CHEMICAL NEWS, Jan 21, 1910 Quantitative Determination of the Acid Earths. Reactions in the Wet Way. (a) Using the Solution of any Alkaline Tantalate. (i.) Mineral Acids. * (NOTE. The reactions marked are quite new, or else do not confirm previous statements). Concentrated sulphuric acid dissolves precipitated tantalic acid when warmed, bnt not the ignited substance. If the solution of tantalic acid in concentrated sulphuric acid is poured into water and boiled, almost all the tantalic acid is precipitated. Dilute sulphuric acid in the cold produces a slight turbidity, which is increased on standing, and becomes almost quantitative on boiling. Hydrochloric acid produces in dilute solutions of a tantalate no precipitate even on warming. In concentrated solutions it produces an opalescent turbidity in the liquid; sulphuric acid does not precipitate quantitatively the tantalic acid from this hydrochloric acid solution. Nitric acid behaves like hydrochloric acid, but its solvent action is smaller. *Perchloric acid precipitates tantalic acid quantitatively in the form of easily filtered flakes on boiling a tantalate solution. *Phosphoric acid precipitates no tantalic acid from a tantalate solution; even in presence of a large excess of phosphoric acid the liquid remains clear, and is not made turbid by the addition of a mineral acid even on heating. Only acetic acid can produce a slight turbidity. Apparently a complex salt is formed, but in its solution the phosphoric acid can be precipitated with magnesia mixture. No alkaline liquids, e.g., ammonia, precipitate these phosphate solutions. *Phosphorous and hypophosphorous acids behave like phosphoric acid. *Hydrofluosilicic acid also produces no precipitate as tantalic acid is exceedingly soluble in it. *Carbon dioxide decomposes sodium tantalate completely, tantalic acid being separated; also a tantalate solution which has been prepared by fusion with soda and saltpetre (difference from niobic acid). Hydrofluoric acid does not precipitate tantalate solutions; after neutralisation of the hydrofluoric acid solution with potash microscopic needles form; they can very readily be distinguished microscopically from the tablets of the analogous niobium compound. (Best method of qualitatively detecting the two acids). (ii.) Organic Acids. Oxalic acid produces in tantalate solutions in the cold a precipitate of tantalic acid, which again dissolves when the liquid is warmed. Ammonia precipitates tantalic acid quantitatively from this solution." Tartaric acid behaves like oxalic acid, but neither ammonia, ammonium sulphide, nor a mineral acid again precipitates the tantalic acid from the solution. *Acetic acid precipitates tantalic acid quantitatively from tantalate solutions on boiling. (iii.) Ammonium Salts. Ammonium chloride precipitates the greater part of the tantalic acid from a tantalate solution on boiling. *Ammonium nitrate behaves like ammonium chloride. (NOTE. None of the last three precipitates marked are formed in presence of tartaric acid, oxalic-tartaric acid, or hydrogen peroxide). Ammonium acetate when added in sufficient quantity precipitates tantalic acid quantitatively on boiling. (b) Using Freshly Precipitated Tantalum Hydroxide in Hydrochloric Acid Solution. 29 Sodium carbonate precipitates a portion of the tantalic acid in the cold; it re-dissolves in an excess of the reagent. *Sodium hypochlorite precipitates tantalic acid quantitatively from acid, also from oxalic acid solution. *Sulphuretted hydrogen precipitates tantalic acid almost quantitatively in the cold, especially from sulphuric acid solution. Sulphurous acid precipitates tantalic acid quantitatively on boiling. *Hydrogen peroxide dissolves freshly precipitated tantalic acid exceedingly easily on warming if a base or an acid is present. Hydrogen peroxide alone does not dissolve tantalic acid. *Hydrofluosilicic acid dissolves precipitated tantalic acid very easily. *Phosphoric acid cannot dissolve precipitated tantalic acid. (See, however, the behaviour of phosphoric acid towards an alkaline tantalate solution). The presence of hydrogen peroxide, tartaric acid, and oxalic-tartaric acid prevents all these precipitations. *Tincture of gall-nut (according to Marignac) produces no light brown precipitate in acid solutions of pure tantalic acid. Tannic acid solution in water or glycerine produces neither coloration nor coloured precipitate. *Potassium ferrocyanide gradually produces in acid solution in the cold a red brown precipitate at a gentle heat, and on addition of sulphurous acid it appears more quickly. *Potassium ferricyanide produces a colourless solution. *Potassium sulphocyanide behaves like potassium ferricyanide. * Ammonium molybdate also behaves similarly. (NOTE. In this reduced tantalum solution the last four named reagents may also produce only colourless precipitates). Zinc and hydrochloric acid produce no coloured solutions. Reactions in the Dry Way. Tantalic acid is infusible and possesses a pure white colour both when hot and cold. The borax bead remains colourless in the oxidation and reduction flame, and in the *latter also on addition of tin or zinc oxide. 