Obrazy na stronie


On Lecture Illustrations.


July 28, 3865.

Fig. 1.

subsist between hydrochloric acid, water, and ammonia ; This apparatus has to be filled with an appropriate and in particular I have shown you that some of the best volume of the gas to be examined. For this purpose the known products of tissue metamorphosis are in reality U-tube is first filled with mercury, and then the nipperonly the ammoniated forms of comparatively well known tap is set open, so as to afford a gradual exit to the metal bodies. In my next lecture I shall endeavour to satisfy in the open limb. The delivery-tube of a gas.generating you that the complex character of many organic bodies is apparatus is then passed down the open limb to the bend more apparent than real, and that most of them may be of the tube, in such a manner that the gas bubbles up resolved into comparatively simple molecules, which are through the mercury into the sealed limb, from which, capable of being distributed into certain well defined groups of course, the metal and series; and I shall take, as a concrete illustration of the escapes as the gas enters point I wish to establish, the composition of salicine among volume for volume. An vegetable, and of hippuric acid among animal products. appropriate quantity of

dry hydrochloric acid

gas having been thus ON LECTURE ILLUSTRATIONS.

introduced, the nipperBy A. W. HOFMANN.

tap is closed, and mer

cury is poured into A Discourse Delivered to the Members of the Chemical the apparatus, until it Society, Thursday, February 2.

stands at the same level (Reprinted by permission of the author from the Journal of the in both limbs. The Chemical Society, Ser. 2, vol. iii., p. 156.)

space occupied in the The introduction into modern chemistry of the idea of tube by the gas is then structural types, and the prominence given thereby to marked in any convevolumetric considerations, involve the necessity of modi- nient way; preferably fying, to a certain extent, our present style of experi- by a caoutchouc ring mental illustrations. This necessity, I believe, has been slipped over the tube felt by many teachers who have endeavoured to reflect (Fig. 1).* the present aspect of chemistry in their lectures. In

That portion of the open limb which is unoccupied by these endeavours many new and interesting experiments mercury is then filled with sodium-amalgam, and the must have been devised already; and if an interchange orifice of the tube is closed, either by the thumb, or more of the valuable information thus acquired could be conveniently, hy a glass stopper. The gas way now, by effected, a large expenditure of time and labour would inclining the tube adroitly, be easily transferred from the be saved to those engaged in teaching chemistry. The sealed to the stoppered limb; traversing of course, in its Chemical Society, comprising as it does a great many passage, the column of sodium amalgam, and being thereprofessors of our science, appears to be an appropriate by decomposed. To insure complete decomposition, the centre to attract this floating knowledge for condensation and distribution. It is in the conception of this mutual apparatus should be once or twice shaken, so as to bring benefit which we might derive from communications of amalgam ; after which, by reversing the previous inclina

every portion of the gas into thorough contact with the this kind, that venture to submit to the Society an account of some of the volumetrical experiments on the sealed limb of the apparatus. On removing the stopper

tion of the tube, the gas may be re-transferred to the composition of the typical hydrogen compounds, with

or thumb from the the study of which, during the last few years, I have mouth of the open

Fig. 2. been in the habit of opening my course of lectures on limb, the mercury experimental chemistry.

falls a little therein, HYDROCHLORIC ACID.

and may be further The usual method of illustrating the composition of lowered by opening hydrochloric acid, recommended in Manuals on Experi- the nipper-tap. As mental Chemistry, consists in introducing a small ball of soon as the mercury sodium into a volume of the gas, contined over mercury. stands at a uniform Since the metal has to be heated, the upper part of the level in the two limbs tube is bent (cloche courbe). It need scarcely be men- the gas is found retioned that a vessel of this form is very little appropriate duced to exactly half for comparing the rolume of the hydrochloric gas with its original volume the volume of the hydrogen gas evolved by the action of (Fig. 2). The resisodium; hence the necessity of measuring the gas in a duary gas is readily graduated tube, of transferring it to the cloche courbe, and recognised as hydroof re-transferring it to the graduated vessel, after the gen, by transferring action has taken place. The experiment thus becomes it to the open limb; tedious, difficult, and inaccurate. Again, how is it pos- or, the closed limb may be provided with a glass stopsible to introduce the metallic sodium into the gas without cock (see Fig. 11), and ihe hydrogen expelled by pouring its surface having become oxidised : Not to speak of the mercury into the open limb. In either way the gas is rapidity with which the metal is amalgamated during its found to be inflammable, and to burn with the pale passage through the mercury.

