A considerable length of copper must be heated, and the reaction comes to an end when the copper is somewhat thickly coated with oxide. It was suggested to me by Mr. Vernon Harcourt that if the air was mixed with ammonia by bubbling through a strong aqueous solution, the oxide of copper would be reduced as fast as it was formed, and the reaction would be continuous as long as the solution contained any ammonia. Air and ammonia would give nothing but water and nitrogen 3(2N2+0)+2NH3=3H2O+7N2. On trying the experiment I found that about 3 inches of copper-turnings, heated by an ordinary Bunsen burner, served to replace the long furnace and combustion-tube of the ordinary method, and that the slightest excess of air shows itself by tarnishing the surface of the turnings. Indeed, by this method I have several times prepared nitrogen so pure that a stream of it did not alter the surface of fused potassium. 2. Solubility of Naphthalen in Water. Naphthalen is generally stated I think on the authority of Garden-to be insoluble in cold water, and but slightly soluble at the boiling-point. It is found, however, that naphthalen, like camphor, moves spontaneously when placed upon the surface of water. According to the theory of Platteau these movements are due to the high surfacetension of a solution of the moving solid. Hence this theory must be laid aside if Garden's statement be absolutely correct. Naphthalen, purified by re-sublimation through filterpaper, was boiled for some time with distilled water; the solution was allowed to cool to the temperature of the room, and filtered twice through Swedish filtering-paper. A portion of the solution was evaporated to dryness on the water-bath; no residue was left, since naphthalen is very volatile in steam, and this may have occasioned Garden's statement. Another portion of the solution was heated in a glass bulb, and the boiling-point taken by a thermometer immersed in the liquid: it was 103° C., a small piece of clean platinum wire occasioned no change. The boiling-point of freshly-boiled distilled water was then taken under exactly the same conditions; it was found to be 102'4° C., and after throwing in the clean platinum wire 102.1° C. On another occasion the solution was made from ordinary filtered water; the boiling-point, with or without the platinum wire, was found to be 103 2° C., that of the water itself being 1014° C., or with the platinum wire 101.3° C. From these experiments it seems that sufficient naphthalen remains in solution to alter the boiling-point at least half a degree, and that Garden's statement cannot NEWS be taken as being absolutely correct: hence no doubt is thrown on Platteau's theory. It may be remembered that camphor itself is but very slightly soluble in water. 3. Tests for Aniline. a. When aniline is boiled with a dilute solution of chloric acid, the colour changes through mauve, magenta, and vermillion to a clear reddish yellow liquid. Naphthylamin, under the same conditions, passes through blueblack to light yellow. B. When aniline is boiled with excess of potassium ferricyanide, the yellow solution changes to a deep chromegreen. After longer heating a blue-black precipitate falls, apparently similar to that obtained by Letheby by the electrolysis of salts of aniline. Naphthylamin, under the same circumstances, forms a yellow-green solution, with separation of a red resin. 7. When aniline is heated with a 1 per cent solution of osmic acid a thick, black, flocculent precipitate falls. Naphthylamin, under the same circumstances, forms first a purple solution, and after longer heating a brown precipitate. 4. Tests for Succinic Acid. a. Nitrate of uranium, when added to a neutral succinate, forms a very sparingly soluble pale yellow precipitate, which is soluble in acetic acid, but insoluble in solution of oil of amber, alcohol, excess of succinate of ammonia, or acetate of soda. Uranium benzoate is almost identical in appearance and properties. neutral succinate, the liquid changes to a peculiar purple B. When nitrate of cobalt is added to a solution of a or "peach blossom colour," and if the solution be concentrated a precipitate falls. On the addition of ammonia the solution so precipitated becomes more and more blue. This precipitate is soluble in acetate of soda. The presence of oil of amber seems greatly to facilitate the precipitation; as also does alcohol, but in this case the precipitate is pink. Benzoate of cobalt is red when formed in the cold, green when produced at the boiling-point; it is very soluble. ESTIMATION OF MANGANESE IN CAST-IRON. By SERGIUS KERN, St. Petersburg. THE following method is proposed for the estimation of manganese. The process is easily executed, though very accurate results are not obtained; but, however, in laboratories of iron works this method may be used, especially for the analysis of spiegeleisen. 