2. Reactions of Niobium. Niobic acid in its analytical behaviour is very much like tantalic acid. When fused with potassium sulphate it behaves like tantalic acid, with the difference that on boiling the melt with water more niobic acid remains in solution than is the case with tantalum. Reactions in the Wet Way. (a) Using the Solution of any Alkaline Niobate. Concentrated sulphuric acid dissolves ignited niobic acid on heating and the solution remains clear when poured into water. On standing for a long time, and more quickly on boiling, the greater part of the niobic acid separates out. (Difference from tantalic acid). If such a sulphuric acid solution containing niobium is poured into concentrated ammonium sulphate, even on standing for a day or continued boiling no trace of niobic acid separates out. (Difference from tantalic acid). Dilute sulphuric, hydrochloric, nitric acids behave as with tantalic acid, only niobic acid is still more soluble in them. *Perchloric, phosphoric, phosphorous, hypophosphorous, and hydrofluosilicic acids behave in the same way as with tantalum. Hydrofluoric acid dissolves niobium very easily; for further details see under tantalum. *Oxalic, tartaric, acetic acids, and ammonium salts Ammonia precipitates tantalic acid quantitatively from behave as with tantalum. acid solutions; excess of ammonia does no harm. Ammonium sulphide behaves like ammonia, Carbon dioxide partly decomposes sodium niobate solution. On the other hand, a niobate solution which has 30 Effect of Continued Grinding on Water of Crystallisation. CHEMICAL NEWS, Jan. 21, 1910 been prepared by fusion with soda and saltpetre is not | gratifying account of the solution of the difficulty; and is decomposed by carbon dioxide. (Difference from tantalic acid). (b) Using Freshly Precipitated Niobium Hydroxide in Hydrochloric Acid Solution. Ammonia, ammonium sulphide, and sodium carbonate behave as with tantalum, only niobium hydroxide dissolves much more easily in soda when gently warmed. a striking illustration of the immense advantage of handing over industrial enigmas, which have baffled the ingenuity of the practical man, to research laboratories in which the organised investigation of obscure problems is systematically carried out as a matter of daily routine. WATER OF CRYSTALLISATION. *Sodium hypochloric, sulphuretted hydrogen, sulphurous THE EFFECT OF CONTINUED GRINDING ON acid, and hydrogen peroxide behave as with tantalum, but the last dissolves niobic acid in acid or alkaline solution more easily than tantalic acid. Tincture of gall-nut and tannic acid solution in water and glycerine behave in the same way as with tantalum. *Hydrofluosilicic and phosphoric acids exhibit the same behaviour as with tantalum. *Potassium ferrocyanide produces a greyish green precipitate. (Difference from tantalic acid). For potassium ferricyanide, potassium sulphocyanide, and ammonium molybdate see tantalum. *Zinc and hydrochloric acid produce a dirty blue coloration which loses its colour directly. From this reduced niobic acid solution the last of the above named reagents can produce no coloured precipitates. Reactions in the Dry Way. Niobic acid is infusible and lemon coloured when hot; in the cold it also possesses a yellowish tinge. The borax bead is colourless in the oxidation and reduction flames. ON THE EROSION OF BRONZE PROPELLERS. THE phenomenon of the erosion of propellers made of high tension bronze has of recent years assumed a serious practical importance, and it is satisfactory to find that the solution of the problem of the best method of preventing it has been found by Oswald Silberrad, Dr. Phil., M.R.S.A., F.C.S., in the Silberrad Research Laboratories. It was observed that the damaged propellers looked to a certain extent as if they had been subjected to galvanic action, the maximum erosion occurring at places not always similarly situated on the propellers. The primary cause appeared to be surface friction, but, on the other hand, propellers exposed to the same tests showed very different results; for instance, in the case of the Cunard Liner Lusitania both the backs and faces were equally affected, while the actions on the two surfaces of the propellers of the Mauretania were widely different. Moreover, where the surface friction was a maximum it was found that the minimum damage was done on the propellers of certain destroyers. Hence a search was made for secondary causes. The most obvious of these-the presence of dirt in castings and galvanic action-had to be dismissed as impossible, and it was ultimately found that the specific nature was primarily erosion, though secondary causes had important influence. Many tests were carried out in the laboratories with a very large number of alloys of different composition, and the conclusions drawn were as follows:- (a) The capacity to withstand this deterioration is not, strictly speaking, dependent on any one physical property, but must rather be regarded as a property peculiar to itself; in short, it would appear to constitute a new physical constant for alloys. (b) In the new alloy, "Parsons' Turbine Alloy," this property has been brought to a remarkable pitch, its resistance to the