摘要:

NOVEMBER, 1905, Vol. XXX., No. 356. A RAPID METHOD FOR THE DETERMINATION OF TIN IN COPPER-TIN ALLOYS. BY ARTHUR GARFIELD LEVY, B.Sc. (Read at the meeting, November 1, 1905.) IN the analysis of bronzes and similar alloys a good deal of time is required for the determination of tin by the ordinary methods of separation, as copper and lead must first be removed, unless the metal is treated with nitric acid and the tin precipitated 8s stannic hydroxide. In this case, however, as is well known, the washing out of the copper is generally tedious, and if the quantity of tin exceeds 1 or, at most, 2 per cent. the precipitate obtained is certain to be contaminated with oxides of362 THE ANALYST. other metals, the quantities of which must be determined and subtracted from that of the tin dioxide found.These considerations led to a search being made for another method which should give a direct and accurate determination of the tin in a few hours. The ease witb which arsenic in copper is separated by the distillation of its chloride suggested an analogous method being tried for tin. For this purpose the alloy was dissolved in various solutions, such as aqua regia, ferric chloride solution, and potassium cupric chloride solution into which chlorine was led. It was found, however, that distillation from these aqueous solutions was a tedious process, even when a stream of dry hydrogen chloride was led through the retort during the operation; several distillations to dryness, with fresh quantities of hydrochloric acid, were always necessary to remove the tin completely.Consequently, this method was abandoned. The general method of separating tin, antimony, arsenic, and bismuth from the other members of the second group by heating the metals in a stream of chlorine is well known, though perhaps little used. I t is mentioned already in the first edition of Rose’s “ Lehrbuch der Analytischen Chemie.” The same author states, however, that if the method is used to separate copper and tin, a trace of tin remains behind with the copper (Pogg. Anal., 1861, CXII., 169). The method is briefly described in Fresenius (“ Quantitative Analysis,” vol. ii., 431), Rose’s statement being quoted. Menschutkin (“ Analytical Chemistry,” English edition, 349) mentions the general method as affording an easy means of separation, but does not apply it to the particular case of tin and copper.Lunge (‘‘ Chemisch-Technische Untersuchungs Methoden,” vol. ii., 285) recommends the decomposition by heating in a stream of chlorine only for white metals rich in tin and antimony. Other works on technical analysis, such as those of Clsssen and of Brearley and Ibbotson, do not give the method at all. I t seemed worth while, then, to see what results could be obtained in this way for copper-tin bronzes. For this purpose the alloy was at first heated in the ordinary double-bulbed, hard glass tubes in a stream of chlorine. It was found, however, that the reaction was so violent that a good deal of spirting took place, so that whilst it seemed an easy matter to drive the whole of the stannic chloride into the receiver, the solution obtained contained considerable quantities of copper and any other metals present.The heavy vapour of the stannic chloride seems to lend itself especially to the sarrying forward of particles of the solid or liquid chlorides of other metals. In Lunge’s work this difficulty is mentioned in connection with the analysis of white metals rich in lead. With this method the fault appeared to lie chiefly with the apparatus employed. Consequently, this was modified until the following form was evolved, with which good results have since been obtained: The alloy is placed in a 30-C.C. distillation flask, the side tube of which is bent first up for a short distance, and then down again, so as to allow arty drops of liquid projected into the opening of the side tube to drain k y k into the flask.The entry tube for the chlorine reaches about halfway down the bulb part of the flask; around it, and below the side tube, is wrapped fairly tightly a plug of glass wool, which effectually retains the fine spray of other chlorides carried up by the stannic chloride. The distillation flask is connected by a, bent glass tube with two Volhard receivers containing water, into which the stannicTHE ANALYST. 363 chloride distils. I t has been found practicable to use rubber stoppers and joints, as, although these perish eventually, they last for a sufficient length of time to render the use of ground-glass joints unnecessary. In making a determination with this apparatus, 4 gram of the alloy in the form of sawdust or drillings is weighed into the flask, which is then placed in position.I t is necessary to use the alloy in a fairly finely divided state, as, if pieces are employed, they become coated with a skin of chloride, which stops the further action of the chlorine completely, until a fairly high temperature is reached, at which this skin melts and a violent reaction takes place, during which chlorides of other metals than tin may be projected into the first receiver in spite of the glass-wool plug. The chlorine contains hydrogen chloride, derived from its passage through a wash-bottle containing fuming hydrochloric acid ; it must be thoroughly dried before it enters the distilla- tion flask. The object of having hydrogen chloride present is to convert any oxide formed from air accidentally present into chloride, which the chlorine alone would not be able to do.After the flask has become filled with chlorine it is gently warmed. The reaction takes place readily, and it is an easy matter to drive the stannic chloride into the receivers. I t has been found, however, that it is difficult to sweep out the last traces of the vapour, using only a gas. For this reason, when apparently the whole of the stannic chloride has been distilled off, the heating is stopped, and the flask allowed to cool ; the flask is then unstoppered, the glass plug pushed down into the flask by means of the chlorine entry tube, and 10 C.C. of hydrochloric acid are added, aEter which the stopper is replaced, and the flask again heated in the current of chlorine until the bulk of the liquid has been distilled off.This treatment sweeps out the last traces of stannic chloride into the receivers, and only occupies a few minutes. The tin in the receivers is precipitated as sulphide, after partial neutralization, if necessary, of the acid liquid by ammonia. The precipitate will, of course, contain. any antimony, arsenic, or bismuth present in the alloy. Antimony and, especially, bismuth do not occur in ordinary bronzes in weighable quantities, and hence may generally be neglected ; arsenic is removed during the subsequent ignition to oxide. The further treatment of the sulphide obtained depends on whether antimony is especially to be looked for or not. If it is, the thoroughly washed precipitate is transferred to a small weighed dish, and oxidized as usual with nitric acid, the oxides obtained being finally ignited at a dull red heat. Antimony and, if thought necessary, arsenic are then determined as usual, and tin taken by difference.I n the case of an ordinary alloy, however, the washed tin sulphide is simply ignited directly, at first very gently, and finally at a fairly bright heat. The trace of antimony present is not affected by this treatment, and may be identified as usual with iron wire and platinum after fusing the stannic oxide. I t is well to reignite the latter, as t h e first weight obtained is occasionally slightly too high if the temperature of ignition was too low. The results obtained by using this method for bronzes are shown in the following table : A fairly rapid stream of chlorine is passed through the apparatus.364 THE ANALYST.Percentage of Tin found by NO. Usual Method. 1 ... ... 11.50 2 ... ... 14.37 3 ... ... 9.38 4 ... ... 9-77 5 ... ... 11.55 6 ... ... 10.21 7 ... ... 9.55 8 ... I . . 0.99 Chlorine Method. *. . 11.47 ... 14-32 ... 9.29 ... 9.72 ... 11.58 ... 10.13 ... 9.50 ... 0.98 ... ... ... ... ... ... ... ... Error. Per Cent. - 0.03 - 0.05 - 0.09 - 0.05 - 0.03 - 0-08 - 0.05 - 0.01 Most of these bronzes contained up to 10 per cent. of lead, together with sinnll quantities of phosphorus and arsenic. One or two contained in addition about 10 per cent. of zinc, the balance being copper. A brief description of the ‘‘ usual method ” mentioned in the above table may not be out of place here.I t consists in dissolving the alloy in aqua regia, precipi- tating the copper by means of ammonium thiocyanate and sulphur dioxide, and passing hydrogen sulphide into the filtrate from the cuprous thiocyanate after removing the sulphur dioxide by leading a current of air through the heated solution for some time, From the precipitate of mixed sulphides obtained the atannic solu- tion is dissolved out by sodium sulphide solution. The solution is acidified with hydrochloric acid, after which the stannic sulphide is filtered off, washed, redissolved in ammonium sulphide solution to remove sodium salts completely, and finally oxidized with nitric acid, or ignited to oxide as above. The chlorine method has also been tried on commercial samples of tin, with fairly good results : Percentage of Tin found by Error./ - No. Difference. Chlorine Method. Per Cent. 1 ... ... 