The fused mass was dissolved out of the crucible with water acidified with HCl, and evaporated to dryness; the mixture was then moistened with HCl, and, after adding some water, filtered, to separate the insoluble matter; the sulphuric acid was then precipitated and weighed in the usual manner. Remarks upon the Method of Obtaining Nitrogen by the IT is stated in some treatises on chemistry that nitrogen, = = 2. I boiled another gramme of the same coke with nitric acid; evaporated to dryness; again added nitric acid, and again evaporated to dryness; the dried mass was then moistened with HCl, filtered, and the sulphuric The following shows the results of these two experi-known reaction of chlorine and water, acid determined. ments: in making this experiment, and further, from the wellI was led to believe, however, from what I observed Cl + HO = CIH + 0, that pure nitrogen would not be generated in this way, and that an abstraction of the hydrogen from a portion of the water of the ammonia solution by the chlorine, would result simultaneously with the decomposition of the ammonia itself. When chlorine is passed into the strongest solution of ammonia, a brisk effervescence is produced, with occasionally a sharp cracking noise, attended also with a considerable evolution of heat. At the same time, a always, however, containing in admixture (both at the tolerably copious extrication of nitrogen takes place, commencement and termination of the operation) a considerable proportion of oxygen. In addition to these two gases, the only other product is chloride of ammonium, for I do not find that any chlorate of ammonia is formed throughout the process. Neither is there any of the highly explosive chlorine-nitrogen compound produced, so long as a portion of ammonia in some excess be present in the solution. If it be suffered to cool, however, when saturated with chlorine, deposition of this violent body in oily drops may speedily occur. The mixture of the two gases, collected in a perfectly dry state, over mercury, gave on analysis the following results: Corrected vol. at 60° and 30 in. bar. 244.8 Mm. 211'0 Mm. 33.8 Mm. 244.8 millimètres of the nitrogen (as heretofore considered) contain, therefore, 33.8 of oxygen = 13.8 per cent. The following equation will explain the changes occurring in this decomposition: 5 NHHO + 4 C1=4NH,C1+N+0. with solutions of ammonia of different degrees of satuI may remark, that in repeating these experiments ration, I have ascertained that the proportions of oxygen and nitrogen in the evolved mixture of those gases are subject to considerable variation. But I have not found the oxygen to exceed, in any instance, the amount stated 417 per cent. in the analysis now given; neither have I observed that •603 any definite series of decompositions control the relative proportions of oxygen and nitrogen so obtained. .604 '93 per cent. 1'23 I'20 I have drawn attention to the above subject because I think it essential that chemists should be careful that they do not throw discredit on analyses by adopting incorrect processes. Determination of the Specific Gravity of Mineral Substances, by Dr. T. L. PHIPSON, F.C.S., Member of the Chemical Society of Paris, &c. I MAKE use of a very simple method for taking the the volume of water displaced by a given weight of the specific gravity of minerals. It consists in measuring "Miller's Elements," vol. ii. p. 539. CHEMICAL NEWS, May 3, 1862. On the Alteration of Tincture of Iodine. 247 known, but deserves the preference on account of the intensity of the colour, and for the durability in fire of the product. A pure pentasulphide of potassium is necessary; those prepared by boiling an excess of sulphur in potassa, or by fusing potash with sulphur, are unfit for the purpose on account of the hyposulphite or the sulphate of potassa which is formed. Pure sulphide of potassium can only be obtained by reducing sulphate of potassa with charcoal; by saturating its solution afterwards with sulphur the liquid is rendered fit for the process. Hessian crucibles are filled to three-fourths of their capacity with an intimate mixture of 20 parts finely powdered sulphate of potassa, and 6 parts powdered charcoal, and heated, well covered in a furnace until effervescence ceases. This monosulphide is dissolved in 3 parts of rain water, heated to boiling in an iron kettle, filtered and cooled to separate any undecomposed sulphate of potassa; the purified liquor is again On the Alteration of Tincture of Iodine, and the Means boiled and saturated with powdered sulphur, of which of Preventing it, by M. DROPET. It is known that tincture of iodine does not long preserve its colour, a portion of the iodine changing to hydriodic acid. M. Dropet endeavours to show that the hydrogen necessary for the reaction comes from the water, and