is only compatible with the conservation of the original density on the assumption of some form of packing which is not the closest possible. It would therefore seem that the solution of the problem must be sought from the crystallographers, whose newly added resources enable them to determine the direction of the planes of closest packing within a crystal, and the actual form of the spacelattice. the same mixture." It is therefore to be expected that j the attraction, and consequently the hardness, should be a maximum in the solid solution containing equal molecular proportions of the two components, and this rule is approximately fulfilled in the case of several of the series in vestigated by Kurnakoff and Schemtschuschny (Zeit. Anorg. Chem., 1908, lx., 1). It may be noted that the rule is confirmed by application to cases in which an intermetallic compound is formed. Thus, the compound MgCd forms a continuous series of solid solutions with both of its components. The maximum hardness is not that of the compound, although this is harder than either (B). NOTE ON CRYSTAL TWINNING and the component, but the curve plotted with atomic percentages presents two maxima, approximately midway between Mg and MgCd and between MgCd and Cd respectively. These are the two compositions at which there is the greatest admixture of foreign molecules. Direct evidence of a constrained condition of the molecules of a solid solution, or of a disturbance of the internal crystalline structure, is not easy to obtain in the case of metals, but the conditions are more favourable in that of isomorphous salts. These salts frequently exhibit optical anomalies," indicating the presence of internal strain, and such a condition is often assumed to be usual. It is, however, by no means necessarily the case. In his very careful work on isomorphism, Retgers (Zeit. Physikal. Chem., 1889, iii., 497) has shown that the anomalies do not always occur, and has used their absence as one of the tests of the homogeneity of isomorphous "mixed crystals" required for investigations of density. The most con spicuous examples of crystals exhibiting optical anomalies are those of salts crystallising from solutions containing dyes. Here there is no question of the interpenetration of space-lattices, and the production of a strain in the crystals is readily comprehensible, but where two salts of almost identical molecular volume are concerned, it seems probable that Retgers' view is correct, and that optical anomalies are absent when sufficient care is taken to conduct the crystallisation slowly and in presence of a large excess of the saturated solution. It is usually stated, also, that solid solutions crystallise less readily, or yield less perfect crystals, than pure substances. This is not invariably the case, but the fact has been observed so frequently that it must be regarded as evidence for a certain disturbance of crystalline structure in solid solutions. MARTENSITIC STRUCTURE. By Dr. CECIL H. DESCH (Glasgow). THE present note deals with certain points in the paper The present writer has never accepted the hypothesis of a hard modification of iron, and has always regarded the hardness of martensite as being connected with a partial resolution of austenite. That the resolution should proceed along gliding and twinning planes by preference is only in accordance with the usual behaviour of solid solutions, as evidenced by the formation of the Widmanstätten structure when such solid solutions undergo partial reso The heat of formation of solid solutions has hitherto been determined only in the case of isomorphous salts, and then by an indirect method, the heat of solution of the solid solution in water being compared with that of a mechanical mixture of the components in the same pro-lution (see paper by N. T. Belaiew in Journ. Inst. Metals, portions. The pairs of salts which have been examined satisfactorily by this method-NaCl-KCl, NaBr-KBr, NaI-KI, KC-RыC, KCl -KBr, KBr-KI, KCI-KI, NaNO2-NaNO3 -all give results indicating a negative heat of formation for the solid solution (G. Bruni, Mem. R. Accad. Lincei, 1912, p. 50). For two of these pairs, namely, KC-KBr and KBr-KI, the hardness curve, as determined by measuring the pressure required to produce flow through an orifice, passes through a maximum not far from the middle of the series (T. B. Vrshesnevsky, Fourn. Russ. Phys. Chem. Soc., 1911, xliii., 1364). 