99.88 ... 99.66 ... - 0.22 2 ... ... 99.35 ... 99.38 ... + 0.03 3 ... ... 96.73 ... 96-62 ... - 0.11 A determination of tin by the chlorine method can be finished in about five hours. The method, therefore, is of value where a rapid and accurate check on the percentage of tin is wanted. If a complete analysis of the alloy is to be made, it has not very much to recommend it, although even in this case several hours can be saved by determining the tin on a separate portion treated as above. Naturally, the use of chlorine tends to make it somewhat disagreeable for the operator. The work described was carried out in the laboratory of Mr. Bertram Blount, to whom I am very much indebted for permission to publish the results.DISCUSSIOX. The PRESIDENT (Mr. Bevan) having invited discussion, Mr. BLOUXT said that the history of Mr. Levy’s work on this subject turned on the fact, long ago observed and generally known, that stannic chloride was volatile. I n analysing samples of ordinary commercial tin, he (Mr. Blount) had sometimes found it convenient to get rid of the tin by repeatedly evaporating with hydrochloricTHE ANALYST. 365 acid the solution of stannic chloride obtained by dissolving the metal in aqua regia. That had been found effective. He then conceived the idea of distilling over the tin from alloys in the same way, and that was the genesis of Mr. Levy’s work. I t was found, however, that the volatilization of the stannic chloride in that manner was impracticably slow, and SO the more conventional process was adopted of converting it into chloride and getting over the chloride at a, higher temperature than that of distillation from an aqueous solution ; and, the difficulties connected with the apparatus having been solved as Mr.Levy had described, a really good working method was obtained for the determination of tin in alloys that were not too com- plicated. Ordinary gun-metal, for instance, which was somewhat troublesome in the ordinary way of analysis, could be readily dealt with. The determination of the tin after distillation was much simpler than had been previously supposed, no greater precautions being necessary in dealing with the tin sulphide than were necessary with zinc sulphide.Mr. ARCHBUTT said that the use of chlorine was, of course, the great objection to a process of this sort, and probably if it were an odd sample to be dealt with, and especially if it had to be analysed completely, such a method would not be advisable ; but if there were a number of analyses to be made regularly, and it was known how much tin was usually present, and that the samples were fairly free from antimony m d other volatile metals, the method should prove most useful. With regard to the prevention of splashing, he thought the glass-wooi plug might be dispensed with if the neck of the flask were made very long, say 12 inches. This expedient, which he had found very useful in determining ammonia in water, and also in distilling arsenic from copper, enabled boiling or distillation to be carried on very rapidly without any loss through splashing.He should like to hear more details than Mr. Levy had given of the process used when antimony was present. Most of these alloys, in his ex- perience, contained small quantities of antimony, the influence of which was some- what important. He had himself found, though he had not gone into the matter very closely, that the ordinary nitric acid method of separating tin from other metals, such as copper, when the proportion of tin was more than 10 or 12 per cent., was by no means so inaccurate as the books stated. Very good results could be obtained by dissolving the metal in nitric acid of 1.2 specific gravity, evaporating to a small bulk, diluting, filtering, and washing the tin oxide, which was far from being so impure as to invalidate the use of the method. I t contained nearly all the anti- mony present, and if, after being weighed, the mixed oxides of the tin and antimony were fused with sulphur and sodium carbonate, dissolved in water, and treated with 5t large excess of strong oxalic acid solution, the antimony was precipitated.For foundry analyses he had found that method very satisfactory, and with a little management it was possible to get the tin oxide filtered and washed within a reason- able time. He did not, however, doubt that the method now described was a great improvement. Mr. BODMER asked what method had been found most convenient for generating the chlorine, and how the gas was obtained in a perfectly dry condition.Mr. CHAPMAN said that Vortmann and Metzl had recently published a method for the separation of antimony from tin, in which the mixed sulphides were dissolved3GG THE ANALYST, in hydrochloric acid, the greater part of the acid being then neutralized and a certain quantity of syrupy phosphoric acid added. The authors claimed that the antimony could then be quantitatively precipitated by sulphuretted hydrogen. One advantage of such a method would be the ease with which the tin could be determined in the filtrate. The results of the specimen analyses that were given seemed to be very satisfactory, and if the statements made with regard to it were correct the method would be a good one. Mr. RICHARDS said that some years ago he had had occasion to examine certain dental alloys containing platinum, gold, silver, and tin, and had determined the tin with good results by a process somewhat similar to that used by Mr.Levy. The formation of tin chloride was complete in every case, and the use of a little glass-wool effectually prevented any trouble from the passing over of other chlorides. The separation of the other metals afterwards was effected without difficulty. The PRESIDENT asked how Mr. Levy ascertained that sufficient antimony was present in the distillate to make its determination worth while. Mr. LEVY, in reply, said that alloys of this kind were generally made from care- fully chosen metals, and he thought that in most cases the tin used would not contain more than 0.1 per cent. of antimony at the outside, so that, with alloys such as those he had referred to in the paper, it would be scarcely worth while to actually determine the antimony.If any fairly large proportion of antimony were present, a sufficient indication of it would be obtained in the course of the operations he had described, and in that event one would have to repeat the determination and treat the antimony more carefully. The usual method of testing for antimony was to fuse the stannic oxide again with a small quantity of soda, dissolve the melt in a small excess of hydro- chloric acid, and treat in a platinum dish with a piece of iron wire. The merest trace of antimony would thus be shown after heating for a quarter oflan hour on the water- bath. He had seen the paper to which Mr.Chapman had referred, but had never tried the process. The results given, however, appeared to be excellent. He had seen a good many results obtained by the oxalic acid method, and some of them were very good, but he had never been able himself to get very good results with it, as far as the determiaa- tion of antimony was concerned. The method he preferred for the separation of considerable quantities of tin and antimony was that of Rose. I t was certainly a long and cumbrous method, but when carefully carried out it yielded very good results, both for small quantities of tin in presence of large quantities of antimony, and vice t w s k The chlorine, for a distillation process like this, where not very much was required, was conveniently generated from hydro- chloric acid and ordinary granulated manganese dioxide in a 16 or 20 ounce flask.The drying was effected simply by leading the chlorine through sulphuric acid wash-bottles and tubes. I t was important to see that the sulphuric acid was really fresh and good. He had lately used a Streatfeild drying-tube. He did not think that the liability of other chlorides to be carried over was a question of ordinary splashing. The stannic chloride vapour seemed to lend itself specially to the carrying over of the chlorides of other metals in a finely divided form, probably because, being heavy, it did not readily allow any dust that got into it to fall down, so that the use of The tin precipitates were treated in that way as a matter of routine. As a rule, the tin was taken by difference.THE ANALYST. 367 something which, like glass-wool, acted mechanically as a sort of sieve, was necessary. He thought that the most troublesome part of the nitric acid method was the filtering off of the stannic hydroxide or stannic oxide. The precipitate was very troublesome to wash if it was at all large in quantity, and perhaps the correctness of the results might be attributed to a sort of compensation of errors. I€, however, the alloy contained, say, 15 per cent. of tin and only about 0.1 or 0.2 per cent. of lead, it did not seem quite fair, as far as his experience went, to throw a fairly considerable percentage error on the lead. The PRESIUEXT said that he had found the simplest way of generating chlorine to be to drop hydrochloric acid on to permanganate of potash. The production of chlorine in that way could be regulated with the utmost nicety.

