arsenical vapours are given off during the action of, CHEMICAL NOTICES FROM FOREIGN arsenical sulphuric acid on bones or coprolites. On the medical question involved I have no opinion to offer.I am, &c., 83, Hope Street, Glasgow. ALEX. T. MACHATTIE. [We have also received a long communication on this subject from Dr. Adams, and a further letter from Dr. Milne stating that blank experiments were made. This fact should, in our opinion, have been stated more explicitly in the book. We can devote no more space to the subject, it being contrary to our custom to insert letters referring to our reviews of books, unless, indeed, | they point out a manifest injustice to the author, and this we do not admit to have been the case in the present instance.-Ed. C.N.] IMPROVED FORM OF ASPIRATOR. To the Editor of the Chemical News. SIR,-In the CHEMICAL NEWS (vol. xxxiv., p. 141) Mr. Richards describes an "Improved Form of Aspirator." This is somewhat similar in principle to one I constructed about four months ago, the chief difference being that Mr. Richards's pump requires a water pressure of 20 pounds to the square inch to exhaust "to within 1 m.m. of the tension of aqueous vapour," while mine takes less than 5 pounds only to produce a vacuum (less, of course, by the tension of aqueous vapour.) I append a drawing of my arrangement. SOURCES. NOTE. All degrees of temperature are Centigrade, unless otherwiɛe expressed. Comptes Rendus Hebdomadaires des Seances, de l'Academic des Sciences. No. 12, September 18, 1876. Lighting by means of Products Extracted from Resinous Trees.-M. A. Guillemare.-The author remarks that if an attempt is made to burn in a common lamp, adapted for oil of colza or petroleum, either oil of turpentine, "essentia viva," or the oil known as pyrogene (the two latter being extracted from resin by fractional distillation over 4 per cent of quicklime), two difficulties are met with which have hitherto proved insurmountable. The resinous liquids of commerce only rise into the wick for a few minutes, after which the capillary action slackens considerably and soon stops. In all the lamps of commerce these same liquids burn imperfectly and diffuse an intense smoke. It is therefore needful to purify them perfectly, aud to contrive a special jet or burner for their use. The clogging of the wick is due to the presence of resin or of naphthalen in solution. These impurities are removed by distillation over an equal volume of water rendered slightly alkaline, a current of steam being passed through the apparatus, and by exposing the oils to the direct and prolonged action of concentrated solutions of alkaline carbonates. The oils may be regarded as perfectly pure when they are no longer rendered milky by the addition of ammonia. A new burner has been devised, the construction of which is not quite clear, but which is said to prevent the formation of smoke. Physical Properties of Gallium.-M. Lecoq de baudran.-Inserted in full. Justus Liebig's Annalen der Chemie, Investigations on Bodies of the Hydrobenzo and Stilben Series.-T. Zincke.-An introduction to th next paper. Various Hydrobenzoins, or Stilben Alcohols.-C Forst and T. Zincke.-A very bulky essay, extending 50 pages, and unfit for abstraction. Apparatus for the more Convenient Determination of Nitrogen. Karl Zulkowsky.-An improved instrument for the determination of nitrogen by the method of Dumas, calculated to be of great value in laboratories where such determinations are frequent. The apparatus cannot be described in an intelligible manner without the aid of the accompanying illustration. On Ultramarine.-Dr. Carl Boettinger.-It has always been assumed that the formation of the blue colour of ultramarine depends on the action of oxygen: but in cracked ducts are often observed, which, on washing with water, crucibles and on the edges of the blue mass white prolose almost all their sulphur in the form of sulphate. That this phenomenon is due to oxidation seems to require no destroyed by oxidation. In the author's opinion ideal further proof. Hence, then, it appears that the colour is ultramarine is a compound of silicate of alumina and soda with pentasulphide of sodium. Communications from the Chemical Laboratory of the University of Moscow.