1914, xii., and Discussion), and by the fact that corrosion proceeds preferentially along twinning planes (S. Whyte and C. H. Desch, Ibid, 1914, xi., 235). Narrow twins (Neumann's lines) are readily developed in many metals. Professors Edwards and Carpenter have instanced the case of tin. Bismuth is also a convenient material for exhibiting the effect. Fig. 1 shows a portion of a crystal grain in a small ingot of cast bismuth, every grain of which is traversed by numerous Neumann's lines, as well as by broader and less regular twin lamellæ. In cast zinc the lines may be so closely packed and so narrow as to simulate very closely the structure of martensite. Whether these lines owe their origin to casting strains or to strains produced in cutting and filing the ingot is not decided, and there is no evidence that the abundance of very narrow twin lamellæ is accompanied by increased hardness. It will be seen that the data which are available for drawing a conclusion as to the hardness of solid solutions, even in such a simple case as the alloys of gold and silver, are very scanty. The complete proportionality which exists between density and composition by volume (or between specific volume and composition by weight) seems to exclude any important differences in the close- The presence of a martensitic structure without increase ness of packing. There remains a difference in the of hardness is illustrated by Figs. 2, 3, and 4, which repreattractive forces between the atoms-what is usually sent fields from a piece of overheated steel. A piece of called internal pressure, and even here it is not easy to steel plate, o 28 per cent C., was heated to a white heat in realise why the attractive force between gold and silver a coke fire, and allowed to cool down with the furnace. A should be twice as great as between gold and gold or very coarse structure, like the Widmanstätten structure between silver and silver. A distortion of the space-but with less regular outlines, was developed. The ferrite lattice, producing a more or less irregular arrangement, | cell-walls were fringed with ferrite (Fig. 3), and the FIG. 4.-Pearlite in same specimen with 2 mm. Objective of 14 NA. the distribution of the pearlite in the slowly cooled specimen records the earlier stages of the resolution. On this view, the martensitic structure of a quenched steel is an accompaniment and not the cause of its hardness. The writer is aware that this suggestion does not provide any explanation of the hardness of martensite, but only opposes the view that that hardness is due to twinning. Martensite is so much harder than its components as to suggest the presence of a solid solution, but whether that solid solution be a distinct phase, not yet recorded in the equilibrium diagram, or an unusual type of highly strained solid emulsion, remains doubtful. The investigation of the distribution of pearlite in a slowly cooled steel is being continued. RADIUM. (Continued from p. 286). APPENDIX I. (continued). THE Colorado carnotite deposits were apparently first noted as far back as 1881, when Andrew J. Talbert mined some of the ore and sent it to Leadville, where it was reported as carrying 5 dols. in gold per ton. This must have been an unusual ore as the carnotite now found does carry the precious metal. In 1896, Gordon Kimball and Thomas Logan sent specimens to the Smithsonian Institution, Washington, D.C., and were informed that the minerals contained uranium. Shortly thereafter they mined 10 tons of ore, shipped it to Denver, and sold it for 2700 dols. on account of its uranium content. Three years later, in 1899, Poulot and Voilleque collected and sent to France specimens which were examined by Friedel and Cumonge, who recognised the existence of a new mineral and named it "Carnotite," in honour of M. Carnot then President of the French Republic. In 1900, Poulet and Voilleque leached carnotite ores at Cashin, in the Paradox Valley, to extract the uranium. They shortly after completed a small mill in the McIntyre district south of the Paradox, and in this project had the cooperation of James McBride, a mining engineer of Burton, Michigan. Their mill ran until 1902, and during that time produced 15,000 pounds of uranium oxide. The mill was started again in 1903 by the Western Refining Company, but ran only a year. Up to 1904, the mills appear to have been run wholly with the idea of obtaining the uranium and vanadium from the ore for no radium was extracted. Shortly afterwards the Dolores Refining Company built a new mill a short distance from the old one, but after running for some years, this mill, too, shut down. In 1912, the American