flame of hydrogen gas. By adopting the following mode of proceeding these This experiment shows us that a given bulk of hydrodifficulties are in a great measure obviated.

chloric acid contains half that bulk of hydrogen. It only A U-shaped glass tube, about 50 centimetres long by remains, therefore, to determine with what proportion, by 1'5 in diameter, having one sealed and one open limb, is volume, of chlorine, this bulk of hydrogen is combined in fixed upon a convenient stand. Just above the bend of hydrochloric acid. the tube, the open limb has a small outlet tube (blown on at the lamp), and to this is affixed a piece of caoutchouc hydrochloric acid to electrolysis in any convenient appa

This we learn from a second experiment. We submit tubing, with an elastic wire nipper (nipper-tap) attached, or provided with a screw (screw-tap), by the action of * The illustrations given in this lecture are taken from a little which the caoutchouc tube is pinched close, but can be work shortly to be published, entitled, " Introduction to Modern readily opened at pleasure.

: Royal College of Chemistry, London."

FIG. 4:

, }
On Lecture Illustrations.

43 July 28, 1865. ratus which permits collecting the gases evolved during water (the receptacle for which should be a tall glass the process. At starting, the chlorine is almost entirely cylinder, to facilitate this part of the manipulation), until absorbed by solution in the surrounding liquid : nor is it the level of the liquid within and without the tube is till this is saturated that the chlorine begins to be mani. brought into coincidence. It is then found that the tube fested in a stream of bubbles, like those which, from the is just half filled with liquid ; in other words, that just first, mark the escape of hydrogen at the opposite pole. half its gaseous contents have been absorbed. That the At this stage of the process the delivery-tube of the appa- absorbed gas is chlorine is readily proved by the bleaching ratus is attached, by means of a caoutchouc connector, to effect exerted by it on the log wood solution. a glass tube, about 40 or so centimetres long by 1'5 centimetre in diameter, drawn out, before the lamp, to a fine point at each end. This tube is thus filled with the mix. ture of hydrogen and chlorine evolved by the electrolysis of hydrochloric acid. In order to expel every trace of air, it is necessary that the mixed gases should be suffered to traverse the tube for a considerable time. To prevent the chlorine escaping into the air, the free end of the tube is connected with the lower part of an upright cylinder containing coke, moistened with an alkaline liquid capable of absorbing the chlorine. After the lapse of one or two hours the operation may be considered complete. The tube being now detached, its fine-drawn ends are immediately sealed.

The tube having been sealed at each end, its gaseous contents have next to be examined. For this purpose it is requisite to bring the mixed gases into contact with a liquid capable of absorbing the chlorine, but not the hydrogen. Water, of course, answers this purpose, but a little soda may be conveniently mixed with it to increase its absorptive power. Again, the addition of a vegetable colour-of an infusion of logwood, for instance-to tint the soda solution employed, is useful as a means of evincing the presence of chlorine by exhibiting its bleaching action on the colour, so soon as it comes into contact therewith. By plunging the sealed finely-drawn extremity The nature of the residuary gas is as readily demon. of the tube into a solution so prepared, and then breaking strated by immersing the tube more deeply in the surit off, the desired contact is effected, absorption begins, rounding liquid, then breaking off its upper finely-drawn and the liquid is seen slowly rising into the tube to occupy point and applying to the jet of gas, thus forced out by the space vacated by the absorbed chlorine. This absorp- water pressure, a lighted taper, when it immediately tion goes on very slowly, however, because of the extreme takes fire, and burns with the characteristic pale flame minuteness of the surface of fluid exposed to the gas in of hydrogen. the finely-drawn tube represented by the broken extremity. These phenomena furnish a simple and satisfactory reply A great acceleration would evidently be obtained if the to the question left unanswered by our previous experiment. surface of contact could be extended; if, for example, we The action of sodium upon hydrochloric acid has taught could wet the whole interior surface of the tube with the us that 2 volumes of hydrochloric acid contain 1 volume absorptive liquor.

