments on the Precipitation of Phosphoric Acid as Phosphomolybdate of Ammonia under various Circumstances," merits a full abstract, which we shall give in an early number. Braun also contributes some useful analytical notes. One of them is "A New Reaction of Cobalt," upon which is also founded a new test for nitrites. A solution of cyanide of cobalt in cyanide of potassium treated with nitrite of potash and a little acetic acid gives a deep blood red or a beautiful orange red solution, according to the strength of the cobalt solution. Further communications by the same author “On Detecting Cobalt in Presence of Nickel," and "On a Method of Separating ẞ from a and y Phosphoric Acids," we defer for a longer notice. A paper by Habich "On Guyard's Process for Estimating Manganese," communicated to the CHEMICAL NEWS (see vol. viii., p. 292), describes a series of experiments which confirm the value of the process with sundry precautions. The author states that the results are correct with neutral solutions. Dilute sulphuric and hydrochloric acids do not much interfere, but with a strongly acid solution the method is useless, as it is also in the presence of ferric or chromic oxide. The presence of the lower oxides of nickel and cobalt, zinc oxide, alumina, and lime, does not interfere with the results. The reports on the progress of 762. T. Kenyon, Miles Platting, Manchester, "Improveanalytical chemistry by Neubauer and Braun will furnishments in preparing, fixing, and mordanting cloth and us with many short notices of novelties. yarns."-March 18, 1865. Bulletin Mensuel de la Société Chimique de Paris. July, 1865. THE proceedings of the Parisian Chemical Society during the month offer nothing specially interesting. The most important papers read have been as usual communicated to the Academy, and noticed in our reports. Among the novelties we find a paper by Schutzenberger, giving the results of some researches "On Catechine," which lead the author to consider it probable that the true formula for this substance is C22H22O9. M. Lauth described "The Reaction of Sodium upon Pure Benzine." Hydrogen is disengaged and a solid substance is deposited, which the author believes to be phenylide of sodium; but he found it impossible to separate it completely from sodium for analysis. MM. Friedel and Crafts continued the account of their researches" On Silicium Ethyl," describing on this occasion monochlorated silicium ethyl obtained by the action of dry chlorine on the latter body. With an alcoholic solution of acetate of potash and the chlorinated body a double decomposition takes place, and an acetic compound boiling at 210° is formed. The researches of the authors, it is said, confirm the analogies which exist between carbon and silicium. The analysis of foreign memoirs contains nothing of interest which has not already been noticed in our pages. 1818. G. J. Livesey, Old Kent Road, Surrey, "Improvements in treating ammoniacal liquors for purifying gas and other purposes."-Petition recorded July 10, 1865. 1840. A. Denayrouze, Espalion, Aveyron, "Improvements in apparatus and equipments used by persons employed under water, part of the improvements being also applicable for the use of persons employed where noxious gases or vapours prevail."-July 12, 1865. 1855. A. E. Molin, Fahlun, Sweden," Improvements in separating gold from ores containing copper and gold." -July 14, 1865. 1875. T. Metcalf, H. Metcalf, and T. Clayton, Manchester, "An improved apparatus for cooling liquids and cooling or condensing vapours or gases." 1877. D. M'Crummen, Gourock, Renfrewshire, N.B., "An improved process of preparing sea-weeds and other vegetable substances for the production of artificial guano, felt, alkaline, salts, and iodine." 1885. G. Nimmo, Jersey, New Jersey, U.S.A., "An improvement in the mode of uniting different metals, such as iron or copper, or alloys, to form compound metallic castings."-July 19, 1865. NOTICES TO PROCEED. 700. J. Wright, Dudley, Worcestershire, " Improvements in puddling, heating, and other furnaces." 705. F. Wise, Chandos Chambers, Adelphi, “Improvements in preparing certain colouring matters for dyeing and printing."—A communication from J. Levinstein, Berlin.-Petitions recorded March 13, 1865. 717. G. T. Bousfield, Loughborough Park, Brixton, "Improvements in apparatus for vaporising hydrocarbon liquids for illuminating and heating."-A communication from J. Griffen, Meridan, Conn., U.S.A.-March 14, 1865. 730. J. F. Brinjes, Fieldgate Street, Whitechapel, "Improvements in apparatus for cooling animal and other charcoal."-March 13, 1865. 797. H. Potter, Manchester, "Improvements in treating the waste liquors obtained in bleaching certain vegetable substances." 804. A. Paraf, Glasgow, N.B., "Improvements in dyeing and printing cotton or linen fabrics or yarns."March 22, 1865. 46 877. R. Young, North Frederick Street, Dublin, and C. F. O. Glasford, F.C.S., Galway, Improvements in the preparation or treatment of seaweed, and in obtaining products therefrom."