Rare Metals Company acquired the mill of the Dolores Refining Company and is now operating it, with the special purpose of obtaining radium from the ores. The first attempt to attract radium in this country appears to have been made by the Rare Metals Reduction Company, under the management of Stephen T. Lockwood, of Buffalo, N.Y. In September, 1900, Mr. Lockwood brought back from Richardson, Utah, samples of carnotite ore, and in 1902 he published (Eng. Min. Jour., of September 27th) the first radiographic plate from pro ducts of American carnotite. In June, 1902, he received 500 pounds of specially picked high-grade ore from Richardson, Utah, and in May, 1903, as a result of experimental work on this ore, he incorporated what was probably the first American company to operate a plant to produce radium as one of its products. In October, 1903, the first experimental plant was constructed, and in April, 1904, the first 17-ton car of ore reached Buffalo from Richardson, Utah. The company obtained a fair percentage of extraction but the ore proved to be too lowgrade, and the Richardson deposits were abandoned. No radium in concentrated form was put upon the market, although barium sulphate concentrates were produced. The General Vanadium Company which, with the Radium Extraction Company, is a subsidiary of the International Vanadium Company of Liverpool, England, was formed in 1909 and began work in 1910, the same year that the Standard Chemical Company of Pittsburgh, Pa., entered the field. Since that time these two companies have been engaged in mining carnotite. The ores from the General Vanadium Company have been shipped almost entirely abroad, while the Standard Chemical Company has shipped several hundreds of tons of carnotite to its works at Canonsburg, Pa. While it was stated at the time of the advance announcement of the bulletin to be be issued by the Bureau of Mines that one American company had actively entered into the production of radium no actual sale of American-produced radium could be * Report No. 214, presented to the House of Representatives, U.S.A., at the 63rd Congress. authenticated. Since that time, however, the Standard Chemical Company has entered the American markets. Besides the American Rare Metals Company and the Standard Chemical Company, a third company-the Radium Company of America with mines near Green River, Utah-has undertaken the production of radium in its plant at Sellersville, Pa. There is, therefore, every reason to hope that more and more of our ores will be worked up at home. Besides the companies already mentioned, a number of independent operators mine and ship carnotite from the Paradox region and for the main part send their ores to Hamburg. Among the more prominent of these may be mentionedT. V. Curran, Placerville, Colo. W. L. Cummings, Placerville, Colo. O. B. Wilmarth, Montrose, Colo. David Taylor, Salt Lake City, Utah. The costs of mining, and especially of transportation, are an important factor in the marketing of carnotite. The Green River deposits have a distinct advantage over the Colorado deposits in this respect, as they are nearer the railroad, but, as their ores do not average so high in uranium, this advantage is more apparent than real. The present costs of mining, sorting, and packing in the Paradox apparently vary from about 28 dols. to 40 dols. per ton. To this must be added an 18 dols. to 20 dols. hauling charge to Placerville, and, in most instances, an additional charge for burros from the mines to points that can be reached by wagon. The freight rate from Placerville to Hamburg via Galveston is 14 dols. 50 cents per ton, so that the average cost at present to the miner of laying down his ore at the European markets approximates 70 dols. per ton. The selling price varies with the uranium content but is by no means proportional thereto, since a premium is always paid for rich ores. Very recently, however, a decided improvement has taken place, and for 2 per cent ore the price is now around 2.50 dols. per pound for the contained uranium oxide delivered in Europe with an allowance of about 13 cents per pound for the vanadium oxide content, so that the 2 per cent ore will now bring in Hamburg about 110 dols. per ton. One per cent ore is now saleable, but unless this ore is taken from the dump, so that the mining cost may be disregarded, it will scarcely bear present transportation charges from the Paradox, although it is more than probable that it will soon be shipped regularly from the Utah field. A price of 