摘要:

THE ANALYST. NOVEMBER, 1904. OBITUARY NOTICE. THE LATE WILLIAM CHATTAWAY, F.I.C. As already announced in our last issue, we have to mourn the loss of William Chattaway, who for many years worked in close association with another of our highly-valued members, the late Alfred H. Allen, whose loss we have had so recently to deplore. Though a much younger member of our Society than Allen, Chattaway was scarcely less popular. His death took place on October 7, following upon an operation for appendicitis. Chattaway, who was originally a pharmacist, commenced his career with Mr. Joseph Young, pharmacist and analyst, of Leicester, from whom he received an excellent training. After leaving Mr. Young, he spent some time in Paris. Here he became acquainted with Chevreul, with whom he remained in touch until the death of the aged chemist.Subsequently Chattsway became assistant t o Mr. R. C. Mason, of Bromsgrove, one of whose daughters he afterwards married. After filling situations in Twickenham and Folkestone in 1885, he became A. H. Allen’s chief assistant at Sheffield. Here he remained for seven years, during which time he did much useful research work, most of which was made use of and acknowledged by Allen in his ‘‘ Commercial Organic Analysis.” Early in 1889 Chattaway came to London to manage the branch laboratory that Allen had opened there. In 1893, during the illness of the late Mr. R. H. Davies, he temporarily undertook the duties of Superintendent of the Apothecaries’ Hall, and, soon after the former’s death in November of that year, Chattaway was appointed his successor in this position, which he occupied until his decease.He also held the appointments of Public Analyst for Hammersmith and for Colchester, and, in addition, had a consider- able private practice. On the resignation of Dr. Attfield, Chattaway was appointed reporter on the British Pharmacopceia by the General Medical Council, and under- took the task of preparing a ‘‘ digest of researches and criticisms ” on the British Pharmacopceia. This important work he completed for the years 1899 to 1902. Chattaway was a member of the Council of the Roentgen Society, member of the Pharmaceutical Society and of the Royal Institution. For several years he was a meinber of the Editorial Committee of this Journal, where his wide and detailed knowledge of the chemistry of drugs was very valuable to his collesgues.Outside his own profession he had several other interests. He was an ardent photographer, having done much good work in colour photography; also a skilful mechanic and practical electrician. Possessed of a charming personality, modest330 THE ANALYST. to a degree, always freely disposed to place his extensive knowledge at the service of his fellow-workers, even at much sacrifice on his own part, his memory will long live in the minds of his many friends and admirers. A wife and two quite young children survive him. The following is a list of the papers, contributed either by Chattaway himself or in conjunction with others, to the Society of Public Analysts, which have been published in the ANALYST : Allen and Chat taway : Examination of Spirituous Liquids for Secondary Constituents, xvi., 102.Note on the Composition of some Preparations Sold as Hop- substitutes, xii., 112. Note on the Detection of Hop-substitutes in Beer, xv., 181. Suggestions for the more ready Employment of Adams’ Milk-fat Method, xi., 71. Chattaway, Pearmain and Moor : Composition of Cheese, xix., 145. Note on the Valenta Acetic Acid Test, xix., 147. Composition of some English Cheeses, xx., 132. Cbattaway : Ginger Adulteration, xxiv., 156. British Pharmacopoeia, the Legal Standard, xxvi., 89. Use of Partially Sterilized Milk Cultures in Judging the Purity of Water, xxvi., 264. Note on the Volatility of Aqueous Solutions of Acetic Acid, xxviii., 29. Chattaway and Wharton : Note on a Convenient Apparatus for the Chemical and Bacteriological Examination of the Atmosphere, xxvii., 243. Chrtttaway and Moor : Notes on the Ash-yield of Crude Drugs and Compounds, xxviii., 202. Analysis of Preparations containing Opium, xxvii., 358.

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DOI:10.1039/AN9042900329

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年代:1904

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330 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Composition of Two Commercial Indian Sugars. E. Bourquelot. (Jourrt. Pharm. Chim., 1904, xx., 193, 194.)-Two samples of crude sugar sold in the Indian markets in the form of loaves weighing 4 to 1 kilogramme, and consisting of agglome- rated crystals, were examined by the author. One had been prepared from the milk of the cocoanut (Cocos nucifera), and the other from the sap of the tree Borassus Jlabelliformis, the juice of which is also converted into a fermented beverage known as '' palm wine." Both were of a dark colour, the cocoanut sugar being much less pure than the other sample. The following results were obtained on analysis : Reducing Sugars. Saccharose. Water. Ash. COCOS nucifera ...... 1.99 74.95 8.03 4.73 Borassus Jlabelliforma's . . . 2.40 79.12 9.15 3-20 C. A. M. Per Cent. Per Cent. Per Cent. Per Cent. Sugar of- The Detection of Boric Acid. L. Robin. (Ann. de Chzim. anal., 1904, ix., 336-338.)-Tincture of mimosa flowers, or paper prepared from the tincture, is a sensitive reagent for the detection of traces of boric acid. I n testing a mixture ofTHE ANALYST. 331 salts the solution is rendered alkaline with sodium carbonate, heated to the boiling- point, and filtered. A few drops of the filtrate are mixed with a drop of mimosa tincture in a porcelain crucible, and after the addition of hydrochloric acid until the yellow colour just disappears, the mixture is evaporated to dryness on the water-bath. When boric is present the residue is of a yellow colour, which changes to red on the addition of a few drops of a 10 per cent.solution of sodium carbonate. In the absence of boric acid the residue is gray, and becomes yellow on the addition of alkali. In applying the test to milk, 15 to 20 C.C. of the sample are treated with 2 drops of acetic acid and filtered, and the filtrate neutralized with sodium carbonate, boiled for a few seconds, and filtered. The liquid is then evaporated to dryness, the residue calcined, the ash taken up in a few drops of boiling water, and the solution filtered, rendered acid with the smallest possible quantity of hydrochloric acid, and tested with mimosa paper. C. A. M. The Decomposition of Potassium Iodide by Fats. A. Heffter. (SCkWeiZ. Woch. f. Chenz. [No. 241, Biochenz. Centralbl., 1904, iii., 121.)-The well-known spontaneous decomposition of lard ointments containing potassium iodide was at first attributed by the author to the fat becoming rancid, but experiments with free fatty acids did not confirm this conclusion. It was found that the substance that caused the liberation of the iodine could be extracted from the fat by means of water, and it was subsequently identified as hydrogen peroxide. Experiments showed that fresh lard contained traces of hydrogen peroxide after standing for only t'wo days. Lanoline also undergoes a similar auto-oxidation. C. A. M.