ISSN:0003-2654    

DOI:10.1039/AN905300361b

出版商:RSC    

年代:1905

数据来源: RSC

摘要:

THE ANALYST. 367 WATER FROM THE SIMPLON TUNNEL. BY ARTHUR GARFIELD LEVY, J3.Sc. A SAMPLE of water from one of the hot springs encountered during the construction of the Simplon tunnel between Switzerland and Italy, obtained from Mr. Francis Fox, the well-known engineer, was recently examined by the author in the laboratory of Nr. Bertram Blount. The spring was situated at a point between 9.1 and 9.4 kiloms. from the Italian end of the tunnel. It discharged water at the rate1of 230 litres per second, the temperature of the water being 45.9' C. The water itself was clear, colourless, and devoid of smell, and had a somewhat saline taste. It was free from organic niatter and from chlorine, the total absence of the latter being rather remarkable. The mineral constituents present are as follows : Silica ...... ... Alumina and ferric oxide ... Calcium oxide ... ... Strontium oxide ... ... Potassium oxide . . . ... Sodium oxide . . . ... Carbon dioxide (combined) . . . Magnesium oxide . . . ... Sulphur trioxide . . . ... Grams per Litre. 0.0102 ... 0.0022 ... 0,4910 ... 0.0030 ... 0.0655 ... 0.0050 ... 0.0086 ... 0.0267 ... 0-8000 Grains per Gall. 0.71 0.16 34.37 0.21 4.59 0.35 0.60 1-87 56-00 Combined water and loss ... Total solids ... 1.4122 ... 0.1098 98.86 7.68 ... 1-5220 106.54 A trace of lithium was also present. No barium, czsium, or rubidium could be detected by the spectroscope.368 THE ANALYST. From the above analysis the salts probably present in the water are calculated to be as follows : Calcium carbonate ... Strontium sulphat e ...Calcium sulphate ... ... Magnesium sulphate ... Potassium sulphate ... Sodium sulphate ... ... Silica ... ... ... Alumina and ferric oxide ... Grams per Litre. ... 0.0607 ... 0.0053 ... 1.1099 ... 0.1965 ... 0.0092 ... 0-0170 ... 0.0102 ... 0.0022 1.4110 Grains per Gall. 4.25 0.37 77.69 13-77 0.65 1.27 0.71 0.16 98.77 -~ . The water is very rich in calcium sulphate, besides which there are present a considerable quantity of magnesium sulphate and small amounts of other salts. An examination of the gases expelled by boiling the water showed it to contain only the ordinary constituents of the atmosphere, the quantities found being as follows : C.C. Dry Gas per Litre a t 0°C. and 760 Mm. Percentage on Total Gas. Carbon dioxide ... ... 2-0 ... 9.6 Oxygen ...... ... 6.1 ... 29.4 Nitrogen ... .. ... 12-3 ... 59.1 Argon ... ... ... 0.4 ... 1.9 ... ... ... 20-8 100.0 Total The gases are evidently due to absorption from the air. To Mr. Francis Fox for providing the opportunity to examine a water of con- siderable chemical interest, and to Professor Herbert Jackson for kindly making the necessary spectroscopic tests, I wish to offer my acknowledgments and thanks. DISCUSSION. Mr. BLOUNT said that, as this water was possibly entirely plutonic, having never seen the surface of the globe, something out of the common had been looked for in its results. The only interesting point, however, was the complete absence of chlorine. H e had never met with a natural water before that was completely destitute of chlorine ; it was unique.The PRESIDENT (Mr. Bevan) inquired to what extent the water had been concen- trated before the test for chlorine was made, and also whether the water had been tested for barium. Mr. W. T. BURGESS remarked that, as a rule, the quantity of chlorine in natural water became less as the distance from the sea was greater. In France, for instance, it was possible to get rain-waters much freer from chlorine than in England, and possibly the distance from the sea which the water had to travel before being deposited as snow and subsequently melted might have some bearing on its freedom from chlorine. Mr. FAIRLEY said that in Asia and in America it was possible to get muchTHE ANALYST. 369 farther from the sea than anywhere in Europe, but the Great Salt TAake of Utah and some of the lakes of Central Asia were exceedingly saline.Mr. BLOUNT suggested that possibly those lakes were themselves the remains of ancient seas. Mr. LEVY, in reply, said that chlorine was only looked for in the water as received, without any concentration. The tests, however, were allowed to stand for a very long time, in one case (using 250 C.C. of water) for four or five days. It was a difficult water to concentrate, because, on account of the large quantity of calcium sulphate present, a crust separated out. Professor Herbert Jackson had kindly made a spectroscopic examination of the sample, and had found in it a trace of lithium, but no bariuni or cmium. Probably about 200 miles was the distance of the source of this water from the sea.* No doubt the altitude would also have to be taken into account. At the same time, to have attained so high a temperature in such a region, it must have travelled a considerable distance underground, and it was rather remarkable that it did not take up chlorine somewhere on its way.

ISSN:0003-2654    

DOI:10.1039/AN9053000367

出版商:RSC    

年代:1905

数据来源: RSC

摘要:

THE ANALYST. 369 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Determination of Higher Alcohols in Spirits. E. Beckmann. (Zeit. Nalar.-Ge?zuss., 1905, x., 143-152.)-The following method is a modification of the one described by the author some years ago (qf. ANALYST, 1902, xxvii., 88). The spirit is diluted with water until it contains not more than 20 per cent. of alcohol by volume. Fifty C.C. of this solution are then shaken out with four successive quantities of carbon tetrachloride, using 50 C.C. of the latter each time and shaking vigorously for a few seconds. The united carbon tetrachloride extracts are washed twice with about 20 C.C. of water and then treated in a stoppered flask with 2 grams of potassium hydrogen sulphate and 1 gram of sodium nitrite.After shaking for a few minutes, the mixture is transferred to a separating-funnel, the carbon tetrachloride is drawn off and the residue extracted twice with a little carbon tetrachloride, The whole of the solution is now shaken with about 20 C.C. of saturated sodium- hydrogen-carbonate solution to remove excess of nitrous acid, and separated. The carbon tetrachloride is then carefully mixed with about 75 C.C. of concentrated sulphuric acid previously placed in a separating-funnel, and well shaken. The mixture is finally run on to about 150 grams of crushed ice and the resulting solution titrated with permanganate solution. To obtain a sharp end-point, it is advisable to add an excess (about 20 per cent.) of the permanganate and to titrate back with ferrous ammonium sulphate solution.w. P. s. Detection of Methyl Alcohol in Liquids containing Ethyl Alcohol. J. Kahn. (Merck’s Beport, September, 1905, 271 ; through Pharm. Jozw., 1905, * The actual distance to Genoa, the nearest point on the Mediterranean, is 200 kilos (about 125 miles). -A.G.L.370 THE ANALYST. lxxv., 387.)-The test proposed depends on the oxidation of the mixed alcohols to the corresponding aldehydes by the action of heated copper, any formaldehyde formed being detected by the appearance of a violet-blue coloration when tested with milk and commercial sulphuric acid. After dilution, the solution to be tested is warmed in a large test-tube, into which a red-hot copper spiral is dipped several times. Five C.C. of milk and a trace of ferric chloride are now added, and the mixture carefully poured on the surface of concentrated sulphuric acid contained in another test-tube.If methyl alcohol is present in the original solution, the formaldehyde produced by the oxidation will cause a violet-blue coloration to appear at the junction of the two liquids. The milk used must, of course, be free from formaldehyde. w. P. s. The Characteristics of Camel's Butter. J. Vamvakas. (8127~. de C'llim. anal., 1905, x., 350.)-Butter prepared in the laboratory from camel's milk was of firm consistency and had a grayish-white colour and a peculiar odour. Its physical and chemical values were as follows : Melting-point, 38' C. ; melting-point of fatty acids, 47" C. ; volatile fatty acids, 8.6 per cent. ; insoluble fatty acids, 88.29 per cent.; saponification value, 208 ; iodine value, 55.1 ; and oleo-refractometer reading, 20. C. A. M. Detection of Small Quantities of Sesame Oil in Butter, etc. H. Sprink- meyer and H. Wagner. ( h i t . Nahr.-Gemss., 1905, x., 347-353.)--1n the method proposed, the substances which give the colour-reaction with Baudouin's test are concentrated in a fraction of the fat by extracting the latter with acetic acid. About 100 grams of the melted and filtered butter-fat are twice extracted with from 20 to 30 C.C. of glacial acetic acid at a temperature of 60" C. After separation, the acid layers are evaporated, and the residue obtained tested as usual. As many samples of butter contain colouring substances which give a red tint when treated with hydrochloric acid, it is better to remove these substances before applying the test.This may be done by adding 10 C.C. of alcohol and 5 C.C. of saturated barium hydroxide solution to the acetic acid residue, and again evaporating to dryness. The residue is then extracted several times with light petroleum, which dissolves the substances yielding Baudouin's reaction, the colour- ing matter of the butter remaining insoluble in the barium soaps. The residue obtained on evaporating the petroleum extracts is then tested with the reagent. As little as 0.1 per cent. of sesame oil in butter may be detected by proceeding as above. w. P. s. Test for the Purity of Cocoanut Oil. E. Milliau. (Compt. rend., 1905, cxl., 1702; through Pharm. Joum., 1905, lxxv., 361.)-Four C.C.of the fat are mixed in a test-tube with 2 C.C. of a solution of phloroglucinol in ether ; 2 C.C. of a solution of resorcinol in benzene are then added, and the tube and its contents cooled to a temperature of 10" C. After adding 4 C.C. of nitric acid, of specific gravity 1.36, the tube is closed with an indiarubber stopper (washed with the same acid) and shaken for five seconds. Pure cocoanut oil remains unaltered, negligible traces of impurities imparting a scarcely perceptible rose tint to the mixture, whilst the presence of anyTHE ANALYST. 371 seed oil, such as cotton, sesame, arachis, etc., is at once indicated by a distinct currant-red coloration, even if only 5 per cent. of the adulterant be present. The colorations which appear later are to be disregarded.w. P. s. The Composition of Chestnut Flour. P. Comte. (Journ. Pharm. Chiwz., 1905, xxii., 200-210.)--Flour obtained from the dried chestnut is used by the peasants throughout Corsica in place of cereal flours. Five samples from different parts of the island, examined by the author, had the following composition : Moisture, 11.20 to 12.46 ; nitrogenous substances, 5.82 to 6.60 ; fat, 2.65 to 2.85 ; fiugars and starch, 72.60 to 73.83; cellulose, 2-90 to 3.96; and ash, 2.34 to 2.50 per cent. The mineral matter contained from 32 to 36 per cent. of phosphoric acid, and from 8 to 12 per cent. of silica, derived almost entirely from the mill-stones. Manganese was also present. A superior quality of the flour prepared from hand-sorted and cleansed chestnuts was almost free from the brown particles and hard lunips found in the ordinary grades, and had the following composition : Moisture, 17.90 ; nitro- genous substances, 7.46 ; fat, 2.72 ; sugars and starch, 68.30 ; cellulose, 1.52 ; and ash, 2.10 per cent.The flour is but little adulterated in Corsica owing to its low price (0.2 to 0.25 franc per kgm.), though powdered acorn flour is sometimes added. Chestnut flour is very refractory to the action of yeast, and therefore does not make good bread. C. A. M. Investigation of Mace. Utz. (Chem. Zeit., 1905, xxix., 988.)-Pritchard’s method of distinguishing true Banda mace from the so-called “ Bombay ” mace by means of I per cent. caustic soda solution has been investigated by the author. The result of the experiments was that with Banda mace 1 per cent.caustic soda gave either no colouring or only a very slight yellow, and this tint was not deepened by warming. I n the case of Bombay mace there was obtained in the cold a yellow-red colour, which appeared rather more quickly on gently heating. The test is clearer and more delicate if strips of filter-paper are used to absorb some of the liquid from the mace and alkali, and dried. The Banda mace gives completely colourless strips, whilst those from the Bombay mace are deep orange. An addition of 5 per cent. of Bombay mace can be easily detected by this means. Another method of using this test is to examine the alkaline solutions spectro- scopically. Banda mace does not affect the spectrum, whilst Bombay mace shows a broad absorption-band near the D line.In place of caustic soda, a diluted Nesder solution (1 : 1) may be used, with filter-paper strips. The permanency of the colour on the strips is being investigated, The colour then obtained with Bombay mace is raspberry red. E. K. H. Determination of Citral in Lemon Oil. G. Romeo. (Chemist and Druggist, 1905, lxvii., 408)-The method proposed is based on the fact that when citral is absorbed by potassium sulphite or sodium hydrogen sulphite, with sufficient excess of the hydrogen sulphite for the solution to remain acid after the absorption, the acidity is reduced in the proportion of 3 molecules for each molecule of citral present. The sulphite solution employed is prepared by dissolving 400 grams of372 THE ANALYST. crystallized sodium sulphite in 1 litre of water, and adding enough saturated sodium hydrogen sulphite solution to make each 25 C.C.sufficiently acid to neutralize 20 C.C. of F potassium hydroxide solution. Five C.C. of the lemon oil are heated with a sufficiency of this solution in a closed flask for three hours on the water-bath, and the residual acid then titritted. Theoretically, 152 grams (1 mol.) of citrsl should neutralize 3,000 C.C. (3 mols.) of N acid. (In three experiments the actual results were : 2,955 c.c., 2,957.7 c.c., and 2,962.7 c.c.) One C.C. of N acid therefore corre- sponds with 0,05066 gram of citral, and the amount of citral in the 5 C.C. taken is a matter of simple calculation. In four samples of oil the author found 3-64, 4.48, 3.54, and 3.80 per cent. of citral, whilst an artificial mixture containing 4-98 per cent.yielded 4.86 per cent. These figures corroborate the views held by many analysts that the 7 per cent. citral value is too high. w. P. s. On the Resins of Scammony. P. Guigues. (JOUYW Pharm. Chim., 1905, xxii., 241.)-It is commonly accepted that scammony resin is soluble in ether, but the author finds that certain scammony roots occurring in commerce contain two resins, one of which is soluble and the other insoluble in ether. The insoluble resin, how- ever, is soluble in an ethereal solution of the soluble resin, but is precipitated on the addition of an excess of ether. The scarnmony resins prepared some five or six years ago were completely soluble, and this is to be attributed to their having been obtained from roots derived from a very limited area, whereas, owing to the exhaustion of the former sources of supply, they are now derived from other countries and presumably other species of plants.Resins actually in commerce contain as much as 50 per cent. of brown resins insoluble in ether and 25 per cent. of white resins. The much greater commercial value of jalap resin is opposed to the conclusion that the latter is present as an adulterant in these resins, and the author's explanation is that the original roots belonged to a species intermediate between Convolvulus scummoizia and C. turpethunz, or were mixtures of the two, or that they had undergone some alteration in the course of drying, Some samples of Aleppo scammony root, examined by the author, were found to yield 79 per cent.of resin soluble in alcohol, whereas other chemists had found from 46 to 77 per cent. soluble in ether. In four other samples extracted from the roots by digerent methods the insoluble portion varied from 9 to 14 per cent. A portion of one of these resins taken up with alcohol, decolorized, and filtered, had an optical rotation of aD= -20" 43' and a refrac- tive index (in 4 per cent. solution) N~=1-3659, whilst the corresponding figures obtained with a decolorized ethereal solution of another portion of the resin were WD = - 21' 43' and N, = 1.3659. C. A. M. Tests for distinguishing between Nieotine, Conine, and Sparteine. Reichard. (Pharm. Centr., xlv., 300 ; through Pharnz. Jouryz., 1905, lxxv., 333.)- Nicotine and conine may be distinguished by means of a reagent made by moistening a little cuprous chloride with water, and heating until the mass assumes a bright green colour.A small quantity of this reagent is mixed with a drop of either alkaloid and a drop of hydrochloric acid. With nicotine, it violet-blue colour is at once formed; with conine, a bright green solution is produced ; with sparteine no im-THE ANALYST. 373 mediate reaction occurs. If a few drops of a solution of a-nitroso-P-naphthol be evaporated to dryness, and the residue treated with a trace of these bases, a yellow-brown tint is obtained in the case of nicotine and a fine dark green with conine. Ammonium molybdate in sulphuric acid gives a yellowish-green with nicotine, but no reaction with conine or sparteine. On adding ammonium per- sulphate to the mixture nicotine gives a purple colour, conine and sparteine an intense yellow.Another colour-reaction is obtained with ferric thiocyanate. A mixture of solutions of ferric chloride and potassium thiocyanate is evaporated in a thin film. To the residue thus obtained a trace of nicotine, conine, or spartcine is added, and then a little water ; sparteine gives a violet-blue or reddish-violet tint ; nicotine and conine yield a green colour. These colours are permanent on drying. By substituting potassium ferrocyanide for the thiocyanate, and proceeding as before, the blue colour which remains after drying is changed to brown by conine, to bright green by nicotine, and to pale violet by sparteine. On treating the dried spots with a drop of potassium thiocyanate, those of nicotine and conine show no change, whilst the sparteine spot becomes pale blue, passing to deep blue on drying.w. P. s. Determination of Phosphorus in Phosphorized Oil. H. Enell. (Pharm. Zeit., 1905, l., 601 ; through Zeit. Nnhr.-Ge?zzm., 1905, x., 355.)--The method is based on the determination of the acidity of the oil before and after oxidation with iodine. A weighed portion of about 1 gram of the oil is placed in a stop- pered flask and dissolved in.a mixture of 10 C.C. of alcohol and 20 C.C. of ether. Twelve C.C. of TG iodine solution are added, the whole is well shaken for three minutes, and the excess of iodine titrated back with & thiosulphate solution. A little phenolphthalein is now added, and the acidity titrated with Tv sodium hydroxide solution. The titration should be continued until the pink coloration no longer disappears on shaking the mixture. The original acidity of the oil is now determined on a fresh quantity of about 1 gram, dissolved in the above proportions of alcohol and ether. The difference in the acidity before and after the treatment with iodine gives the quantity of free phosphorus in the oil. 0.01 gram of phosphorus is equivalent to 16.12 c.e. of TG sodium hydroxide solution. w. P. s. The Aetion of Arrhenal (Sodium Methyl Arsenate) on Alkaloids. Vitali. (Boll. Chim. Farm., 1905, No. 7 ; Journ. Pharnz. Chim., 1905, xxii., 227, 228.)-The formation of an insoluble precipitate on adding arrhenal to the solution of the salt of an alkaloid has usually been attributed to the alkaline reaction of the reagent, but, according to the author, the reaction is more complicated. With strychnine sulphate, for instance, sodium sulphate and the methyl arsenate of the alkaloid are formed, and it is this latter which is precipitated. Other alkaloids also yield insoluble methyl arsenates, many of which are in the form of microscopic crystals, the appearance of which might afford a means of identifying the alkaloids. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9053000369