-These communications include a paper by W. Markownikoff on isomeric tartaric acids, and one by the same author on the normal oxypyro-tartaric acid (glutanic acid), and the isomerism of the pyrocitric acids: an account of the preparation of trimethylen-bromide, by J. Lermontoff; on aceton in the urine of diabetic patients, by W. Markownikoff; on certain constitnents of Adonis vernalis, by F. Linderos; and a preliminary communication on isomeric dibrom-anthracen, by Oswald Miller. Les Mondes, Revue Hebdomadaire des Sciences, Adulteration of Wines.-The author remarks that so long as falsification consisted merely in heightening the colour of wines with logwood and other vegetable matters it was only a semi-evil, though still considerable enough, since one of the dyes most commonly used was a drastic purgative. But magenta has now come into use on a scale scarcely to be imagined. A small commune in the neighbourhood of Béziers, containing only 1800 inhabitants, has consumed in one year 30,000 francs worth of this colour entirely for sophisticating wines. MISCELLANEOUS. Birmingham and Midland Institute.-The following are the lecture arrangements for the session 1876-7 :— This day (Friday), October 13.- Lieut. Cameron, D.C.L., on "Recent Explorations in Africa." An Analytical Query.-In separating arsenic, &c., from copper' &c., by treating with an alkaline sulphide, I generally get the filtrate rather dark, and it seems to contain not copper in solution, but finely divided. I believe there is a way of preventing even a slight trace of copper getting through. I have looked at many analytical works but have failed to see anything about it, except the diluting, but that I have always done. I have taken in the CHEMICAL NEWS for years but have never seen anything on the subject.-ROBERT MONGER. October 16.- Captain Davis, R.N., F.R.G.S., on "Antarctic Discovery, and its Connection with the THE Transit of Venus, 1882. October 23, 30.-Prof. W. C. Williamson, F.R.S., on "The Early Forms of Animal Life," and "The Early) Forms of Vegetable Life." November 6, 13.-George Dawson, M.A., on "Horace Walpole." November 20.-Wm. Huggins, D.C.L., LL.D., F.R.S., on "Spectrum Analysis Applied to the Heavenly Bodies." November 27, December 4.-Arthur Arnold, on "Persia." December 11.-Prof. Boyd Dawkins, M.A., F.R.S., F.S.A., on "The Ancient Inhabitants of the Caves of Derbyshire." January 22, 29.-E. Ray Lankester, M.A., F.R.S., on "Rots and Ferments, our Unseen Enemies." February 5, 12.-Edward Dannreuther, on "The Pianoforte Works of Liszt and Chopin." February 19, 26.-Prof. Sidney Colvin, M.A., on Olympia and Greek Athletics; a Study of Ancient Usages and Recent Discoveries." March 5.-Prof. J. M. D. Meiklejohn, M.A., on "Parody." March 12.-Prof. Sir C. Wyville Thomson, LL.D., F.R.S., on "The General Results of the Challenger Expedition." March 19, 26.-Prof. W. Barrett, F.R.S.E., on "Radiation and Radiometers." April 9, 16.-George Dawson, M.A., on “Sir Walter Raleigh.' NOTES AND QUERIES. ** Our Notes and Queries column was opened for the purpose of giving and obtaining information likely to be of use to our readers generally. We cannot undertake to let this column be the means of transmitting merely private information, or such trade notices as should legitimately come in the advertising columns. Fluoride of Potassium.-Can any of your readers give me a process for the ready production of Aluoride of potassium.-FLUORINE. LECTURE NOTES FOR THE USE OF CHEMICAL STUDENTS preparing for Matriculation (University of London), aminations. By THOMAS ELTOFT, F.C.S., Chemical Teacher to the College of Surgeons, Science and Art Department, and other ExMatriculation Classes, St. Bartholomew's Hospital; Chemical Lecturer, City of London College, St. Thomas, Charterhouse, Science Schools, &c. Cloth, post 4to. London: SIMPKIN, MARSHALL, and CO., Stationers' Hall Court Manchester: JOHN HEYWOOD, Deansgate. ANDERSON'S UNIVERSITY, GLASGOW. THE "YOUNG" CHAIR OF TECHNICAL CHEMISTRY. Professor E. J. MILLS, Dr. Sc. (Lond.), F.R.S. SESSION 1876-7. LECTURES. A COURSE of FIFTY LECTURES on TECHNICAL CHEMISTRY will be Delivered during the Session, on MONDAY, TUESDAY, and WEDNESDAY in each Week, at 9 a.m., beginning on WEDNESDAY, 1st NOVEMBER. The Lectures will be ilustrated by the actual Inspection of Manufacturing Processes. They will include this year, as special subjects, the ALCOHOL INDUSTRY, Potable Waters, Sewage, and General TECHNICAL SANITATION. Fee for the Course Two Guineas; Laboratory Students Free. The attention of Young Men qualifying for the Professions of Civil and Mining Engineers, Architects, &c., as well as those more immediately interested in the Study of Chemistry, is called to this Course of Lectures. A Course of Thirty Lectures on TECHNICAL ORGANIC CHEMISTRY will be commenced on April Is". These Lectures are more especially intended for Dyers, Colour Manufacturers, Brewers and Distillers, Tar Rectifiers, and Drysalters. Fee for the Course Two Guineas. LABORATORIES.