segregation of the earths of higher atomic weights in the first fractions and a better concentration of the earths of lowest atomic weight (chiefly yttrium) in the last fractions. Vigorous stirring also accelerates in the precipitation of erbium, bolmium, and thulium, which results in a higher concentration of neodymium (and yttrium) in the last fractions. A third series of electrolyses in which the stirring was still more rapid showed further accentuation of the differences. TABLE I. Cathode area-452'4 sq. cm. Atomic weight of original mixture-106'95. Catholyte stirred vigorously by means of 12 air jets. Number of fraction. 2 3 Atomic Weight of Volts. described, the hydroxides of the earths are precipitated in the order of their basicities, and their separation is the more complete the more vigorously the mercury cathode and the catholyte are stirred (R. J. Meyer, Abegg's "Handbuch der Anorganischen Chemie," iii., 147). II. Electrolysis of Neutral Solutions of the Nitrates of the Rare Earths and Thorium Nitrate. The weakly basic character of thorium seemed to render it probable that electrolysis of a solution containing thorium nitrate and nitrates of the rare earths might result in the rapid concentration of thorium in the early fractions. Thorium for commercial uses is now extracted on a large scale (about 300,000 kgrms. of thorium nitrate per annum) from monazite. For this reason the electrolytic separation of thorium from the earths with with it is associated in monazite, possessing as it does a practical interest, was investigated. The mixture of the rare earths was prepared from the by-product of the technical separation of thorium from monazite. This material was carefully purified and was freed from cerium and thorium. The earths were converted to the oxides, and from this mixture of the oxides a neutral solution of the nitrates was prepared. The concentration of the solution was then determined by precipitation with oxalic acid and ignition of the Pptd. by oxalic acid oxalate to oxide. 7'4 7.6 Ampere weight. oxides (grms.). hours. 34'5 7 27 7 8 A clear, neutral solution of thorium nitrate was prepared by adding pure, moist thorium hydroxide to cold, dilute nitric acid until the hydroxide was in excess, and then allowing the material to stand until a test with Congored paper showed the absence of free acid. The solution was then separated from the undissolved hydroxide, and its concentration was determined. The electrolysis was conducted in the manner already described, very vigorous stirring of the catholyte and mercury cathode being employed. (a) Electrolysis of Solutions of Thorium Nitrate.Electrolyses of solutions of thorium nitrate alone were first made to ascertain whether the precipitation of the hydroxide may most satisfactorily be made from cool or from hot solution. The electrolyses were made in two cells, connected in series. The solution in one cell was kept at 22° during the run; that in the second cell at about 90°. A dilute solution of thorium nitrate (1'3 grms. ThO2 in 100 cc.) was placed in each cell. The electrolysis was conducted as before described, a current of two amperes being employed. The voltage across the cold cell rose from 6 volts at the beginning to 40 volts at the end of the run; that across the warm cell, from 5 volts to 30 volts. The current required for practically complete precipitation in the cold cell was 5 ampere hours; in the warm cell, 4'75 ampere hours. The current required by theory for complete precipitation was 4 ampere hours. This showed a current efficiency in the cold cell of 80 per cent; in the warm cell of 84.2 per cent. The precipitate of thorium hydroxide in the cool cell was granular, was easily filtered and washed, and contained almost no finely divided mercury. The thorium hydroxide thrown down in the warm cell was flocculent, contained much finely divided mercury, and was filtered and washed with difficulty. From these results it was apparent that the electrolysis of a solution of thorium nitrate operates most satisfactorily when conducted at about room temperature. To determine the influence of the concentration of the electrolyte upon the character of the precipitate, three solutions of thorium nitrate containing o'5 per cent, 5 per cent, and 20 per cent of thorium dioxide, respectively, were electrolysed in small cells of about 300 cc. capacity. The thorium hydroxide precipitated from the 20 per cent solution in very finely divided form resembling a colloidal solution. The character of the precipitates in the other 13 12 Angew. Chem., 1902, xv., 303), the solution was then heated to from 60-80°, and an excess of 10 per cent hydrogen peroxide was added. Thorium is thus