not, as is supposed by other chemists, from the alcohol. Among other experiments, he has shown that a tincture prepared with almost absolute alcohol, 34 centigrammes out of 3 grammes of iodide, were in eighteen months transformed into hydro-iodic acid. Another tincture, prepared with the same proportion of alcohol at 95°, lost 41 centigrammes; and a third, with alcohol at 86°, 67 centigrammes. These tinctures were preserved together in a dimly-lighted cupboard. M. Dropet concludes that in making tincture of iodine it would be better, for two reasons, to replace the alcohol at 86° by that at 95°. In the first place, the tincture keeps better; in the second, it is made more quickly, since iodine is much more soluble in concentrated than in weak alcohol.-Repertoire de Pharmacie, xviii. 214. Chloride of Lime as an Insecticide. IN scatterin chloride of lime on a plank in a stable, all kinds of flies, but more especially biting flies, were quickly got rid of. Sprinkling beds of vegetables with even a weak solution of this salt effectually preserves them from the attacks of catterpillars, butterflies, mordella, slugs, &c. It has the same effect when sprinkled on the foliage of fruit trees. A paste of one part of powdered chloride of lime and one-half part of some fatty matter, placed in a narrow band round the trunk of the tree, prevents insects from creeping up it. It has even been noticed that rats and mice quit places in which a certain quantity of chloride of lime has been spread. This salt, dried and finely powdered, can, no doubt, be employed for the same purposes as flour of sulphur, and be spread by the same means.-Dingler's Polytechnisches Journal, clxi. 240. On the Preparation of Cinnabar, by MAGNUS FIRMENICH, of Cologne. CINNABAR is most generally prepared in the dry way, and on a large scale, by fusing one part of sulphur and seven parts mercury, and subjecting the fused mass to sublimation; or, as in Idria, by mixing the two elements in rotating barrels, and subliming afterwards from iron vessels. The process with sulphide of potassium is less four equivalents are required. It must be well protected from the atmosphere. To prepare now the cinnabar, bottles are filled with 10 lbs. mercury, 2 lbs. sulphur, and 4 lbs. of the above liquor; they are moderately heated, and placed in a swing in boxes, which are lined with straw, usually contain two such bottles, and are rocked against a straw cushion to increase the motion. The bottles commence to get warm after 1 to 2 hours, and the mixture assumes a greenish brown colour; the mercury combines with the sulphur of the dissolved sulphide, which is replenished by the sulphur of the mixture; to keep the latter in a loose condition, the bottles ought to be turned occasionally. The combination is completed in about 3 hours, and the colour of the mixture is now dark brown. After having been cooled slowly, the bottles are placed in a room, the temperature of which is between 35° and 43° R. (111° and 122° F.), for two or three days, during which time the mixture is well agitated three or four times daily. The temperature has an important influence on the shade of the colour, which is lighter the cooler the mixture has been on being put in the swing. Light carmine cinnabar, with a tinge of yellow, is obtained by exposing the bottles in winter to the cold atmosphere for one hour, or by setting them in summer in cold water for the same space of time. the sulphur. About half a quart of water is added to each bottle, and the contents thrown on a filter; the cinnabar is 'then treated in stone pots with caustic soda; and, after the sulphur is dissolved, the liquor is decanted and the residue washed repeatedly with fresh water, which usually requires two or three days. The complete removal of the sulphur and of the alkaline liquor is most important, the durability in fire depending on the former, and the permanence of the colour upon the latter. In order to dry the cinnabar, it is first transferred to the grate in a drying closet, where a very The cinnabar is now to be freed from the excess of moderate heat is used for desiccation, until it breaks into pieces, and does not appear moist to the touch. Placed upon iron pans, it is introduced into a drying oven, where it is constantly turned, and gradually heated to 50° R. (144° 5 F.) This last manipulation is finished in about five hours. By the higher heat the cinnabar assumes temporarily a darker shade, and its durability in fire is much increased thereby. This process I believe to be superior to all others, for the qualities of the product are equal to or surpass those of cinnabar made in other ways, and at the same time the cost is much lower.