-March 28, 1865. 1785. C. F. Claus, Fearnhead, near Warrington, "Improvements in obtaining sulphates and carbonates of potash and soda."-July 6, 1865. CORRESPONDENCE. Continental Science. PARIS, August 1. Ar the last meeting of the Academy M. Le Verrier explained the system now adopted here for collecting meteorological observations, and foretelling the weather, &c. He paid a passing tribute to the memory of Admiral Fitzroy, but did not acknowledge how much the world owes the unfortunate Admiral for the establishment of the system which M. Le Verrier would have us believe is almost his own creation. It seems that seventy dispatches from different parts of Europe arrive at M. Le Verrier's bureau between 9 and 11'30 a.m. every day. The observations in these are immediately reduced, the weather forecasts drawn, and between 12 and 1 they are telegraphed to all parts of France and various European capitals. At 2'30 p.m., the daily Bulletin is issued, and circulated to all correspondents for the cost of the paper and printing. M. Le Verrier dwelt on the necessity for combined observations, and suggested the formation of a central and European bureau for contracting the international part of the service. He quoted from Commandant Maury that Paris is best situated geographically for location of the bureau. At a late meeting M. Dumas presented to the Academy the third volume of his edition of the works of Lavoisier. This volume contains a hitherto unedited paper, on fermentation, of which it is truly said that Lavoisier gave the first rational explanation. He determined the amounts of carbonic acid and alcohol produced in the fermentation of sugar. Lavoisier appears to have worked very hard on this subject, and it seems drew the conclusion from his analyses that sugar must be regarded as a compound of carbon and water, an idea subsequently published by Gay Lussac and Thénard. It seems, too, that Lavoisier must be regarded as the father of organic analysis. He burnt sugar by means of oxide of mercury, and collected the carbonic acid in a weighed flask of potash. This volume shows more plainly than ever how much was lost to science when that great genius went to the scaffold, not for any crime of his own, but as the representative of an obnoxious system. You have lately noticed Dr. Tyndall's lecture on Radiation, in which he insists on the identity of heat and light. Most physicists, I believe, agree with Dr. Tyndall; but we have a dissentient here in the person of M. Baudrimont, who publishes in Les Mondes his reasons for believing that heat and light are two entirely distinct_things. It will not be worth while going through all M. Baudrimont's arguments; but I will give one or two as specimens. Firstly, he says light does not expand bodies; heat does. Secondly, heat gives rise to various changes of state in a number of bodies, even in the deepest obscurity; it combines with these bodies, and remains with them as long as circumstances allow. Light does nothing like this, Again: M. Baudrimont asks if light and heat were identical, would it be possible to separate them as in the experiments of Melloni and Tyndall? But calorific and luminous rays, having the same refraction index, can be separated, and produce their special effects as before separation it is absolutely impossible, then, that the two things can be identical. What, then, is light, and what is heat? Light (says M. Baudrimont) is due to vibrations of elementary atoms; heat, on the contrary, is a molecular phenomenon, produced by vibrations of the whole system which represents a molecule. In obscure heat these two orders of phenomena are separated; but when the temperature is high the movement of the molecule is extended to the constituent atoms, and light begins to appear. I need not pursue the subject further; you will find all M. Baudrimont's reasons in Les Mondes, together with a quiet hint from the editor that the author is fighting a windmill. A very ingenious addition has been made to the Lenoir engine by M. Arbos. The engine would often be extremely useful where gas could not be procured, and to make coalgas would be impracticable. In a very simple apparatus M. Arbos vaporises water, and passes the vapour over redhot charcoal dust. The mixture of carbonic acid, carbonic oxide, and hydrogen produced is then passed through milk of lime to remove the first, and the other two go on to be mixed with air and exploded in the cylinder of the engine. Extending the use of the engine as mentioned above, M. Arbos' apparatus effects a great saving in the cost of working the machine. Gas produced for two francs will do the work of six or eight francs' worth of coal gas. Ointment of Yellow Oxide of Mercury. To the Editor of the CHEMICAL NEWS. SIR, I notice in the last number of the CHEMICAL NEWS an article "On the Yellow Oxide of Mercury Ointment as applied for Therapeutical Purposes," taken from the Ophthalmic Review. May I beg the favour of your calling