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年代:1904

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THE ANALYST. 331 ORGANIC ANALYSIS. The Identification of Methyl Anthranilate. P. Freundler. (Bull. Soc. Chinz., 1904, xxi., 882-884.)-Methyl anthranilate, when heated in alcoholic solution with picric acid, forms a picrate, CI4Hl2N4O9, which crystallizes in fine yellow needles, melting at 103.5' to 104' C., and dissolving readily in alcohol. A less soluble derivative, which is therefore more suitable for analytical purposes, is the condensation product obtained by heating on the water-bath equimolecular proportions of the anthranilate and phenylisothiocyanate. After two to three hours the mass becomes completely solid, a crystalline product having been formed. This melts above 300" C., sub- limes at about 160" to 170" C., and appears to be identical with MacCoy's ketol. H- N-phenyl- 3 - t hio- 4- tetrahydroquinazoline.x: I t dissolves in sodium hydroxide solu- tion, bub is nearly insoluble in boiling alcohol. I n the absence of other anthranilic esters, the formation of this thioquinazoline is a characteristic test for methyl anthranilate. In applying the test the anthranilate should be separated by treat- ment with sodium carbonate, extracted with etherp and the residue from the ethereal * Berichte, vol. xxx., p. 1688.332 THE ANALYST. extract heated at 100' to 120° C., with a, slight excess of isothiocyanate. After three or four hours a little alcohol is added, the mixture heated for a shwt time, then left to cool, and the solid product collected and dried at 100' to 120' C. In the author's opinion, this method is to be preferred to that of Hesse or of Erdmann for approximate determination of the anthranilate. Thus, 5.1 grammes of pure methyl anthranilate yielded 8.4 grammes of the quinazoline derivative, or 98 per cent.of the theoretical amount. C. A. M. Analysis of Commercial Acetate of Lime. W. M. Grosvenor, Jun. (Journ. SOC. Chem. Ind., xxiii., 530.)-Sampling is difficult owing to the hygroscopic nature of the product, and to its variable quality in different parts of the same bag. The author uses a, brass sampling tube, not less than 24 inches long, tapering backwards from 18 to 2 inches bore, and mounted in a strong handle. This is screwed into the acetate to a depth of about 18 inches. The samples are stored in small thin-walled rubber bags, from which they are passed through a grinding-mill into similar bags, and very little loss of weight should occur.The operation is carried out almost without contact with air, since the necks of the bags fit into the inlet and outlet tubes of the mill. When too moist for immediate grinding, the samples are left overnight in their rubber bags, attached to an exhausted receiver containing pumice and sulphuric acid. Two determinations each of moisture and total acetic acid are made. The moisture is determined by drying a known weight of the sample at 100' C. for not more than three hours. The substance is somewhat liable to decomposition by heat. The dried samples are kept between watch-glasses while cooling in the desiccator prior to weighing. For the determination of the total acetic acid, from 25 to 30 grammes are removed by a glass tube of 1 inch bore and poured directly into a beaker, which is immediately covered.The powder is gently stirred with successive quantities of water, and the liquid poured off into a litre flask. The residue is then further reduced in a mortar, and again treated with water until nearly all is dissolved, when the liquid is diluted to 1 litre. The solution is thoroughly mixed by shaking, and 50 C.C. withdrawn by a capillary pipette. This solution is treated in a 200 C.C. round-bottomed flask with 15 C.C. of 50 per cent. phosphoric acid (free from nitric and other volatile acids), connected by a wide-bore tube with a condenser, and rapidly distilled for one and a half hours. The flask, which must be inclined at an angle of 60°, rests on an asbestos sheet having a central hole, which prevents over- heating of the sides of the flask.The volume of solution in the flask is kept at a constant level by means of a slow stream of very weak phosphoric acid solution (free from carbonic acid), which is run in during the distillation. The end of the condenser tube dips down nearly to the bottom of a Woulffe's bottle, the other neck of which contains a soda-lime tube. This is replaced by the burette during the subsequent titration of the distillate. The bottle contains 100 C.C. of standard caustic soda solution containing about one-tenth as much barium hydroxide as sodium hydroxide, and the solution is of such strength that 100 C.C. are equivalent toTHE ANALYST. 