stances which might otherwise erroneously have been supposed to be identical.

The second object is that of enabling us to follow a particular substance through mixtures containing it, and thereby to determine its principal reactions before it has been isolated, or even when there is small hope of being able to isolate it; and to demonstrate the existence of a common proximate element in mixtures obtained from two different sources. Under this head should be classed the detection of mixtures in what were supposed to be solutions of single substances."

Setting aside the labour of quantitative determinations carried out by well-recognised methods, the second object is that the attainment of which is by far the more difficult. It involves the methods of examination required for the first object, and more besides; and it is that which is chiefly kept in view in the present discourse.

The optical properties of bodies, properly speaking, include every relation of the bodies to light; but it is by no means every such relation that is available for the object in view. Refractive power, for instance, though constituting, like specific gravity, &c., one of the characters of any particular pure substance, is useless for the purpose of following a substance in a mixture containing it. The same may be said of dispersive power. The properties which are of most use for our object are-first, absorption; and, secondly, fluorescence.

Colour has long been employed as a distinctive character of bodies; as, for example, we say that the salts of oxide of copper are mostly blue. The colour, however, of a body gives but very imperfect information respecting that property on which the colour depends; for the same tint may be made up in an infinite number of ways from the constituents of white light. In order to observe what it is that the body does to each constituent, we must examine it in a pure spectrum. [The formation of a pure spectrum was then explained, and such a spectrum was formed on a screen by the aid of the electric light. On holding a cell containing a salt of copper in front of the screen, and moving it from the red to the violet, it was shown to cast a shadow in the red as if the fluid had been ink, while in the blue rays it might have been supposed to have been water. Chromate of potash similarly treated gave the reverse effect, being transparent in the red and opaque in the blue. Of course, the transition from transparency to opacity was not abrupt; and for intermediate colours the fluids caused a partial darkening. Indeed, to speak with mathematical rigour, the darkening is not absolute even when it appears the greatest; but the light let through is so feeble that it eludes our senses. In this way the behaviour of the substance may be examined with reference to the various kinds of light one after another; but in order to see at one glance its behaviour with respect to all kinds, it is merely requisite to hold the body so as to intercept the whole beam which forms the spectrum, to place it, for instance, immediately in front of the slit.]

To judge from the two examples just given, it might be supposed that the observation of the colour would give almost as much information as analysis by the prism. To show how far this is from being the case, two fluids very similar in colour, port wine and a solution of blood, were next examined. The former merely caused a general absorption of the more refrangible rays; the latter exhibited two well-marked dark bands in the yellow and green. These bands, first noticed by Hoppe, are eminently characteristic of blood, and afford a good example of the facilities which optical examination affords for following a substance which possesses distinctive characters of this nature. On adding to a solution of blood a particular salt

The detection of mixtures by the microscopic examination of intermingled crystals properly belongs to the first head, the question which the observer proposes to himself being, in fact, whether the pure substances forming the individual crystals are or are not identical.

of copper (any ordinary copper salt, with the addition of a tartrate to prevent precipitation, and then carbonate of soda), a fluid was obtained utterly unlike blood in colour, but showing the characteristic bands of blood, while at the same time a good deal of the red was absorbed, as it would have been by the copper salt alone. On adding, on the other hand, acetic acid to a solution of blood, the colour was merely changed to a browner red, without any precipitate being produced. Nevertheless, in the spectrum of this fluid the bands of blood had wholly vanished, while another set of bands less intense, but still very characteristic, made their appearance. This alone, however, does not decide whether the colouring matter is decomposed or not by the acid; for as blood is an alkaline fluid, the change might be supposed to be merely analogous to the reddening of litmus. To decide the question we must examine the spectrum when the fluid is again rendered alkaline, suppose by ammonia, which does not affect the absorption bands of blood. The direct addition of ammonia to the acid mixture causes a dense precipitate, which contains the colouring matter, which may, however, be separated by the use merely of acetic acid and ether, of which the former was already used, and the latter does not affect the colouring matter of blood. This solution gives the same characteristic spectrum as blood to which acetic acid has been added; but now there is no difficulty in obtaining the colouring matter in an ammoniacal solution. In the spectrum of this solution, the sharp absorption bands of blood do not appear, but instead thereof there is a single band a little nearer to the red, and comparatively vague [this was shown on a screen]. This difference of spectra decides the question, and proves that hæmatin (the colouring matter prepared by acid, &c.) is, as Hoppe stated, a product of decomposition.