-Polytechn. Centralbl. NEWS PHYSICAL SCIENCE. On the Molecular Dissymmetry of Natural Organic (Continued from p. 233.) VII. This general conclusion from the preceding studies throws new light upon our ideas of molecular mechanism. We see that if natural products, organised under the influence of vegetable light, are ordinarily dissymmetric, contrarily to what mineral and artificial products offer us, this disposition of elementary particles is not a condition of existence of the molecule, that the twisted organic group can untwist itself and then take the general character of artificial or mineral substances. On the other hand, it seems to me logical to regard the latter as susceptible of presenting a dissymmetric arrangement of their atoms in the manner of natural products. The conditions of their production are to be discovered. As final analysis and summing up of what precedes, the groups of elementary atoms which constitute compound matter may cover two distinct states, corresponding to two general types, to which every material object may be referred. The form of the group is with a superposable image or with a non-superposable image; but this latter type is double, because its inverse can exist on the same ground as itself. We must add the case of the association of these two inverse types, which recalls the union by pairs of the identical and non-superposable members of the superior animals. So that there is, in reality, four remarkable dispositions for the groups of atoms which constitute matter. All our efforts should tend towards producing them for each particular species. There is in almost all these considerations such exactitude that it seems impossible to call them in question. How refuse to admit that a right body has its possible left, knowing as we know the signification of the right or left character? This would be to doubt that an irregular tetrahedron has its inverse; that a dextrorse helix has its sinistrorse inverse; that a right hand has its possible left. And hence, if the mysterious influence to which the dissymmetry of natural products is due should come to change in sense or direction, the constituting elements of all living beings would take an inverse dissymmetry. Perhaps a new world would be presented to us. Who could foresee the organisation of living beings, if the cellulose which is right should become left, if the left albumen of the blood should become right? There are here mysteries which prepare immense labours for the future, and from this hour invite the most serious meditations of science. VIII. Only because chemistry has been, up to the present time, powerless in the preparation of dissymmetric bodies, might we fear that we may be always ignorant of the mode of production of the inverse bodies of natural organic substances. Happily this fear is exaggerated. I have ascertained, indeed, that, by ordinary chemical processes, such as the action of heat, a right body can be changed to its left, and inversely. Thus, in warming right tartaric acid under certain determinate conditions, which it would be too long to specify here, it is transformed into left tartaric acid, or, rather, into paratartaric acid; and inversely, under the same conditions exactly, left tartaric acid becomes right. Here are ten or twelve grammes of entirely pure left tartaric acid, which were thus procured. Their prepara | tion cost me much trouble. But M. Biot desired to study in a very particular manner the characters of dispersion of this left tartaric acid, so remarkable on account of its origin. He desired himself to be at the cost of the operation,-very expensive, because the transformation depends upon the employment of the tartrate of cinchonine or of quinine, and the base is lost because the tartrate must be heated to a temperature which destroys it. I have prepared by this process sufficient paratartaric acid to take from it twelve grammes of left tartaric acid, which presents rigorously, in an inverse sense, the same optical characters as tartaric acid. Every analogous transformation of a natural dissymmetric body into its inverse should be regarded as a great advance in organic chemistry. IX. At the conclusion of our first lecture, I alluded to observations to which it is time we should give all the attention they merit. These observations are relative to the comparison of the physical and chemical properties of right and corresponding left isomerics. I have already insisted upon the perfect identity of all their properties, excepting, however, the inversion of their crystalline forms, and the opposition of direction of their optical deviations. Physical aspect, lustre of the crystals, solubility, specific gravity, single or double refraction, all is not only alike, similar, very near, but identical, in the most rigorous acceptation of the word. This identity is the more remarkable, as we shall see it replaced by a general and considerable opposition of the properties of