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Newspaper. POST FR 414. Price 2s. 6d. net. A B C FIVE - FIGURE LOGARITHMS and Tables for CHEMISTS By C. J. WOODWARD, B.Sc. Logarithms of Numbers with Thumb Lateral Index-Instructions for using the Tables, with Examples and Exercises.-Hydrometer Tables. -Electrochemical Equivalents.-Gas Correction or Nitrometer Tables from 680 to 799 mm. pressure and 7 to 23° C.-Thermometer Equivalents, -99° F. to +2990° F. in C. and vice versa.-Weight and Measure Conversion, Imperial to Metric and vice versa.-Factors and Logarithms of Factors for use in Gravimetric Analysis. All tables involving atomic weights calculated from the International Atomic Weights. LONDON: E. & F. N. SPON, 57, Haymarket. J. & A. CHURCHILL'S NEW BOOKS. OSTWALD'S GREAT BOOK on COLLOID CHEMISTRY. Translated into English by Dr. MARTIN FISCHER, Prof. of Phys., Univ. Cincinnati. 60 Illustrations, many Tables. 12/6 net. EXPLOSIVES: their Manufacture, Properties, Tests, MICA. Telephone No. 2248 Avenue, F. 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Persons desiring to send newspapers, &c., to neutral European countries should therefore give their orders for execution to publishers or newsagents who have obtained such permission. The Publisher of the CHEMICAL NEWS has obtained the required permission of the War Office, and he will forward copies direct from the Office to any neutral country on receipt of instructions. THE CHEMICAL NEWS VOL. CXIII., No. 2945. Research Apparatus. THE standardisation of research apparatus for the laboratory is a great convenience to the chemist who wishes 10 make investigations with ozonised air under his own superintendence and control. Such outfits cannot, however, be built up from the apparatus found amongst an ordinary laboratory equipment, as they include parts which cannot be used for any other purpose. Standardised outfits which will cover the whole range of possible laboratory or research work are, however, available. The most important item of these outfits is the Ozone Generator with the high tension transformer for furnishing the necessary high voltage, and in addition, where a continuous current only is available, a rotary converter. A small switchboard is always advisable, mounted with the necessary controlling and regulating apparatus, and an ammeter or a wattmeter is useful although not absolutely necessary for small experiments. The outfits should include the necessary aspirator or pump for drawing or pushing the ozonised air through the material to be experimented with, treatment and air drying vessels, &c., but in some cases these bottles, vessels, &c., and the connection tubes and corks may be omitted if the user is already in possession of such accessories. Ozone generators are standardised in several sizes. Fig. 2 shows a small generator suitable for ordinary experiments of a qualitative or quantitative nature. It is mounted on a rigid metal frame and enclosed in a bellglass, which is mounted on a glass-lined base provided with a stopcock. The top of the bell-glass is fitted with an outlet tube for the ozonised air and the necessary hightension terminals. This generator can be used with air or oxygen, and concentrations from air up to 6 grms. of Ozone per cbm. may easily be obtained with suitable conditions. All the technical applications of Ozone, such as sterilising water, bleaching, and deodorising of various substances, preparation of chemicals, &c., can be performed with this apparatus on The yield of Ozone at a concentration sufficient to bleach a small or trial scale. oils, fats, &c., is about 1 grm. per hour, while the energy used in the generator will not exceed 25 watts for alter nating current supply. A larger type of Ozone generator is illustrated by Fig. 3, which is a reduced size of the generator referred to for industrial processes. It is intended for experimental in vestigations on a more extended scale and under similar conditions to the actual commercial operation. The electrodes, which are of special design, are contained in a water-tight aluminium case, capable of working under pressure. The high tension connecting cables are arranged with plug fittings, so that they can be readily disconnected. The range of concentrations with this apparatus is very large, and the treatments can be carried out in an expeditious manner involving a minimum of labour. With an energy consumption in the generator of 100 watts, the yield of Ozone is about 4 grms. per hour at a concentration sufficient to bleach oils, &c. The capacity for bleaching in a day of ten hours may be as high as 50 lbs. of certain materials. At lower concentrations the yield will be greater, and vice versa. A new type of Ozone generator has recently been designed which is particularly valuable for research work, as it enables concentrations to be obtained up to 8000 parts per million, equal to 16 grms. of Ozone per cbm. of air. This concentration implies that 4 per cent of the oxygen of the air is