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年代:1905

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374 THE ANALYST. ORGANIC ANALYSIS. The Determination of Acetaldehyde. Seyewetz and Bardin. (132~11. Soc. C ~ L . , 1905, xxxiii., 1000-1002).--The solution of aldehyde should be diluted, so that its strength does not exceed 7 or 8 per cent. Ten C.C. of the liquid are mixed with about 40 C.C. of a 10 per cent. solution of anhydrous sodium sulphite and 1 drop of a 0.2 per cent. alcoholic solution of phenolphthalein, and titrated with standard sulphuric acid, the amount of aldehyde being calculated according to the equation- 2Na,SO, + 2CH,.COH +H,SO, = (HNaSO, + CH,.COH), + Na,SO,. In order t o prevent loss of aldehyde from volatilization the temperature should be kept at 4" to 5" C. during the dilution and addition of the sulphite. Alcohol, paralde- hyde, or acetal, have no appreciable influence on the results, but acetic acid when present must be determined separately.Trioxymethylene is converted into for- maldehyde by sodium sulphite, and can then be determined in the same way as formaldehyde itself. The method is stated to give good results with very dilute solutions of aldehyde (1 : 3000). C. A. M. The Detection and Estimation of Ketones, and the Differentiation of Acetone from other Ketones. M. Kutscheroff. (Zeit. anal. Chem., 1905, xliv., 622 -625.)-On applying Rosenthaler's reaction (ANALYST, xxx., 247) to the detection of ketone oil (chiefly methyl-ethyl-ketone), which is used in the proportion of 1 per cent. for '' denaturing " spirit, the author was unable to obtain satisfactory results, since vanillin in the presence of strong hydrochloric acid gave either no coloration at all or only a faint one, appearing after hours or even days.Similar results were obtained with certain other ketones, such as methyl-propyl ketone, ethyl-butyl ketone, and acetone. The substitution of concentrated sulphuric acid (specific gravity 1.84) for hydrochloric acid, however, proved satisfactory, and also enabled acetone to be distinguished from other ketones. A solution of 0-3 gram of vanillin in 5 C.C. of rectified spirit gives only a faint yellow coloration with 1 C.C. of sulphuric acid, but if about 1 per cent. of a ketone be present, a bright coloration is immediately produced, which is carmine red in the cage of acetone and blue in the case of other ketones, with sometimes a greenish shade (methyl-butyl ketone), which soon disappears.The carmine red colour obtained with acetone changes to lemon yellow on the addition of water, but the blue colour given by the higher ketones is not affected by water. If, however, a dilute solution of sodium or potassium hydroxide be added to the diluted liquids, the yellow acetone solution becomes an intense orange red, whilst the solutions of the other ketones are decolorized, or, rather, changed to a faint yellow. The sensitiveness of the vanillin reaction is very great, and the test is capable of detecting mere traces of ketones. Hence, with the aid of a colour scale prepared with a ketone solution of known strength, quantitative colorimetric determinations can be made. A freshly prepared solution of 15 grams of vanillin in 100 C.C. of concentrated spirit (as free as possible from aldehyde) has proved the most suitable The intensity of the blue coloration increases on standing.THE ANALYST, 375 strength in the author's hands.Of this solution, 2 C.C. should be added to 3 C.C. of the solution under examination, and then 1 C.C. of sulphuric acid. When the ketone amounts to 0.1 to 1 per cent., the coloration is immediately produced, but with smaller quantities (0.1 to 0.01 per cent.) it only occurs after some time, and the solutions should not be compared until after the lapse of ten to fifteen minutes, or longer. For the detection of acetone in the preaence of other ketones, the coloured solution obtained in the reaction should be diluted with water, which changes the colour to green, the carmine red of the acetone being changed to yellow.As a corroborative test, the green solution is treated with a 25 per cent. solution of sodium hydroxide, when it becomes orange red in the presence of acetone. The reaction is so sensitive that it will detect 0.01 per cent. of acetone out of a total amount of 0.1 per cent,. of ketones. I n like manner very small quantities of higher ketones can be identified in the presence of acetone. As regards the influence of other substances present as inipurities in spirit, ainyl alcohol and fnrfural have no disturbing influence. Acetaldehyde, when present in quantity (1 per cent.), produces a coloration similar to that given by higher ketones, but when present in the usual quantity of 0.1 gram per litre, can be neglected.When, however, it reaches the maximum of 0.3 gram per litre observed in crude spirit, it should be expelled by boiling before the vanillin test is made. On distilling the liquid to half its volume, almost the whole of the ketones of higher boiling-point will be found in the residue, whilst about half of any methyl-ethyl ketone present will have passed over with the alcohol. The amount of aldehyde left in the residue is then too small to have any influence upon the test. C. A. M. Quantitative Hydrolysis of Saecharose, Maltose, Lactose, and Raffinose. B. Pfyl and €3. Linne. ( Z c i t . N(LILI-.-Gcu~~ss., 1905, x., 104-110.)-Under the following conditions of pressure, temperature, acidity and time, these sugars may be quantitatively hydrolysed without the products undergoing any change. The apparatus employed consists of a bronze pressure cylinder, about 30 cine high, and of 3-2 em.internal and 4 em. external diameter. The cylinder is provided with a screw head carrying a valve-chamber, which is fitted with a manometer and a side-tube. By connecting this side-tube with a carbon dioxide cylinder, any desired pressure UP to fifty atrnospheres may be obtained. Both screw-joints are made tight by lead packing. Inside the pressure-cylinder is placed a thick walled glass tube, constricted at the top and provided with a mark so that an exact volume of solution may be used each time. During the hydrolysis the cylinder is suspended in a glycerol bath heated to the required temperature. I t is impossible to completely hydrolyse saccharose in the presence of inorganic or organic acids without destroying some of the inversion products, but in the presence of carbon dioxide at a pressure of 20 atmospheres and at a temperature of 1250 C., saccharose is quantitatively hydrolysed in two and three-quarter hours, The invert sugar formed remains unchanged after a further heating for thirty minutes.Experiments show that neither dextrin, maltose, nor lactose undergoes any change under these conditions.376 THE ANALYST. When subjected for three hours to a pressure of 20 atmospheres and a temperature of 125' C., raffinose is completely hydrolysed into melibiose and levulose. Maltose and lactose are best hydrolysed in a 2 per cent. aqueous solution of benzene-sulphonic acid, kept at a temperature of 110" C.for two and a half hours; varia- tion of the pressure from 0 to 50 atmospheres produces no effect on the completeness of the hydrolysis. If saccharose, or invert sugar, be subjected to these conditions, about 17 per cent. of it is destroyed, and this proportion is independent of the concentration of the sugar solution or intensity of the pressure. The purity of various sugars may be determined by means of the above-described methods, the latter also further serving for the determination of sugars in the presence of each other, as, for instance, saccharose in honey, condensed milk, etc. w. P. s. Examination of Linseed Oil used in the Manufacture of Lacs, Linoleum, etc. (ClLem. h i t . , 1905, xxix., 898.)-Linseed oil, suitable for these purposes, should not form flocks when quickly heated to boiling in a test-tube.Recently oils have been introduced under the title of '' lac linseed oil " (Lackleinol) which apparently exhibit this characteristic, but are still not suitable. I n the case of this class of oil, however, the boiled sample showed a turbidity after several days' st anding. Only those oils should be used which give no deposit after -standing for a year or so, and on being boiled acquire a clear greenish colour, and show no turbidity on standing for a month in an open test-tube. C, Niegemann. E. K. H. The Estimation of Sulphur in Liquid Fuel and Petroleum. A. Goetzl., (Zeit. aizgezu. Chenz., 1905, xviii., 1528.)-To 2 to 3 grains of the liquid fuel in a roomy platinum crucible 4 C.C.of fuming nitric acid are added, and the cruciblo covered by a watch-glass and allowed to stand for some time, preferably overnight. The crucible is then cautiously shaken, and when no further reaction takes place, even with gentle warming, the contents are cautiously evaporated to dryness on the water-bath, To the brown aromatic residue, 6 to 8 grams of a mixture of sulphur, silica-free soda and pure nitre, in the proportions of 5 to 1, are added and the mixture heated to incipient melting on the water-bath. After stirring well with a platinum wire, and covering again with more of the soda-nitre mixture, the crucible is heated ucder the hood directly over a rose-burner. Under these conditions, the combustion takes place very quietly, and when this is complete, the white mass is dissolved in hot water, the solution acidified with hydrochloric acid, and the sulphate precipitated with barium chloride.The results are very accurate. Sulphur can be estimated in petroleum by the same method, but it is necessary to use some 10 grams of the oil, and the various operations are rather more troublesome. A. N. C. The Determination of Carbon, Hydrogen, and Nitrogen in Cyanides. (Bull. SOC. C'hinz., 1905, xxxiii., 951-953.)-The combustion of the J. A. Muller.THE ANALYST. 377 most refractory metallic cyanides is readily effected by the use of an oxidizing mixture of .83 parts of potassium bichromate (previously fused and powdered) and 13 parts of lead chromate (Ann. Chim. Phys., xxii., 141). The combustion tube used by the author is of Jena glass, 87 cm.in length by 15 mm. in internal diameter. Within it is placed a column of copper oxide 26 cm. in length, which is kept in position by rolled strips of platinum-foil at one end and by a roll of copper-wire gauze at the other. After each combustion this copper is reduced by passing a slow current of hydrogen through the tube, which is only heated at the end for a distance of about 10 to 12 em. The determinations of carbon and hydrogen are made with a, slow current of air during the combustion, whilst the tube is subsequently swept out with a more rapid current for about an hour. The columns of copper and copper oxide are first heated to redness, and about a litre and a half of air are passed through the tube during the whole operation, which takes about one hour and fifty minutes, The semicircular boat in which the substance is introduced is 117 mm.in length by 12 mm. in width, and 6.5 mm. in depth. The material is covered with the dry combustion mixture, of which nearly sufficient to fill the boat is introduced. I n determining the nitrogen, the part of the tube placed in the furnace is progressively heated to redness, while a current of carbon dioxide, supplied under a pressure of about a metre of water, is meanwhile passed through it. The tube is then cooled to a little beyond the column of copper oxide, the boat charged with the substance and combustion mixture introduced, and auy air admitted immediately swept out by means of a rapid current of carbon dioxide. The rate of the current of gas is then reduced to about 30 bubbles per minute, and the tube progressively heated, beginning with the copper oxide. The nitrogen evolved is collected, and after about fifty minutes the combustion will be complete, and the tube, still main- tained at a red heat, is swept out for an hour with the current at the rate of about 65 bubbles per minute. The results of four parallel determinations of the carbon and nitrogen in potassium ferrocyanide are given, the mean results being C = 19.32 and N = 22-72 per cent., as against the theoretical C = 19.49 and N == 22-79 per cent. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9053000374