of hydrogen; the electrolysis of hydrochloric acid proves A very simple contrivance (Fig. 3) accomplishes that, to form hydrochloric acid, i volume of hydrogen

combines with i volume of chlorine. It consists of a caoutchouc connecter tightly The two experiments, taken together, supply us with fitted to the end of the tube, so as to cover and the exact points of information which our previous enclose its fine-drawn sealed neck. This con- investigation of hydrochloric acid left deficient; so that, necter is provided with a small glass funnel, summing up our previous and present results, we now through which it can be filled with a tinted possess a complete and irrefragable demonstration-first, solution of soda ; and has also a stop.cock, by that hydrochloric acid is composed of hydrogen and which, when so filled, it can be closed. These chlorine; secondly, that these two elements are its sole arrangements being made, the fine-drawn neck constituents ; thirdly, that they are united in equal is immersed in the solution, so that, on breaking volumes to form it; and, lastly, that, in so uniting, they it (Fig. 4), which the flexibility of the connecter undergo no condensation, but produce a volume of comallows to be easily. done, the solution finds its pound gas equal to the sum of the volumes of its

way through the orifice into the interior of the elementary constituents. apparatus. By suitably inclining this, the solution may This last-mentioned fact-the union of hydrogen and be caused to extend in a film over its interior, so as to chlorine without contraction or expansion-may be illusexpose a widely-spread surface to the gaseous mixture. trated by another, and an equally conclusive, experiment. The absorption of the chlorine is thus made to proceed While the electrolytic apparatus, used in the experiment with greatly increased rapidity, as is evinced by the speedy just made, is still evolving hydrogen and chlorine in the ascent of a small volume of the liquid into the wide part proportion in which the two gases exist in hydrochloric or body of the tube. This accomplished, that end of the acid, we may replace the wide glass tube, previously used, tube which is armed with the tap-funnel and its flexible by another tube of equal length, but of stouter glass, and connecter may be plunged under water, the connecter of smaller bore, half a centimetre being a convenient withdrawn, and the experiment continued in the ordinary diameter. The two ends of this tube are, like those of the way, by allowing the absorption to proceed, and the tube used in the previous experiment, drawn out into very column of liquid to ascend in the tube till all the chlorine fine necks. As soun as the tube is thoroughly purged of is absorbed. This is known to have taken place by the air, and exclusively filled with the gaseous constituents of liquid ceasing to rise in the tube.

hydrochloric acid, its fine necks are sealed by the blowThe tube is now to be more deeply immersed in the l pipe jet, and its contents are exposed to the action of light

FIG. 3. this object.

On Lecture Illustrations.


July 28, 1865. for the purpose of inducing the combination of the mixed from which it is clear that the combination of the gases gases.

has taken place without either contraction or expansion This effect, as is well known, may be obtained either by of their volume. natural or artificial light. The direct rays of the sun pro- The next indication is obtained by pouring water on duce instantaneous combination. But as such rays are the mercury, and raising the tube so that its orifice, not at our command in all seasons and at all places, as, for instead of plunging into mercury, may open into water. instance, during the earlier weeks of a London winter, it The water no sooner comes into contact with the gas than is necessary to employ an artificial light sufficiently intense this latter is dissolved ; and so rapid is the absorption that to bring about the same effect. Such a light is that of the water rising in the tube fills it almost instantaneously. the blue flame produced by the combustion of bisulphide We thus obtain an additional experimental proof that of carbon in nitric oxide. The manipulation for generating hydrochloric acid is formed by the union of hydrogen and this light is very simple.

chlorine gases, in equal volumes, without condensation. For this purpose some eight or ten cubic centimetres of In performing this experiment, whether sunlight or the bisulphide of carbon are introduced into a tall glass light of bisulphide of carbon be employed, some manipucylinder filled with nitric oxide gas. This is most con- latory precautions are necessary to shield the operator veniently accomplished by means of a very thin bulb of from possible injury by the explosion of the tubes. The glass, blown to the required size, filled with ihe bisulphide, experimentalist should not omit to protect himself by a and then sealed at the lamp: The glass cover of the screen, for which purpose a sheet of stout plate-glass may vessel, already filled with nitric oxide gas, is drawn aside, be conveniently employed. Thus, even should the tube the bulb drawn in, and the cover quickly replaced. Con explode, the dangerous scattering of its fragments is pretact of atmospheric air is thus almost entirely obviated. vented. It is, however, only rarely that the body of the The vessel is then shaken, so as to break the glass bulb, tube is shattered ; in most cases the fracture is confined and the desired mixture of gas and vapour is at once to one or other of the sealed points. To avoid the loss of obtained. A match is now applied to the opened mouth of the experiment by an accident of this kind, the upper the cylinder, when the mixture within takes fire, and burns point of the tube may be strengthened by imbedding it in with a brilliant, intensely blue flame, which descends into sealing-wax, which may be most conveniently applied by the vessel. The radiance of this light instantaneously fusing a little in a small piece of glass tube sealed at one induces the combination of hydrogen and chlorine ; the end, and plunging the point to be protected into the fused effect being indicated by a flash of light, accompanied by mass, which is then allowed to cool and harden. As for a slight clicking sound, and followed immediately by the the lower point, escape of gas from this, in case of rupture, disappearance of the greenish colour of the mixture. is readily obviated by keeping it immersed in a trough

