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FEBRUARY, 1908. Vol. XXXIII., No. 383. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. ANALYTICAL CAEMISTRY INVESTIGATION SCHEME. THE Secretaries having frequently been asked for information in reference to the scheme for promoting research in Analytical Chemistry, which was adopted by the Council of the Society of Public Analysts, it has been thought desirable to'publish the following statement, showing briefly the circumstances which led to its adoption, and the results which have been obtained. Members of the Editorial Committee of THE ANALYST, when revising proofs of abstracts of papers appearing in British and foreign journals, frequently meet with descriptions of new analytical processes which would appear to be of exceptional utility and value.Since these emanate very often from private laboratories, and are %he work of men whose names are practically unknown outside a limited circle, the results stand in need of confirmation before they can be generally accepted, though the processes appear to be of such value as to merit careful examination. I t was therefore felt that it would be well if members of the Society of Public Analysts could be induced to undertake the '' revision " of such pieces of work ; and it was suggested that their results, after having been submitted to the Editorial Committee, should, subject to the approval of that body, be published in THE ANALYST. I t was, however, recognised that there would be great difficulty in successfully carrying out this scheme owing to the fact that comparatively few of the members were able to afford the necessary time.Several important investigations have, as a matter of fact, been made in this way ; but it soon became obvious that, unless the scheme could be considerably extended, it must, sooner or later, die of exhaustion. Anrtlysts with large practices, and more particularly those who specialise, are frequently brought face to face with analytical problems the accurate study and careful solution of which would be of the very greatest value, and it was felt that the idea above referred to might well be extended to cover original investigations of this character. The following, therefore, is the kind of work with which the scheme proposed to deal : 1. The investigation of analytical procesges, and of problems in analytical 2.The revision of certain published processes, and, assuming it to be chemietry. desirable, their extended study.42 THE ANALYST. I n order to overcome the difficulty referred to above, it was suggested that such investigations might be undertaken by some of the senior students working in the laboratories of the larger colleges and teaching institutions. In such laboratories there are frequently students who are being trained for the profession of analytical chemistry, and who have arrived at a point in their studies when original problems are put into their hands by their professors. I t was thought that if important subjects for investigation in the domain of analytical chemistry were suggested to the professor by some competent specialist or body of specialists, he might be willing to place them in the hands of such senior students as are referred to above, and to maintain a careful supervision over the execution of the work.I t may be pointed out that this scheme would not interfere in any way with the research work which is at present being done in other branches of the science. Students in course of training for a professorial career, or those specialising in certain departments of chemistry, would continue to concern themselves with such researches as are a t present suggested to them by their professors, the analytical investigations being assigned to some of those students who are working with the intention of becoming analytical or technical chemists. I t seemed probable that these, realising the importance and practical value of their results, would take special interest in such investigations, whilst there could be no doubt that their work, if carefully done, would be of the greatest value to the science of analytical chemistry.I t had to be remembered, moreover, that in the case of candidates for the examinations of the Institute of Chemistry, such investigations would be taken into account by the examiners in deciding the examinations. The following are the only conditions in connection with this scheme : 1. The matters for investigation to be in all cases subject to the approval of the Editorial Committee of the Society. 2. An account of the work when completed to be published, subject to the approval of the Editorial Committee, in THE ANALYST, and, when possible, to be brought before the Society in the form of a communica- tion.A fund has been established, and investigators undertaking work under this scheme are entitled to make a claim on this for any special apparatus or chemicals they may require. I n addition, members of the Society having special knowledge of any of the subjects being dealt with are always very willing to assist investigators either with their, advice, or by supplying them with specially pure materials or specimens, should they happen to possess such. All papers are published under the names of the investigators, and due recognition is given to the college or institution in which the work has been done. I t may be added that particulars of this scheme were brought directlyunder the notice of the heads of the chemical departments in all the large teaching institutions in London, and in every case the project received unqualified approval, and many offers of assistance were forthcoming. Several most useful investigations have already been undertaken by members of the Society, and the results published in THE ANALYST; and at the moment other investigations are in progress at King’s College and the Royal College of Science, whilst papers have recently been publishedTHE ANALYST, 43 describing the results of researches undertaken at University College and the Borough Polytechnic Institute. The Council are earnestly desirous of enlisting the sympathy and active co- operation of all members of the Society, and any members who have time to under- take investigations are requested to communicate with the Honorary secretaries.