these same substances, when they are found in particular conditions which I am about to point out. We have seen that we must distribute all chemical compounds, artificial or natural, mineral or organic, in two great classes,-compounds non-dissymmetric with non-superposable image. This stated, the identity of properties of which I have just spoken in the two tartaric acids and their similar derivatives, constantly exists with the absolute characters I have named, whenever these substances are placed in presence of any compound of the class of bodies with superposable image, such as potassa, soda, ammonia, lime, barytes, aniline, alcohol, the ethers,—in a word, of all compounds, whatever they may be, not dissymmetric, not hemihedric in form, without action on polarised light. Submit them, on the contrary, to products of the second class with non-superposable image, asparagine, quinine, strychnine, brucine, albumen, sugar, &c.,bodies dissymmetric like them all change in an instant. Solubility is no longer the same. If there is combination, the crystalline form, specific gravity, the quantity of water of crystallisation, the more or less ready destruction by heat, all differ as much as the most distant isomeric bodies differ. Here, then, we have the molecular dissymmetry of bodies introducing itself in chemistry as a powerful modifier of chemical affinities. In presence of the two tartaric acids, quinia does not behave like potassa, only because it is dissymmetric, and potassa is not. Molecular dissymmetry is hence offered as a property capable by itself, as far as dissymmetry, of modifying chemical affinities. I do not believe any discovery has yet entered so far into the mechanical part of the problem of combinations. Let us endeavour to present the cause of these identities and of these dissemblances. Let us suppose a dextrorse helix and a sinistrorse helix separately penetrating two blocks of identical wood, and in right lines. All the mechanical conditions of the two systems will CHEMICAL NEWS,) Manchester Literary and Philosophical Society. (To be continued.) PROCEEDINGS OF SOCIETIES. MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY. E. W. BINNEY, F.R.S., F.G.S., Vice-President, THE REV. ROBERT HARLEY, F.R.A.S., Corresponding 249 The be the same. It will be no longer so from the moment much more hydrogen, and I am prepared for a considerthese same helices shall be associated with blocks, them-able variation in the amount of the several gases. selves shaped in helices of the same direction or of nitrogen came to a minimum whenever the decomposition became slow. This might be interpreted in two waysopposite directions. first, by the absence of air to continue the process; and second, by absence of the nitrogen from the decomposed albuminoids. I do not see from my experiments a sufficient proof of the elimination of nitrogen. The amount was in a state of constant decrease, suggesting a gradual removal of atmospheric air. I mentioned that by passing the gas through lead and other metallic salts, only a small amount of organic matter was collected; but by passing it through caustic potash the amount was considerable. A flocculent matter fell, but the chief amount remained in solution. The solution was boiled down, and, when heated, a perfectly fresh odour of soup was spread through the room; everything offensive had been removed, and the smell was for the first time very agreeable. Here we find that the substances sought for are decomposed by the very means which we take to retain them. But in this experiment we see a demonstration that substances of an organic nature pass over with the gases. When strong sulphuric acid was added to the potash solution there was an abundant black precipitate of carbon and carbonaceous matter. More than enough for an analysis had been made. There was a fatty odour from it when sulphuric acid was added, leading me to think of Chevreul's remarks on a similar occasion. As these compounds were not retained by acid salts, but by alkalies, I concluded that they were acids; but on allowing some of the solution to stand for a few hours, I was surprised to find that the organic matter had almost disappeared. We see clearly how differently the organic substances act from carbonic acid. I took home a small piece of cotton wool through which the gas had passed for some days. My intention was to examine it with the microscope. Less than a grain of this cotton was taken out of the tube in which it was enclosed, but so thoroughly did the room become offensive that some friends, not aware of my pursuits, were much annoyed. This is one of those many facts which lead to the conclusion that the amount of carbonic acid is entirely incapable of showing the true condition of an atmosphere unless we estimate the gas at once on its formation, as