The figure (5) shows the disposition of the apparatus. cylinder filled with mercury. To the left is the glass cylinder in which the light is

WATER. generated ; to the right are placed the mixed gases to be acted on, two tubes instead of one being filled therewith in water is, of course, most conveniently established by

The ratio in which hydrogen and oxygen are associated and employed in the experiment, to afford a double chance the electrolysis of this compound. of success, since the combination occasionally fails from

Among the numerous contrivances used for decomposcauses not yet perfectly ascertained.

ing water, an apparatus constructed some time ago by Professor Buff, of Giessen, deserves to be especially mentioned. The two tubes for the collection of the gaseous constituents of the water are provided with brass stopcocks, and plunged into a deep cylinder filled with water. As the gases are evolved, the water-level in the tubes is depressed below the level in the cylinder, and on opening the stop-cocks, the gases escaping under the pressure of the short water column may be conveniently examined.

Fig. 6 shows an improved form of this apparatus. Instead of the two stop-cock tubes separately inverted in a basin, as just described, I have adopted a three-branched tube, with one long and two short limbs. The long limb acts as a water-reservoir, instead of the basin ; the two short limbs, which are fitted with stop-cocks, or nippertaps, above, and which communicate freely with the long limb below, contain, intermediately each a platinum electrode. When this apparatus is used, the water in the short limbs is forced downward out of these so as to rise in the long limb, forming a column, the weight of which serves afterwards to expel the gas from each short limb through the corresponding stop-cock, when this is opened for the purpose of testing the nature of the gas obtained.

It now remains only to be demonstrated that two volumes of hydrogen and one volume of oxygen, when combined, yield two volumes of water-gas. This fact, familiar to us from the earliest stage of our chemical education, is, strangely enough, scarcely ever demonstrated by experiment in our lectures. As to myself, I have only since the volumetric conception of matter has acquired such predominant importance, commenced performing this experiment.

The object to be achieved is the comparison of the For the purpose of examining the product, one point of volume of the elementary water-constituents with that of the tube is broken under mercury, when the first indica- the water formed, at a temperature high enough to maintion is immediately obtained. It is observed that neither tain the latter in a purely gaseous condition. des gas escape from, nor mercury penetrate into the tube; The experiment is made in a U-tube similar to that used

Fig. 5.


July 28, 1865.5

On Lecture Illustrations- Academy of Sciences.


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one of oxygen; it is, however, prepared much more readily in due volumetric proportion, and in a state of perfect purity, by the electrolysis of water. The gas-filled limb of the apparatus is surrounded by a high glass cylinder, the lower mouth of which is fastened around it by means of a perforated cork, whilst its upper mouth (likewise closed by a cork) rises about five centimetres above the sealed extremity. The annular space thus formed communicates, at its upper end, by means of a bent glass tube and a perforated cork, with a flask which contains a liquid having a boiling point considerably above that of water ; amylic alcohol, which boils at 132° C., is well adapted for the experiment. On protracted ebullition, the vapour descends from the flask into the annular space, which rapidly acquires a uniform temperature of 132o. To prevent the vapours from escaping into the atmosphere, the lower extremity of the glass cylinder is connected with an appropriate rapour-condenser, such as a glass coil kept cool by water. Under the influence of heat, the column of mixed hydrogen and oxygen in the tube expands. The level of the mercury in both limbs of the apparatus having been adjusted, the height of the gas columns is now marked by any suitable means; preferably by slipping a caoutchouc ring over the outer glass cylinder. A little more mercury is then poured into the open limb, which is, lastly, closed by a well-fitting cork. Between this cork and the mercury intervenes a column of air, some eight or ten centimetres in length, and capable of yielding to pressure,