The spectrum of blood may be turned to account still further in relation to the chemical nature of that substance. The colouring matter contains, as is well known, a large quantity of iron; and it might be supposed that the colour was due to some salt of iron, more especially as some salts of peroxide of iron, sulphocyanide for instance, have a blood-red colour. But there is found a strong general resemblance between salts of the same metallic oxide as regards the character of their absorption. Thus the salts of sesquioxide of uranium show a remarkable system of bands of absorption in the more refrangible part of the spectrum. The number and position of the bands differ a little from one salt to another; but there is the strongest family likeness between the different salts. Salts of sesquioxide of iron in a similar manner have a family likeness in the vagueness of the absorption, which creeps on from one part of the spectrum to another without presenting any rapid transitions from comparative transparency to opacity and the converse. [The spectrum of sulphocyanide of peroxide of iron was shown for the sake of contrasting with blood.] Hence the appearance of such a pecular system of bands of absorption in blood would negative the supposition that its colour is due to a salt of iron as such, even had we no other means of deciding. The assemblage of the facts with which we are acquainted seems to show that the colouring matter is some complex compound of the five elements, oxygen, hydrogen, carbon, nitrogen, and iron, which under the action of acids and otherwise, splits into hæmatin and globulin.

This example was dwelt on, not for its own sake, but because general methods are most readily apprehended in their application to particular examples. To show one example of the discrimination which may be effected by the prism, the spectra were exhibited of the two kinds of red glass which (not to mention certain inferior kinds) are in common use, and which are coloured, one by gold, and the other by suboxide of copper. Both kinds exhibit a single band of absorption near the yellow or green; but the band of the gold glass is situated very sensibly nearer

to the blue end of the spectrum than that of the copper glass.

In the experiments actually shown, a battery of fifty cells and complex apparatus were employed, involving much trouble and expense. But this was only required for projecting the spectra on a screen, so as to be visible to a whole audience. To see them, nothing more is required than to place the fluid to be examined (contained, suppose) in a test tube, behind a slit, and to view it through a small prism applied to the naked eye, different strengths of solution being tried in succession. In this way the bands may be seen by any one in far greater perfection than when, for the purpose of a lecture, they are

thrown on a screen.

(To be continued.)

ACADEMY OF SCIENCES.
April 18.

A NOTE entitled "Theoretical Researches on the Formation of Positive Photographic Prints," by MM. Davanne and Girard, was presented. The authors do not seem to have discovered anything new in the course of their researches, unless the following method of restoring faded prints be considered a novelty:-"If, in consequence of defective preparations, a print fades (yellow), the change may be arrested, and a part of its primitive brilliancy restored by toning it afresh in a concentrated solution of neutral chloride of gold. A note "On the Action of Chlorine on Methyl," by Mr. Schorlemmer, was read. The author exposed to diffused light bottles full of a mixture of equal volumes of chlorine and methyl, and so obtained chlorhydric ether of vinic alcohol and a monochlorinated compound of the M. F. Pisani presented An Analysis and Chemical Study of the Mineral Pollux found in the island of Elba. This rare mineral had only been analysed by Plattner, who found it to be principally composed of silica, alumina, potash, and soda, but could only make the percentage sum of the constituents 92 75. M. Pisani has recently analysed a specimen of pollux, and found it to contain 34 per cent. of casium. The author points out that Plattner took the precipitated chloro-platinate as a potassium compound, and calculated accordingly; but if the chloroplatinate be calculated for cæsium, the numbers are found to closely agree with those obtained by M. Pisani himself. This shows the importance of setting down the results of analyses conscientiously without making up the

same ether.