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年代:1905

数据来源: RSC

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THE ANALYST. 377 INORGANIC ANALYSIS. The Action of Aldehyde rend Acetone on Mercuric Acetate. A. Lasserre. (Journ. Pharm. Chim., 1905, xxii., 246-249.)-When acetaldehyde is added to an aqueous solution of mercuric acetate, a crystalline deposit of mercurous acetate is produced after some hours. The same result is produced by formic, propionic, and butyric aldehydes, by paraldehyde, acetal, and by sugars with an aldehydic function (arabinose, xylose, dextrose, galactose, mannose, lactose and maltose). On the other hand, no such deposit is obtained with methyl, ethyl, propyl, butyl, or amyl alcohols, with acetone or sugars with an acetonic function (levulose and sorbose), or with other carbohydrates (saccharose, trehalose, rafkose, glycogen, inuliu, dextrin, and soluble starch).The reaction with acetaldehyde takes place both in the hot and in the cold; and the quantity of mercurous acetate formed depends upon the temperature and length of time.375 THE ANALYST. If sodium hydroxide be cautiously added to an aqueous solution of mercuric acetate containing acetaldehyde, and the temperature maintained at about 0" C., a yellowish-red precipitate eventually changing to gray is formed. This substance, when washed and dried on a porous plate in the dark, is an amorphous powder of a faint yellow tint, deflagrating, when heated, to 180" C. in contact with the air. It contains (according to the mean of several determinations) 77.3 per cent. of mercury, approximating to the 76.9 per cent. required by the compound CH,.COH.HgO. and is thus quite distinct from the analogous compound described by Leys (AN~~LYST, this volume, p.341). If acetaldehyde be replaced by acetone, a precipitate of mercuric oxide is formed, but disappears on the addition of an excess of alkali. The liquid, when allowed to stand, yields a white precipitate, which when dried and distilled with dilute phosphoric acid yields acetone, and deflagrates when heated in the air. I t contains 81.5 per cent. of mercury, which corresponds with the formula CH,.CO.CH,, 2Hg0. Ethyl-methyl-ketone yields a yellowish-white powder, whose composition corresponds with the formula C,H,.CO.CH,, 3HgO. C. A. M. The Separation of Arsenic from Vanadium and Molybdenum. C. Fried- heim, 0. Decker, and E. Diem. (Zc,it. anal. Chcm., 1905, xliv., 665-686.)-The following is recommended as the most simple method of analysing a compound con- taining arsenic, vanadium, and molybdenum, such as, e.g.-- G ( N H j 0, AS 0 j, 7 V 0 j, 1 1 0"to 0 + 4 0 H20.One gram of the substance is treated with 1 to 11 grams of potassium iodide and 70 C.C. of hydrochloric acid (specific gravity 1.19) in a flask connected with a condenser. The flask is heated with a flame carefully regulated to prevent stoppage of the tube during the distillation of the iodine. Subsequently a larger flame can be used, until after about twenty minutes the whole of the arsenic has passed over. The distillate is first filtered through glass-wool in ordor to remove the separated iodine, and is then evaporated on the water-bath with the continual addition of chlorine water until it is of the consistency of a syrup, when the arsenic will have been completely oxidized to arsenic acid without loss, whilst iodine chloride is expelled. The residue is dissolved in water, the solution treated with ammonia in excess, and the arsenic precipitated with magnesia mixture.The residue in the distillation flask contains the molybdenum and vanadium in a reduced state. It is washed into a flask by means of hot water and treated with hydrogen sulphide, which precipitates the molybdenum as trisulphide. This is filtered off, converted into trioxide, and weighed. The filtrate is freed from hydro- chloric acid by evaporation, the residue taken up with sulphuric acid, re-oxidized with potassium permanganate, then reduced by means of sulphurous acid, and titrated with potassium permanganate.C. A. If. A New Reagent for Nickel. L. Tschugaeff. (Berichte, 1905, xxxviii., 2520-2541.)-Hitherto the most sensitive reaction for nickel has been the brown coloration obtained with alkali thiocarbonates, but this has the drawback of beingTHE ANALYST. 379 considerably influenced by cobalt. The author finds that a-dimethyl glyoxime, CH,.C(: N.OH).C(: K.OH).CH,, is a more characteristic and sensitive reagenk. The solution under examination is treated with ammonia or sodium acetate solution to remove excess of acid, and then boiled with it little of the powdered dioxime. I n the presence of a considerable amount of nickel a scarlet precipitate, NiD.I)H, (DH, =dioxime), is produced, but when only traces are present the solution is at first coloured yellow, and the red compound does not separate until the liquid cools. The test is capable of detecting 1 part of nickel in 400,000 parts of water, and is not affected by the presence of ten times the amount of cobalt.The salts of cobalt, however, form brown compounds with the reagent, and when they are present in quantity the following method of detecting small amounts of nickel should be employed : The solution is shaken with ammonia in large excess in order to convert the cobalt salts into ammonium Compounds, and is then boiled with an excess of the dioxime. The froth at the sides will be scarlet when considerable quantities of nickel are present, but with traces, such as 0.1 mgm. in 500 mgms. of cobalt, the liquid must be cooled and filtered, and the residue, when washed, will be found to have a pink shade.The dimethyl glyoxime can be obtained as a commercial preparation from Iiahlbaum. (Cf. this volume, p. 352.) C. A. M. The Iodometric Determination of Aluminium in Aluminium Chloride and Sulphate. S. E. Moody, ( A m c r . JOZL7*71. of Science, 1905, XX., 1Sl-lS4.)- Stock’s gravimetric method, based on the reaction- and ignition of the aluminium precipitate, is shown to give excellent results, and the author has therefore devised the following more rapid volumetric method, in which the liberated iodine is determined : Twenty-five C.C. of the approximately :F solution of the neutral aluminium salt to be analysed are mixed with 10 C.C. of a neutral solution o€ potassium iodate (30 grams per litre) and 1 gram of potassiuiii iodide in a Voit’s distillation-flask, and the liquid heated for fifteen to twenty-five minutes until nearly colourless, whilst a current of hydrogen is passed through it.The liberated iodine is collected in a Drexel’s flask containing water with 3 grams of potassium iodide in solution. Finally, the iodine that has passed over and that left in the Voit’s flask is titrated with standard sodium thiosulphate, and calculated into the corresponding amount of alumina in accordance with the equation. The results thus obtained are concordant and in close agreement with those obtained by the gravimetric method. Al,(SO,), + 5KI + KIO, + 3H20 = 2Al(OI3), + 3KZS0, + 61, C. A. M. Estimation of Manganese in Presence of Chromium.Max Griiger. (C’hen2. Zeit., 1905, xxix., 987.)-The author has tested a modification of Tolhard’s method for estimating manganese in presence of iron by removal of the iron through zinc hydroxide, and subsequent estimation of the manganous salt by means of potassium permanganate. I t was found that excess of zinc oxide was necessary to precipitate the chromium and that the chromium hydroxide carried down some manganese. The addition of zinc sulphate prevented this, and the author therefore employed basic zinc380 THE ANALYST. sulphate in place of hydroxide. A magma of basic zinc sulphate was prepared by dissolving 288 grams of crystallized zinc sulphate in 500 C.C. water, and mixing with a solution of 28 grams caustic soda in 500 C.C. The mixed solution must be well shaken each time before using.The author performed experiments on (a) mixtures of manganese sulphate and chrome alum, ( b ) manganese sulphate and potassium dichromate, ( c ) potassium manganite and potassium dichromate, and ( d ) manganese chromate. I n the last three cases the mixture was first reduced in presence of sulphuric acid by sulphurous acid, and the excess of the latter removed by evaporation. Quantities of about 6 grams of the two substances were used in each experiment. The residues, etc., in the original mixture were dissolved in water and made up to a litre. A certain fraction of this solution was then taken and the zinc sulphate magma added until the precipitate was no longer green but gray-violet in colour, the mixture being kept pn a boiling water-bath during precipitation.It was then cooled, made up to 250 c.c., well mixed, and filtered through a dry filter. Fifty C.C. of the filtrate were heated to boiling in a good-sized flask, with a solution of 20 grams of crystallized pure zinc sulphate in 150 c.c.’ of water, and a standard solution of potassium permanganate (1 C.C. corresponding to 0.001746 grams manganese) was run in, until a permanent rose colour was obtained. The author gives figures which show that the method is quite reliable as long as, in the portion of solution used, the amount of chromium is not much above 0.1 gram. If the amount is greater, the chromium hydroxide is apt to carry down manganese with it. E. K. H. The Use of Zinc Hydroxide as a Reagent, Bacovesco. (Bull. Plza1.1n. Chim.cle Roumanie, 1905,ll; Ann. de Chim. anal., 1905, x., 358,359.)