333 the acetic acid from 2 grammes of 80 per cent.calcium acetate. The excess of alkali after the distillation is determined by titration with standard hitric acid and phenolphthalein. The cloudiness due to phosphoric acid which is sometimes carried over is usually obviated by using an inclined flask, as described. If when the liquid in the receiver is titrated with nitric acid the solution be left faintly alkaline, and the distillation continued, the fading of the phenolphthalein coloration shows that the distillation is not complete. '' Steam " distillation lengthens the time required. Carbonic acid and hydrochloric acid are sometimes present in calcium acetate. The precipitate of barium carbonate in the neutral distillate should be filtered and its amount determined by titration, and the chlorides determined in the filtrate with silver nitrate, as usual.Any phosphate should be looked for in the barium carbonate quantity by means of molybdate. The alkali and acid should be standardized against sodium carbonate prepared by washing some recrystallized sodium bicarbonate with cold water until free from chlorides and sulphates, and heating the purified substance at 300" C. until constant The method has several sources of error. in weight. A. R; T. Characteristics of the Gum of Cochlospermum Gossypium. P. Lemeland. (Journ. Pharm. Chim., 1904, XX., 253-260.)-The Cochlospermum Gossypium, which grows in various parts of Southern India, is valued by the Hindoos as a source of cotton and for its gum, which latter is a common commercial product. The gum is sold in the form of drops, more or less contaminated with foreign d6bris.They are of a light colour, and have numerous circular and elliptical striations on the surface. A specimen examined by the author gave the following results : Water, 22.72 ; ash, 4-65; and organic matter (by difference), 72-63 per cent. Only a very small proportion was soluble in water, and the insoluble deposit had little viscosity or cohesive properties. One hundred grammes of the gum yielded on hydrolysis with acid 25.795 grammes of pentoses and 34.995 grammes of d-galactose. No other sugar than galactose could be isolated, nor was any oxidizing enzyme detected by Bourquelo t's method. C. A. M. The Technical Analysis of Spirits of Turpentine, with a New Method for the Detection of Petroleum Adulterations and of Wood Spirits of Turpentine. J.M. McCandless. (JOZLWZ. Amer. Chem. Xoc., xxvi., 981,)-The author finds that determinations of the specific gravity, iodine number, and flash-point are of little value in judging of the adulteration of spirits of turpentine. Armstrong's polymeriza- tion methcd is better, but tedious, and allows adulteration with less than 5 per cent. of kerosene to escape detection. The author consequently worked out the following method for kerosene, depending on the measurement of the refractive index of the oils resulting from steam distillation and polymerization: 100 C.C. of the oil are placed in a 600 C.C. flask, and 50 C.C. of concentrated sulphuric acid are gradually added from a burette, with constant cooling and agitation; 25 C.C.of water are then334 THE ANALYST. added, and the contents of the flask distilled in a current of steam until a total distillate of 100 C.C. is obtained. The refractive index is now determined on a few drops of the separated oil in the distillate ; the remainder is measured approximately, and treated with an equal volume of fuming sulphuric acid in a stoppered flask. The resulting mixture is poured into cold water ; the oil is separated and steam-distilled until 100 C.C. of distillate have been obtained. The refractive index of the distilled oil is again taken, after which the remainder is treated with twice its volume of fuming sulphuric acid, and the foregoing operations repeated. Expressed in terms of the centesimal scale of the Zeiss butyrorefractometer, at 25’ C., using sodium light, the oil from the third polymerization never gave a lower reading than 30 in the case of pure spirits of turpentine, whilst with oils containing only 1 per cent.of kerosene the reading was as low as 25, and could be slowly reduced to 22 by con- tinued treatment with funling sulphuric acid. The method is not quantitative, but the final volume obtained may be taken as a minimum value for the petroleum present. Adulteration with rosin spirits may be shown by the Liebermann-Storch test. Adulteration with refined wood spirits may be detected as follows, after kerosene has been shown to be absent by the above process: 100 C.C. of the oil are slowly distilled, and the refractive index of the first 0.5 C.C. measured. I n the case of genuine oils this is never below 60, usually 61 to 63.Several samples of wood spirits show readings as low as 57. Wood spirits which do not show a low initial reading nearly always show a high reading on the final portion of the distillate. For the 97th and 98th C.C. of the distillate the reading in the case of a genuine sample will never exceed 77, and usually be much less, whilst with wood spirits the reading will be above 77 and may reach 90. A further distinction noticeable during the distillation is that wit4 nearly all genuine spirits 95 per cent. will have distilled over by the time the temperature reaches 165” C., whereas with wood spirits the thermometer will be much higher when 95 per cent. have come over. A. G. L. The Oxygen Content of India-rubber.P. Alexander. (Gummi-Zeit., 1904, 867 ; through Chew,. Zeit. Rep., 1904, xix., 227.)-The author considers Weber’s opinion, that caoutchouc may contain as much as 20 per cent. of oxygen, as erroneous. He has analysed the carefully purified product from Guayle and Pontiazac without finding more than 1 to 2 per cent. Weber’s method-the formation of additive compounds with bromine or nitrogen dioxide-is unsatisfactory, as the action is irregular. H. A. T. “Sodium Peroxide Baryta” Method for the Estimation of Carbon in Organic Compounds, especially Explosives and Substances which Burn with Difficulty. (Zeit. f. angew. Chem., 1904, xxvi., 888.)