0'5 grm. of the sample is dissolved in a high glass in 15 c.c. of hydrochloric acid, 112 sp. gr. At the end of this operation about o2 grm. of potassium chlorate is added in order to convert all the iron into ferric chloride. If silica occurs in the sample it is found in the form of a precipitate which is filtered from the solution. The liquor then contains ferric chloride (Fe2C16), and manganous chloride (MnCl2). A solution of caustic potash is next added; Fe2(HO)6 and Mn(HO)2 fall down as precipitates; to the solution is immediately added about 40 to 50 c.c. of a concentrated solution of ammonium chloride (NH3HCI), and the mixture is boiled for about ten to fifteen minutes. The liquor is then filtered from the brownish-red precipitate of hydrated ferric oxide, and to the colourless solution ammonium sulphide (NH4.SH) is added; a flesh-coloured precipitate of manganese sulphide (MnS) is obtained, which is filtered from the solution, quickly washed, placed in a porcelain crucible, and heated with sulphuric acid. Manganous sulphate (MnSO4) is then obtained, which, evaporated to dryness and next ignited, yields red mangano-manganic oxide (Mn3O4). This oxide is weighed, and as it contains 72.05 per cent of manganese, the percentage of manganese in the sample may be easily calculated. This process is based on the solubility of freshly precipitated Mn(OH)2 in a concentrated solution of NH3HCI, and on the insolubility of the hydrated ferric oxide in the same solution. My method has been used in several analyses of spiegeleisen with success, and thus may be proposed for the use of analysts. | power and of cold. The machine was constructed by L. Seyboth, of Vienna, and was contrived as follows:The carbonic acid, generated from sulphuric acid and iron-spar, was evolved in a closed receptacle at the pressure of 4 to 6 atmospheres. (To be continued.) REPORT ON THE DEVELOPMENT OF THE CHEMICAL ARTS THE difference in the effect can only be explained by the production of a far lower temperature. Within the entire machine also there is an excessive tension, so that the vapour seeks to escape at the joints, thus debarring the air from entering. The air-pump also is of much smaller dimensions as it draws and compresses a far denser vapour, thus notably reducing the loss of power due to the friction of the piston. If, however, the work is carried on at greater differences of temperature than in the common ether machine, the engine must expend more power, as appears from the theory of the air machine. For equal temperatures of evaporation and condensation the theoretical effect of the two machines is equal. Tellier keeps a sufficient quantity of methylic ether stored in cast-iron vessels capable of bearing a pressure of 10 atmospheres. On opening a cock the gas streams out, the liquid is cooled, and if the vessel is set in water this soon becomes frozen. The ether is thus certainly lost. Occasionally this method may be found useful. Other substances of low boiling-points may, like the above-named ethers, be applied for producing a fall of temperature, but no different result can be expected from their theoretical action. Thus Van der Weyde, of New York, makes use of chymogen, a constituent of natural petroleum, evaporating between o° and 16° C., of which, in the United States, a litre costs only 14 to 24 Pfennige (12 Pfennige Id. English). Liénard and Hugon, of Paris, are said to use sulphide of carbon. An original proposal by Mort and Nicolle, which may be regarded as a combination of the above-described system with the following, will be considered below. Application of Carbonic Acid.-Carbonic acid has been repeatedly proposed as an agent for the production of cold. In 1867, a provisional protection for this principle was taken out in England, but the patent was never completed. A priori carbonic acid cannot be regarded as a very suitable means for effecting a fall of temperature. It has, indeed, in comparison with all other materials hitherto proposed (except air), the advantage of cheapness, and in contrast to the ethers that of incombustibility, and therefore of freedom from danger. The pressure of the liquefied acid is, however, enormous, and hence the receivers require to be made very strong, and the connections occasion much difficulty. The temperature and tension of liquid carbonic acid show the following relations: THE most ancient chemical manuscript extant is believed to be a Greek papyrus of Egyptian origin, preserved in the library of the University of Leyden, and supposed to date from the third century A.D. This manuscript has never been fully described; the little known of it is contained in Kopp's Beiträge der Chemie, vol. i., p. 97. Some months ago, however, the