quantitatively precipitated as the hydrated peroxide, the rare earths remaining in solution (Meyer and Hauser, "Die Analyse der Seltenen Erden und der Erdsäuren," p. 250). The precipitate was collected on a filter, thoroughly washed, and then dissolved in 2 N hydrochloric acid. The solution was diluted to one litre and 25 cc. portions were precipitated by ammonium hydroxide, and the thorium hydroxide ignited to the oxide, and weighed. The filtrate from the first thorium precipitation by hydrogen peroxide was diluted to 500 cc., 25 cc. portions were precipitated by oxalic acid, and the oxalates of the rare earths were ignited to oxides and weighed. The filtrate from the first fractional precipitate of the hydroxide, together with the wash water, were returned to the cell and electrolysed as before. The procedure was again repeated, three fractional precipitations in all being made. The results are set forth in Table III. The results show that fractional electrolysis effects a marked concentration of thorium in the early fractions, from about 15 per cent in the original mixture to over 78 per cent in the first fraction, and nearly 35 per cent in the second fraction. Tm two cells showed that as the concentration of the solution is lowered (down to 0.5 per cent) the granular form of the hydroxide becomes more pronounced. Because of these results the later electiolyses of mixtures of thorium nitrate and the nitrates of the rare earths were made with solutions that contained about o'5 grm. thorium dioxide per 100 cc. (b) Electrolysis of Solutions containing Thorium Nitrate and Nitrates of the Rare Earths.-A solution containing, in 3'5 litres, 14'72 grms. of thorium oxide and 85 grms. of the oxides of the rare earths (av. at. wt. 1405) was electrolysed with a current of one ampere. The mercury cathode was vigorously stirred during the electrolysis and the concentration of the acid in the porous cup was kept practically constant. At the end of six hours the electrolysis was interrupted and the precipitated hydroxides were collected and purified in the manner already described. The hydroxides were then dissolved in 2 N nitric acid, an excess of acid being avoided. To this solution there was added one-fifth of its volume of a concentrated solution of ammonium nitrate (Benz., Zeit. Nd TABLE IV. Wt. in grms. Per cent. Fraction Ampere number. hours. ThO2. R203. ThO2. 52 1 3 1953 48 From these results it is seen that a single fractional electrolysis of three hours' duration precipitates nearly 26 per cent of the thorium present, and that the precipitated bydroxides contain 52 per cent of ThO2 as against 5 per cent in the original mixture. limiting case be approached that would agree with the rate claimed by Cameron and Ramsay, proportional to the decay of emanation with a half period of three days and twenty-one hours. This case is illustrated by the cylinder with very low emanation, chosen purposely to parallel Cameron and Ramsay's conditions and shows how the limiting case can be attained with the limits of experimental precision. The reaction can come to an end by approximate exhaustion of either the emanation or the reacting gases; the former takes place in small bulbs with high emanation, the latter in larger bulbs. The actual final pressure after decay of all the emanation may be calculated from CHEMICAL ACTION PRODUCED BY RADIUM Equation I for any given case. EMANATION. I.* THE COMBINATION OF HYDROGEN AND OXYGEN. By S C. LIND. (Continued from p. 19). 4. The Course of the Reaction. A KINETIC equation was previously deduced by the writer (Fourn. Phys. Chem., 1912, xvi., 592) for gaseous reactions being produced by radium emanation in fixed volume when accompanied by change in pressure. It was assumed that for a given gaseous mixture maintaining constant composition during reaction, the rate of action would depend on two variables only, the pressure and the quantity of emanation present. The integrated form of the kinetic equation was 3 0.58 69.7 1.805 kp/λ= constant = (log P/Po)/(Eo [e-λt] − 1) The constancy of the first term kulλ holds only for a gaseous mixture in which the specific ionisation remains constant during the reaction. The numerical value of kula also depends on the volume of the reaction bulb. The definition of the terms of kufλ will be given later; for the present purposes it may be regarded only as a velocity of reaction constant. Po and P are respectively the initial | Vol. = 13 272 cc. Exact diam. = 2924 cm. E。 = 0.1682 pressure and that at any time t expressed in millimetres of mercury, Eo is the initial emanation expressed in curies, which is decaying proportionally to the factor ext to be found in the Kolowrat table for radium emanation (Le Radium, 1910, vi., 195; Mdme. Curie, "Traité de Radioactivité," ii., 361; Chemiker Kalendar, 1914, ii., 361; Rutherford, "Radio-active Substances and their Radiation," 1913, p. 665). The actual course of the reaction in spherical bulbs of several different sizes can be seen in Table I., in which the application of Equation I is to be found in the last column. The degree of constancy is satisfactory, and proves that the velocity of reaction in a given volume depends only on the two variables mentioned above, the quantity of emana. tion and the pressure of the gas. This test of Equation I is far more rigid than the one earlier obtained (S. C. Lind, loc. cit.) with the data of Cameron and Ramsay, in whose experiments the total change of pressure was frequently quite limited, owing to the small quantities of emanation Vol. = employed. It will be observed by comparing Cols. 4 and 5 that the percentage of reaction completed runs well ahead of the percentage of emanation decayed, but it approaches it as the quantity of gas to be acted on is increased and the quantity of emanation decreases. Notice that in the case of very fast reactions where the quantity of gas is small and the quantity of emanation high, half of the chemical reaction is completed in 1 days, or less; and only in reactions where the quantity of gas to be acted on is relatively large and the quantity of emanation small, and hence the total change in pressure very slight, would the Published with permission of the Director of the U.S. Bureau of Mines. From the Journal of the American Chemical Society, xli., Time. Days Hours. Per cent Per cent kulλ reaction Em completed. decayed. 5 cm. Sphere. (constant). The question of chemical equilibrium in the reaction between hydrogen and oxygen has recently been considered by the writer in another paper (Am. Electrochem. Soc., 34th General Meeting, Advance Copy No. 5), where it was 0'1640 shown that the equilibrium in some cases can attain 99 per cent of the total combination of the hydrogen and oxygen. This is mentioned here to show that it is not necessary to consider the possibility that either hydrogen or oxygen is removed by side reactions permanently from the main reaction. Although Scheuer (loc. cit.) has reported the formation of some hydrogen peroxide it is evident that its formation must be of somewhat temporary nature, and that the reaction later proceeds to the practically complete formation of water. 3'47 Vol. = 3.36 I 18.50 478.9 6.357 3'40 7.318 40'48 31°40 3'45 2 18.08 50.16 37'08 3'51 3 1.67 437'9 9.668 53'47 42'45 3'47 63.19 50'19 3°56 76.43 59'52 3.76 12 7 18.25 362.6 22.50 333.6 15'74 18.08 87'06 70.26 3.73 100'00 90'26 3'47 Average (To be continued). 3'52 0'2078 2.74 2.73 2.76 2.71 Vol. = curies. I 23'50 425'2 11.85 51.62 41.39 15.58 384.8 14'57 57.86 48.15 16.83 365.6 16.91 6 7 22 0*33 350'2 18.79 15°17 344'5 19.48 20'42 334'0 20.76 9 19.58 321'5 22.28 14 15°33 305'2 24'28 21.25 297'7 25.19 2.72 2.62 2.64 74'59 66.12 77.36 69.61 82.41 75.66 2.62 88.47 92.91 2.62 96'36 92'79 2.61 98.37 2:58 100'00 Cylinder 4 cm. long, 1-8 cm. diam. 2.68 6.787 cc. Diam. of equiv. sphere =2'375 cm. SOLDERS FOR ALUMINIUM. THE following general conclusions concerning Aluminium Solders have been issued by the Bureau of Standards, Washington, U.S.A. : 1. Ali metals or combinations of metals used for aluminium soldering are electrolytically electronegative to aluminium. A soldered joint is therefore rapidly attacked when exposed to moisture and disintegrated. There is no solder for aluminium of which this not true. 2. Joints should therefore never be made by soldering unless they are to be protected against corrosion by a paint or varnish, or unless they are quite heavy, such as repairs in castings, where corrosion and disintegration of the joint near the exposed surface would be of little consequence. 3. Solders are best applied without a flux, after preliminary cleaning and tinning of the surfaces to be soldered. The composition of the solder may be varied within wide limits. It should consist of a tin base with addition of zinc or of both zinc and aluminium, the chief function of which is to produce a semi-fluid mixture within the range of soldering temperatures. Suggested Ranges of Composition. Tin.. Zinc, per cent Tin-zinc-aluminium solders Eo =0'01219 curies. Tin 5 4'00 14'9 Zinc, per cent 12 18 517'7 505'1 1'00 491'5 22.00 484'0 30 2.00 480.5 O'5394 61.89 60'54 0.6519 74'80 76.08 14'6 0'7734 88.74 88.55 15'4 0.8405 96.42 96.37 15'1 0.8716 100'00 99'54 15'2 While the ratio of emanation to gas affects greatly the actual velocity of the reaction it does not influence the constancy of kμ/λ, thus proving that the