110 dols. at Hamburg for 2 per cent ore leaves a good margin of profit to the miner, as mining profits go, but when it is considered that this price represents only a little over one-sixth of the value of the radium content of the ore, and that from this fraction of the value the American miner has to meet the outlay represented by the investment, by mining costs, transportation and assay costs, and by losses in transit, it seems scarcely just that nearly five-sixths of the value should go to foreign manufacturers of radium, especially when the fact is considered that radium can be produced much more readily from carnotite than from pitchblende. There are two ways of reducing this difference between the actual value of the ore and the price that the miner receives. One is to hold our American ores for a higher price, and the second is to manufacture radium at home. Large wastes are still taking place in the mining of carnotite, owing to the inability of the low-grade ores to bear transportation charges. As has already been pointed out, however, a distinct improvement in this respect has taken place within the last few months. The miners are beginning to realise the value of their old dumps and are attempting to save the low-grade non-shipping ore in such ways as will render its marketing possible when prices advance. The Bureau of Mines has done everything it can to impress the necessity of this truest kind of conservation upon the mine operator. In addition there is prospect that most of the low-grade ores can be successfully concentrated by mechanical methods, and experiments at the Denver office of the Bureau of Mines indicate that a concentration of four to one can be obtained. In this concentration, however, there are losses which could be prevented by chemical concentration, but at the present time it costs more to ship the necessary chemicals to the mines than it does to ship the ores to places where these chemicals can be cheaply obtained. It would appear, however, that mechanical concentration can save at least one-half of the material that is now going to waste. PROCEEDINGS OF SOCIETIES. ROYAL SOCIETY. Ordinary Meeting, December 3, 1914. Sir WILLIAM Crookes, O.M., President, in the Chair. PAPERS were read as follows: "The Thermophone, a New Form of Telephone." By M. DE LANGE. "Hermann's Phenomenon." By Dr. G. S. Walpole. At the boundary between two solutions of unequal difference of potential be maintained between them. Alkali is liberated if the current passes from the better conducting solution to that not conducting so well; acid, if the current passes in the opposite direction. The amounts may be calculated from the potential gradients in the solutions on each side of the boundary, the time for which the difference of potential is maintained, the resistance constant of the vessel employed, the dissociation constant of water, and the known migration velocities of hydrogen and hydroxyl ions. Although until recently, the manufacture of radium from carnotite has been carried on almost wholly in France and Germany, there appears to be no good reason why our American carnotite should not be treated at home. Carnotite is much more easily treated than pitch-specific conductivity a change of reaction is developed if a blende and the essential features of methods for its chemical treatment are well known, although much of the mechanical detail of operation has been kept secret. As the mechanical requirements, however, are those which any well-grounded chemical engineer should be able to solve, there seems to be no good reason why any of our carnotite ores should be shipped abroad, even at two or three times the present market price of the material. As before stated, the essential features of chemical methods of extracting radium from its ores are well known. As regards the principles involved, the methods have advanced little beyond the original method published by Debierne. The methods for carnotite may be described best in the words of Soddy, in an extract from "The Chemistry of the Radio Elements," by Frederick Soddy, p. 45, published in 1911 by Longmans, Green, and Co. "The most important operations in the working up of radium-containing materials are the solution of the materials, consisting usually of insoluble sulphates, and the separation of the halogen salts of the alkaline-earth group in a pure state, followed by their fractional crystallisation. The first operation is usually effected by vigorous boiling with sodium carbonate solution, filtering and washing free