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The compound is introduced into the boiling tube and closed with a rubber bung through which a glass tube passes connecting to the vacuum pump. When the necessary temperature is reached the compound will sublime into the interior of the sleeve which may be withdrawn with the sublimate intact. Sanitäts Porzellan-Manufaktur W. HALDENWANGER, SPANDAU, GERMANY. Representative: E. O. Maempel, Finsbury Pavement House, Moorgate Street, London, E.C.2. BERLIN-PORCELAIN-HALDENWANGER Can be obtained from all businesses which deal in Chemical Apparatus. LEWIS'S TECHNICAL AND SCIENTIFIC CIRCULATING LIBRARY from One Guinea. Latest Works obtainable on Publication. Prospectus and Monthly List of additions to the Library sent on request. READING ROOM OPEN DAILY. H.K. LEWIS & CO. LTD. 136, GOWER STREET, LONDON, W.C.1. THE CHEMICAL NEWS, VOL. CXXXII. No. 3435. MERTON HOUSE, SALISBURY SQUARE, TELEPHONES : DVI-MANGANESE AND EKA-CAESIUM By F. H. LORING. In this Journal, towards the end of last year, Dr. Druce and the writer contributed a series of articles which related to the existence of elements of atomic numbers 75, 85, 87, and 93. The first proper evidence of the existence of element 75 in manganese compounds appeared to be revealed on the X-ray Film No. 3. Films Nos. 1 and 2 were inconclusive, as the range of exposure was limited to a narrow region on the film and the X-ray tube was not working at its best then. Reference to the above-mentioned articles and a letter in Nature by the present writer (January 30, 1926) will make this matter clear. Film No. 3 showed a line agreeing closely with the La, theoretical line of element 87 (eka-caesium). The Lẞ, line of this element came in the Br-Ag region, and it was difficult to see it clearly, but by using the spectrum comparator, this line was roughly foreshadowed (see Chem. News, December 11, 1925), at least, so it would seem. This film has been intensified, with the result that some incomplete and very very faint lines now appear on the film, but they would hardly be regarded as proper lines. Those proper lines seen before were, however, made strong enough to measure rather more accurately; and consequently Messrs. Adam Hilger, Ltd., were asked to remeasure and recalculate the lines with the following result. The wave-lengths are in Angström units, as before. The estimated intensities of the five strongest lines are relatively about as follows: 3 Lu, 125, Lß, 100, LB, 49, Ly, 38, LB, 15. The 75 LB, line was looked for on the intensified film, but not found thereon. It is rather surprising that this line did not show as the film was a good clear one, free from defects, and the lines above indicated were of moderate strength and could be easily seen. This may throw some doubt on the existence of element 75 in the sample examined by X-rays, but the mercury difficulty is removed. The supposed 87 La, line is now nearer to its calculated value and further removed from the LB, line of mercury of wavelength 1.0458, which was not, therefore, on the film. FILM NO. 3. Our technique was good, for two consecu tive controls were run at the same time (see Nature, cited above). Moreover, in another experiment, Kahlbaum's normal manganese phosphate was rubbed on the face of the copper anticathode, and a film exposed 10 hours to the resulting radiation. The current and voltage conditions were as described in this Journal (October 30, 1925). Except for the strong copper lines, only two very faint (hardly visible) lines of wave-lengths 1.433 and 1.233 (the experimental error being 0.005 as before) were seen. The range of exposure was the same as Film No. 3. Intensifying Film No. 3 has not helped us with regard to the suspected Lẞ, line falling in the darkened region on the film. On examination with diffuse radiation, i.e., with the film held against an anteriorly illuminated smooth opal shade and examined with a lens large enough to admit the image to both eyes without strain, and giving slight magnification, the line in question seemed to be partly visible. In conclusion, it will be seen (1) that the presence of a mercury line 1.0458 is completely ruled out; (2) that the La, line of eka-caesium is made more probable; (3) that the absence of the Lẞ, line of 75 is an element of discord in the scheme as developed from the first sample and the earlier films; (4) that no further evidence of the existence of the LB, line of eka-caesium is obtained, though the findings previously published in this respect are in no way discredited; (5) that sufficient control experiments were made to show good technique. THE ELECTROLYSIS OF LEAD By ROBERT SAXON, B.Sc., F.C.S. Using a carbon anode and an iron cathode throughout these experiments, there is much to record in the way of failure to get a good deposit of the metal from lead chloride, which is very sparingly soluble in cold water, but much more so in hot. The plain chloride solution conducts very badly, and there is no deposit of the metal except on the introduction of impurity, and then only traces after hours of running. As the resistance heats the liquid, more of the chloride is ionized and the oxide is deposited, but in very meagre quantities. The addition of sodium chloride improves the yield of oxide, but very little of the metal is thrown down. On the introduction of an idle electrode (one between the others unconnected) the yield is greatly improved. The acceleration brought about by this is by no means so great as with copper, nickel or cobalt salts. Caustic potash or soda retards the reaction, tending to form the hydrate and oxide of lead as soon as the chloride dissolves. Ammonium hydrate and ammonium chloride have a like effect. Ammonium nitrate in which lead chloride is somewhat soluble does not assist appreciably, as the current discharges the ammonia, and the disintegrating nitric acid thus cast loose, produces oxide instead of nitrate of lead. At no stage is it possible to get lead nitrate to crystallise out on evaporation, though the crop of oxide increases as electrolysis proceeds. As there is a superabundance of water, it is oxygen and not chlorine liberated at the anode, and the carbon disintegrates rapidly. This carbon heated along with the lead oxide rapidly reduces it, as both are in a finely divided state, and this fact suggests the addition of some finely divided reducing agent in the electrolyte. soluble one, sugar was tried. As a A saturated solution of sugar containing more lead chloride than boiling water will dissolve, acts well. A copious rain of lead appears as soon almost as the current is switched on, and the electrolyte offers little resistance to the flow. What is more important, the carbon anode suffers no appreciable disintegration. The deposit of lead is fine enough to float. The whole is filtered and the deposit washed with boiling water until the filtrate shows no cloudiness with ammonium sulphide. The lead may now be partly dissolved in nitric acid, and tested for lead. The rest may be melted in a crucible, when it turns yellow though refusing to flow, being too fluffy and ready to oxidise. This proves to be lead oxide on solution in nitric or acetic acids. This spongy lead dissolves in nitric acd with the production of brown fumes, always a rough and ready indication of a metal as against an oxide. There is produced during electrolysis hydrochloric acid, and an indicator such as methyl orange is reddened immediately action begins. By dilution and comparator tests with known strengths, the amount of acid may be computed. Thus may be set up a standard list of speeds of electrolysis |