then it is mixed with organic matter. If, however, we allow even a short time to pass, a separation takes place, the carbonic acid diffuses, and the organic matter clings to substances to be gradually given off; the tendencies of the two are entirely different, and the separation begins at once. When the gases were previously passed through charcoal, it was difficult to obtain a trace of organic matter. I imagine that I see my way now to a very satisfactory and comparatively easy investigation, although for the time I must leave it to others. Dr. R. ANGUS SMITH, F.R.S., read a Paper entitled "On the Putrefaction of Blood, No. 2." The following is an abstract: When I first began to examine the products of the putrefaction of blood, it was merely with the object of ascertaining the nature of the gases, and of ascertaining whether any matter in them exists in a so-called organic condition, and, if so, in what quantity. I have ascertained the nature of the gases. So far as I see, however, I have added no new one; but I believe that for the first time I have given the proportionate amount of each. I have also decided on a simple and certain method of collecting some organic substances from the gases, namely, the use of caustic potash, which I find superior to acid salts. Other methods also I have found promising, but I have been compelled to give up the inquiry, at least for a long time, on account of the extremely nauseous emanations which penetrated every room in the laboratory, and were, no doubt, waiting for a favourable opportunity of changing into deadly poisons. These, by proper arrange ments, might be avoided. I mentioned formerly that the temperature of 54° Fahr., or 12° C., was a very marked one in favouring putrefaction. I now find that on to 120° Fahr., (49 C.) at least, the process, if it ceases, may be set in motion by raising the temperature. After that point it is difficult to induce putrefaction. I give here a specimen of the Nov. 9 12 Progress of the Decomposition. » 13 ❞ 14 " 15 Gases Absorbed. Not Absorbed. 8.44 88.65 91'56 95.90 4.10 NOTICES OF BOOKS. Metallurgy. By JOHN PERCY, M.D., F.R.S. London: Methods of Estimating Copper.-In continuation of the author's remarks upon the disadvantages and inaccuracy of the Cornish method of dry assay, we propose now to give a brief description of the several wet processes recommended as being applicable for the estimation of copper in all kinds of ores and metallurgical products. The first step in any of these operations consists in procuring a solution of the copper by means of acids; the blue and green native carbonates are easily attacked by dilute nitric acid; but in the case of copper-pyrites and other sulphuretted ores it is expedient to roast a weighed portion of the sample in a small porcelain capsule, then to moisten with concentrated sulphuric acid, lastly adding nitric acid, when the whole of the copper is readily dissolved, and the liquid requires merely to be boiled in order to expel the red nitrous fumes, and diluted with water to furnish a solution fit for testing. The amount of copper may now be determined either by standard solution of cyanide of potassium, as proposed by Mr. Henry Parkes in 1851; or by solution of hyposulphite of soda, as recommended by Mr. E. O. Brown ;* by a process of precipitation, as disulphide, suggested by the author; or by the "coloration test," which last seems only applicable to the examination of copper slags. NEWS order to be enabled to determine with greater precision the last effects of the cyanide of potassium; and in the event of requiring to know the amount of iron present in the ore, the precipitated peroxide on the filter is re-dissolved in dilute sulphuric acid, reduced to the state of protoxide by metallic zinc, and then tested in the usual way with a standard solution of permanganate of potash. The metals which interfere with this mode of valuing copper ores, are silver, nickel, cobalt, and zinc. The first may readily be separated by adding a few drops of hydrochloric acid to the original solution; the other metals may be excluded by following one of the methods pointed out by the author for that purpose. 