-Carbon is oxidized by deflagration with sodium peroxide to carbonic acid, and may be estimated by ascertaining the quantity of barium chloride that is converted into carbonate.From 0-25 to 0.5 gramme of the substance to be analysed is intimately Fritz von Konek.THE ANALYST. 335 mixed with a weighed quantity of 10 to 12 grammes of sodium peroxide, and fired in a bomb. The contents are dissolved out, and made up to 500 C.C. with boiled distilled water. Of this solution 100 or 200 C.C. respectively, accordiug to the quantity of substance originally taken, are transferred to a 200 or 250 C.C. flask, and 30 to 25 C.C. of a solution of barium chloride of about decinormal strength are added. The contents of the flask are well shaken, made up to the mark, allowed to settle, and filtered. OE the filtrate 100 C.C. are taken, acidified with hydrochloric acid, boiled and precipitated with sulphuric acid; the barium sulphate is filtered off and weighed.As sodium peroxide always contains a little carbonate, it is necessary to make a blank determination. Determinations upon a number of pure organic compounds gave results which agreed satisfactorily with the theoretical percentages. A. M. Estimation of Phosphorus in Organic Substances by Means of Sodium Peroxide. Fritz von Konek. (Xeit. f. nngew. Chenz., 1904, xxvi., 886.) About 0.5 gramme of the finely-divided organic substance is mixed with 10 to 15 grammes of peroxide, and introduced into a nickel or steel crucible resembling that used in the Parr calorimeter, but larger (see ANALYST, 1901, 52). If the substance contain less than 80 per cent. of carbon, a few decigrammes of an organic substance free from nitrogen or phosphorus should be added.The crucible is immersed in cold water, and the contents are ignited by means of a red-hot wire ; the substance is thus entirely oxidized, and the phosphorus is converted into sodium phosphate. When cool the contents are dissolved out, hydroxide of nickel or iron is filtered off, the filtrate is acidified with hydrochloric acid, and boiled to drive off carbon dioxide, and cooled. An excess of ammonia is added, and the phosphorus is precipitated as magnesium phosphate in the usual way. If there be elements present which would interfere with the direct precipjtation, nitric acid is used instead of hydrochloric, and the phosphorus is precipitated first as phosphomolybdate. The results obtained with a number of phosphine derivatives agree well with the per- centages calculated.A. M. Estimation of Nitrogen in Organic Substances by Means of Sodium Peroxide. Fritz von Konek and Arthur Zohls. (&t. f. mzgeeo. Chenz., 1904, xxxi., 1093.)-Whereas the sulphur, phosphorus, and even carbon of organic bodies are entirely oxidized by combustion with sodium peroxide, only in some cases is the nitrogen converted quantitatively into sodium nitrate ; with such substances as pyridine and quinoline the nitrogen partly escapes oxidation. Such materials as flour, however, can be analysed satisfactorily by this method. Not more than 0.5 gramme is mixed in a steel or nickel bomb with 12 grammes of dry pure sodium peroxide; 5 or 6 grammes of peroxide are then added, and about a gramme of a mixture of potassium persulphate and tartaric acid, containing two parts of the former to one of the latter. The lid of the bomb is then screwed on,336 THE ANALYST.and the whole is immersed in water, with only the tube projecting above the surface, and the mixture is ignited by dropping a red-hot piece of wire down the tube. When cool, the fused mass is dissolved in water, transferred to a Jena glass flask, and made up to 500 or 600 C.C. A little pumice is added, together with 15 C.C. of alcohol and 3 grammes of Devada’s aluminium-copper-zinc couple (see ANALYST, 1893, 92). The flask is connected with a condenser and receiver containing standard acid, as in a Kjeldahl determination, and is heated at first with a very small flame. When all the hydrogen has been evolved, the ammonia is distilled over and estimated. The author prefers Congo red as an indicator for the titration. The results are practically identical with those yielded by the Kjeldahl method. A. RI. The Determination of Phosphorus and Arsenic in Organic Compounds. C. Monthulb. ( A w . de Chim. mal., 1904, ix., 308, 309.)-The followink method is stated to give as accurate results as any of the known methods, while being much more easily applied. The oxidizing reagent consists of calcined magnesia dissolved in nitric. acid of specific gravity 1-38, so as to give a solution containing 10 grammes of magnesia per 100 C.C. The organic substance is mixed with a sufficient quantity of this reagent, and the mixture evaporated on the water-bath, then dried on the sand-bath and ignited at a bright-red heat. The carbonaceous mass in the crucible is again treated with the nitric acid and the evaporation and ignition repeated, which is usually sufficient to give an ash free from carbon. Finally, the residue is taken up with hydrochloric acid, and the solution treated with ammonia, which precipitates the ammonium magnesium phosphate or arsenate. These are weighed as pyrophosphate or pyroarsenate in the usual manner. C. A. M.