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DOI:10.1039/AN9083300041

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年代:1908

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THE ANALYST. 43 TITRATION WITH PERMANGANATE IN PRESENCE OF HYDROCHLORIC ACID. BY THOMAS WEATHERILL HARRISON, B.Sc., AND FREDERICK MOLLWO PERKIN, PH.D. (Read at the Meetiug, December 4, 1907.) IT is generally understood that potassium permanganate cannot be employed as an oxidising agent in presence of hydrochloric acid owing to reduction of the per- manganate, according to the equation : 2KMn0, + 16HC1= 5C1, + 2MnC1, + 2KCl+ 8H,0. With pure dilute hydrochloric acid this reaction is slow, but the presence of an iron salt acts as an accelerator. Manchot (Annalen, 1902, 325, 114) believed this accelerating influence was due to the formation of an unstable higher oxide of iron (Fe,Oj), which is only formed in presence of hydrochloric acid, and as it requires more oxygen for its formation than Fe203, more permanganate is required for titration in presence of hydrochloric acid.Further, this higher oxide oxidises a portion of the hydrochloric acid, and chlorine is liberated. But with hydrochloric acid, to which no iron has been added, chlorine is not liberated on addition of permanganate. Kessler (Zeit. f. anal. Chem., 1863, 1, 329), and later Zirnmerman (Ber. deut. Chem. Ges., 1881, 14, 779), state that satisfactory results may be obtained when manganous sulphate is added to the solution to be titrated. I t is, however, some- what difficult to appreciate the retarding effect of the manganous salt. According to Volhard, the permanganic acid acts upon the manganous sulphate, with formation of manganese peroxide, which then reacts with the ferrous salt.I t also prevents the formation of the higher oxide of iron by receiving the oxygen, and carrying it to the unoxidised ferrous sulphate. Wagner (Zeit. f. physik. Chem., 1898, 28, 33) considers that when the manganous salt is not present the hydrochloric acid forms a ferrous hydrochloric acid (FeC122HC1), and that this is then rapidly oxidised, not only the iron being subjected to oxidation, but also the hydrochloric acid. This last explana- tion seems imaginative, for it is cliflicult to conceive such a compound being formed in dilute solution, since hydrochloric acid is highly ionised and ferrous chloride considerably so. We prefer the explanation of Manchot (Zoc. cit.), which is in agreement with the explanation given for the catalytic action of iron and nickel salts in the decomposition of hypochlorite solutions.I n Sutton’s ‘‘ Volumetric Analysis ”44 THE ANALYST. it is suggested that salts, such as potassium sulphate, magnesium sulphate, or mercuric sulphete, may be used in place of manganous sulphate. On account of the difficulty of judging the end-point when titrating with dichromate solution in artificial light, we thought it desirable to study further the reaction between permanganate and iron salts in presence of hydrochlorio acid. XXPERIMENTAL. 1. In the first place we studied the effect of dilution with permanganate solutions and sulphuric acid without hydrochloric acid, and then with hydrochloric acid and sulphuric acid. The iron salt used was ferrous ammonium sulphate; in each titration 25 C.C.of the iron solution was taken. At the beginning of a series of experiments the value of the solution was determined in terms of permanganate, and in the case of long periods of working at the end of each period, in order to ascertain whether the strength remained constant. This was always found to be the case. TABLE I.