action under standard conditions being nearly five times as great as that of the old alloy, from which it will be seen that the new alloy is likely to resist all reasonable conditions of wear indefinitely. Thus the report, which is fully illustrated by photographs of the state of propellers after use, contains a By IRVING B. BLEEKER. MAUZELIUS (Sveriges Geol. Undersökning, Arsbok i., 1907; Day and Allen (Bull. U.S. Geol. Survey 305, p. 55); Hillebrand (Fourn. Am. Chem. Soc., xxx., 7); and Knight (CHEMICAL NEWS, xcvii., 122) have shown the effect of fine grinding on the water and ferrous content of minerals and rocks. In this paper we are able to show the effect of continued grinding on a few hydrates. The water was determined in each specimen after grinding it a half-hour, an hour, an hour and a-half, and two hours. The two hours' grinding seemed to give the maximum results. The grinding was done by hand in an ordinary Wedgwood mortar. In each determination about a grm. of the substance was weighed into a porcelain crucible, and the water was removed by heating to constant weight with a Bunsen burner. For purposes of comparison the water was first determined in the unground specimen. All the conditions were maintained as nearly uniform as possible. 1. Magnesium Sulphate. CHEMICAL NEWS, Jan. 21, 1910 Potassium Iodide Starch Paper. ON THE SUBSTITUTION OF BROMINE AND OF IODINE FOR CHLORINE IN THE SEPARATION OF CERIUM FROM THE OTHER CERIUM EARTHS. By PHILIP E. BROWNING and EDWIN J. ROBERTS. ONE of the best known processes for the separation of cerium from lanthanum and didymium is that of Mosander (Fourn. Prakt. Chem., xxx., 267). This process consists in passing chlorine gas into a mixture of the hydroxides suspended in a distinct excess of a fixed alkali hydroxide until the solution is saturated and the reaction of the liquid is no longer alkaline to litmus. Under these conditions nearly all the cerium remains undissolved as the ceric hydroxide, while the other cerium earths go largely into solution. In treating mixed material the residue of ceric hydroxide generally retains some of the cerium earths, so that the treatment with chlorine must be repeated. Two disadvantages associated with this method, therefore, are the preparation and use of chlorine gas, and the solvent action of the hydrochloric acid formed in the reaction upon the ceric hydroxide 2Ce(OH)3 + Cl2 = 2CeO2 + 2HCl + 2H2O. The work to be described was undertaken to study the effect of substituting bromine or iodine for chlorine in this process. A preliminary experiment was made by suspending a precipitate of the washed hydroxides of the cerium earths in water, adding a little liquid bromine, and allowing the action to go on for several hours with occasional stirring. The precipitate took on the colour of the ceric hydroxide, and on filtering the filtrate was found to contain a considerable amount of cerium earths free from cerium. In the following experiments solutions of known amounts of the mixed oxides, composed of about 50 per cent of cerium and 50 per cent of the cerium earth oxides other than cerium, were treated with a slight excess of sodium or potassium hydroxide. To these hydroxides suspended in the alkaline solution, liquid bromine or bromine water was added in distinct excess, and the mixture was placed upon a steam-bath until the greater part of the free bromine was expelled. The residue was then filtered off, washed, and treated as before. This process was repeated twice, and the filtrate after each treatment was found to contain the amounts of cerium earth oxides, free from cerium, indicated in the table. The residue from the last treatment on being dissolved in acid showed only faint didymium bands. In experiment 6 the indication of the presence of didymium was very faint. In another experiment the same amount of material used in 5 and 6, 10 grms., was subjected to a fourth and fifth treatment with bromine, the fourth treatment yielding a small fraction of a grm. of the oxides, and the fifth only a few mgrms. In both cases these oxides were free from cerium. The oxides from the first filtrates were much lighter in colour than those obtained from the last, which, of course, indicates that the lanthanum is dissolved by the action of the bromine more readily than the didymium. The results follow in the table : Mixed oxides Oxides found Oxides found Grm. Grm. 0.0720 31 method are, the convenience in the use of the bromine, and the apparent lack of tendency of the hydrobromic acid to dissolve the ceric hydroxide. An experiment was made, using iodine in place of bromine, as follows:-The precipitated and suspended hydroxides from 2 grms. of the mixed oxides were treated with 1 grm. of solid iodine. After standing for about two hours on a steam-bath, the excess of iodine was removed by boiling, and the residue of hydroxides was filtered oft. The filtrate gave o 0980 grm. of oxides, free from cerium, and of a slight brown colour. This shows that the action of iodine is the same, in a general way, as that of chlorine and bromine, but is too incomplete to be of any practical value.