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DOI:10.1039/AN9042900331

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年代:1904

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336 THE ANALYST. INORGANIC ANALYSIS. A Crucible Charge for Gold and Silver in Zinc Ores. E. J. Hall. (School of Bines Quarterly, xxv., 355.)-As the result of a large number of experiments with different mixtures, the author recommends the following crucible charge for the gold and silver assay of zinc ores : Ore, + A.T. ; sodium carbonate, 19; borax glass, 4 ; litharge, $; argol, if necessary, suficient to reduce all the lead. If more than 15 per cent. of pyrites is present, two nails may be added to prevent the formation of a, brittle button. The best temperature for the fusion was found to be 750' to 775" C., a higher temperature giving low results. The time required for the fusion is thirty to thirty-five minutes. The results obtained in this way compare very favourably with those given by the troublesome scorification method, for which only 0.1 A.T.of ore can be takm. Copper in quantities of less than 74 per cent. does not interfere with the method. A. G. L.THE ANALYST. 337 On the Colour produced in Borax Beads by Means of Noble Metals in Col- loidal Solution. 3. Donau. (MoAatsch. f. Chern., xxv., 913.)--According to the author’s experiments, gold imparts to a borax bead a ruby red colour, which, on prolonged heating, changes to blue, or bluish-green, and t+hen disappears. If the quantity of gold present is considerable, the bead becomes liver coloured by reflected, and blue by transmitted light. In the presence of much sodium chloride, the bead may be violet instead of red, and the reaction is not quite so delicate.Silica and soluble silicates do not interfere. Iron alEo is without influence on the reaction, unless present in large quantity. Platinum, however, if present to the extent of more than 6 per cent. of the gold, masks the reaction. The presence of free sulphuric acid or free halogens also vitiates the test. Free hydrogen chloride is without influence. Silver gives a yellow colour to the borax bead after one or two minutes’ heating, destroyed on prolonged heating. I n transmitted light the bead appears clear, in reflected opalescent. Platinum causes the borax bead to appear fawn coloured in transmitted, milky in reflected light. The colour does not disappear as readily as that due to gold on further heating. Iridium and osmium also give the fawn colour, but not the milkiness to the bead.Rhodium gives a brown colour in transmitted, slate-gray in reflected light. Silver and platiniim beads behave much as,gold beads in the presence of other bodies. The smallest quantities of these metals which could be recognised by means of the borax bead colorations was, in milligrammes, 0*000025 of gold, 0.00018 of silver, and 0.00005 of platinum. (For cobalt or chromium, the values are 0 0002 to 0.0003.) After appropriate separation, it was found possible to recognise in 5 gramrnes of a mixture of iron and copper oxides, sand and lime, the presence of 0.00005 milli- gramme of gold, 0.0005 milligramme of platinum, and 0-005 milligramme of silver in this way. A. G. L. Palladium and ruthenium give a black colour. The Estimation of Small Amounts of Ferric Iron by Acetylacetone (especially applicable to Water Analysis).(Jouriz. Amer. Chem. SOC., xxvi., 967.)-Acetylacetone, the iron salt of which is dark red, is proposed by tbe author as a substitute for potassium thiocyanate, as the colour produced is permanent, whilst that given by the thiocyanate fades quickly. Comparison of the colours must, of course, be made under identical conditions. The iron solution should be only faintly, but distinctly, acid. For a total dilution of 50 c.c., 2 C.C. of a 0.5 per cent. solution of acetylacetone should be added. An aqueous or alcoholic liquid may be used. Change of temperature and the presence of most ordinary substances are without influence on the colour, but oxides of nitrogen must be entirely absent. The method is said to work exceedingly well with quantities of iron of from 0-000003 to 0.0006 gramme.For water analysis, either 100 C.C. are evaporated to dryness, or the residue of the total solids used, organic matter being destroyed in either case by treatment with sulphuric and nitric acids. The ferric oxide left is dissolved by warming with a few drops of sulphuric acid and a drop of nitric acid, water added, and if much insoluble H. B. Pulsifer.338 THE ANALYST. matter is present the solution filtered. The. iron is then oxidized with hydrogen peroxide or dilute nitric acid, excess of acid remoied by evaporation, the residue dissolved in water, placed in a Nessler tube, made up to the mark with water, and treated as above. A. G. L. The Volumetric Determination of Chromium and Vanadium in the Presence of each Other.(Bz1.12. SOC. Chim., 1904, xxxi., 962-965.) -The method is based on the fact that divanadyl sulphate is rapidly oxidized by a cold solution of potassium permanganate, while chromium sulphate is perfectly stable under the same conditions : 5V,O,( SO,), + 2KMn0, + 8H,SO, = 5V,02( SO,), + K2S0, + 2Mn80, + 8H20. The chromium sulphate is then oxidized into chromic acid by means of a boiling solution of potassium permanganate, and the filtrate treated with a known quantity of a solution of ferrous sulphate, the excess of which is titrated back with standard permanganate. 2Cr0, + GFeSO, + 6H2S0,== Cr,(SO,), + Fe,(SO,), + 6H20 IOFeSO, + 2KMn0, + 8H,SO, = 5Fe.,(S04), + K,SO, + MnSO, + 8H,O. In reality, it is not the excess of ferrous sulphate that is titrated, but the divanadyl sulphate resulting from the action of the excess on the vanadium sulphate.E. Campagne. This, however, does not affect the results of the calculation. Analysis of’ Ferro-chrow~o-vanadiui,z.--The alloy is treated with nitric acid, and the resnlting nitrates slightly ignited to convert them into oxides, which are dissolved in concentrated hydrochloric acid. The bulk of the iron is eliminated by Rothe’s method (treatment of the chlorides with ether), and finally an aqueous solution is obtained containing only traces of ferric chloride, in addition to the chlorides of chromium and vanadium. This solution is evaporated several times in the presence of a large excess of strong hydrochloric acid, in order to convert the vanadium into the oxychloride, VOCl,, and the chromium into chromic chloride.After the reduction the liquid is mixed with 10 C.C. of sulphuric acid, and evaporated on the sand-bath until white fumes appear, when the chromium will have been converted into chromic sulphate and the vanadium into the blue divanadyl sulphate, V20,(SO,),. The solution is then cooled, mixed with 250 C.C. of water, and titrated at the ordinary temperature with a standard solution of permanganate, the eqd of the reaction being shown by the rose coloration lasting for several minutes after the liquid has been shaken. The amount of vanadium is then calculated in accordance with the equation given above. The liquid is next treated with a large excess (5 to 10 C.C. of a 10 per cent.solution) of potassium permanganate, and boiled briskly. The excess of the reagent (shown by the rose coloration) is destroyed by adding a few fragments of filter-paper, and again boiling the liquid. The solution of vanadate and chromate is filtered, when cold, from the precipitated manganese dioxide, and treated with ferrousTHE ANALYST. 