"loss."

M. Remalé communicated a note "On the Sulphur Compounds of Uranium." The author poured an excess of sulphide of ammonium into a solution of nitrate of uranium in alcohol, and obtained a brown precipitate which he believes to be a sulphide of uranyle (Ur2O2)S. M. Peligot supposes the existence of the radical uranyle to account for the circumstance that sesquioxide of uranium forms neutral salts with one equivalent of acid. Thus, the sesquioxide is the oxide of uranyle (Ur2O2)O.

MM. Berthelot and Fleurica contributed a note" On the Proportion of Tartaric Acid in Grape Juice and Wine."

The researches of the authors show that the vinous fermentation is a very complicated process-much more complicated than the alcoholic fermentation properly so-called. It seems that in the course of fermentation much of the acidity of the grape juice disappears beyond that which can be accounted for by the precipitation of cream of tartar-" a circumstance the more unexpected," say the authors, "since the fermentation itself produces acids."

processes.

It was just before the Exhibition of 1851 that Mr. Young began to distil boghead coal at a low red heat, and so commenced in this country the manufacture which has received such an extraordinary development. In 1857 Mr. De La Rue took out a patent for distilling Rangoon tar, first with a current of steam to remove the lighter oils, and then with superheated steam to obtain paraffin. At the date of the French Exhibition (in 1855) the condition of the industry is thus summed up:-1. Boghead coal was being largely distilled for the liquid and solid products, used, for the most part, as lubricating, but also to some extent as illuminating agents. 2. The same products were also obtained from gas tar. 3. Bituminous schist, resin, and peat were being largely worked for similar purposes, chiefly for illuminating agents. 4. Lastly, Mr. De La Rue had called attention to the value of native tar as a source of similar products.

This, it must be confessed, is but a very meagre sketch of the early (some will say late) history of the industry of distilled hydrocarbons; but it is all this report affords us, and we pass on to the processes of distillation and now knows, distils boghead coal at a low red heat; the purification now in use. Mr. Young, as everybody crude oil so obtained is treated with a current of steam to remove the naptha; the residue is then treated with strong sulphuric acid, whereby naphthaline and a number of products of a similar composition to olefiant caustic soda now causes the separation of tarry matter, gas are decomposed. Agitation with a strong solution of which takes its place between the soda lye and the purified oil, when the mixture is left at rest. The oil is now run off, and rectified by distillation; the more volatile part is sold as an illuminating, and the less volatile as a lubricating agent.

the distillate is then mixed with a solution of chloride of Gas-tar is treated differently. It is first rectified, and lime. The mixture is then briskly agitated, and diluted hydrochloric acid is added until all the chlorine is expelled from the chloride. The more alterable portion of the oil is thus oxidised, and subsequent treatment with soda lye, as in the former instance, separates the tar, and leaves the supernatant oil free for rectification. The richer tar from Scotch cannels it seems can be profitably treated in this

way.

Petroleum or rock oil, from the United States and Canada, are, however, at present formidable competitors with the distilled oils; but how little the manufacture of the oils has been affected may be judged from the stateoil in the United Kingdom "during the last year [1862, ment made in this report, that the production of paraffin we presume] reached the enormous amount of 2,300,000 gallons."

The manufacture of paraffin and the accessory products from a light coloured lignite, is carried on to a considerable extent in Prussia, and a very good description of the processes employed is given in the Report. The lignite appears to be first distilled for tar, which is first freed from water, and then rectified: the distillate now obtained is treated with caustic soda to remove carbolic acid. After the separation of the carbolate of soda solution, the

acid, and the purification The acid solution sepa

NOTICES OF PATENTS.

Grants of Provisional Protection for Six Months. 3307. John Dale and Heinrich Caro, Manchester, "Imprinting."-Petition recorded December 31, 1863.

We may quote here the results obtained by Wagenmann, who made numerous determinations of the amounts of products obtainable by the distillation of peat, lignite, and bituminous shale.

