difficulty of finding any material capable of withstanding reduced pressures at temperatures above 1400° C., and the consequent necessity for limiting the temperature by the use of very high vacua. This difficulty was avoided in the present experiments by arranging the whole furnace inside a vacuum enclosure. The investigations may be divided into three main sections: 1. A study at atmospheric pressure of the boiling-points of a number of metals which do not combine appreciably with carbon (antimony, bismuth, copper, lead, magnesium, silver, tin). 2. A study at atmospheric pressure of the boiling-points of some metals which are readily attacked by carbon with the formation of carbides (aluminium, chromium, iron, manganese). 3. The influence of diminished and increased pressures on the boiling-points of certain of the metals under I (bismuth, copper, lead, silver, tin, zinc). PART I.-Non-carburisable Metals. In some earlier experiments carried out by Dr. L. Bradshaw the loss in weight of the metal maintained at fixed points over a wide range of temperature was determined. The loss by volatilisation, however, was found to take place over such a large temperature interval that in the present investigation other methods were adopted. Experiments were carried out in which a considerable quantity of metal, contained in a thin-walled graphite crucible, was heated in a carbon tube resistance furnace so chosen that the temperature could be quite rapidly raised, it being hoped that when the metal entered into ebullition a discontinuity in the rise of temperature would be observed, as shown by optical temperature readings on the outside of the crucible. Such, however, was not the case, the temperature of the walls rising considerably above the boiling-point of the metal. It was eventually found that the best results were to be obtained by gradually raising the temperature of the metal and taking observations of the surface from above through an absorbing glass. The surface at first remains perfectly still, but on approaching the boiling-point a slight agitation is observed to set in, which rapidly becomes vigorous. In most cases the difference between the temperatures indicated, when a gentle agitation is first apparent and when the ebullition is so vigorous that globules of metal are projected to a height of over 10 cm., does not exceed 100°. By taking the boiling-point as that temperature at which ebullition first becomes decided, quite concordant results were obtained in different experiments (cf., records of experiments given in Table I.). From observations of a number of metals in this manner it seems probable that the boiling-point may with fair approximation be taken as the temperature at which the vaporisation becomes sufficiently vigorous to cause a decided projection of drops from the surface (e.g., 1955° in the above cited three experiments with silver). In most of the experiments the furnace employed was of the vertical carbon tube resistance type (see Fig. 1), tubes 25 cm. long and of 20 and 30 mm. internal diameter respectively being used. The ends were electro-coppered and soldered into brass castings provided with water circulation at A and B, and a side tube of carbon was fitted to the centre of the resistor, and continued at the other end by a brass fitting furnished with a window. The whole was packed in crushed wood charcoal, this being a good heat insulator, and also desirable as regards absence of vapours at high temperatures. Suspended and fitting fairly closely inside the resistance tube was a long graphite crucible, made as thin as possible (about 1 mm.) in the walls, and containing the charge of metal. This form of crucible acts as a reflux condenser, and the amount of metal does not rapidly decrease. Graphite being an excellent conductor of heat, the error due to temperature difference between the outer and inner surfaces of the crucible walls was thus rendered negligible. A depth of about 30 mm. of metal was ordinarily used, and tempera ture readings were taken on the walls of the portion thus occupied (this being arranged immediately opposite the side tube) by means of a Wanner optical pyrometer. Freedom from fumes in the side tube was secured by the passage of a current of hydrogen admitted at c. With CHEMICAL NEWS, July 21, 1911 Boiling-points of Metals. 