like a spring. It now only remains to inflame the gaseous mixture by causing the current of the inductioncoil to leap, in the form of a spark, between the platinum

points. The gases combine with an explosion, which is, however, much mitigated in violence by the elastic action of the above-mentioned air column. At the high temperature employed (1329) the water formed retains the gaseous condition. On removing the cork, and allowing the mercury to flow through the nipper-tap, until it is level in both limbs, it becomes obvious that the original measure of mixed gases is diminished by one-third ; the residuary twothirds are water-gas, which condenses into liquid water so soon as the apparatus is allowed to cool.

Thus, therefore, it stands experimentally demonstrated, first, that hydrogen and oxygen undergo condensation in combining to form water; and, secondly, that the volume of the water-gas produced holds an extremely simple ratio to the volume of its constituent gases, two volumes of hydrogen and one volume of oxygen condensing, by their union, into two volumes of water-gas.

(To be continued.)

Fig. 7.


July 17.

in analysing hydrochloric acid. The closed limb of the

ACADEMY OF SCIENCES. tube is, however, fitted, at a point near its sealed extremity, with two platinum wires, for the purpose of passing the electric spark ; this operation I now invariably perform by M.Troost communicated some " Researches on Zirconium." means of the induction-coil.

To obtain crystallised zirconium, the author heated in a A glance at Fig. 7 shows how this apparatus is employed. retort-coke crucible to the temperature of melted iron a Into the sealed limb of the apparatus, which is filled with mixture of the double fluoride of zirconium and potassium mercury, we admit a column, about 25 or 30 centimetres and metallic aluminium. When the crucible was cold the high, of a mixture of hydrogen and oxygen in the propor- surface of aluminium was found covered with crystallised tions in which they form water. This mixture may, of lamellæ, lying one on the other, like the leaves of a book. course, be obtained by adding two volumes of hydrogen to. There were crystals of zirconium. This element also exists


Notices of BooksNotices of Patents.

July 28, 1865.

in the graphitoidal form, the preparation of which is the Action of Sodium Amalgam on Hippuric Acid." These, uncertain. M. Troost establishes that zirconium stands it would appear, are two : hydrobenzuric acid, 18H4N206, in the carbon group in the same position as antimony in and hydrobenzyluric acid, 616H2, NO. The author fully the nitrogen group.

It comes between the metalloid describes the relations of these bodies, and the products of silicium and the metal aluminium, as antimony comes their decomposition by alkalies and hydrochloric acid. between arsenic and bismuth. The carbon group, then, A note by H. Limpricht, “ On Phosphoric Ethyl-ether," is constituted as follows: · Carbon, boron, silicium, follows. The author's mode of preparing this body is as zirconium, aluminium.

follows:-Sodium is dissolved in absolute alcohol, and anhydrous ether added; a quantity of oxychloride of

phosphorus calculated according to the following equaNOTICES OF BOOKS.


36,H.NaO + POCI, = 3NaCl + P(€,H). A Letter to the Members of the British Medical Association is then added in small quantities, so that the temperature

on the Subject of their Future Journal. By R. B. CARTER, is not much raised. The liquor is filtered from the chloride F.R.C.S., etc. London. 1865.

of sodium, and rectified by distillation. The properties of The author of this letter is of opinion that, to advance the phosphoric ether are well known to our readers. interests of the medical profession, it is advisable that the

The title of a paper by Carius sufficiently describes its British Medical Association should give up their present contents : "On the occurrence of Cæsium and Rubidium in Medical Journal, and publish a Quarterly Journal of Plutonic Silicates of the Rhine Provinces. Literature, Science, and Politics." He complains that In a note "On a New Transformation of Leucin," Dr. the educated public do not sufficiently appreciate the Pro- Kohler makes known that, when leucin is treated with fession, which he says has no means of influencing public dry hydrochloric acid, an atom of water is eliminated, and opinion, and he thinks that by establishing such a journal a new body_formed, which the author proposes to call as that mentioned above, and by dosing the public (gently leucinimid. In the next paper Dr. Preu shows that when at first) with medical topics, they might be gradually alanin, an analogue of leucin, is similarly treated, the brought to entertain sound views on the rights, dignities, same change takes place, and lactimid

is formed. and duties of Doctors.