-Zinc hydroxide mixed with about 5 parts of water gives characteristic reactions with aqueous solutions of different salts. Marcuh chloride yields a rose-coloured precipitate turning red after some time, the reaction only taking place in the cold. With mercuric nitrate there is a reddish precipitate, and with i7zercurozis ititi*ate a light yellow precipitate, which turns black on boiling. With copper chlorides the whole of the copper is precipitated, even in the cold. The soluble salts of lead, cadnaiurtz, silver, and manganese do not yield any precipitate either in the hot or the cold. Chromium salts give a green precipitate of chromium hydroxide, and this is also the case with chromate8 and bichromates in the presence of sulphur dioxide.With ferrous salts the precipitate is white, gradually becoming green ; on boiling it changes to yellowish-red. With ferric salts there is a blood-red precipitate gradually changing to yellow. Aluminizm salts give a precipitate. I n quantitative analysis, zinc hydroxide can be used to separate copper from cadmium and iron from manganese. C. A. M. On the Estimation of Sulphur in Pyrites. M. Dennstedt and F. Hassler. (Zeit. angezo. Chena., 1905, xviii. 1562.)-In an investigation of Lunge’s method of estimation, the authors find that low results are often caused by the formation of basic sulphates of iron during the evaporations with nitric acid ; these are insoluble in dilute hydrochloric acid. If, after the second evaporation, Lunge’s direction to addTHE ANALYST.381 '' 1 C.C. concentrated hydrochloric acid and 100 C.C. hot these basic sulphates are not completely dissolved. On the other hand, if the 1 C.C. hydrochloric acid is warmed gently for a short time before the 100 C.C. of sulphates present are easily dissolved. water " is strictly followed, added first, and the mixture water are added, any basic By this simple means a common and principal cause of a low sulphur result ie avoided. For their analyses during these investigations the authors used the simplified combustion method previously described by one of the present aiithors (ANALYST, this vol., p. 348). A. N. C. A New Method for the Estimation of Sulphur in Coal. 0. Brunek. (&it. angezo. Clzem., 1905, xviii., 1560.)-This method depends on the combustion of the coal mixed with cobaltic oxide in a current of oxygen.One gram of the finely-powdered coal is intimately mixed with 2 grams of a mixture of 2 parts cobaltic oxide to 1 part sodium carbonate. The mixture is placed in a small platinum boat and inserted in a cornbustion tube, open a t one end, and fitted at the other with a leading tube, through which the current of oxygen is supplied. When the current is started, the tube is gently heated with a small flame till the contents of the boat begin to glow. At this point the burner is removed, and the heating only renewed for a short time, when the combustion is almost complete. The whole process is finished in about a quarter of an hour. The contents of the boat are extracted with warm water and filtered, a few drops of sodium carbonate being added to the wash water to prevent any oxide from passing through the filter.The filtrate is warmed with a few C.C. of hydrogen peroxide acidified with hydro- chloric acid, and the sulphate precipitated in the usual way. The results are satisfactory, and agree well with those obtained by Eschka's method, or by combustion in a closed bomb. Care must be taken that the cobaltic oxide used is free from sulphur. I t can be prepared pure by gently igniting the dried nitrate. A. N. C. The Differentiation of Nitrates from other Oxidizing Agents by the Diphenylamine Reaction. C. G. Hinriehs. (Bull. SOC. Chim., 1905, xxxiii., 1002-1005).-1f concentrated hydrochloric acid be used in place of sulphuric acid in this test, no blue coloration is given by nitrates until the temperature is raised to 50" C., or to 100" C.in the case of very dilute solutions. Nitrites, on the other hand, are decomposed by concentrated hydrochloric acid at the ordinary tempera- ture, and so give the blue coloration witholit heat being applied. I n order to demonstrate the absence of other oxidizing agents, the solution under examination is mixed with an equal volume of concentrated hydrochloric acid, and then with one drop of a solution of diphenylamine in glacial acetic acid. A blue colora- tion is produced in the cold by nitrites, peroxides of hydrogen, sodium, barium, manganes,e, and lead ; chromates, bichromates, molybdates, vanadates, and per-382 THE ANALYST. manganates ; chlorates, perchlorates, iodates, ferricyanides, etc.I n the case of iodates, the colour has a greenish shade changing to brown. The reaction is very sensitive and rapid, except in the case of barium peroxide, which requires nearly a minute for the development of the blue colour. Should no blue coloration have been obtained in this way, the test is repeated with concentrated sulphuric acid, and an immediate blue coloration then indicates the presence of nitrates. The reactions of nitrates with brucine and ferrous sulphate are also only pro- duced after heating when concentrated hydrochloric acid is substituted for sulphuric acid. Nitrites do not give any reaction with brucine, but if a little of a vanadate solution be added to the brucine, and several drops of concentrated hydrochloric acid introduced, they give a bright red coloration.Ferricyanides, etc., behave in an analogous manner. C. A. M. The Preservation of Solutions of Sodium Hydrosulphite. A. L. Lumiere and Seyewetz. (Bzd. SOC. Clzim., 1905, xxxiii., 931-944.)-Solid sodium hydro- sulphite alters very rapidly in moist air, but the anhydrous powder can be kept unchanged in a stoppered flask. In solution it undergoes alteration even in the absence of air, slowly in a 3 per cent. solution, and rapidly in concentrated solutions. The tribasic phosphate of sodium is the most effective agent for retarding the decomposition, and then come sodium silicate, potassium and sodium carbonates, ammonia, and methylamine. Other preservative substances, which, however, cause the hydrosulphite to lose its power of decolorizing indigo in the cold, are trioxy- methylene in the presence of sodium sulphite, formaldehyde, acetaldehyde, hexa- methylene, tetramine and benzaldehyde. In the presence of these substances the reduction of indigo by the reagent is only effected at a temperature of about 100" C.C. A. M. procedure for Solution and Reprecipitation of Precipitates. F. A. (Zeits. m o l y . Chcm., 1905, xlvi., 208.)-Solution of difficultly soluble preci- Goo&. pitates, which have to be collected and washed on a filter, is facili- tated by the use of the two simple devices shown. The first, which is used with ordinary funnels, con- sists of a circular piece of platinum gauze (Fig. l), cut and bent so as to form a cone having an angle FFz of nearly 60". This is placed inside the filter-paper in the funnel, the spring of the gauze making it fit the paper very closely. Practically the whole of the precipitate may easily be washed into the platinum cone. To dissolve the precipitate, the cone is lifted by nieans of ivory-tipped forceps into the vessel in which solution is to be made, any traces of precipitate adhering to the filter-paper beiug easily washed into the same vessel by means of a jet of water. The second figure shows a perforated platinum plate, which is used in a similar way in connection with Gooch crucibles, the disc being placed above the asbestos in the crucible. - -- - -- -___=i __ _- - - q -- - ------ ___- ----- _- - - _=_=_=_ __ rE?% -T-.z=x.== - *-5----- - FIG. 1. FIG. 2 . A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9053000377