-The Laboratories will be Open Daily, on and after Wednesday, 1st November, from 10 a.m. to 4 p.m. (Saturdays 10 a.m. to I p.m.), under the Superintendence of the Professor and his Assistants. Instruction given in the Preparation of Chemical Substances and Original Research, especially as relating to Manufacturing Processes. Fees-Whole Session of Nine Moaths, £18; Six Months, £13; Three Months, £7; or for One Month, £2 105. Students eatering upon Laboratory Instruction are required have a fair knowledge of Elementary Chemistry. BURSARIES.-A Few Bursaries of £50 each per Annum, Tenable for Three Years, are now at the disposal of the Trustees, who will receive Applications in writing up to the 18th October. 166, St. Vincent Street. Glasgow, October, II, 1876. ALEX. MOORE, Secretary. NEWS 81. THE present paper is in continuation of one which I had the honour of reading before the Royal Society, December 11, 1873, and which was published in the Philosophical Transactions, vol. clxiv., part 2, p. 501. In that paper I described various pieces of apparatus, chiefly in the form of delicate balances suspended in glass tubes, by means of which I was enabled to show attraction or repulsion when radiation acted on a mass at one end of the beam, according as the glass tube contained air at the normal pressure, or was perfectly exhausted. At an intermediate internal pressure the action of radiation appeared nil. Towards the end of the paper I said (70), "I have arranged apparatus for obtaining the movements of repulsion and attraction in a horizontal instead of a vertical plane. Instead of supporting the beams on needle-points, so that they could only move up and down, I suspend them by the centre to a long fibre of cocoon silk in such a manner that the movements would be in a horizontal plane. With apparatus of this kind, using very varied materials for the index, enclosing them in tubes and bulbs of different sizes, and experimenting in air and gases of different densities up to Sprengel and chemical vacua, I have carried out a large series of experiments, and have obtained results which, whilst they entirely corroborate those already described, carry the investigation some steps further in other directions." 82. I have introduced two important improvements into the Sprengel pump† which enable me to work with more convenience and accuracy. Instead of trusting to the comparison between the barometric gauge and the barometer to give the internal rarefaction of my apparatus, I have joined a mercurial siphon-gauge to one arm of the pump. This is useful for measuring very high rarefactions in experiments where a difference of pressure equal to a tenth of a millimetre of mercury is important. By its side is an indicator for still higher rarefactions; it is simply a small tube having platinum wires sealed in, and intended to be attached to an induction coil. This is more convenient than the plan formerly adopted (51) of having a separate vacuum tube forming an integral part of each apparatus. At exhaustions beyond the indications of the siphon-gauge I can still get valuable indications of the nearness to a perfect vacuum by the electrical resistance of this tube. I have frequently carried exhaustions to such a point that an induction spark will prefer to strike its full distance in air rather than pass across the inch separating the points of the wires in the vacuum tube. A pump having these pieces of apparatus attached to it was exhibited in action by the writer before the Physical Society, June 20, 1874. 83. The cement which I have found best for keeping a vacuum is made by fusing together 8 parts by weight of resin and 3 parts of bees'-wax. For a few hours this seems perfect, but at the highest exhaustions it leaks in the course of a day or two. Ordinary or vulcanised india-rubber joints are of no use in these experiments, as when the vacuum is high they allow oxygenised air to pass through as quickly as the pump will take it out. Whenever possible the glass tubes should be united by * From the Philosophical Transactions of the Royal Society of London, vol. clxv., pt. 2. 