33 this arrangement only the radiation from the crucible walls | hydrogen employed in the side tube of the furnace. If could fall upon the pyrometer, and a close approximation to black body conditions was obtained. Using the two sizes of carbon tube mentioned, currents of about 500 and 900 ampères at 8 and 10 volts respectively were required to raise the temperature to 2500° C. moderately quickly. The temperature was under delicate control by manipulation of a rheostat in the field circuit of the separately excited dynamo supplying the current. Although experiments made up to 1500° in comparing the optical temperature readings with those of a thermo-couple immersed in the metal indicated that the difference between the temperature of the metal and that of the outer walls was negligible, it was thought desirable to obtain further proof of this. With this object in view and to make use of a somewhat different method of measurement, the apparatus shown in Fig. 2 was devised, the metal being con this current were stopped when the metal was gently boiling ebullition ceased. On substitution of nitrogen for hydrogen the temperature readings agreed among themselves in similar experiments, but were always considerably higher (50° to 100°) than those obtained in a hydrogen atmosphere. This curious effect is probably to be explained by the ease with which hydrogen diffuses through the crucible walls, dislodging the heavy vapours above the surface of the metal. That this action actually occurred could be distinctly seen by interrupting and then suddenly restarting the current of hydrogen whilst looking down the crucible. Measurements were in most cases made with both nitrogen and hydrogen, but it seems probable that the results obtained with the use of the latter approximate more closely to the true boiling points at atmospheric pressure. Accuracy of the temperature measurements was ensured by the insertion of an ammeter and rheostat in the standard lamp circuit of the optical pyrometer. Comparison with a thermoelement up to 1500° showed that the readings closely agreed with the thermoelectric temperatures (due allowance being made for the difference between the two scales). A further check was secured by determining the "black body" melting-points of strips of platinum, rhodium, and iridium specially prepared in a high state of purity by Messrs. Johnson, Matthey, and Co. These strips, which were 4 mm. wide and 8 cm. long, were mounted horizontally and heated electrically. A series of results obtained for the melting-points of these metals is given below. Platinum (deg.). TABLE II. Rhodium (deg.). Iridium (deg.). FIG. 2. tained in the annular portion of a graphite crucible of the form shown, heating being effected internally by radiation from the intensely heated central carbon rod supplied with current from the two thick graphite rods. To attain the boiling-point of lead, i.e., about 1500° C., a current of about 200 ampères at 20 volts was necessary, using a central carbon rod of 9 mm. diameter. The arrangement was fixed inside a wide carbon tube lagged with Kieselguhr, and temperature readings taken on the outside of the crucible down a side tube exactly similar to that used in the apparatus shown in Fig. 1. Here the effect of temperature errors due to imperfect thermal conductivity of the crucible walls is reversed, and the possibility of reflexion from the resistor altogether removed. Experiments with lead gave results in agreement with those obtained by the other method, but it was equally impossible to obtain limitation of the temperature of the outer surface of the crucible when the contents were caused to vigorously boil. It was therefore concluded that the apparatus shown in Fig. I was introducing no error due to this source. A curious effect was, however, traced to the current of The values given by Holborn and Henning (Sitzungsber. K. Akad. Wiss. Berlin, 1905, xii., 311) for the "black body" melting-points are as follows: Platinum 1545°, rhodium 1650°, iridium 2000°. Seeing that the readings obtained with this optical pyrometer are now capable of reference to some definite standard, it was thought best to publish the results without further correction, all temperatures being given on the optical scale. In the following table will be found a list of the boilingpoints experimentally determined, and also of the data previously available. In the case of magnesium the boiling-point was determined by the use of a protected thermocouple immersed in the metal, the temperature remaining steady while the metal distilled into the upper portion of the crucible. 