-EFFECT OF DILUTION. Volume of 4N.QS0, Solution. Volume of 4N. HCI. Solution. Volume of Solution, Acid and Water, and Iron Salt. - I - 10 10 10 Lmount of Permanganat required. 26.50 C.C. 26.50 ,, 26-50 ,, 26-80 ,, 26.95 ,, 27.10 ,, These results show that dilution up to half a litre, when sulphuric acid alone is employed, does not in any way affect the sensitiveness of the reaction. On the other hand, when hydrochloric acid is present, more permanganate is required to get the end reaction, and the increased dilution then appears to be disadvantageous. Experiments were then tried, using varying quantities of potassium sulphate, magnesium sulphate, borax, sodium acetate, or mercuric sulphate, to ascertain whether the addition of these salts would make it possible to titrate with perman- ganate in presence of hydrochloric acid.The only salt which had 8 retarding effect was mercuric sulphate, and this only to a small extent when the hydrochloric acid is extremely dilute. Manganous chloride was also tried, but the end-point was ren- dered uncertain owing to the solution becoming brown in colour. Table 11. shows that the retarding effect of manganous sulphate is very distinct; the chief disadvantage is the difficulty of distinguishing the end reaction owing to the yellow colour of the solution.In each case the volume of the solution titrated was 500 C.C. It will be noticed that the amount of manganous sulphate employed does not materially affect the titration, 1 gram giving practically the mme result as 5 grams. According to Treadwell (“Analytical Chemistry,” first edition, vol. ii., p. 483),THE ANALYST. 45 23.50 C.C. 23-50 ,, 23.50 ,, 23.50 ,, the amount of manganous sulphate present should not exceed the amount of iron salt in the solution to be titrated. On the other hand, A. Miiller (Stahl zc. Eisen, 1906, 26, 1477) employs much larger quantities. 23.50 C.C. 24-40 ), 24.30 ,, 24.25 ,, TABLE 11. - 20 C.C. 20 $ 9 20 9 , Volame of 4N.H2SO, Solution, - 500 C.C.500 - 500 9 1 7 C.C. 500 9 , 7 9 ) Volume of 4N. HC1 Solution. I’erman mntt te SolutLn. 23.50 C.C. 23.75 ,, 23.60 ,, 23-70 ,, 23.65 ,, Difference. - + 0.25 + 0.10 + 0-20 + 0.15 Weight of MnSO,. 4H,O taken. 5 grams 5 9 , 1 gram 5 grams 5 9 1 I t is known that the addition of phosphoric acid to iron titrations prevents the yellow colour being produced as the salt is oxidised to the ferric condition,’probably owing to the formation of feebly ionised ferric phosphate. I n the following titration we used Treadwell’s met hod of preparing a manganese sulphate-phosphoric acid solution : 67 grams MnS0,.4H20 was dissolved in 500 C.C. water, 138 C.C. phosphoric acid of specific gravity 1.7, and 130 C.C. concentrated sulphuric acid added. The mixture was then cooled and diluted to 1 litre.TABLE III.-PHOSPHATE SOLUTION FRESHLY PREPARED. Volume of 4N. €I,SO, Solution. Volume of 4N. HC1 Solution. Volume. Phosphate Solution. Blank. 26-50 C.C. 26 50 ,, 26.50 ,, 26.50 ,, 26.50 ,, 26.50 ,, 26.50 ,, 26-50 ,, 26.50 ,, 26.50 ,, Volume of KMnO, Solution 26.50 C.C. 27.00 ,, 26.70 ,, 26-70 ,, 26.65 ,) 26-70 ,, 26.60 ), 26.70 ,, 26.80 ,, 26.90 ,, Difference. - 0-50 0.20 0.20 0.15 0-20 0.10 0.20 0.30 0.40 - 0-90 0.80 0.75 From the above results it is evident that the phosphate solution behaves Consequently, experiments differently when it has been made up for some days.46 THE ANALYST. were carried out to determine whether this was due to some accidental circumstance or to an inherent property of the mixture. TABLE IV.-FRESHLY PREPARED PHOSPHATE SOLUTION.Volume of 4N. H,SO, Solution. Volume of 4N. HC1 Solution. Final Volume. Phosphate Solution. Blank. 