from sulphate. This is the well-known reaction studied dynamically by Guldberg and Waage, whereby an equilibrium is attained between the two pairs of soluble and insoluble sulphates and carbonates Naturally the greater the excess of sodium carbonate the larger the proportion of insoluble sulphate converted into insoluble carbonate. In this operation it is advisable not to wash at once with water but with sodium carbonate solution until most of the sulphates are removed, as thereby the reconversion of the carbonates back into insoluble sulphates is largely prevented. In dealing with crude materials, for example, the radium-containing residues from pitchblende, it is often advantageous to precede this operation by a similar one, using a sodium hydrate solution containing a little carbonate which dissolves part of the lead and silica present. The carbonates washed free from sulphates are treated with pure hydrochloric acid which dissolves the alkaline earths including radium. From the solution the latter may be precipitated as sulphates by sulphuric acid acid and reconverted back into carbonates as before. Or sometimes more conveniently they may be precipitated directly as chlorides by saturating the solution with hydrogen chloride; this is a very elegant method of great utility in the laboratory, for the most probable impurities, chlorides of lead, iron, calcium, &c., remain in solution, and only the barium and radium chlorides are precipitated, practically in the pure state, ready for fractionation." (To be continued.) Royal Institution.-A General Meeting of the Members of the Royal Institution was held on the 7th inst.; Sir James Crichton-Browne, Treasurer and Vice-President, in the Chair. His Highness Maharaja Gaekwar of Baroda, and Mr. Archer M. Huntington, were elected Members. It was announced that the Managers had elected Charles Scott Sherrington, M.D., D.Sc., F.R.S., Fullerian Professor of Physiology, for a term of three years, the appointment to date from January 13, 1915. CHEMICAL SOCIETY. (Concluded from p. 294). THE following communications have been received during the vacation : 254. "The Preparation of Phenyl Benzyl Ether." By DAVID HENRY PEACOCK. For the preparation of fairly large quantities of phenyl benzyl ether the ordinary method is neither convenient nor economical. According to Beilstein (3rd. Ed., II., 1049), the compound is prepared by the action of benzyl chloride on potassium phenoxide. The method usually employed is to dissolve 94 grms. (one moleculǝ) of phenol in a concentrated solution of the equivalent quantity of potassium hydroxide, and then, after the addition of 128 grms. (one molecule) of benzyl chloride, and about 20 cc. of alcohol, to heat on a water-bath under a reflux condenser for four hours. The yield of crude phenyl benzyl ether is only about 70 grms. A great disadvantage of this method is that the benzyl chloride and solution of potassium phen oxide do not mix, and therefore that reaction only occurs at their common surface. The liquid does not boil on the water-bath, which again militates against intimate contact. It was found that the addition of copper powder as a catalyst greatly improved the yield; the following summary of two experiments shows this : I. 9'4 grms. of phenol, 5.6 grms. of potassium hydroxide in 5.6 cc. water, 2 cc. of alcohol, and 12.8 grms. of benzyl chloride heated on a water-bath for four hours-yield, 6.5 grms. II. Same quantities as in I., but o'i grm. of copper powder added-yield, 10'1 grms. The final method of preparation adopted was the following: Four hundred and seventy grms. of phenol were dissolved in a solution of 280 grms. of potassium hydroxide in 300 cc. of water. This was heated to about 80°, and a mixture of 500 grms. of benzyl chloride, 80 cc. of alcohol, and o'5 grm. of copper powder added with frequent shaking. The mixture was heated under reflux in an oil-bath at 105-115°. It reacted vigorously at first, and was then kept in gentle ebullition for three hours. The non-aqueous layer was washed with warm water, dissolved in ether, and the solution dried. On removal of the ether and fractional distillation of the residue, 73 grms. of benzyl chloride were recovered and 575 grms. of phenyl benzyl ether obtained, a yield of about 90 per cent of the theoretical, calculated from the benzyl chloride consumed. Phenyl benzyl ether can be economically purified by fractional distillation under a pressure of 60-80 mm. NEWS The method described above would obviously be applicable, after suitable modification, in the preparation of ethers of substituted phenols, using other halogen derivatives than benzyl chloride. 