kinetic equation applies in all cases. The ratio of radium emanation to reacting gases may rise continuously as in small bulbs, may pass through a maximum as in 3 cm. bulbs, or may fall continuously as in larger bulbs without affecting the constancy. However, for reasons to be brought out in Part II., the gas pressure may not fall too low in a small (1-2 cm.) bulb without affecting the velocity constant, due to action of the "recoil atoms." Experiments with and without drying agent show, in agreement with Cameron and Ramsay, that the presence of moisture does not influence the velocity of the reaction. However, in larger bulbs starting with dry gases and no drying agent, some time would be required to saturate the gases with water-vapour, which would lead to unnecessary complications in applying the kinetic equation during this period, which are best avoided by having drying agent present in the reaction bulb. Aluminium, per cent Remainder 15-50 Remainder 8-15 5-12 4. The higher the temperature at which the "tinning" is done the better the adhesion of the tinned layer. By using the higher values of the recommended zinc and aluminium percentages given above, the solder will be too stiff at lower temperature to solder readily, and the workman will be obliged to use a higher temperature, thus securing a better joint. A perfect union between solder and aluminium is very difficult to obtain. 5. The joint between previously tinned surfaces may be made by ordinary methods and with ordinary soft solder. Only the "tinning" mixture need be special for aluminium. 6. There is no reason why a good solder for aluminium need be brittle as several commercial varieties are, and it is very undesirable that it should be. 7. The tensile strength of a good aluminium solder is about 7000 pounds per square inch. The strength of a joint depends upon the type and upon the workmanship. Much dependence should not be placed on the strength of a joint. NOTICES OF BOOKS. The National Organic Colouring Malters. By ARTHUR GEORGE PERKIN, F. R.S., F.R.S.E., F.I.C., and ARTHUR ERNEST EVEREST, D.S., Ph.D., F.1.C. London, New York, Bombay, Calcutta, and Madras: Longmans, Green, and Co. 1918. Pp. xxii+-655. Price 28s. net. THIS treatise provides an admirable survey of a subject which has not been adequately treated by any book in the English language, since the appearance forty-five years ago of Sir William Crookes' "Handbook of Dyeing and Calico Printing." Very considerable advances in our knowledge of the chemistry of natural dyes have been made since 1874, and a complete account of the results of modern researches will be of great value to investigators and students. The natural colouring matters are nowadays being more extensively used than heretofore for colouring articles of food, and their production in the pure state may develop into a comparatively important industry. There is plenty of scope for research work on the dyes of unknown composition, and the treatise contains many suggestions of profitable lines of study, while it provides also a most comprehensive account of all that has already been done. The authors' knowledge of their subject it is unnecessary to say is quite unrivalled, and their investigations have extended to many of the natural groups. The various dyeing materials are classified according to the constitution of their chief constituents, and a detailed account is given of all the most important representatives of each of the 17 groups, while not the least important chapter is that on the natural dyes of unknown constitution. NOTES. THE May number of the Journal Chimie et Industrie, the organ of the Société de Chimie Industrielle, contains an exceedingly interesting article decribing the visit of the members of the Inter-Allied Conference of Associations of Pure and Applied Chemistry to Chauny, which visit was made at the invitation of the Compagnie des Produits Chimiques de Saint-Gobain. This company was the owner of some of the oldest chemical factories in France, situated at Chauny, which are now nothing but a mass of ruins. A special train from Paris was placed at the disposal of the guests, and déjeuner was served in the restaurant cars attached to the train. Cbauny was reached at II o'clock, and the members of the party were immediately conducted round the ruined factories by the president, vice-president, and other officials of the Société de Saint-Gobain. The products manufactured before the war included sulphuric and hydrochloric acids, sodium sulphate, chlorine, and various artificial manures, as well as smaller quantities of nitric acid, sodium fluosilicate, &c. The Germans reached Chauny on September 1, 1914, and at once began