23.50 C.C. 23.50 C.C. 23.50 ,, 23.50 ,, 23.50 ,, 23.50 ,, 23-50 ,, 23-50 ,, 23.50 ,, - Volume of KMnO, Solution. 23-30 C.C. 0.10 ,) 23.90 ,, 23-45 ,, 23.60 ,, 23.70 ,, 23-80 ,, 23.80 ,, 23.95 ,, 23.85 ,, Difference. 0.2 0.40 - 0.05 0.10 0.20 0.30 0.30 0.45 0.35 - 2orrection. 0.15 0-30 0.40 0.50 0.50 0.65 0.55 The ‘(correction ” in the last column is made by adding 0.2 to the difference, as the first titration shows that the phosphate solution itself exerts an oxidising action upon the iron solution, and therefore a fimaller quantity of permanganate is required than would be the case were the phosphate solution not present. The second titra- tion shows that this oxidising agent has a reducing action upon the permanganate in a similar manner to that of hydrogen peroxide; but the reducing action is not equal to the oxidising action upon the iron solution. Now, as the phosphate solution is added before the permanganate, the oxidising action will exert itself entirely upon the ferrous iron, and then, when the permanganate is added, it will have no reducing action upon the latter.The next table shows the action of the same phosphate solution after it had been kept for three days. I t will be noticed that the differences obtained agree very closely with the corrected numbers in the preceding table. TABLE V.-SOLUTION AFTER STANDING THREE DAYS. Volume of 4N. H,SO, Solution. 50 C.C. 50 >, 40 8 , 30 9 , 20 3 , 10 , 9 Volume of 4N.HU1 Solution.Filial Volume. Phosphate Solution. 7 C.C. 25 ? ¶ 7 9 , 7 9 9 7 9 , 7 ?, Volume of KMnO, Solution. 23.15 C.C. 23.15 ,, 23-30 ,, 23.40 ,, 23.55 ,, 23-05 ,, Difference. 0.15 0-25 0.35 0.70THE ANALYST. 50 C.C. 50 7 1 50 ,, 50 > ? 47 - 23.10 C.C. - - 23.45 ,, 0.35 - 500 C.C. - 23.50 ,, 0.40 5 C.C. 500 9 , 5 1 1 500 ,, 5 ? l 500 9 , 7 C.C. 23.30 ), 0.20 Finally, experiments were tried with extremely small quantities of hydrochloric acid, but even in this case the action is decided. TABLE VI. Volume of Volume of Volume of 4N.H,SO, 1 4N.HC1 1 Final Volunw. 1 1 ~ ~ ~ $ ~ ~ 1 KMnO, 1 Diffe~nce. Solution. Solution. Solution. From the results obtained by us it is only possible to draw one conclusion- that for exact titrations potassium permanganate cannot be employed in presence of hydrochloric acid. When very small quantities of hydrochloric acid are present, the addition of manganous sulphate and phosphoric acid is distinctly advantageous.The negative result of this investigation is unfortunate, as potassium permanganate is SO much easier to work with than dichromate solutions. Also iron ores in general dissolve more readily in hydrochloric acid than in sulphuric acid, especially fn presence of a small quantity of stannous chloride, the best reducing agent which can be used. DISCUSSION. Mr. HEHNER said that hydrochloric acid solutions of ferrous salts could be accurately titrated by perrnanganate if Fresenius's directions were followed. Fresenius operated in very dilute solutions, and added, after the titration, to the same liquor a second measured volume of the ferrous solution, titrated again with permanganate, and repeated this twice more, always in the same solution, taking only the figures obtained in the third and fourth titration, which are constant, while those of the first and second titration are too high. The chlorine which is liberated by tho action of the hydrochloric acid upon the permanganate, and which in the first and second titrations causes an excessive consumption of permanganate, reaches equilibrium, and then no longer interferes. (See Loewenthal and Lenssen, Zeit. f. anal. Clzcm., 1861, 1, 329 and 361.)