-American Journal of Science, xxix., No. 169. POTASSIUM - IODIDE STARCH PAPER. By C. G. STORM. THE facts which are noted in the literature of explosives concerning the potassium-iodide starch paper used in the heat test or Abel test, are found to be misleading in many cases, particularly as to its keeping qualities and the effect of light on the paper. The following work on this subject was carried out by the author while in charge of the chemical laboratory of the Navy Smokeless Powder Works at Indian Head, Md. Heat test paper prepared in this laboratory with proper precautions and preserved in tight stoppered dark bottles has been found in perfect condition after a period of eight years. The method of preparation is about the same as that usually employed, except that the paper before treating is washed for only a short time in distilled water (dipping for about ten seconds), also the potassium iodide and starch solutions are cooled before mixing. The paper used is Schleicher and Schull's 597. This qualtity of paper weighs about 5 grms. per 100 sq. in. It is cut in strips about 24 by 6 inches, and after washing hung on clean cords over-night to dry in a room free from fumes. The best quality of potassium iodide obtainable is recrystallised three times from hot absolute alcohol, then dried, and I grm. dissolved in 8 oz. distilled water. Cornstarch is well washed by decantation with distilled water, dried at a low temperature, 3 grms. rubbed into a paste with a little cold water, and poured into 8 oz. boiling water in a flask. After boiling gently for ten minutes, the starch solution is cooled and mixed with the potassium iodide solution in a glass trough. The washed and dried paper is then at once dipped in this mixture, immersing each strip for about ten seconds, and hanging one end over a clean cord to dry. The dipping is done in a very dim light, and the paper left over-night to dry in a perfectly dark room. Every precaution must be taken to ensure freedom from contamination in preparing the materials, and absence of laboratory fumes which might cause decomposition. When dry, the paper is cut into pieces about 1 by inches, and preserved in tight glass-stoppered bottles, the edges of the large strips being first trimmed off about of an inch, to remove portions which are sometimes very slightly discoloured. The finished paper should be of good white colour. It has been found that the test-paper will invariably give a coloration with acetic acid, the intensity of the test depending on the strength of the acid used. In the report of His 47340 Majesty's Inspector of Explosives for 1907, it is stated 6. 10'0000 that washing the paper in 10 per cent acetic acid and then 4.8390 in water, before dipping in the KI-starch solution, removes So it has been shown that by substituting bromine for impurities from the paper, thus preventing the discoloration chlorine in the Mosander process about 50 per cent of the in the acetic acid test. These results have not been conother cerium earths can be separated from ceric hydroxide firmed by experiments made by the author. in one treatment, and that after three treatments practically all the other cerium earths are removed without any solvent action upon the ceric hydroxide. The advantages of the 0.3310 Grm. I. 1'0000 2. I'0000 0 2900 Ο ΙΟΙΟ 3. I'0000 0'2250 4. O'1290 0.0860 1'0050 Oxides found Total 0 ̊5240 0.8560 The method of testing relied on is that of comparing the new paper with regular stock paper which has been found satisfactory. This is done by making comparative tests at 12-7-06 2 months 2446 12-7.06 50 12-7-06 0-8-06 45 I months 2401 B 16 18 7 months 2401 B (a) The papers of 5-23-03 and 10-11-02 were preserved wrapped in paper, and placed in a tin box with loosely fitting cover, within a closed drawer. The low test is undoubtedly due to deterioration. Except where noted, all samples had been kept in tight glass-stoppered black bottles since manufacture, being opened only occasionally for the purpose of taking out a supply of paper. From these results it is evident that potassium-iodide starch paper, when properly prepared, is in condition for use within twenty-four hours after dipping, and when properly preserved will remain in good condition practically indefinitely. To determine the effect of light, a batch of test-paper was divided up in four bottles of different coloured glass plain colourless, amber, blue, and black (opaque)-the bottles tightly stoppered and sealed, and placed in a window ledge receiving good light, but not direct sunlight. After three weeks' exposure, the same lot of nitrocellulose was tested with paper from each bottle, and also from the regular stock paper. Results of test : During a further exposure to light for two months, a large portion of the time to direct sunlight, the blue and brown bottles were broken. Tests of the other samples were as follows: Heat Test at 65.5° C. Paper. Regular stock Colourless bottle Black bottle Sample C. Mins. 45 48 44 Apparently the action of light on heat test paper for even considerable periods is not in the least deleterious, provided there is no contact with moisture or fumes. There are reasons, however, for the belief that the paper, when freshly prepared, is more sensitive to the action of light than after it has aged for a time.