0*125 2.8 0'070 460,000 480,000 550,000 580,000 to to TUNGSTEN has heretofore been known chiefly as a steel- is evidenced by publications emanating from various Lbs. per sq. in. hard and brittle and are not ductile, either at ordinary Kg. per sq. mm. .. The metal has ordinarily been obtainable in commerce form of a dark gray powder, usually made by the reduction of yellow oxide by hydrogen or by carbon. This powder, when bought on the open market, is generally impure, and is purified by various well-known methods, particularly if the method is to be used for filaments of incandescent lamps. These filaments have been made on a large scale and are in common use in this country and abroad. Even in ordinary commercial lamps, the filaments are of a degree of purity so high that no impurities can be discovered by the most searching methods of chemical analysis known. Not only is this true, but these filaments, during the course of chemical production, are exposed to temperatures high enough to drive out by mere vaporisation almost any impurity. Nevertheless, these filaments show no traces whatever of ductility, or even pliability, but on the contrary, though strong enough for mounting in commercial lamps, they are exceedingly brittle and incapable of taking a permanent set. Attempts have hitherto been made-but always without success-to produce ductile tungsten by various purification processes, varying the ore from which the tungsten is obtained by trying first wolframite (an ironmanganese tungstate) and then scheelite (the calcium tunstate). Whichever ore is used, it is customary to produce from it the yellow oxide, and a high degree of purity has been sought by repeated precipitations. Various methods of reduction have been tried; among other reducing agents, hydrogen, carbon, aluminium, zinc, and magnesium have been used. Reduction has also been effected by electrolytic methods. Since tungsten metal produced in this way has been so pure that no impurities could be detected by ordinary chemical or physical means, and has yet retained its characteristic hardness and brittleness, it has generally been concluded that the metal is entirely lacking in that physical property which is ordinarily termed ductility. Announcement has recently been made, however, of the production of tungsten in a form in which it is ductile. This ductile tungsten would seem to be a new substance from the point of view of the physical chemist, and it has seemed to me that this society would be interested in learning something of the properties of this product, since only those of us who have been connected with the Research Laboratory of the General Electric Co. have as yet had an opportunity to study it. Ductile tungsten is a bright, tough, steel-coloured metal, which can be drawn into the finest wire, much below one-thousandth of an inch. The tensile strength of the wire increases as the drawing proceeds; or, in other words, the more the metal is mechanically worked, the tougher and stronger it gets. In the following table a few figures on the strength of tungsten wires are given. They are the average obtained from a large number of measure ments: 1'5 1.2 0.038 0'030 to to 490,000 530,000 600,000 610,000 A piece of hard drawn piano wire, tested with the same apparatus, registered, on the average, 507,000 lbs. (35 kg. per sq. mm.), the diameter of the wire being 3-thousandths of an inch (0.075 mm.). According to Schnabel, aluminium shows a similar behaviour as regards the effect of drawing: cast aluminium gives but 17,000 lbs. per square inch (11.9 kg. per sq. mm.), whereas the drawn metal has a tensile strength of 36,000 to 39,000 lbs. (25.2 to 27.3 kg. per sq. mm.). The density or specific gravity values of ductile tungsten likewise increase with the amount of working. The values of ductile molybdenum were also determined at our laboratory. TABLE II.-Specific Gravity. Tungsten. 18.81 Diameter. mm. Inches. Before Drawing. 19.30 to 19.30. Molybdenum. 