339 siilphate solution, the excess of which is titrated back with potassium permanganate solution. The amount of ferrous sulphate absorbed by the chromic acid is thus obtained. Small quantities of ferric sulphate do not affect the results; but when the proportion of chromium is much larger than that of the vanadium it is necessary to use a small amount for the analysis, since otherwise the green colour of the chromic sulphate interferes with the rose colour of the end reaction in the titration of the vanadium.C. A. M. The Determination of Tungsten. L. Desvergnes. (Ann. de Chim. anal., 1904, ix., 321-323.)-The author, being unable to obtain good results by any of the methods previously described, has devised the following modification of Carnot’s method of determining tungsten in the form of mercurous tungstate : Twenty-five C.C. of the solution of the alkali tungstate are neutralized w’ith dilute nitric acid (with turmeric as indicator), then heated to the boiling-point, mixed with a solution of mercurous nitrate containing precipitated mercuric oxide in suspension, and again boiled. The mercurous tungstate is allowed to settle, collected on a filter, dried, ignited (apart from the filter-paper) in a weighed crucible, which is finally heated in a muffle, and the residual tungstic acid weighed.C. A. M. A Rapid Method for the Determination of Lime in Cement. Bernard Enright. (Joumz. Amer. Chem. SOC., xxvi., 1003.)-The method depends on the pre- cipitation, and titration with permanganate, of lime as oxalate, after removal of the iron and alumina and niost of the silica. One-half gramme of the cement, powdered in an agate mortar, is weighed out into a dish ; 100 C.C. of hot water are ‘added in such a way as to keep the cement in suspension, after which 30 C.C. of hydrochloric acid (1 : 1) are added in the same way. A few drops of bromine are added, and the whole is boiled for a few minutes. A small excess of ammonia is then added, and the solution again boiled.The precipitate is then filtered off, washed once, then washed back into the dish, and 10 C.C. of hydrochloric acid and enough water to make up to about 100 C.C. are added. The solution is again made faintly ammoniacal, boiled, and filtered, the precipitate being washed thoroughly. I t contains all the iron and alumina and about three-quarters of the silica. The mixed filtrates are made slightly acidwith hydrochloric acid, heated to boiling, and 25 C.C. of saturated ammonium oxalate solution are added. Hot dilute ammonia is then added to the boiling liquid until an excess equivalent to 5 C.C. of concen- trated ammonia is present. Boiling is continued for five minutes more, and the solution is then set aside in a hot place for fifteen minutes, after which the calcium oxalate is filtered off, and washed three times by decantation and eight times on the filter.The permanganate solution should be standardized by determining the lime in a cement containing a known percentage. It is then titrated with permanganate as usual,340 THE ANALYST. The method is stated to require only one-fifth of the time occupied by the usual lime determination. No test results are given. A. G. L. The Analysis of Portland Cement. Bertram Blount. (Journ. Amer. Chem. SOC., xxvi., 995.)-The author discusses some points regarding cement analysis on which he still differs from Hillebrand, who has, however, now recognised the sub- stantial correctness of the author’s method of analysing Portland cement (cf. Jown. SOC.Chern. Ind., xxvi., 19 ; Journ. Amer. Chem. SOC., xxv., 1180).-He determines the insoluble residue by dissolving the cement in hydrochloric acid, evaporating to dry- ness, treating with hydrochloric acid, filtering, washing, dissolving out the pre- cipitated silica with sodium carbonate solution, washing and igniting the final insoluble residue. Hillebrand believes this method to be too drastic, and prefers to dissolve the cement in dilute hydrochloric acid, filtering at once, and then to dissolve the silica with Rodium carbonate. His method yields higher results, but the author now shows that the amount of insoluble residue obtained in this way decreases with increasing fineness of grinding of the cement, and also that it is not wholly composed of inert substance, but reacts as a puzzuolanic material.On the other hand, the insoluble residue obtained by the author’s own method consists almost wholly of silica, and is substantially inert. The author also shows that, notwithstanding Hillebrand’s assertions, silica can be completely separated by a single evaporation (maximum error, 0.32 per cent.) ; that the quantity of silica contaminating the iron and alumina precipitate is negligible, and that a single precipitation suffices for the separation of iron and alumina from lime, and of lime from magnesia. A. G. L. The Determination of Fluorine in Martin-Slag. L. Fricke. (StahZ. u. Eisen, 1904, 889; through Chem. Zeit. Rep., 1904, xix., 224.)-Five grammes of the slag are fused with 20 to 30 grammes of potassium carbonate, the melt dissolved in water, and the resulting solution filtered.The solution is boiled with ammonium carbonate, filtered; the filtrate heated with a solution of zinc oxide in ammonia, evaporated to dryness and taken up with water. Again filtered, 1 to 14 grammes of calcium chloride added and the solution rendered faintly acid with acetic acid. The carbonic acid is boiled off, and after addition of excess of potash the solution again acidified with acetic acid. The resulting precipitate, which contains the fluorine as calcium fluoride mixed with calcium phosphate, is ignited and weighed as CaF, + Ca,P20,. Phosphoric acid is estimated in this, and the fluorine deter- mined indirectly. H. A. T. The Determination of Citric-Soluble Phosphoric Acid in Thomas Slag. 0.Bottchsr. (Zezt. f. angew. Chem., 1904, xxix., 988.)