literary and scientific world came into the possession of a work far surpassing in antiquity the Leyden manuscript, and of infinitely greater interest and value to the student of the history of chemistry. This remarkable work is a facsimile of an Egyptian medical treatise, written in the sixteenth century B.C., and consequently more than 3400 years old. Though strictly a medical work, it is of no less interest to the chemist than to the physician. G. F. Rodwell, F.R.A.S., author of "The Birth of Chemisty," in a recent letter to the CHEMICAL NEWS, refers to our knowledge of Egyptian chemistry in the following language:-"When we remember that the science originated in Egypt, and that the very name is derived from an Egyptian source, we can but hope that, in the progress of Egyptian discovery, as valuable information in regard to the history of chemistry as has already been found in regard to astronomy may be brought to light." This Egyptian papyrus is a first and opportune response to the desire herein expressed. The title reads thus:"PAPYROS EBERS, das Hermetische Buch über die Arzneimittel der alten Egypter in Hieratischer Schrift. Translated, the title is as follows: "PAPYRUS EBERS, the Hermetic Book of Medicine of the Ancient Egyptians, in Hieratic Writing. Published, with Synopsis of Contents and Introduction, by George Ebers. With a Hieroglyphic-Latin Glossary by Ludwig Stern. Under the patronage of the Royal Bureau of Education in Saxony. Leipzig: William Engelman, 1875, 2 vols. folio." The papyrus of which this work is a facsimile reproduction was discovered by the archeologist Ebers, during his visit to Egypt, in the winter of 1872-73. Ebers and his friend Stern were residing at Thebes, collecting archæological data, and there became acquainted with a wellto-do Arab from Luxor, who brought to them for sale a modern image of Osiris, and a papyrus of no special value. Suspecting that the Arab was holding in reserve objects of greater interest, Ebers offered him a considerable sum for any remarkable specimens in his possession. This induced the Arab to return on the following day, bringing with him a metallic case containing a papyrus roll enveloped in mummy cloths. Ebers immediately perceived he had a prize, but was unable to command the large sum of money demanded for it, until provided with the means through the liberality of a German gentleman, Max Günther, travelling in that vicinity. According to the Arab's account, the papyrus had been discovered fourteen years previously by since dead. 92 Flow of Electricity in Plane Bounded Surfaces. The original papyrus was discovered between the bones of a mummy in a tomb of the Theban Necropolis. Ebers hastened back to Leipzig with his precious roll, and deposited it for safe keeping in the University Library of that city. And now, with the co-operation of an enterprising publisher, and the assistance of royal patronage, he places it at the disposal of the civilised world by reproducing it in these handsome volumes. The papyrus, as received by Ebers, consisted of a single solidly-rolled sheet of yellow-brown papyrus, of finest quality, o'3 metre wide and 20'23 metres long. It formed one enormous book, but was divided into 110 pages, which were carefully numbered. For purposes of preservation and exhibition in convenient form the roll has since been cut into several lengths. The writing, which is exceedingly clear and regular, is partly in black and partly in red ink, the latter occurring at the heads of sec ions and in the expression of weights and measures. The characters are known as Hieratic, being a cursive form of the hieroglyphic method of writing, and bearing the same relation to the latter that our ordinary written hand does to printed characters. Hieratic script resulted from attempts to simplify the forms and outlines of the idiographic characters employed in hieroglyphic writing, which is essentially a combination of picture writing with a phonetic system. Hieroglyphics, in ancient Egypt, was the written language of the people, and Hieratic writing was chiefly confined to the sacerdotal caste. The papyrus Ebers is so remarkably well preserved that not a single letter is lacking in the entire roll. The material of the papyrus itself, the inner bark of Cyperus Papyrus, was examined by Prof. Schenck, Professor of Botany in the University of Leipzig, who established its identity with that of similar rolls, and pronounced it of remarkably good manufacture. The age of the manuscript was determined by a consideration of three points: 1. Palæographic investigations of the form of the written characters. 2. Occurrence of names of kings. 