The results seem to show that the extraction of these illuminating and lubricating agents from peat is not likely to be profitable as long as they have to compete with the products from coal and lignite.

Photogen, according to Herr Wagenmann, "should be very mobile, as it has frequently to ascend a wick to the height of six inches. The best has the sp. gr. 0815 to 9.835. Those which have the sp. gr. of only 0.78 are dangerous, as they contain oils which boil at 60° C., and readily forming explosive mixtures in the air-spaces of the lamps in which they are consumed. On the other hand, photogen sp. gr. o.840 and upwards is nearly useless, as it cannot ascend a wick with sufficient facility.

"Solar oil should not contain any oils of less sp. gr. than 0.870, nor more than o'920. Its sp. gr. generally ranges between 0.885 and 0.895. Cooled to 10° C., it ought not to deposit paraffin; and when agitated the bubbles of air ought not to rise to the surface more rapidly than in colza oil.

"Lubricating oil ought to have a sp. gr. varying from o'920 to 0.950, and to possess but a very slight odour. It is frequently mixed with Gallipoli oil. Although it contains paraffin, it ought not to deposit any when cooled

to 2o C."

The report gives no account of the practical mode and the results of coal distillation in this country, which it is remarked "is a source of considerable disappointment."

We can notice but briefly the Russian works, near Bakou, on the Caspian. Here the inflammable gas which issues from the earth is collected in gasholders, and used as a source of heat for the distillation of the petroleum, and also a bitumen, called naphthagil. There is another factory on the island Svatoi, on the Caspian, where a substance resembling dark coloured wax and named naphthadehyl is distilled. The substance is found in large quantities on the island, and also on the eastern shores of the Caspian. The successful working of these deposits suggests the possibility of the similar utilisation of the analogous deposit found in Derbyshire. In the hope of this, it seems that this substance, locally known as "Devil's dung," is being stored in caves on the High Peak.

543. Alfred Ford, Trafalgar Works, Peckham, Surrey, "An improved method of manufacturing floor cloth."Petition recorded March 4, 1864.

605. John Clayton, Wolverhampton, Staffordshire, "Improvements in reverberatory and other furnaces for heating and melting iron and steel, and for other like purposes.'

627. Robert Hanham Collyer, M.D., Ph.D., F.C.S., Beta House, Alpha Road, St. John's Wood, London, "An improved apparatus and process for the conversion of substances into material for the manufacture of paper and textile purposes."

632. John Henry Johnson, Lincoln's Inn Fields, London, "Improvements in the manufacture of soap."-A communication from Jean Baptiste Vasseur and Alexis Mahot, Paris.

635. Raymond Fletcher, Siddall's Road, Derby, "A new compound used for varnishing paperhangings and other articles."

674. Richard Archibald Brooman, Fleet Street, London, "Improvements in treating vegetable textile matters in separating filamentous matters therefrom, and the application of such matters to spinning, weaving, and dyeing." -A communication from Etienne Mallard, Florentin Bonneau, Adolphe Dumont, and Napoleon Jean Claude Canoby, Paris.

677. John Dauglish, M.D., Reading, Berkshire, "Improvements in the manufacture of aërated bread, and in apparatus to be used in this manufacture."

695. Frederick Tolhausen, Boulevart Magenta, Paris, "An improved process for preserving iron from corrosion, as produced by the influence of air and sea water."-A communication from Mr. Charles de Bussy, Avenue de Villars, Paris.-Petition recorded March 18, 1864.

Notices to Proceed.

584. James Preston Worrall, Ordsall, Lancashire, "Certain improvements in dyeing or colouring looped, cut pile, or raised textile fabrics composed of cotton and silk.”. Petition recorded March 9, 1864.

2951. Davis Wilson Rea, Upper Thames Street, London, "Improvements in preserving animal and vegetable substances."-Petitions recorded November 29, 1863.

2963. George Parkin, Tryddyn, Flintshire, "Improvements in apparatus employed in the manufacture of paraffin and other like oils from shale, cannel, and other minerals.”