-The author insists upon the reliability of the method proposed by himself (see ANALYST, this vol., p. 131), andTHE ANALYST. 341 states that it is not necessary to remove silicic acid before precipitating the phos- phoric acid, unless it be present in large amount. I t is essential that the operation be carried out rapidly. A. M. Determination of Phosphates in Natural Waters. A. T. Lincoln and Perry Barker. (Journ. Amer. Chem. Soc., xxvi., 975.) - The authors have examined Schreiner’s method (Jozmz. dnzer. Chem. Soc., xxv., 1056) for the colorimetric determination of phosphates in the presence of silica, and confirm his statement that the method gives good results if the quantity of P,O, present is equal to or greater than that of SiO,.As this is not the case with very many waters, they tried the effect of adding 0.5 milligramme of P,O, to every 75 C.C. of water .before making a determination, and found that this procedure gave excellent results with all but the smallest (0.13 part per million) proportions of P,O,. Schreiner’s method itself (loc. cit.) depends on the fact that the colour due to phospho-silicates is twice 51s intense when nitric acid and molybdate are added together to the silicate solution as when the nitric acid is added one hour after the molybdate. The colour of phospho- molybdates, on the other hand, is the same in both cases. The quantities of reagents used are 5 C.C. of nitric acid (specific gravity 1.07) and 4 C.C. of ammonium molybdate solution.The standard employed is a solution of sodium phosphate containing 0-1 milligramme of P,O, per 1 C.C. A. G. L. The Analysis of Bauxite. Taurel. (Ann. de Chim. aizal., 1904, ix., 323-327.) -The presence of titanic acid introduces considerable difficulties in the analysis of bauxite and certain other aluminous earths, and the author has, therefore, devised the following method, which is based on Leclerc’s observation that titanic acid is precipitated from a boiling solution by formic acid : Two grammes of the finely- powdered and dried mineral are fused in a platinum crucible with 8 to 10 grammes of an intimate mixture of equal parts of potassium and sodium carbonates, the fused mass taken up when cold with water containing 20 C.C. of sulphuric acid specific gravity 1.85 (Be 6 6 O ) , and the liquid evaporated in a porcelain crucible until white fumes appear.The residue is cooled and taken up with water, heated until the sulphates of aluminium and iron dissolve, and then filtered from the silica, which is washed, ignited, and weighed in the usual way. If the titanic acid and iron oxide are to be determined together, the cold filtrate is diluted to one litre, and 100 C.C. of the solution allowed to fall slowly, and with continual shaking, into a flask containing 10 C.C. of ammonia solution diluted with 50 C.C. of water. The mixture is boiled, the precipitate collected, washed with boiling water, dissolved in water acidified with hydrochloric acid, reprecipitated with ammonia, collected, washed, ignited, and weighed as a mixture of alumina, iron oxide, and titanic acid.On the other hand, 200 C.C. of the original solution (=0-4 gramme of mineral) are neutralized with ammonia, and the resulting precipitate redissolved by means of342 THE ANALYST. formic acid, of which an excess of about 5 C.C. is added. About 1 gramme of pure sodium sulphite or a current of sulphur dioxide is then introduced, and the liquid kept gently boiling for about an hour, after which the titanic acid will have been completely precipitated. Without waiting for the precipitate to subside, a solution of ammonium citrate or tartrate is now added in such quantity that the amount of organic acid shall be eight to ten times that of the alumina present, and this is followed by ammonia solution in excess, and finally by ammonium hydrosulphide.The alumina remains in solution, and the precipitate consists of only titanic acid and iron sulphide. The liquid is heated to about 80" C . , and after standing for some minutes is filtered, and the precipitate washed with water containing some ammonium hydrosulphide un ti1 the washings leave no residue on evaporation, and finally ignited and weighed as a mixture of ferric oxide and titanic acid, the difference between the result and that previously obtained giving the amount of alumina. I n the case of white bauxites, or when a separate determination of the titanic acid in red bauxites is required, the method is modified as follows : After separation of the silica the filtrate is neutralized with ammonia, and the precipitate redissolved with formic acid, of which an excess of about 10 C.C.is added. The sulphur dioxide or sodium sulphite is then added, and the liquid boiled gently for about an hour (evaporated water being renewed), and then allowed to settle for several hours. The supernatant liquid is siphoned off, and the precipitated titanic acid collected, washed, ignited, and weighed. The united filtrate and washings are made up to a definite volume, and aliquot portions taken for the determination of the iron as iron sulphide, and of the iron and aluminium together as oxides. The author states that he has tested the accuracy of this method on mixtures containing known quantities of aluminium, iron oxide, and titanic acid. C. A. M. Note on the Effect of Old Filter-paper on Iodate-free Potassium Iodide. E. Mallinckrodt, Jun., and W. N. Stull. (Joum. Amer. Chem. Soc., xxvi., 1029.)- The authors found that iodate-free solutions of potassium iodide were often coloured brown after filtering through filter-paper and adding a few drops of sulphuric acid. They traced this reaction to the fact that the filter-papers had absorbed nitrites from the laboratory air. Thus, 3 or 4 grammes of fresh filter-paper of various makes, tested by the Griess reaction, contained nitrite equivalent to 0.0001 to 0.0005 milli- gramme of nitrogen, whilst the same quantity of old filter-paper contained nitrite corresponding to 0.0060 milligramme of nitrogen. A. G. L. Note on the Standardization of Iodine Solutions. S. W. Young. (Jowrn. Amer. Chem. SOC., xxvi., 1028.)-In standardizing iodine solutions, the author obtained excellent results by the use of anhydrous sodium thiosulphate. The salt was prepared by recrystallizing the ordinary pure salt from a solution saturated at 30" to 35' C. The crystalline powder obtained was dried first on filter-paper, and $hen over sulphuric acid until it fell to powder, and a portion heated to 50" C. showed no signsTHE ANALYST. 343 of fusion. Finally, it was heated for two hours or more at 80" C. in an air-bath. The salt did not take up any moisture after three days' keeping in a stoppered bottle. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9042900336