出版商:RSC    

年代:1905

数据来源: RSC

摘要:

THE ANALYST. 383 APPARATUS. A Practical Form of Crucible Triangle. Hermann Lienau. (Clzem. Zeit., 1905, xxix., 991).-In the ordinary form of pipe-c1a.y triangle, the clay tubes are only very slightly larger in internal diameter than the wire. Through the expansion of the latter on heating, the pipe-clay is frequently broken up, and the triangle spoilt. The author recommends triangles of the kind shown in the figure. The chief advantages it possesses are that it can be easily made ; the diameter of the mire can be chosen by the analyst ; the wire is in a single piece with the joint inside one of the clay tubes; it also has a greater stability on a tripod, or ring-stand, than the ordinary form, as it possesses six points of contact instead of three; and it oan be more easily transported with a crucible iiz sit7c.E. I<. H. The Obliteration of the Colours in Graduated Glass Instruments. A. Kiihn. (Clzenz. Z&., 1905, xxix., 990.)-A colour for all kinds of scales which resists the action of boiling water, boiling oil, sulphuric acid at 500" C., and does not require burning in, has been found after long research by the firm of Dr. Kiebert and Kiihn, Cassel. E. K. H. A Tap for Glass Apparatus whilst using Alkaline Liquids. Lassar- Cohn, (Clwm. Zed., 1905, xxix., 901.)-Ordinary glass taps cannot be used satisfactorily where they come into contact with alkaline liquids, and metal taps cannot be fused on the glass parte. The author tried a modification of a glass tap by employing a hard rubber tap-plug, but that '' stuck," owing to the formation of water- glass.A rubber shell was then placed in the glassibody in which the hard rubber tap-plug could turn, but it was found impossible to make such a tap tight. The author finally had recourse to phosphor bronze, which is very resistant to alkaline liquids, and replaced the hard rubber parts by this material (see figure). This tap can be obtained from Dr. R. Muencke, Berlin, N.W. E. K. H.384 THE ANALYST. Testing Apparatus for Butter and Margarine. C. Kippenberger. (Zed. nizgezo. Chem., 1905, xviii., 1024).-In determining sesame oil in margarine, it is often dificult to separate all the coloured solution obtained by shaking the fat with hydrochloric acid owing to the solidification of the fat. This apparatus is provided with a stop-cock, through which the whole of the coloured liquid can be drawn off, and is also conveniently graduated for the measurement of the fat and necessary reagents. I t is made in three forms, all of which can be placed in the water-bath if necessary. Of the three, the author has found form c the most convenient. A. N. C. 1: c A A Burette for the Amy1 Alcohol in Gerber’s Fat Separator. C. Kippenberger. (Zeit. aizgezo. Chem., 1905, xviii., 1025.)-This is a capillary burette, conveniently graduated, and connected by a double cock with a supply tube. Only filtered ainyl alcohol must be used with it, The apparatus is made by the firm of C. Gerhardt, of Bonn. A. N. C.

ISSN:0003-2654    

DOI:10.1039/AN9053000383

出版商:RSC    

年代:1905

数据来源: RSC

摘要:

384 THE ANALYST. REVIEW. CHEMISTRY FOR EKGINEERS AND MANUFACTURERS. By BERTRAM BLOUKT, F.I.C., and A. G. BLOXAM, F.I.C. Vol. 11. London : Charles Griffin and Company, Limited. 1905. This text-book has been thoroughly revised and brought up to date, a good deal of entirely new matter having been included in the second edition recently published. Among the more important additions will be found descriptions of the Contact Process for the Manufacture of Sulphuric Acid, Electrolytic Processes for Alkali Manufacture, and Improvements in Incandescent Gas Lighting. As a practical text-book, giving accurate and concise explanations of the principles which underlie the manufacturing operations which are described, it is of the highest value. The descriptions of the various manufactures dealt with are unburdened by detail, and are remarkably clear. The book contains a fund of well-compiled and reliable information.

ISSN:0003-2654    

DOI:10.1039/AN9053000384

出版商:RSC    

年代:1905

数据来源: RSC