attention to an article of my own which you will find in the Pharmaceutical Journal for April, 1865, and which is "On a Better Mode of Preparing Red Oxide of Mercury Ointment?" Since this paper, as I believe, first called the attention of the medical profession to the therapeutical advantages of the "yellow oxide," it may possibly have suggested the paper in the Ophthalmic Review; for although apparently written from Germany at the end of June, it is not too early for the author to have seen my paper, published in a largely circulated medical journal in England in the beginning of April. Indeed, in my paper I especially drew attention to the advantages that would accrue from the introduction of the yellow oxide into ophthalmic practice. As no reference is made to my name in the paper in the Ophthalmic Review, I trust you will regard it as only fair to give at the same time the details of my paper and the respective dates of the two communications. I am, &c. BALMANNO SQUIRE. 12, York Place, Regent's Park, July 26. [The abstract of Mr. Squire's paper was published in the CHEMICAL NEWS for March 10, 1865.-ED. C. N.] MISCELLANEOUS. University of London.-The following is the list of gentlemen who passed the first B. Sc. pass examination:-Entire-First Division: Tempest Anderson, University College. Second Division: Sidengham Duer, private study; James Scotson, University College; Alfred Micaiah Smith, Owens College. Excluding Mathematics-First Division: William Martin, B.A, private study. Second Division: Arthur William Kay Griffith, B.A., Spring-hill College. Spiller's Boiler Fluid (for the prevention and removal of calcareous incrustation from steam boilers).— This chemical solution, to which our attention has been drawn, has been employed for several years past in the Royal Arsenal, Woolwich, and other manufacturing branches of the War Department, besides being used successfully in many private establishments. It possesses the advantage of being perfectly soluble, so that it may be introduced into the boiler with the feed-water at any time when, from the pressure of steam, it may not be convenient to pour it through the safety valve, or other openings in the boiler. It does not exert the slightest corrosive action upon the metal plates or fittings of the boiler; but, on the contrary, has a tendency to clear off any existing rust, and preserve the iron from oxidation, whereby any slight flaws or cracks in the boiler-plate become immediately apparent a point of great importance in connexion with the periodical inspection of the boiler. The use of this agent does not involve the introduction of a poison into the water of the boiler, so that the water drawn off may be fearlessly employed for many purposes, which, under other systems, would be attended with risk. "Mr. Spiller's Boiler Fluid" has been favourably reported upon by the Inspector of Machinery, Royal Arsenal, and other officers superintending the manufacturing departments at Woolwich. It has likewise been used with success at the Royal Gunpowder Factory, Waltham Abbey. The manager of the Royal Laboratories, Woolwich, reports (April 18, 1864) that "the chemical agent proposed by Mr. Spiller as a means of preventing incrustation in steam boilers has been tried in this department during the last two years, and found to be superior to any other boiler composition which has been used here; but it is only a partial remedy, inasmuch as it does not prevent a sediment forming in the boiler, but reduces it in quantity and keeps it in a soft pulpy state, which enables it to be the more easily removed if proper precautions are taken. The material is also advantageous in preventing rust or dirt settling about the boilers generally, thereby leaving bare whatever flaws may exist, which is a very important point." New Method of Salting Meat.-At the last meet. ing of the Academy of Sciences, M. Pienkowski detailed some experiments which showed that meat salted with and, moreover, is more easily unsalted than meat preacetate of soda is easily dried, keeps an agreeable odour, pared with common salt. Cochineal Colouring.—Take of best carmine 3j., liq. ammon. fortiss. q. s., about 3vj., macerate for a few days, and when the carmine is dissolved gently heat the mixture so as to drive off the excess of ammonia, taking care not to carry it too far, so as to precipitate the carmine. Put this into a wine quart bottle, add sp. vin. rect. živ., sacch. alb. lbiij.; then fill up the bottle with warm water, and shake it occasionally, till the sugar is dissolved.— R. Palmer, Phar. Journ. ANSWERS TO CORRESPONDENTS. All Editorial Communications are to be addressed to the EDITOR, and Advertisements and Business Communications to the PUBLISHER, at the Office, I, Wine Office Court, Fleet Street, London, E.C. Private letters for the Editor must be so marked. In publishing letters from our Correspondents we do not thereby adopt the views of the writers. Our intention to give both sides of a question will frequently oblige us to publish opinions with which we do not agree. A Constant Subscriber.