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年代:1904

数据来源: RSC

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THE ANALYST. 343 APPARATUS. Some Notes on Laurent Polarimetric Readings. Geo. W. Rolfe and Chas. Field. (Joum. Amer. Chem. SOL, xxvi., 986.) - Defending the Laurent polari- meter from criticisms, the authors state that instruments of this type, if of French make, using sodium light filtered through a section of a potassium bichromate crystal, give resultgconcordant within at least one minute, but about 0.2 per cent. lower than those obtained with the Lippich ray filter consisting of potassium bichromate and uranyl sulphate solutions. Hence, by increasing Laurent measurements by 0-2 per cent., they may be converted to the standard of spectrally purified light. The authors insist that, in stating the light factor of a saccharimeter, reference should always be made to the exact nature of the light used ; to the saccharimetric standard of the scale of the quartz-wedge instrument ; to the nature of the substance measured ; and to the temperature at which the comparisons are made.A. G. L. Variations of Standard among Ventzke Saccharimeters. Harris E. Sawyer. (Journ. Amer. Chem. SOC., xxvi., 990.)-As the result of a lengthy examina- tion of a number of saccharimeters in use at Boston, the author concludes that a, double standard exists amongst the instruments of Schmidt and Haensch. The earlier instruments appear to be graduated for use with true cubic centimetre vessels, intermediate ones for Mohr cubic centimetres, and the latest, again, for the true cubic centimetres. Unless this fact is allowed for, an error of 0.23 per cent. on the sugar may be incurred if the wrong set of graduated vessels is used with any particular instrument.A. G . L. - Absorption Apparatus for Combustion Analysis. N. Wolff. (Chem. h i t . , 1904, liv., 644.)-The apparatus consists of a small Erlenmeyer flask, closed by a hollow glass stopper. At opposite sides of the neck are inlet apd outlet tubes which can be closed by rotating the stopper, the sides of which are furnished with corresponding perforations. Communicating with one of these holes a piece of tubing is fused on to the stopper, which reaches to about a centimetre from the bottom of the flask containing the desired absorbing medium (phosphoric anhydride, soda-lime, etc.) and to about 1 millimetre from the surface of this absorbent. With the stopper in a certain position, therefore, the inlet tube is in immediate communication with the inside tube ; and the incoming gas impinges on the absorbent, passing out through the aperture in the stopper communicating with the outlet tube.The absorber shows a high degree of efficiency, is readily cleaned, and is much easier to weigh than the cumbersome U-tube. Obtainable from Messrs. H. Besser, Stutzerbach, Thuringia. H. A. T.344 THE ANALYST. Explosion Pipette. Dr. Otto Pfeiffer. (Chem. Ze& 1904, Mi., 686.)-In this pipette the usual mercury is replaced by water (+ 0.5 per cent. sulphuric acid), and it is, consequently, much cheaper. The gases are introduced by sucking the water from the explosion chamber (A) to the coutainer (B), only the con- necting-tube remaining filled. Taps a and b are closed, and after explosion the resultant gases are forced into the measuring-tube by allowing the water to slowly run back to A. The pipette is fused into the metal stand with paraffin To be obtained from H. Horold, Glass Works, a wax. Magd eburg . H. A. T.

ISSN:0003-2654    

DOI:10.1039/AN9042900343

出版商:RSC    

年代:1904

数据来源: RSC

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344 THE ANALYST. REV1 EWS. LABORATORY EXERCISES IN PHYSICAL CHEMISTRY. By Dr. F. H. GETMAN. (New This work, which is essentially a student’s book, has been written to supply a want which has arisen for a laboratory manual of the new science that has arisen between physics and chemistry, and which should be of a more elementary nature than the classical works of Ostwald and of Traube. These, owing to the amount of detail they contain and the many references to the literature of the subject, have not proved themselves practical guides in the laboratory. With this end in view, the author has produced a book eminently fitted for its purpose. His descriptions, though condensed, are couched in exceedingly lucid language, and the general clarity of the work is considerably heightened by the numerous well-chosen illustrations of apparatus, etc., which are to be found on nearly every page of this handy little book.W. J. S. THE ANALYST’S LABORATORY COMPANION. By ALFRED E. JOHNSON, B.Sc., F.I.C. This is a third edition of Mr. Johnson’s useful collection of tables and data for the use of analysts, which we have had occasion to favourably notice in these columns on previous occasions. The general utility of the book is further enhanced by more space being devoted to chemical calculations, the author strongly favouring logarithmic methods. Why one of the several slide-rules, such as the one described in the ANALYST, xi., p. 101, has never come into vogue for this purpose seems enigmatical, since by its use all reference to logarithmic tables is avoided. The notes on indicators have been thoroughly revised, and the former specific gravity tables replaced by the most modern tables procurable. I n the section devoted to water analys’is the mode of preparation of the reagents employed has been added. These are merely a few of the many other additions to and improvements in the work, and evidently considerable care has been expended in ascertaining that the information given is accurate in every detail. I t is a most useful book, and is one which ought to be in the hands of every practising analyst. York : W h y and Sons. London : Chapman and Hall.) Price 8s. 6d. net. (London : J. and A. Churchill.) Price 6s. 6d. net. W. J. S.

ISSN:0003-2654    

DOI:10.1039/AN9042900344

出版商:RSC    

年代:1904

数据来源: RSC