3. Examination of a calendar which occurs on the back of the first page. These data enable Ebers to assign the writing to the middle of the sixteenth century, or, more precisely, 1552 B.C. Accepting this date-and it has been established beyond reasonable doubt-the writing was prior to the exodus of the Israelites; in fact, according to the commonly received chronology, Moses, in 1552 B.C., was just 21 years of age. The authorship of this ancient work is not revealed, but it bears internal evidence of being one of the six Hermetic books on Medicine named by Clement of Alexandria (200 A.D.). The Egyptian priests, who were also the physicians, in order to give greater authority to their writings, were wont to ascribe them to their gods, and their codified medical knowledge was generally ascribed to the god Thuti (or Thoth). In proof of this Ebers quotes the following passage from page 1, lines 8 and 9, of the papyrus in question:"Ra pities the sick; his teacher is Thuti, who gives him speech, who makes this book, and gives the instruction to scholars, and to physicians in their succession." This god Thuti, also written Thoth and Taaut, is the famous Hermes Trismegistus of the Greeks, the same who was regarded by the alchemists of the Middle Ages with superstitious reverence as the father of alchemy. However this may be, all historians accord in representing Hermes as the inventor of arts and sciences. He first taught the Egyptians writing, invented arithmetic, geometry, astronomy, and music; gave laws to the people, and regulated their religious ceremonies. At the time of Jamblichus, who lived A.D. 363, the priests of Egypt showed forty-two bocks, which they attributed to Hermes (Thuti). Of these, according to that CHEMICAL NEWS { March 3, 1876. author, thirty-six contained the history of all human knowledge; the last six of which treated of anatomy of disease, of affections of the eye, instruments of surgery, and medicines. The papyrus Ebers is indisputably one of these ancient Hermetic works; a study of the Synopsis of the Contents, given further on, will justify this belief. (To be continued.) PROCEEDINGS OF SOCIETIES. PHYSICAL SOCIETY. Professor G. C. FOSTER, F.R.S., President, in the Chair. Mr. A. HADDON exhibited and described a form of tangent galvanometer, so arranged that by the aid of an electric lamp an image of the needle can be projected on the screen, and its deflections thus made evident to large audiences. A horizontal beam of light falling on a mirror inclined at 45° is thrown vertically upwards. In its path it meets with a glass box containing a lozenge-shape magnet about three-quarters of an inch long: above this needle is a graduated semicircle. The pivot supporting the needle is fixed in the centre of the glass plate which forms the bottom of the box. Above this box is a lens, and on the top of the whole is a second reflector parallel to the first. On either side of the needle is a hoop of stout brass wire, 14 inches in diameter, one end of each hoop being insulated by a piece of ebonite, while the other end is in metallic connection with a brass ring, which slides easily over the circular base of the instrument. The hoops are separated from each other by a distance equal to half the diameter of either hoop, i.e., 7 inches. The instrument having been placed at a distance from the screen equal to the focal length of the lens, and the needle brought to zero by rotating the graduated scale, the hoops are placed parallel to the magnetic meridian, and the instrument is ready for action. As an illustration of the manner in which the galvanometer is employed, Ohm's law was proved in the cases of large and small external resistance. Mr. O. J. LODGE, B.Sc., then described some investigations on which he has recently been engaged in reference to the flow of electricity in plane bounded surfaces, in continuation of a paper read before the Society in the early part of last year, by Prof. G. C. Foster and himself. After some introductory considerations, he pointed out that all the conditions of the flow of electricity are known for any number of poles in an unlimited sheet. The problem, then, consists in reducing cases of poles in bounded plates to corresponding cases in the unlimited plane, such that the flow conditions on the bounding line may be the same in both cases. The determination of these data, however, for limited planes of certain forms, presents considerable difficulty. In studying questions of this nature, there are two kinds of lines which must be considered. These are "equipotential lines" along which no electricity passes, and "lines of flow," across which no electricity passes. The boundary of any conducting surface will, of course, always be a line of flow, and, in a bad conductor, we can form an equipotential line by laying a band of copper in the required direction. If, therefore, in studying a surface of limited extent in contact with an electrode we can