10'02 10'04 Martin (1907) found the density of melted tungsten, analysing 98.96 per cent pure, to be 16.28; Moissan (1896) and Weiss (1910) give the values of 18.70 and 18.72 for the brittle metal. As is seen from the table, the density increases very appreciably with the amount of mechanical working applied. This same phenomenon is well known in the case of copper, zinc, and other metals. The density of cast copper according to Marchand and Scheerer is 8.92, and that of rolled and hammered copper 9'95. Distilled zinc gives 6'92 and wrought zinc 7.25. The electrical resistance and the temperature coefficient of the two metals are given in Table III. We used the Wheatstone bridge method. The resistance was measured at room temperature and at 170°, employing two oil therTABLE III. The values marked d are for hard drawn wire; those marked a were obtained after annealing. This resistivity value for tungsten is a good deal lower than that given by Gin (Trans. Am. Electrochem. Soc., xiii., 483). The coefficient for copper (0° to 160°) is 0.00445 (Reichardt); the registry values for copper are 1.62 for the hard drawn and 1.58 for the annealed wire. A paper presented before American Electro-Chemical Society pends very much upon the amount of mechanical working The hardness of both tungsten and molybdenum de From the Chemical Engineer (Chicago), xii., No. 2. CHEMICAL NEWS, Chemical Notices from Foreign Sources. 35 have some direct bearing upon the scientific work of the student. The author has revised the second edition in accordance with some of the criticisms passed on the first edition; for instance, the chapter on Fourier's series has been re-written, and many new examples have been added. to which the metals have been subjected, and also upon | examples are worked out in full, all being chosen so as to the presence of impurities. Whereas the hard varieties scratch glass, the soft varieties are easily cut with a file. The thermal coefficients of the two metals were determined on wire 5-thousandths of an inch in diameter. A reading of one degree on the scale was equivalent to an elongation of the wire of 0'000545 inch. The values obtained are 336 × 10-8 for tungsten and 360 × 10-8 for molybdenum, the temperature range being 20°—100°. The platinum value for the same range is 884 × 10n-8 (Dulong and Petit). Chemically, the two ductile metals behave similarly in many respects. The drawn wire retains its lustre almost indefinitely. Both metals are readily attacked by fused oxidising salts, such as NaNO3, KHSO4, and Na2O2. Acids (HCI, HNO3, H2SO4) attack tungsten very slowly, but molybdenum rather readily. I have heated fine drawn tungsten wire in a mixture of chromic and sulphuric acids for sixteen hours, but could detect only a very small loss in weight. Original weight: 16.7330 grms.; after sixteen hours., 16.7329 grms. Original weight: 1.3638 grms.; after fourteen hours, 1.3635 grms. Apparently the metal becomes passive just like iron. NOTICES OF BOOKS. Introduction to Chemistry. By WILHELM OSTWALD. CORRESPONDENCE. PRECIPITATION OF ALUMINIUM HYDROXIDE IN THE GRANULAR FORM. To the Editor of the Chemical News. SIR,-A note by W. E. Taylor appeared in the CHEMICAL NEWS of April 13th (vol. ciii., p. 169), describing the precipitation of alumina in a granular form, easily filtered and washed. According to the author, this is achieved by carrying out the precipitation at a temperature of 66° C. These I have tried the method, using alum solutions containing from 0.26 grm. to o'07 grm. of alumina per 100 cc. were mixed with ammonium chloride, raised to 66° C., and precipitated by adding ammonia solution, also at 66° C., and the mixture was then boiled as directed. In every case the precipitate obtained was gelatinous. On filtering, the precipitate caked in the usual way, and there did not seem to be any increase in the rate of filtration or washing. Other experiments were done, in which no ammonium chloride was added, and again gelatinous pre cipitates resulted. It would seem from these results, that temperature is not the only conditioning factor, and that some unstated condition may be the cause of the granular precipitate. A more detailed account of Mr. Taylor's experiments would therefore be welcome-I am, &c., Chemical Laboratory, SOURCES. RUTH SUGDen. NOTE.-All degrees of temperature are Centigrade unless otherwise expressed. Zeitschrift für Anorganische Chemie. this adaptation of it is intended. It is unnecessary to say CHEMICAL NOTICES FROM FOREIGN that it will make him use his reasoning power and think about his work. The general principles of chemistry are specially emphasised, and instructions for illustrative experiments which can readily be performed by the student are given. In the descriptive portion of the book the commonest elements, including some metals, are treated. Notes on the Fertilisers, Farm Foods, Seeds, and Pest Remedies Act (Cape Province). By Dr. C. F. JURITZ, M.A., F.I.C. Reprinted from the Agricultural Journal of the Union of South Africa. 