-The Journal of Industrial and Engineering Chemistry, i., No. 12. HOW TO RECOGNISE PITCHBLENDE. PROF. HERMAN FLICK, Director of the Colorado School of Mines, gives the following characteristics of pitchblende, the mineral from which uranium and radium are obtained: "Pitchblende occurs in fissure veins, in igneous rocks like granite. It is valued for its uranium and radium contents. It is not found in sedimentary rocks, although alteration products of it may be found therein. Such alteration products are coloured yellow or greenish, and when in sufficient concentration and quantity, are valuable for their uranium contents. The radium value in these is small, as a rule. Pitchblende is found in vein matter in stringers varying from knife-blade thickness to several inches. It is bunchy.' The associated minerals in addition to vein matter are sulphides, such as zinc blende, galena, and iron pyrite. The latter usually predominates. It is detected by the following properties: "Colour.-Pitch-black, velvety-black, brownish sometimes with a greyish or greenish cast. The streak on rough porcelain, i.e., the edge of a broken plate, is brownish black, olive-green, or greyish. "Lustre. Dull, metallic, greasy, pitch-like. Fracture.-Conchoidal; that is, with smooth curved surfaces to uneven. Brittle. "Hardness.-Less than quartz. It is not scratched by a knife blade unless weathered. "Specific Gravity.- Heavier than iron or steel; also heavier than galena. "The following common minerals are likely to be mistaken for pitchblende by prospectors: - Obsidian or volcanic glass, which differs from pitchblende in its lightness, glassy lustre, and light streak. Magnetite, which differs from pitchblende mainly in that it is attracted by the magnet. Hematite, which differs from pitchblende mainly in possessing a red streak. The Chemical Engineer, x., No. 6. CHEMICAL NEWS, Jan. 21, 1910 Secret Mixture Weighing Machine. SECRET MIXTURE WEIGHING MACHINE. THE frequent necessity for privacy in the weight of different ingredients has led to the demand for a machine which will give accurate pre-determined weighings for a required maximum number of mixtures, and at the same time enable the manager to retain the information as to the exact weights to himself alone. The machine as illustrated consists of eight weighing steelyards and a tare-bar. The tare-bar is set to equal the weight of the empty barrow, and each barrow has a number to correspond with the steelyard, which is always in gear with the platform. 33 handle. The barrow is then filled till the steelyard is in equilibrium; when this is done No. 2 steelyard is conneeted with the levers, and No. 2 constituent put into the barrow on the top of No. I constituent until No. 2 steelyard is in equilibrium, and so on. will be seen, the machine is used rather as a balance than This method effects a great saving of time. Thus, it for actual weighing. It shows that the weight on the platform is of a pre-determined magnitude, but the workmen are in total ignorance of the amount. The containing box or frame of the machine is of castiron with flanges all round, and is designed to be sunk in the ground in order to bring the platform flush with the floor level. The person in charge sets the poise on each steelyard at the exact weight of each constituent required. The steelyard case is then locked. The barrow-man runs the barrow on to the machine, turns the handle corresponding to the mixture number to the weighing position, and loads the barrow until the indicator, which is exposed to view through a window at the top right-hand corner of the machine, shows when the steelyards are in equilibrium. As the tare and one of the weighing steelyards are virtually locked together during the operation, the fact that the former is in equilibrium shows that the poises on the two steelyards together balance the weight of the barrow and its contents, and consequently that the right amount of material has been loaded up. In small plants, where only a small charge is required, the materials can be weighed as follows:-The poises corresponding to each constituent are set at the required weight, the barrow is brought on, and No. I steelyard is connected with the levers by means of the projecting The levers are of cast-iron, fitted with hardened steel knife-edges, and are suspended from the frame by means of Avery's patent adjustable links, which allow the platform to swing in any direction, thus preventing undue wear to the knife-edges and bearings. The platform is supported upon a stool of cast-iron, which has four legs, with hardened steel bearing blocks for bearing on the lever knife-edges. The steelyards and poises, of brass, are automatically locked in position on the steelyards at any notch, a distinct improvement over any screw-locking arrangement. within a strong wooden case provided with a door, which The whole of the indicating mechanism is enclosed is secured under lock and key. These machines have proved successful in many parts of the world, and the makers, Messrs. W. and T. Avery, Ltd., of Birmingham, have recently sent several to Rhodesia, |