A notice by Martius and Griess, “ On a Compound from As the Association is just about to meet, and the change Naphthaline Isomeric with Alizarin,” describes the comsuggested in this letter will be discussed at the meeting, pound mentioned in our reports of the

Academy of Sciences we may, perhaps, as part of the public, be allowed to say

as discovered by MM. P. and E. Depouilly (chloroxy. a word on the inatter. We say, then, that to medical naphthalic acid) whose account in the Comptes- Rendus is politics we are profoundly indifferent. What we do feel much fuller than that given here. an intense and personal interest in is the progress of the

The other papers in this journal call for no notice. "healing art," and we believe that just as the knowledge of this is advanced, the medical profession will rise in

NOTICES OF PATENTS. public estimation. The question that the Association should discuss then, we think, is this,–What journal will best aid in developing and diffusing among the members GRANTS OF PROVISIONAL PROTECTION FOR sound scientific information on the art of curing disease?

Communicated by Mr. Vaughan, PATENT AGENT, 54, Chancery

Lane, W.C.
A Course of Practical Chemistry; arranged for the Use of 1585. E. T. Hughes, Chancery Lane, " Improvements

Medical Students. By WILLIAM ODLING, M.B., F.R.S., in the means of producing from rosaniline blue and violet &c., &c. London: Longman and Co. 1865. Second colouring matters soluble in water.” A communication Edition.

from P. Mounet, Lyons.- Petition recorded June 12, 1865. This is the second edition of a good book now greatly

1703. C. Worssam, Kingsland koad, and G. Evans, enlarged and improved. It is said to be specially arranged Gloucester Place, Portman Square, “An improved pulpfor the use of medical students, but, we need hardly say, ing and compressing machine for the treatment of peat as it is equally well adapted for pharmaceutical chemists, and a fuel and gas for illuminating purposes."-June 26, 1865. is indeed an excellent introduction to analysis for any

1716. H. G. Fairburn, St. Luke's, Middlesex, “ An students. It is worth mentioning that the old scale of improved mode of combining and forming small coal or atomic weights has been exclusively employed throughout coal dust into lumps, blocks, or otherwise, to be employed the body of the work ;” and that a very useful chapter on for the purposes of fuel.”—June 28, 1865: Chemical Manipulations, which greatly increases the value

1785. C. F. Claus, Fearnhead, Lancashire, “ Improveof the book, now precedes the analytical part.

ments in obtaining sulphates and carbonates of potash and

soda.”—July 6, 1865. Annalen der Chemie und Pharmacie. June, 1865.

1793. J. M. Macrum, Hill Street, Knightsbridge, “ImHLASIWETZ AND Barth continue their chemical studies tion from J. Williams and J. Copley, Allegheny, Penn.,

provements in the manufacture of iron." A communica“ On Resins," describing in this article the decomposition U.S.A. products of the action of fused alkalies on resins. They have experimented upon benzoin and dragon's blood, and improved portable pocket gas-generator or gazogene."

1795. A. F. Morelle, Boulevard Sebastopol, Paris, “An also upon socotrine aloes. All these bodies, when fused with caustic potash, give paraoxybenzoic acid, 6.11.43, Little Horton, Bradford, " Improvements in manufacturing

1797. J. Peel, Bowling, Bradford, and W. Hargreaves, aloes yielding the largest proportion. Dragon's blood grease from soap suds." --July 7, 1865; yields, in addition, some benzoic acid, protocatechuic acid, and phloroglucin. Benzoin also gives protocatechuic and the production of artificial light and in the apparatus con

1809. J. Baggs, Chancery Line, “ Improvements in oxyphenic acids. The authors append to their paper a table of the composition of guaiacum, dragon's blood,

nectid therewith." gum, benzoin, galbanum, and aloes, the products of their the manufacture of cast steel.”-A communication from

1813. R. A. Brooman, Fleet Street, “Improvements in dry distillation, and the results of their oxidation by C. Pauvert, Tarbé, France.—July 8, 1865: potash. We hope to find room for this table at a future time.

1831. H. A. Dufrené, Rue de la Fidélité, Paris, "ImA paper by Otto describes the " Froducts arising from | A communication from Viscount C. de Sequeville, Milan.

provements in the treatment of copper and nickel ores."

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