find a point or points outside the surface such that, if they be made electrodes, the boundary line of the surface becomes a line of flow, we are at liberty to treat the surface as part of an infinite plane, and all the circumstances are therefore NEWS known. To take the simplest case: a straight line in an infinite surface will be a line of flow if equal sources be placed in pairs on opposite sides of the line, so that one is the virtual image of the other; but if the components of each pair are of opposite sign it becomes an equipotential line. To make a circle of radius (r) an equipotential circle, we require a source, A, within, and a sink, B, without, such that CA.CB=r2. To make it a line of flow we require two sources, such that CA.CA1 = r2, and an equal sink at C, the centre of the circle. The cases of an infinitely long straight strip, and of a surface bounded by two straight lines inclined at an angle 8, were then referred to, and Mr. Lodge showed that the first requires an infinite number of external sources arranged on a straight line, and the second an infinite number on a circle, except when is a sub-multiple of, the number then becoming finite. Diagrams of the images for certain cases of triangles and squares were also shown. The dimensions of the electrodes in contact with conducting surfaces are not matters of indifference. In a plane bounded by straight lines the electrodes within and without the boundary are of equal size, but when the boundary is a circle the areas of electrodes vary as the squares of their distances from the centre. It was then pointed out that not only the poles may be reflected in this way, but also every point in | the sheet; and if the lines of flow or of potential are drawn inside a given circle for any arrangement of poles, the lines outside can be immediately obtained from them by inversion with regard to the centre of the circle by means of a Peaucellier cell. The author then described the manner in which the principle of Wheatstone's bridge can be employed for tracing out lines of equal potential. If A and B be a source and sink on a conducting ring, and P any point on the ring between A and B, and Q any point between B and A, then P and Q are of equal potential whenever PB QB If now the wire under the point P be flattened out into a surface, the above expression holds good for a certain line on that surface, which is therefore an equipotential line. Similarly, by flattening out the wire under the point A, the line for which the expression then holds good is a line of flow for a certain distribution of poles. [At this point the reading of the paper was adjourned to the next meeting of the Society.] Prof. MCLEOD exhibited a glass plate covered with a film of silver, which had in places been deflagrated by means of Leyden jars; the poles being placed at varying distances apart. The form of the surface acted upon tended towards the lemniscate of Bernouilli. NEWCASTLE-UPON-TYNE CHEMICAL SOCIETY. General Meeting, December 24th, 1875. JOHN PATTINSON, President, in the Chair. THE minutes of the previous meeting were read and confirmed. The name of Mr. W. F. Henderson, 35, Leazes Terrace, was read for the first time. Mr. RICHARDSON said he wished to make a correction with respect to what he stated at the last meeting on the subject of working the tanks in continental chemical works. He said that the first liquors which came from the tanks were used for making carbonate of soda, and that the later liquids containing sulphide were used for making caustic soda. He had since referred to his notes, and he found that the cold liquor first drawn off contained caustic soda. Afterwards the liquor contained carbonate of soda with a small quantity of sulphide; then carbonate of soda comparatively pure; and afterwards, when heat was applied, carbonate of soda largely mixed with sulphide. Mr. J. W. SWAN exhibited one of the balances con structed by Herr Bünge, Mechanikus, Hamburg, the detailed description of which would be unintelligible without a drawing. The advantages claimed for the new construction are :— 1. Extreme sensitiveness combined with "quickness." These are obtained by means of a very short and light, but strong beam of aluminum bronze. 2. Convenience in working. 