255. "The Capillary Constants for Liquid Carbon Monoxide and Liquid Argon." (A Correction). By C. A. CROMMELIN. Whilst making calculations some time ago concerning the capillary constants of argon (Mathias, Onnes, and Crommelin, Proc. K. Akad. Wetensch. Amsterdam, 1912, xv., 667, 960) errors were found in the tables of data given by Baly and Donnan in their paper on the surface-energies and densities of some liquefied gases (Trans., 1902, lxxxi., 907). Below are given the corrected data for the surfacetensions of argon and carbon monoxide. Dr. G. Rudorf has already (Ann. Physik., 1909, [iv.], xx., 751) published the corrections for argon, but the complete tables for carbon monoxide and argon are conveniently given here. TABLE XVIII. (corrected). Surface Tensions of Liquid Carbon Monoxide. 70 71 72 73 74 75 76 77 12 11 11.88 11.64 1141 11 18 10 96 10'73 10.50 80 81 82 83 84 85 9.83 9.61 9.39 9.17 8.96 8.74 86 87 88 89 90 8.31 8.10 7.89 7.69 T γ T 78 79 γ 10.28 10:05 T ㄑㄧㄥㄧㄥㄢ 8.53 The y-values for oxygen and nitrogen are correct. 256. "p-Chlorophenylselenious Acid." (Preliminary Note). By GILBERT T. MORGAN and J. CAMPBELL ELLIOTT. P-Chlorophenylselenocyanate, C6H4Cl Se CN (yellow leaflets from alcohol, m. p. 50-51°), was obtained by adding an alcoholic solution of potassium selenocyanate to a well-cooled aqueous solution of p-chlorobenzenediazonium chloride containing excess of sodium acetate. The cyanide group was readily removed by the action of aqueous alkali hydroxide, and the resulting selenophenol, C6H4Cl SeH, oxidised to the diselenide, (C6H4Cl Se)2, by hydrogen peroxide. Oxidation of either of these compounds with alkaline permanganate gave rise to sodium p-chlorophenylselenate. p-Chlorophenylselenious acid, C6H4Cl SeO2H (colourless needles from hot water, m. p. 178°), was produced by boiling the preceding sodium salt with hydrochloric acid; it is an amphoteric substance. giving rise to metallic p-chlorophenylselenites and to salts of the mineral acids, such as the nitrate and hydrochloride. A more detailed examination of these aromatic selenium derivatives is in progress. 257. "Benzenesulphonyl Derivatives of o-Aminoazo-compounds." (Preliminary Note). By GILBERT T. MORGAN and JOHN HARbourne CookE. Benzenesulphonyl derivatives of aromatic o-diamines condense readily with aromatic nitroso-hydrocarbons in acetic acid solution, furnishing azo-derivatives. 4-Benzenesulphonyl-3: 4-tolylenediamine and p-nitrosotoluene give rise to 4-benzenesulphonyl-4-amino-3-azotoluene (I., golden-yellow needles, m. p. 151-152°). 3 Benzenesulphonyl-3-amino-4-azotoluene (II., dark yellow CH3 N:N CH3 needles, m. p. 156°), produced similarly from 3-benzenesulphonyl-3: 4-tolylenediamine, is an acyl derivative of the still unknown 3-amino 4-azotoluene. Experiments on the hydrolysis and oxidation of these azo-derivatives are in progress. 258. "The Possibility of a New Instance of Optical Activity without an Asymmetric Carbon Atom." By HAROLD KING. Up to the present time the only experimentally realised instances of optical activity in the absence of an asym metric carbon atom are furnished by Perkin, Pope, and Wallach's (Trans., 1909, xcv., 1789) resolution of 1-methylcyclohexylidene acetic acid, and Mills and Bain's (Trans., 1910, xcvii., 1866) resolution of the oxime, and later of other simple derivatives of cyclohexanone 4-carboxylic acid. The molecular asymmetry of such substances belongs to the centro-asymmetric type. The possibility of further examples of the centroasymmetric type, differing widely from the previously known cases, is perceivable from the discovery by Cain and his co-workers of two o-dinitrobenzidines, two o- and four m-dinitro-o-tolidines of the formulæ shown below, each representing two isomerides : NO2 where the two planes of the benzene rings are superimposed, but not necessarily parallel to each other. The isomerism is ascribed to the non-rotation of one of the benzene rings. In the particular instance cited, Cain and Micklethwait have been unable to effect interconvertibility of the isomerides by any means, indicating the difficulty of free rotation of one of the rings relative to the other. A transformation, however, has possibly been effected in the case of the two o-dinitrotolidines. Now, Cain and Micklethwait find their difficulty in that they are quite unable to fix the orientation respectively of these pairs of somerides; for example, in the case of the dinitro |