ozonised, the highest figure which has yet been obtained by any apparatus. This new type can always be used in place of Fig. 3 in the outfits about to be described. The diagrammatic illustration (Fig. 4) shows a small outfit consisting of air-drying bottles, ozoniser, treatment bottle, aspirator, transformer, and switchboard. Ozone generator is of the small size with bell-glass. The The aspirator is of 9 to 10 litres capacity, and the maximum rate of the outfit is about 10 litres in five minutes. The aspirator must therefore be refilled after each 10-litre worked continuously. run, so that the experiment in some cases cannot be Where continuous working is required and only qualitative results desired a Bunsen tap pump may be substi FIG. 2. tuted for the aspirator, but where quantitative results and continuous running are required a.small suction air-pump and electric motor can be substituted for the aspirator, by minute. In this case, as the aspirator is not used, an air which the rate may be increased up to about 30 litres per meter is employed, with a maximum reading of 40 litres per minute. electrically driven air-pump and an air meter, and the A still larger outfit is recommended for work on a more through the liquid to be treated, is forced under considerable pressure through small injectors, which have the effect of bringing the Ozone into intimate contact with the whole of the substance to be treated, so that a better result is obtained in a shorter time, and therefore with a smaller expenditure of Ozone. Moreover, certain treatments can be performed which by any other means would be impossible. The set comprises an air cleaning and drying apparatus, an electrically driven air-pump, air meter, air cooling apparatus, Ozone generator, spraying injectors, treatment vessel, transformer, and switchboard. The air-cooling apparatus is not essential except for very exceptional circumstances or in hot climates, and could be dispensed with altogether if the new type of Ozone generator is used. The air cleaner and drier is of advantage, because it enables a considerable increase of yield to be obtained, whilst the possibility of the formation of the oxides of nitrogen at very high concentrations is eliminated. In conclusion it may be pointed out that whilst the foregoing remarks give a fairly wide indication of the field in THE FRACTIONAL PRECIPITATION OF SOME ORE-FORMING COMPOUNDS AT MODERATE TEMPERATURES.* By ROGER C. WELLS. (Concluded from p. 199). SILICATES. Previous Work. SINCE many of the natural silicates have been formed under the condition of equilibrium with a magma it is obvious that they will not be in equilibrium with aqueous solutions. In order to complete the study of fractional precipitation, however, it appeared desirable to see if there would be any selective action when solutions containing more than one metallic salt were precipitated by a soluble silicate. Jordis has already studied the precipitation of single metallic silicates from soluble salts with reference to which Ozone has been proved to play an efficient part, and also of one method of applying the industrial treatment, there is still a very large unexplored tract for the chemist to investigate, particularly amongst the complicated benzine and other organic compounds and derivatives of coal-tar, &c. In this connection it may be hinted that Ozone in some cases acts something like a catalyst in the presence of another oxidiser, in promoting oxidation, which in its absence does not take place. By this is implied that with certain substances the theoretical quantity of Ozone required to perform the process of oxidation may appear to be so large as to preclude its employment on economic grounds, whereas actually the presence of a relatively small quantity of Ozone will induce oxidation by another oxidising reagent to the extent of as much as twenty times more than without Ozone. We may add that we are indebted to Messrs. Ozonair, Limited, of 96, Victoria Street, London, S.W., for the illustrations and information regarding industrial plants and research apparatus. their composition ("Zur Chemie der Silikate," Zeit. Angew. Chem., 1906, xix., 1697; Journ. Prakt. Chem., 1906, lxxvii., 226; 1910, lxxxi., 303). His experiments with ferric salts, however, are probably complicated by the phenomena of hydrolysis, but he suggests that the behaviour of colloids must be considered (E. Jourdis and P. Lincke, "Beiträge zur Kenntnis der Metall-silicate," Journ. Prakt. Chem., 1910, lxxxi., 289). Experiments with Silicates at Ordinary Temperature. My own experiments have consisted of attempts at fractional precipitations of metallic salt solutions by amounts of soluble silicates insufficient for both the metallic constituents. Although it was expected that the sodium silicate, being hydrolysed, would behave like caustic soda, it seemed desirable to determine whether the silicic acid would participate in the reaction. After the results with the * Bulletin 609, United States Geological Survey. |