2980. Thomas Gray, Mitcham, Surrey, "A new method of discharging colour from rags used for papermaking or other purposes, and in treating of vegetable fibres by such process.

Southwark, Surrey, "Improvements in extracting essences 2987. Heinrich Hirzel, Terminus Hotel, London Bridge, and perfumes, and also oils and fats from matters containing them; also in bleaching and purifying oils and fats, and in apparatus employed therein."-Petitions recorded November 27, 1863.

3022. William Wilson, Manchester, "Improvements in generating gas for illuminating and other purposes, when made by passing atmospheric air over or through volatile oils, and treating such gas and the gas made from coal or cannel, after leaving the generators, so as to improve the heating and illuminating qualities thereof, and in the apparatus for effecting the same."

3029. Henry Holdrege, Irvington, New York, U.S., "Improvements in the process and manner of making gas for illuminating, heating, and other purposes, a part of which may also be applied to the production of metallic

oxides.”—A communication from William Henry Gwynne, New York, U.S.

CORRESPONDENCE.

Identity of Aconella with Narcotine.

To the Editor of the CHEMICAL NEWS.

SIR,-Having received, some time ago, from my friend, Mr. H. Draper, a specimen of the alkaloid discovered by Messrs. T. and H. Smith, of Edinburgh, in aconitum napellus, I thought it probable that some interesting results might be obtained by submitting a solution of the alkaloid to the action of polarised light. My object was to compare the change in the plane of polarisation of a ray, produced by transmission through a tube filled with this solution, with the change similarly produced by a solution of narcotine. This I was enabled to do with very great accuracy by means of an instrument which I described at a meeting of the Royal Irish Academy in January, 1863.

The experiment was made as follows:

1. I dissolved 2.95 gr. of aconella in 1 cubic inches of chloroform, and determined the rotatory power of the solution. I then made a solution of narcotine of the same strength, and measured its rotatory power in the same way, Had these powers differed from each other by the th part, I could not have failed to see that they were unequal. No difference, however, could be detected.

2. Knowing the rotation produced by a solution of narcotine to be reversed by the addition of an acid, I was anxious to ascertain whether the same were true of a solution of aconella. In this experiment I was obliged to use as the solvent rectified spirit, inasmuch as the water contained in the dilute acid which I employed would have rendered the chloroform turbid. This made the

experiment more difficult, narcotine being very sparingly soluble in spirit. In fact, I was with difficulty able to dissolve one grain of either substance in a cubic inch of cold spirit.

Having made two similar solutions of aconella and narcotine, I measured their rotatory powers before and after the addition of an acid. The results were as follows:a. In both cases the rotation was reversed.

b. Working by m, the ratio of the left-handed rotation produced by the solution of aconella to the right-handed rotation produced by the same solution when acidulated, and by m', the same ratio for narcotine, I found

Chemistry at the College of Physicians. It is related in the pages of one of our contemporaries, that at a recent meeting of the College of Physicians, Dr. Frederic Farre made the following statement in reference to the change of names of the chlorides of mercury in the British Pharmacopoeia :-" When the chemical equivalent of mercury was 100, calomel was the chloride and corrosive sublimate the bichloride; but at the time of the preparation of the new Pharmacopoeia, most distinguished chemists held that the chemical equivalent of mercury was 200; thus calomel became the subchloride and corro