1 Philosophical Transactions, 1873, vol. clxiii., p. 295; 1874, vol. clxiv., pp. 509, 516. Phil. Mag., August, 1874. fusion, and where this is impracticable mercury joints should be used. The best way to make these is to have a well-made conical stopper, cut from plain india-rubber, fitting into the wide funnel tube of the joint and perforated to carry the narrow tube. Before fitting the tubes in the india-rubber, the latter is to be heated in a spirit flame until its surface is decomposed and very sticky; it is then fitted into its place, mercury is poured into the upper part of the wide tube so as to completely cover the indiarubber, and oil of vitriol is poured on the surface of the mercury. When well made this joint seems perfect; the only attention which it subsequently requires is to renew the oil of vitriol when it gets weakened by absorption of aqueous vapour. Cement has to be used when flat glass or crystal windows are to be cemented on to pieces of apparatus, as subsequently described (99, 102). It would be of great service could I find a cement which is easily applied and removed, and will allow the joint to be subjected to the heat of boiling water for some hours without leaking under the highest rarefactions. Hitherto I have failed to find one which answers these requirements. I mention this in the hope that some one who happens to read this may be in possession of the recipe for such a cement, and will communicate it to me. 84. Before my first paper on this subject was read before the Royal Society I had discarded the balance form of apparatus there described, and commenced experimenting with bulbs and tubes in which quantitative results could be obtained. On December 11, 1873, when illustrating my paper, I exhibited to the Society many of these new forms of apparatus. For the purposes of simple illustrations, and for experiments where quantitative determinations are not required, I find a horizontal index suspended in a glass bulb the most convenient. The apparatus, with its mode of attachment to the pump, are shown in fig. 1. a, b, c, d is originally a straight piece of soft lead-glass tubing 18 inches long, of an inch external and internal diameter. At one end is blown a bulb, de, about 3 inches diameter. The part a b of the tube is drawn out to about half its original diameter, and bent at right angles. The tube is slightly contracted at c, and very much contracted and thickened at b. At a it is also contracted and cemented by fusion to a narrower piece of tube bent in the form of a spiral, and fitting by a mercury joint into the D d Les Mondes, Revue Hebdomadaire des Sciences, Adulteration of Wines.-The author remarks that so long as falsification consisted merely in heightening the colour of wines with logwood and other vegetable matters it was only a semi-evil, though still considerable enough, since one of the dyes most commonly used was a drastic purgative. But magenta has now come into use on a scale scarcely to be imagined. A small commune in the neighbourhood of Béziers, containing only 1800 inhabitants, has consumed in one year 30,000 francs worth of this colour entirely for sophisticating wines. MISCELLANEOUS. Birmingham and Midland Institute.-The following are the lecture arrangements for the session 1876-7 :— This day (Friday), October 13.- Lieut. Cameron, D.C.L., on" Recent Explorations in Africa." October 16.- Captain Davis, R.N., F.R.G.S., on "Antarctic Discovery, and its Connection with the Transit of Venus, 1882. October 23, 30.-Prof. W. C. Williamson, F.R.S., on "The Early Forms of Animal Life," and "The Early Forms of Vegetable Life." November 6, 13.-George Dawson, M.A., on "Horace Walpole." November 20.-Wm. Huggins, D.C.L., LL.D., F.R.S., on "Spectrum Analysis Applied to the Heavenly Bodies." November 27, December 4.-Arthur Arnold, on "Persia." An Analytical Query.-In separating arsenic, &c., from copper' &c., by treating with an alkaline sulphide, I generally get the filtrate rather dark, and it seems to contain not copper in solution, but finely divided. I believe there is a way of preventing even a slight trace of copper getting through. I have looked at many analytical works but have failed to see anything about it, except the diluting, but that I have always done. I have taken in the CHEMICAL NEWS for years but have never seen anything on the subject.-ROBERT MONGER. THE LECTURE NOTES FOR THE USE OF CHEMICAL London: SIMPKIN, MARSHALL, and CO., Stationers' Hall Court 4.- Arthur Arnold, on ANDERSON'S UNIVERSITY, GLASGOW. December 11.