2(CuO,A) +2KI=Cu2I+I+ 2 (KO, A) The completion of the second reaction is manifested by the In carrying out the volumetric estimation according to the directions of Mr. Parkes, a solution of cyanide of potassium is slowly added to a blue ammoniacal solution The process described by Mr. E. O. Brown is particuof copper, when the latter gradually loses its colour, and larly applicable to the determination of copper in gunfinally becomes quite colourless; upon this chemical_re-metal, brass, and other alloys which contain no large action the estimation of copper by cyanide of potassium amounts of iron and lead. It is founded on the reactions depends. By ascertaining by direct experiment the amount between salts of copper and the neutral iodides, and on of cyanide of potassium solution required to discharge the the conversion of the liberated iodine into hydriodic and colour in an ammoniacal solution containing a given weight tetrathionic acids by a standard solution of hyposulphite of copper, it is easy by a comparative experiment to of soda. determine the amount of copper in a given weight of ore. These reactions may be thus expressed :For the preparation of the standard solution 2000 grains of fused cyanide of potassium are to be dissolved in two quarts of water, to produce a solution of which 1000 grains measure will be equal to about ten grains of metallic copper. This solution should be preserved in green glass stoppered bottles, and kept as much as possible away from the light; it is liable to a slow decomposition, which will necessitate the standard being checked at intervals of one or two weeks. In order to standardise the solution, a burette, holding 1000 grains measure, is filled to the zero mark, and a piece of pure electrotype copper, previously cleaned by means of dilute nitric acid, washed and dried, is accurately weighed. About eight grains may be conveniently taken; this is dissolved in a pint flask by dilute nitric acid, and, after the energy of the first action has subsided, the solution is warmed and ultimately boiled to expel all the nitrous acid fumes. It is diluted with cold water to the bulk of nearly half-a-pint, treated with ammonia in excess, and to the deep blue solution the cyanide is added from the burette until the colour is so nearly discharged that a faint lilac tint only remains. This will generally become quite bleached on standing at rest for a short time, so that the cyanide must not be added too hastily towards the end of the operation. It will be advisable to control the standard by a second experiment upon another weighed portion of copper, and to stop short of bleaching entirely the faint lilac tint of the solution. A piece of white paper folded and placed under and behind the flask during the decolorisation, will aid in recognising the proper tint of the solution. In applying this process to the examination of copper ores, a known weight of the finely-powdered sample is introduced into a beaker provided with a glass cover, and moistened with strong sulphuric acid; strong nitric acid is then added, and the whole digested on a sand-bath until nitrous fumes are no longer given off. Should a small quantity of sulphur be separated in the treatment of pyrites ores, the small globules may be taken out, burnt, and the residual copper dissolved in a few drops of nitric acid and mixed with the remainder. Water is now to be added and left in contact for a short time to extract all the metallic salt from the insoluble residue, which need not be filtered off; and so, likewise, when ammonia is added in the next place, any peroxide of iron which may thus be precipitated is left in the solution, for it is apt to contain a small proportion of copper when first thrown down; but this is entirely removed by the cyanide of potassium later in the experiment. When the ore contains much iron it is considered desirable to remove the hydrated peroxide by filtration, in Quarterly Journal of the Chemical Society, April, 1857. From 8 to 10 grains of the copper or alloy are dissolved in dilute nitric acid, and the red nitrous fumes expelled by boiling. The nitrate of copper is converted into acetate by adding carbonate of soda until a portion of copper remains precipitated, and then re-dissolving in acetic acid. The solution is diluted with water, and about 60 grains of iodide of potassium in the form of crystals dropped into the flask, and allowed to dissolve. The standard solution of hyposulphite of soda is now poured in from a burette, until the greater part of the darkcoloured free iodine disappears. A little of the starch solution is now added to make its presence more apparent, and the addition of the hyposulphite continued until the bleaching is completed, when the pale yellow colour of the sub-iodide of copper will alone be visible. The amount of copper in the ore or alloy is calculated from the number of divisions indicated upon the burette. Copper ores containing much iron (which interferes by reason of the dark red colour of the acetate) may be dissolved in nitric acid, and treated with sulphuretted hydrogen to precipitate the copper, the sulphide being collected on a filter, washed, and re-dissolved in nitric acid to produce a solution suitable for testing by this process. Or the hyposulphite may itself be employed to furnish a precipitate of disulphide of copper, according to a method next to be described. NOTICES OF PATENTS. 1387. Manufacture of Kamptulicon. W. R. JEUNE, Bow, |