sive sublimate the chloride, and it was necessary to define them accordingly. He (Dr. Farre) believed that quite recently some chemists had reverted to the old notion that the chemical equivalent of mercury was only 100.” As the meetings of the College are not officially reported, we have no means of knowing whether Dr. Farre's words were correctly taken down or not; but the statement is a series of mistakes from beginning to end. The facts are that when the equivalent of mercury was 200, calomel was the chloride and corrosive sublimate the bichloride, but at the time of the preparation of the British Pharmacopœia some chemists held that the chemical equivalent of mercury was 100; but now (April, 1864), some other chemists are reverting to the old notion that the chemical equivalent of mercury is 200. Thus Dr. Farre's statements ought al! to be reversed in order to be accurate. By the established rules of chemical nomenclature, 200Hg. +72Cl. must be the bichloride, or corrosive sublimate; and 200Hg. + 36Cl. must be the chloride, while if the chemical equivalent of mercury be 100, then 100Hg. +36Cl. must be the chloride (still corrosive sublimate), and 200Hg. + 36Cl. (doubling the equivalent of mercury), must be the subchloride. We offer these remarks to the College of Physicians, and to the Chemical Fellows who were probably present at the meeting, as Dr. Alfred Taylor, Dr. Bence Jones, Dr. Garrod, Dr. Owen Rees, and others.Medical Circular.

Why Bees Work in the Dark. A lifetime bee-hive, and still half of the secrets would be undismight be spent in investigating the mysteries hidden in a brated problem for the mathematician, whilst the changes covered. The formation of the cell has long been a cele. which the honey undergoes offer at least an equal interest the comb is like. It is a clear yellow syrup, without a to the chemist. Every one knows what honey fresh from trace of solid sugar in it. Upon straining, however, it the saying is-and ultimately becomes a solid mass of gradually assumes a crystalline appearance-it candies, as sugar. It has not been suspected that this change was a photographic action. That the same agent which alters the molecular arrangement of the iodide of silver on the excited collodion plate, and determines the formations of camphor and iodine crystals in a bottle, causes the syrupy honey to assume a crystalline form. This, however, is the case. M. Scheibler has enclosed honey in stoppered flasks, some of which he has kept in perfect darkness, whilst others have been exposed to the light. The invariable result has been that the sunned portion rapidly crystallises, whilst that kept in the dark has remained perfectly liquid. We now see why bees are so careful to work in perfect darkness, and why they are so careful to obscure the glass windows which are sometimes placed in their hives. The existence of their young depends on the liquidity of the saccharine food presented to them, and if light were allowed access to this the syrup would gradually acquire a more or less solid consistency; it would seal up the cells, and in all probability prove fatal to the inmates of the hives. - Chronicle of Optics, "Quarterly Journal of Science."

ANSWERS TO CORRESPONDENTS.

W. H. D.-Of Griffin, Bunhill-row, London.

Constant Reader.-Add any soluble sulphide to a salt of silver. Physician. Book Received.-"The Prescriber's Pharmacopoeia," by a Practising

NEWS

Some Curious Properties of Oxide of Silver,
by M. BOETTGER.

M. BOETTGER has remarked that oxide of silver yields its oxygen to combustible matters quite as readily as does peroxide of lead PbO2, which, on account of this property is very largely employed in the manufacture of chemical matches.

A very dry mixture of about two parts of oxide of silver and one of sulphur ignites by friction in a mortar or even between folds of paper. It makes no difference if the antimony compound is replaced by black sulphide of antimony, realgar, or piment.

The same thus occurs with amorphous phosphorus as with tannin. Gallic acid does not induce combustion. A drop of phenic acid or creosote poured on very dry oxide of silver causes an instantaneous flame.

Flour of sulphur also ignites when triturated with this oxide; selenium the same.-Journ. für Prakt. Chemie,

XC., 32.

Preparation of Suboxide of Copper, by M. R. BOETTGER. SUBOXIDE of copper, says M. Boettger, is obtained in great perfection by the following process:-Dissolve in 2 parts of hot distilled water part of crystallised sulphate of copper, 1 part of tartrate of potash and soda and 2 parts of cane-sugar; when the solution is complete, and tartrate of copper formed, add 1 part of caustic soda. By boiling the mixture, the suboxide of copper is gradually precipitated, losing its odour completely, as in saccharometric experiments.

The product is of a beautiful red colour, and after it is washed and dried will keep without alteration; before being dried the author advises its being washed in a little alcohol.-Journ. für Prakt. Chemie, xc., 163.

TECHNICAL CHEMISTRY.