1911. THESE notes give fuller explanations of some points in connection with the Fertilisers, &c., Act, passed by the Cape Legislature in 1007, which might present a difficulty to merchants or farmers. They are written more especially to assist farmers to understand scientific terms, and the time, nature, and value of a merchant's warranty. Some discussion of various types of fertilisers is added, and the principles of commercial valuation are explained. Lehrbuch der Mathematik. New Quantitative Determination of Fluorine.— Gunnar Starck.-The solution of the fluoride is neutralised with dilute hydrochloric acid, and then a large excess of saturated lead chloride solution is added. The precipitate is allowed to stand over night, and is then filtered off and dried for two hours at 140-150°. The precipitate is very heavy, and filtration is easily effected; moreover, the results obtained by the method are very satisfactory. Binary and Tertiary Alloys of Cadmium, Bismuth, and Lead.-William Edward Barlow.-The author gives the solidification curves of alloys of lead and cadmium, lead and bismuth, bismuth and cadmium, and of the ternary system lead-bismuth-cadmium. In the sixteen alloys investigated there is a transition point at a definite temperature in the neighbourhood of 124°. Quantitative Determination of Gold by means of Ether.-F. Mylius.-Gold chloride, unlike other metallic chlorides, is soluble in ether, and the amount of gold in a coin can be estimated by shaking the hydrochloric acid solution with ether and distilling off the ether. The maximum error does not exceed o'o per cent. The author describes a double salt of gold chloride and copper chloride, CuAu2Cl8.6H2O, and gives details of methods of determining small amounts of silver, lead, iron, &c., with the results of the analysis of many specimens of German and foreign coins. Action of Hydrogen Peroxide and Sodium Peroxide on Bismuth Salts.-Jos. Hanus and O. Kallauner. When bismuth nitrate solution is oxidised with ammoniacal hydrogen peroxide solution, yellow preparations are obtained in the cold. They become brown when heated, if sodium peroxide is used. Active oxygen is present in them. They are decomposed by sulphuric acid with liberation of oxygen. Concentrated nitric acid dissolves them slowly in the cold, the colour changing to red brown. The brown products obtained by oxidation with sodium peroxide do not lose their colour when they are boiled for five minutes with water. Electrical and Mechanical Properties of Alloys of Noble Metals.-Wilhelm Geibel.-The author has determined the tensile strength, electrical conductivity, thermoelectric force, and temperature coefficient of alloys of palladium and silver, palladium and platinum, platinum and iridium, platinum and gold, and gives the results of his investigations in the graphic form. Bulletin de la Société Chimique de France. Heat of Fusion of Substances Melting in the Neighbourhood of the Ordinary Temperature.-W. Louguinine and G. Dupont.-Van't Hoff's Law states that if T is the absolute temperature of fusion, F is the F = 0.02 T2. heat of fusion and K the cryoscopic constant, K The authors have determined the conditions in which the constant K can be accurately determined, and have found that with substances melting at the ordinary temperature the law of van 't Hoff holds good if they are not viscous in the liquid state and crystallise quickly. If, however, they crystallise slowly and are viscous (e.g., monohydrated sulphuric acid and acetophenone) the value of the cryoscopic constant generally comes out too high. This may be ascribed to the difficulty of determining K correctly in the case of viscous substances. Rôle of Affinity in Dyeing.-A. Rosenstiehl. — In dyeing textiles both cohesion and affinity are called into play, and both forces are necessary to produce the desired effect. If affinity intervenes to produce a coloured layer on the fibre cohesion ensures the adherence of this layer to the fibre. Determination of Solid Hydrogen Arsenide. Hans Reckleben and Johannes Scheiber.-Like other arsenic compounds arsenic hydride can be oxidised quan- Determination of Nitrates and Nitric Ethers.-M. titatively to arsenic acid by ammoniacal silver nitrate Marqueyrol and D. Florentin.