-Prof. Boyd Dawkins, M.A., F.R.S., F.S.A., on "The Ancient Inhabitants of the Caves of Derbyshire." January 22, 29.-E. Ray Lankester, M.A., F.R.S., on "Rots and Ferments, our Unseen Enemies." February 5, 12.-Edward Dannreuther, on "The Pianoforte Works of Liszt and Chopin." February 19, 26.-Prof. Sidney Colvin, M.A., on "Olympia and Greek Athletics; a Study of Ancient Usages and Recent Discoveries." March 5.-Prof. J. M. D. Meiklejohn, M.A., on "Parody." March 12.-Prof. Sir C. Wyville Thomson, LL.D., F.R.S., on "The General Results of the Challenger Expedition." March 19, 26.-Prof. W. Barrett, F.R.S.E., on tion and Radiometers." "Radia April 9, 16.-George Dawson, M.A., on “Sir Walter Raleigh." NOTES AND QUERIES. Our Notes and Queries column was opened for the purpose of giving and obtaining information likely to be of use to our readers generally. We cannot undertake to let this column be the means of transmitting merely private information, or such trade notices as should legitimately come in the advertising columns. Fluoride of Potassium.-Can any of your readers give me a process for the ready production of fluoride of potassium.-FLUORINE. THE "YOUNG" CHAIR OF TECHNICAL CHEMISTRY. Professor E. J. MILLS, Dr. Sc. (Lond.), F.R.S. SESSION 1876-7. LECTURES. A COURSE of FIFTY LECTURES on TECHNICAL CHEMISTRY will be Delivered during the Session, on MONDAY, TUESDAY, and WEDNESDAY in each Week, at 9 a.m., beginning on WEDNESDAY, 1st NOVEMBER. The Lectures will be ilustrated by the actual Inspection of Manufacturing Processes. They will include this year, as special subjects, the ALCOHOL INDUSTRY, Potable Waters, Sewage, and General TECHNICAL SANITATION. Fee for the Course Two Guineas; Laboratory Students Free. The attention of Young Men qualifying for the Professions of Civil and Mining Engineers, Architects, &c., as well as those mere immediately interested in the Study of Chemistry, is called to this Course of Lectures. A Course of Thirty Lectures on TECHNICAL ORGANIC CHEMISTRY will be commenced on April 1s. These Lectures are more especially intended for Dyers, Colour Manufacturers, Brewers and Distillers, Tar Rectifiers, and Drysalters. Fee for the Course Two Guineas. LABORATORIES.-The Laboratories will be Open Daily, on and after Wednesday, 1st November, from 10 a.m. to 4 p.m. (Saturdays 10 a.m. to I p.m.), under the Superintendence of the Professor and his Assi-tants. Instruction given in the Preparation of Chemical Substances and Original Research, especially as relating to Manufacturing Processes. Fees-Whole Session of Nine Months, £18; Six Months, £13; Three Months, £7; or for One Month, £2 105. Students eatering upon Laboratory Instruction are required have a fair knowledge of Elementary Chemistry. BURSARIES.-A Few Bursaries of £50 each per Annum, Tenable for Three Years, are now at the disposal of the Trustees, who will receive Applications in writing up to the 18th October. 166, St. Vincent Street, Glasgow, October, 11, 1876. ALEX. MOORE, Secretary. NEWS 81. THE present paper is in continuation of one which I had the honour of reading before the Royal Society, December 11, 1873, and which was published in the Philosophical Transactions, vol. clxiv., part 2, p. 501. In that paper I described various pieces of apparatus, chiefly in the form of delicate balances suspended in glass tubes, by means of which I was enabled to show attraction or repulsion when radiation acted on a mass at one end of the beam, according as the glass tube contained air at the normal pressure, or was perfectly exhausted. At an intermediate internal pressure the action of radiation appeared nil. Towards the end of the paper I said (70), "I have arranged apparatus for obtaining the movements of repulsion and attraction in a horizontal instead of a vertical plane. Instead of supporting the beams on needle-points, so that they could only move up and down, I suspend them by the centre to a long fibre of cocoon silk in such a manner that the movements would be in a horizontal plane. With apparatus of this kind, using very varied materials for the index, enclosing them in tubes and bulbs of different sizes, and experimenting in air and gases of different densities up to Sprengel and chemical vacua, I have carried out a large series of experiments, and have obtained results which, whilst they entirely corroborate those already described, carry the investigation some steps further in other directions." 