systematically to remove all the materials and to destroy the buildings and apparatus. All the lead chambers were demolished and the lead requisitioned, as well as copper cables, &c. The illustrations with which the article is provided give some idea of the state of devastation produced, and it is only too evident that the work of reconstruction will be tedious, dangerous, and very costly; it is well to remember that in the meantime German products will be manufactured with comparative ease and will be put upon the markets in abundance. THE monthly periodical Le Radium, published by Masson et Cie., of Paris, has now resumed publication after an interruption lasting nearly five years, and we offer the editor and staff our heartiest congratulations and good wishes for a prosperous and useful future. Unhappily the founder of the paper, M. Jacques Danne, has recently died, and the May number contains a short sketch of this life and work. There are also an original article on ionisation by collision, and translations of articles from English and German periodicals, together with short analyses of papers on radio-activity and radiation which have appeared recently, and a complete bibliography, beginning with the year 1914. FEDERATION OF British IndusTRIES.-H.M. the King granted an audience on the roth inst. at Buckingham Palace to Dr. Pandia Calogeras, one of the Brazilian delegates at the Peace Conference and representative for Brazil on the League of Nations Council. Doctor and Mdme. Calogeras proceed to Edinburgh to join the Brazilian Commercial Delegation which is now visiting various industrial centres of Great Britain under the auspices of the Federation of British Industries. It will be remembered that Dr. Calogeras was chosen by the Brazilian Government as Head of the Commercial Delegation. The following resolution has been passed by the Executive Committee re Nationalisation:"A special Committee of the Federation of British Industries has for some time been considering the question of Nationalisation of industry, and it is hoped that a reasoned and full report will shortly be ready for submission. In the meantime this meeting of the Executive Committee of the Federation of British Industries reaffirms the resolution adopted by the Grand Council on May 14, 1919, viz., That this Grand Council expresses its unanimous opinion against the principle of nationalisation of industry.' BRITISH SCIENTIFIC PRODUCTS EXHIBITION.-At the Central Hall, Westminster, a series of kinematograph films of scientific and technical interest were shown in the Great Hall on the following dates :-Tuesday, July 8; Thursday, July 10; Tuesday, July 15; Thursday, July 17. These will be continued (3.30 to 5.30 p.m.) on Saturday, July 19; Tuesday, July 22; Thursday, July 24; Saturday, July 26; Tuesday, July 29; Thursday, July 31. The films illustrate-Aircraft Construction and Utilisation; The Making of a Big Gun; The Water Powers of Canada and their Industrial Utilisation; Wireless Telegraphy and Telephony; Magneto Construction. The following lectures were delivered in Committee Room B:-Monday, July 7-"Chemistry in Reconstruction," by Sir William Tilden, F.R.S. Wednesday, July 9-"Sound under Water and its Applications," by Prof. W. H. Bragg, F.R.S. Friday, July 11-"Coal Conservation," by Prof. H. E. Armstrong, F.R.S. Monday, July 14-" Progress in Rangefinders," by Prof. Archibald Barr. July 18-"Explosives," by J. Young, of the Royal Military Academy. The following further lectures will be delivered (at 5.30 p.m.):-Monday, July 21-" Progress in Aviation during the War Period," by L. Bairstow, F.R.S. Wednesday, July 23-"How the Cotton Plant Feeds as well as Clothes us," by S. E. de Segundo. Friday, July 25"A Few Thoughts on the Development of London," by Raymond Unwin, F.R.I.B.A. Monday, July 28"Scientific Lighting and Industrial Efficiency," by L. Gaster. Wednesday, July 30-" Recent Progress in BeeKeeping," by W. Herrod Hempsall. Friday, August 1"Applications of Science to Military Mining," by H. Standish Ball. Friday, BRITISH INDUSTRIES FAIR (GLASGOW), 1919, POSTPONED UNTIL 1920.-The Committee of the Glasgow CorporaIndustries Fair to be held within the Kelvin Hall of tion who have charge of the arrangements for the British Industries in September next, have decided to postpone the show until February of next next. This decision was only arrived at after a great deal of serious consideration, and has been brought about largely by the declaration of Peace. The arrangements for the September Fair were well in hand long before the Armistice was signed. Following the cessation of hostilities the Board of Trade with whose authority and support the Fair is held) decided |