-If the values obtained in solution. It exists in one form only, and has the com- determining nitrates by means of a nitrometer (taking into position represented by the formula H2As2 or HAS. The account the solubility of NO in sulphuric acid) are comsolid hydride is formed when a dark discharge passes pared with those obtained by Schlesing's method, it is through arseniuretted hydrogen, when the arsenides of the found that they agree very well if 94-94'5 per cent sulalkali metals are decomposed by water, and when arseni- phuric acid is used. The nitrometer method in certain uretted hydrogen is incompletely oxidised by oxygen or conditions is accurate, and its rapidity and convenience air in the cold. The solid hydride is not formed when make it preferable to Schlosing's method. arsenic is sublimed in a current of hydrogen, nor when arsenic is sublimed by cooling a flame of arseniuretted hydrogen. Determination of Solid Antimony Hydride.-Hans Reckleben and Johannes Scheiber.-Oxidation by means of iodine solution can be used for the quantitative analysis of antimony precipitates. Under the influence of the dark discharge antimoniuretted hydrogen gives pure antimony, and it is also obtained when the compounds of antimony and the alkali metals are decomposed by water vapour at the ordinary temperature. Explosive antimony contains no solid antimony hydride, but traces of hydrochloric acid are present in it. Quantitative Determination of Copper by means of Hypophosphorous Acid.-Jos. Hanus and Arn. Soukup. -The precipitation of copper by means of hypophosphorous acid is not quantitative, the amount of copper remaining in the filtrate depending upon the concentration of the H-ions in the precipitating reagent, upon the length of time the copper remains in contact with the air, and the length of time the oxidised copper is in contact with the acid solution. Only by repeated careful neutralisation can satisfactory results be obtained, and the heating must not be continued too long. Determination of Silver by Electrolytic Separation from Ammoniacal Oxalate Solution.-F. A. Gooch and I. P. Feiser.-In presence of ammonium nitrate or chloride silver can be separated electrolytically from an ammoniacal solution of the oxalate in the pure state and in a form suitable for quantitative determination. It is best to use a low current, and the electrolysis is completed in twenty-five to thirty minutes. Constitution of Metatungstates.-Hippolyte Copaux. -On the ground of dehydration experiments the author considers that his formula for metatungstates, 6M2O.3H2O.24WO3 + Aq, is more probably correct that suggested by Rosenheim, viz., M2WO(WO3)3(H2O)3+Aq, and the same formula is confirmed by the crystallographic comparison of potassium metatungstate with potassium silicotungstate and potassium borotungstate. than Quantitative Dehydration of Pure Pinacone.-M. Delacre. - By direct dehydration pure pinacone cannot be made to give a higher percentage of pinacoline than 70 per cent of the theory. Various products are found in the pinacoline which cannot be ascribed to impurities in the pinacone. Hydrogenation of Essence of Terebenthene.-G. Vavon.-To determine whether an essence of terebenthene is pure it may be subjected to fractional distillation, when at least four-fifths should pass over below 164°. If the product which has passed over between 155° and 158° is subjected to hydrogenation a substance boiling at 166° is obtained if the essence is pure. The volume of hydrogen absorbed ought to be constant for all specimens. Hexahydrohippuric Acid.-Marcel Godchot.-Hexahydrohippuric acid can be made synthetically by making hexahydrobenzoyl chloride react with glycocoll. C6H11COCI+NH2CH2CO2H = =C6Hrr.CO.NH.CH,.CO H+HC. The acid chloride required for this synthesis can be prepared by chlorinating hexahydrobenzoic acid with phos. phorus pentachloride, while the acid is obtained by treating the bromide of cyclohexylmagnesium with CO2— 2C6H11MgBr + CO2 = MgBr2+ (C6H11.CO2)2Mg C6H11CO2H+PCl5= C6H11COCI+ POCI3 + HCI. Preparation of Pseudomorphine by Mineral Catalysis.-Georges Denigès.-The double cyanide of copper and potassium (prepared by adding potassium cyanide to a solution of copper sulphate) can be used as a catalyser to prepare pseudomorphine from morphine chlorhydrate and hydrogen peroxide. The reaction takes place very quickly, and about 20 to 25 per cent of morphine is thus converted into pseudomorphine. Peroxydiastase of Cow's Milk and the Paraphenylene-diamine Reaction.-E. Nicolas. Boiled milk gives an indigo-blue coloration with paraphenylene diamine and hydrogen peroxide. This coloration is due to the presence of casein, which combines with the product of the oxidation of paraphenylene diamine with hydrogen peroxide. |