Preparation of Aniline Green.*

THE first notice of the reaction which produces aniline green was made by M. Eusebe, who dissolved crystallised aniline red in a mixture of alcohol with sulphuric, hydrochloric, or some other acid, and added a certain proportion of aldehyde or wood spirit. The solution becomes at first violet, and passes gradually to a bright blue. (The changes, however, are not constant.) Hyposulphite of soda is now added, and the mixture is heated, when the mixture assumes a beautiful green colour. The above process has many inconveniences; but the colour may be easily and quickly produced in the following

way :

150 grammes of crystallised sulphate of rosaniline are dissolved in 450 grammes of cold diluted sulphuric acid (three parts of acid to one of water). When the solution is complete 225 grammes of aldehyde are added, the mixture being stirred. The whole is now heated in a water-bath. From time to time a drop of the mixture is taken up with a stirring-rod and dropped into slightly acidulated water, and as soon as a deep green solution is obtained the reaction is stopped. The mixture is now poured into 30 litres of boiling water, and to this solution is gradually added 450 grammes of hyposulphite of

* Moniteur Scientifique, April 15, 1864, p. 362. VOL. IX. No. 231.-MAY 7, 1864.

soda, dissolved in the smallest possible quantity of water. The whole is now boiled for some minutes. All the green remains in the solution, which may be used to dye silk. The green is very beautiful, especially in artificial light, which distinguishes it from all other shades of the same colour.

PHARMACY, TOXICOLOGY, &c.

The Alkaloids of Aconite.

Aconella. This substance, the optical properties of which have been investigated by Professor Jellett, was described by the Messrs. Smith in the Pharmaceutical Journal for January of this year. The mode in which they obtained it was as follows:-Juice of aconite root is evaporated to an extract, and then exhausted with spirit of wine; the spirit having been distilled off, the remainder is brought to an extract, which is also exhausted with spirit. Milk of lime is now added to the spirituous solution, and the liquor filtered. After filtration, sulphuric acid is added till there is no further precipitate. The liquor is again filtered, and the spirit distilled off. The watery portion left, after the separation of the green fatty matter, is filtered.

The liquor is strongly acid, and is now nearly neutralised with carbonate of soda. None of the aconitine will be thrown down until the liquor is alkaline.

On being left to itself for a day or two, the still slightly acid liquor deposits an abundant precipitate, which settles partly as a loose powder and partly in a crystalline state on the sides of the vessel. This precipitate furnishes Aconella, which can be obtained in snowwhite crystalline tufts by repeated crystallisations from boiling alcohol and treatment with animal charcoal.

Aconella is very insoluble in water, but moderately soluble in boiling spirit and in ether. It is entirely consumed when burnt on platinum foil, and yields ammonia when treated with soda-lime. Tannin precipitates the oxalate, but not the muriate. It is precipitated by tincture of iodine, by corrosive sublimate, by terchloride of gold, and by bichloride of platinum. A distinguishing characteristic of the alkaloid is its tendency to crystallise. It appears to possess no poisonous qualities.

Besides the identity of optical properties mentioned by Professor Jellett last week, aconella presents so many other resemblances as to lead to the supposition that the two bodies are absolutely identical. Aconella, like narcotine, is tasteless in the solid state, but the solutions of both are very bitter. Both bodies are precipitated by tincture of iodine. Tannin precipitates the oxalate of both, but not the muriate. They have the same solubility in spirit, and the crystallisations of the two bodies are the exact counterparts of each other. Lastly, the equivalent of aconella, calculated from the platinum salt, appears to be 426.68, while that of narcotine is 427. The closeness of these numbers and the identity of the optical properties seem to leave no doubt that the same alkaloid is to be found in opium and the root of the Aconitum napellus.

Preparation of Aconitine.-The process for the Hottot, and given at page 200, vol. viii. of the CHEMICAL preparation of aconitine, extracted from a thesis by M. NEWS, has been somewhat modified by the author, who has adopted the following method of extracting the alkaloid :-Aconite root is digested in rectified spirit for eight days, and then percolated. The spirit is then distilled off over a water-bath, and the residue is treated