82. I have introduced two important improvements into the Sprengel pump+ which enable me to work with more convenience and accuracy. Instead of trusting to the comparison between the barometric gauge and the barometer to give the internal rarefaction of my apparatus, I have joined a mercurial siphon-gauge to one arm of the pump. This is useful for measuring very high rarefactions in experiments where a difference of pressure equal to a tenth of a millimetre of mercury is important. By its side is an indicator for still higher rarefactions; it is simply a small tube having platinum wires sealed in, and intended to be attached to an induction coil. This is more convenient than the plan formerly adopted (51) of having a separate vacuum tube forming an integral part of each apparatus. At exhaustions beyond the indications of the siphon-gauge I can still get valuable indications of the nearness to a perfect vacuum by the electrical resistance of this tube. I have frequently carried exhaustions to such a point that an induction spark will prefer to strike its full distance in air rather than pass across the separating the points of the wires in the vacuum tube. A pump having these pieces of apparatus attached to it was exhibited in action by the writer before the Physical Society, June 20, 1874. inch 83. The cement which I have found best for keeping a vacuum is made by fusing together 8 parts by weight of resin and 3 parts of bees'-wax. For a few hours this seems perfect, but at the highest exhaustions it leaks in the course of a day or two. Ordinary or vulcanised india-rubber joints are of no use in these experiments, as when the vacuum is high they allow oxygenised air to pass through as quickly as the pump will take it out. Whenever possible the glass tubes should be united by From the Philosophical Transactions of the Royal Society of London, vol. clxv., pt. 2. 1 Philosophical Transactions, 1873, vol. clxiii., p. 295; 1874, vol. clxiv., pp. 509, 516. Phil. Mag., August, 1874. fusion, and where this is impracticable mercury joints should be used. The best way to make these is to have a well-made conical stopper, cut from plain india-rubber, fitting into the wide funnel tube of the joint and perforated to carry the narrow tube. Before fitting the tubes in the india-rubber, the latter is to be heated in a spirit flame until its surface is decomposed and very sticky; it is then fitted into its place, mercury is poured into the upper part of the wide tube so as to completely cover the indiarubber, and oil of vitriol is poured on the surface of the mercury. When well made this joint seems perfect; the only attention which it subsequently requires is to renew the oil of vitriol when it gets weakened by absorption of aqueous vapour. Cement has to be used when flat glass or crystal windows are to be cemented on to pieces of apparatus, as subsequently described (99, 102). It would be of great service could I find a cement which is easily applied and removed, and will allow the joint to be subjected to the heat of boiling water for some hours without leaking under the highest rarefactions. Hitherto I have failed to find one which answers these requirements. I mention this in the hope that some one who happens to read this may be in possession of the recipe for such a cement, and will communicate it to me. 84. Before my first paper on this subject was read before the Royal Society I had discarded the balance form of apparatus there described, and commenced experimenting with bulbs and tubes in which quantitative results could be obtained. On December 11, 1873, when illustrating my paper, I exhibited to the Society many of these new forms of apparatus. For the purposes of simple illustrations, and for experiments where quantitative determinations are not required, I find a horizontal index suspended in a glass bulb the most convenient. The apparatus, with its mode of attachment to the pump, are shown in fig. 1. a, b, c, d is originally a straight piece of soft lead-glass tubing 18 inches long, of an inch external and internal diameter. At one end is blown a bulb, d e, about 3 inches diameter. The part a b of the tube is drawn out to about half its original diameter, and bent at right angles. The tube is slightly contracted at c, and very much contracted and thickened at b. At a it is also contracted and cemented by fusion to a narrower piece of tube bent in the form of a spiral, and fitting by a mercury joint into the |