3. Non-liability to derangement. The PRESIDENT said he had found the five-inch beam exhibited to turn with o'oor gr. when loaded with 100 grs., and with o'002 when loaded with 1000 grs. in each pan. Mr. SWAN said it was guaranteed to carry 200 grms. and turn with o'0001 grm. The balance shown had been carried about Newcastle, in bringing it to the meeting, exactly as it then stood. Mr. Swan also exhibited his own improvement on Scheibler's electric thermostat, and several of Mr. Fletcher's gas furnaces in action. The thanks of the meeting were offered to him. NOTICES OF BOOKS. Report of the Public Analyst to the Town Council of the Borough of Portsmouth for the Year ending September 30, 1875. Portsmouth: H. Lewis. MR. G. TURNER, Public Analyst for the Borough of Portsmouth, has officially examined one hundred and forty-five cases. Only four persons have been prosecuted, but he considers that there has been a marked improvement in the articles collected this year, especially milk and coffee. This is very satisfactory intelligence. In the analysis of butter Mr. Turner finds the method of Angell and Hehner satisfactory, though it requires much time. This difficulty he has succeeded in overcoming by the addition of methylated spirit. He On the subject of milk he considers that the average total solids in milk are 125, or 15 higher than the stan dard adopted by the Society of Public Analysts. evidently attaches no value to the results obtained by Dr. Voelcker and so eagerly welcomed by the champions of sophistication. In estimating the fat he prefers benzine to ether as a solvent, and allows the residue to digest over night. Mr. Horsley's process he does not find satisfactory. In one sample of milk, which otherwise came well within the standards, he found 1617 of mucin and a substance insoluble in cold alcohol, possibly vegetable mucin. This subject, he thinks, would well repay investigation. A Set of Chemical Labels for the Laboratory, Alphabetically Arranged. By PHILIP HARRIS and Co., Manufacturing Chemists, Bull Ring, Birmingham. · January, 1876. THESE labels are well arranged, boldly printed, and of convenient size for laboratory use. In our opinion, however, the compilers would have been wise to have simply stated facts. Present chemical theories will probably be old in the course of a year or so, and the system of notation adopted by Messrs. Harris, instead of helping the young student, will be a hindrance to him, unless indeed chemists make it a rule to re-label all their tests and reagents whenever a new system of notation becomes fashionable. Production of Silk in France. The gross weight of cocoons for the year 1873 was 9,883,580 kilos., valued at 68,614,802 francs. Of this amount 94 per cent was furnished by the eight southern departments of Le Gard, la Drome, l'Ardeche, Vaucluse, Bouches, du Rhone, Isère, and Hérault. In twenty-five other departments the production is insignificant, and in fifty-four others it is unknown. In 1874 the yield did not differ much from that of 1873.-Les Mondes. To the Editor of the Chemical News. SIR, The article by Dr. C. R. A. Wright "On the Necessity of Organisation Among Chemists," ventilates a subject of the utmost importance, and it is therefore to be regretted that the ball set rolling by Dr. Wright should be in danger of stopping, as from the paucity of subsequent letters on the subject seems to be the case. No chemist who observes the signs of the times can doubt the necessity for some such guild as that suggested by Dr. Wright, but I think its advantages may be conveniently discussed in detail. The formation of a guild of Analytical chemists would tend to reduce the number of unqualified men now calling themselves analytical chemists, and would effectually prevent further encroachments of a similar kind. As an instance of the annoyance to which professional chemists are now subjected, I may mention that some years ago I heard a druggist say in the witness-box that he was an analytical chemist, though I have good reason to believe he never made an analysis in his life. The extent of his information may be imagined when I say that a youth, since then a pupil of mine, once went to his shop for some "hydrosulphuric acid " for private use, and was instructed by the analytical chemist to "put some water to sulphuric acid, which will make hydrosulphuric acid"! Another class, generally very ready to quack as chemists, though remarkably tenacious of its own privileges, is that of the pseudo-scientific medical men. One of my acquaintance belonging to this class is very fond of talking of the "quantitative analysis he saw when assistant to Professor Brande, forty years ago," while another recently expressed an opinion that "iodide of potassium could not be accurately estimated in admixture, but he supposed it would be best accomplished by means of starch"! Unfortunately, the ignorance of these pretenders is not understood by the public, and their results and opinions are liable at any time to be quoted as gospel. I have myself suffered considerably from my liability to jury-service, and have no doubt other chemists have been similarly inconvenienced. Pharmaceutical chemists, medical practitioners, &c., are exempt from jury-service, and I fail to see why analytical chemists should not have similar advantages. Of course no such concession