-The method is kept a profound secret. Estimation of Uric Acid.-Erratum.-Page 48, line 7, for 16:36, read 17:36 grs, SCIENTIFIC AND ANALYTICAL CHEMISTRY. Facts Relative to the Chemical Metamorphosis of In a previous communication I had the honour of making When pure, photosantonic acid (which would be better called photosantonina, until its chemical constitution is exactly known) is colourless and transparent, with no odour, and a slightly bitter taste; it crystallises in square tables, which do not act on polarised light as does santonina. Exposed to heat, photosantonina fuses between 64° and 65° C. It changes to a colourless transparent liquid, which, if the matter is pure, recrystallises on cooling; but if it contains any trace of resinous substance, or a little acid, it crystallises with difficulty. 64° and 65° C. I must add that at 180° C. it begins to produce vapours, and that at 305° C. it boils regularly. Exposed during 304 days at 100° C. to the air, photosantonina loses a few milligrammes of its weight, and becomes distinctly yellow; when treated by alcohol, it dissolves entirely; setting the solution to evaporate slowly, a yellow substance, apparently amorphous, is first deposited and then crystallised photosantonina. Aqueous potash dissolves the yellow matter, and leaves photosantonina; by saturating the alkali a dark red resinous substance is precipitated. A curious phenomenon, and one for which I am as yet unable to account, takes place when photosantonina is placed in contact with concentrated nitric acid; the and are soon after reduced to small limpid drops floating crystals of photosantonina immediately agglomerate, on the surface of the nitric acid. By diluting the nitric acid with water, the photosantonina thus liquified crystallises after a short time, and the crystals again dissolve in concentrated nitric acid. Nitric acid, diluted with its volume of water, does not liquify photosantonina; it is the same with concentrated hydrochloric acid. Both, however, are sometimes coloured slightly red when cold, but the colour disappears by heating, and I believe it depends on the presence of a trace of resinous matter, which I have observed to be coloured intense red by acids. Monohydrated sulphuric acid first colours photosanto These properties, shared by photosantonina with hellenina and other organic substances, led me for some time to believe it to be uncrystallisable, as I described it in my first memoir, already mentioned; and on account of this property I could not at first obtain it in a crystal-nina orange yellow, and then entirely alters it. lised state. To produce it in this state I isolated photosantonina from its alcoholic solution by diluting this solution, obtained by the action of solar light, with fifteen times its volume of water. The addition of water renders the liquid milky, and on it float oily drops, which, after one or two days, take the form of white crystalline flakes, the greater number being at the bottom of the liquid. When filtered the liquid is always more or less milky; all the crystallised matter remains on the paper, and is purified by being crystallised several times, at intervals, from alcohol. The last crystallisations furnish yellow photosantonina, on account of the resinous matter; it may be purified with a solution of caustic potash acting, in the cold, for two days on photosantonina obtained by precipitation in water; I believe that this method of purification is the most successful, having observed that alkalies notably favour the crystallisation of photosantonina. By next saturating the alk i which has served for the purification, the resin is precipitated, coloured red, and with a bitter flavour. When the action of the light has not been so continuous as is necessary, photosantonina is accompanied by altered santonina, easily recognisable when exposed to the sun, or when examined by a microscope with a Nichol's prism. If the substance is pure the polarised light is not coloured at all; but if it is mixed with santonina, when the prism turns, the colours of the rainbow appear and disappear on some points. Cold water does not dissolve the least quantity of photosantonina, but boiling water dissolves sufficient to acquire a distinctly bitter taste. Alcohol and ether dissolve large quantities of photosantonina, acquiring a very bitter taste. I have already said that photosantonina fuses between * Bulletin de la Société Chimique, ii., 271. + Ibid, ii., 21; CHEM. NEWS, vol. x., p. 110. VOL XII. No. 297.-AUGUST 11, 1865. Such are the results of my elementary analyses on crystallised photosantonina, and which do not entirely lisable matters which I gave in my first communication. differ from those obtained by the analysis of uncrystalThe slight differences are attributable to the traces of resinous matter, from which I was unable to free them. Matter employed. Carbonic acid obtained. Water obtained. |