can be hoped for while anyone can call himself an analytical chemist; but if the proposed guild becomes an accomplished fact, I think we should have a good chance of exemption. I see the Attorney-General intends bringing in a jury bill during the current session, so there is no time to be lost if chemists are to benefit by it. It appears to me that the necessary nucleus of the proposed guild already exists in the Society of Public Analysts; of course, I do not intend to assert that all members of that Society are fit to become members of the guild. The Public Analysts' Society was originally formed to discuss and influence the proposed legislation on Adulteration, and admirably it has answered its purpose. It is well known that the Public Analysts under the Sale of Food Act are many of them quite unused to general analytical work, and would never desire or expect to be recognised as members of a Guild of qualified Analytical Chemists. Still, the Public Analysts' Society, now numbers either among its honorary or its ordinary members, nearly all the consulting analytical chemists in the Kingdom, and if it were to take in hand the work of formation of a Guild of Professional Chemists, those analysts who are not yet enrolled as members would probably give it their influence and support. Dr. Wright's proposal of a committee of leading analysts to whom all claims for admission as original members of the Guild should be referred, is, I think, an exceedingly good one. There would be no difficulty in finding half-a-dozen chemists whose decision would give general satisfaction, and I hope we may see something of the kind done without more delay. Unfortunately, we provincial chemists are too isolated to afford much active assistance in such matters, though we are probably the greatest sufferers; but if the metropolitan analysts will only take the matter up, I think they may rely on receiving the hearty support, both moral and pecuniary, of their brother chemists throughout the country. Now is certainly the time for action, and the proposal likely to receive the support of a Conservative than of a of a corporation of analytical chemists is perhaps more Liberal Ministry; but while there is a Lyon Playfair in Parliament the interests of chemists are sure to be efficiently represented. Sheffield, February 21, 1876. ALFRED H. ALLEN. SPRENGEL'S WATER-VACUUM PUMP. To the Editor of the Chemical News. SIR,-Mr. Thomson (vide CHEM. NEWS, vol. xxxiii., p. 73) should not feel any doubt as to the advisability of replying to a letter in a public journal simply because it is anonymous. If he can impugn my statements it matters not if I can sign myself the President of the Society. If, on the other hand, my argument is not refutable, it will not be weakened by having attached to it the name of the merest tyro in science. Whatever idea Mr. Thomson wished to convey by the expression "Bunsen's vacuum pump," the effect produced on the mind of the general reader is that Bunsen was the inventor of the water-vacuum pump, which is simply not the fact. In support of this assertion I think I have already adduced sufficient proof. I may, however, add that in nearly every case in which mercury is mentioned in Sprengel's paper he adds "or any other liquid. He also gives the mathematical data for calculating the proportions of the pump when water is employed. He has since told us that he preferred mercury as the most suitable of the two liquids for exhibiting the truth which he had discovered by means of a water-air pump in 1863. Mr. Thomson says the history of this matter is well known to every chemist. Herein I must differ from him, for I cannot believe that, if it were so, such misrepresentation would occur. If Mr. Thomson knows more than has been furnished by Sprengel and Bunsen let him tell us what it is. Till he does so I must believe Sprengel and Bunsen's statement (Philosophical Magazine, February, 1873).--I am, &c., SODIUM AMALGAM. F.C.S. To the Editor of the Chemical News. SIR,-Were one to judge from the writings of practical chemists (and by way of example I may take the wide range afforded by Roscoe's "Primer to the excellent paper in the CHEMICAL News, vol. xxxiii., pp. 47, 58, by Dr. Davy "On the Detection of Arsenic ") the preparation of sodium amalgam is not an easy, and may be a dangerous process. The proper modus operandi is certainly not original with me (I think I saw it many years ago in the CHEMICAL NEWS), but as it would seem to need recalling, and as I have always used it with much comfort, I think it not inopportune to describe it. Melt the sodium under solid paraffin, then pour in the mercury in a thin stream. Of course any quantity of mercury may be used from equivalent proportion to that necessary for the production of a fluid amalgam. There |