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DOI:10.1039/AN9083300043

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年代:1908

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THE ANALYST. 47 ERRATUM. " ANALYST," VOL. XXXII., 1907. Owing to an error, the June nuniber leaves off' on p. 244, and the July number starts on p. 241 ; consequently there is a double set of pages-Kos. 241 to 2-14.

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DOI:10.1039/AN9083300047

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年代:1908

数据来源: RSC

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48 THE ANALYST+ ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Detection and Estimation of Benzoic Acid in Ketchups, Fruits, and Ciders. H. S. Reed. (Journ. Amer. Clzenb. SOC., 1907, 29, 1626-1629.)-For the detection of benzoic acid a modification of Mohler's test is used. One hundred grams of the substance under examination are acidified with dilute sulphuric acid, and then thoroughly ex- tracted with chloro- form. The chloroform solution is placed in the reservoir A of the apparatus shown. This part of the apparatus is detached, and con- nected directly with a suction-pump, and the chloroform is allowed to evaporate spontane- ously under a current of air. When the evaporation is complete, the reservoir is placed in a desiccator until perfectly dry.It is then attached to the vessel B and submerged to the neck of the funnel C in a sand-bath, about 12 C.C. of N sodium hydroxide being placed in B. The suction-pump is connected to the latter vessel, and the sand-bath is heated to a temperature of 145' C., and then raised to 260° C. The benzoic acid is thus sublimed and retained in B as sodium benzoate. This solution is next trans- forred to a separating funnel, acidified with sulphuric acid, and extracted with chloroform. The chloroform solution of the benzoic acid is rendered alkaline by the addition of alcoholic potassium hydroxide solution, and the mixture is evaporated. The residue of potassium benzoate is heated with concentrated sulphuric acid until white fumes are given off, and the sulphobenzoic acid formed is converted by the use of potassium nitrate to m-dinitrobenzoic acid. The acid solution of the latter is cooled, diluted with water, again cooled, made alkaline with ammonia, and treated with hydrogen sulphide gas.A cherry-red coloration is produced by the reduced product, the ammonium salt of m-diaminobenzoic acid. The method proposed for the estimation of benzoic acid is based on two conditions : the first, that chloroform extracts benzoic acid from many other vege- table acids (malic, tartaric, oxalic, etc.) in aqueous solution; and the second, thatTHE ANALYST. 49 calcium benzoate is far more soluble in cold water than the calcium salts of the above- mentioned acids, The chloroform solution obtained from the sodium benzoate solution contained in the part B of the apparatus is allowed to evaporate spontaneously in a beaker.To the residue are added 25 C.C. of milk of lime containing 0.0145 gram of metallic calcium per C.C. This milk of lime is prepared by acting on water with rrietallic calcium. Another 25 C.C. of the milk of lime are placed in a second beaker, and subjected to the same treatment as the former. The contents of the beakers are evaporated to dryness, and the residues are taken up with 25 C.C. of water, filtered, and washed with 15 C.C. of water. The filtrates are collected in platinum basins, evaporated to dryness, and the residues ignited over a blast burner. The amount of calcium oxide in each basin is then obtained by titration in the usual way. The quantity present in the blank is subtracted from that found in the test, and the difference is calculated into benzoic acid.w. P. s. A New Constant for Butter Analysis and the Detection of Cocoanut Oil in Butter-Fat. T. R. Hodgson. (Chcm. News, 1907, 96, 273-274, 288, 297.)- The constant described in this paper depends on the oxidation with potassiuni permanganate of the acids obtained from butter-fat. The author finds that the quantity of oxygen required to osidise a given quantity of the saponified fat is invariable. The method used is as follows : One gram of the filtered fat is placed in a flask and saponified with 25 C.C. of alcoholic potassium hydroxide solution, the mixture being boiled for thirty minutes under a reflex condenser to ensure complete saponification. The solution is then evaporated to dryness on the rater-bath.Fifty C.C. of water are added to the residue, and the whole again evaporated to dryness. The residue is then dissolved in water and diluted to 1 litre. Twenty C.C. of the solution are transferred to a beaker, 50 C.C. of 2; potassium perinanganate solution and 50 C.C. of 50 per cent. sulphtlric acid are added; the beaker is heated in a water-bath for thirty minutes, and the excess of permanganate is then titrated back with ferrous ammonium sulphste solution. Butter-fat uses 41.8 C.C. of & permanganate solution. From this figure the number of grams of oxygen required for the oxidation of 1 gram of butter-fat can be calculated, and the result multiplied by 100 gives the " oxygen equivalent" of the fat. Twenty samples of cocoanut oil examined required from 18.0 to 26.8 C.C.of :;i permanganate, correspond- ing with '' oxygen equivalents " of from 72.0 to 107.2, the average value being 88-66. Results of analyses of test samples consisting of butter and cocoanut oil are given, from which it is seen that the method enablee the quantity of the latter oil present This operation is repeated until all the alcohol has been removed. This number for butter-fat is 167.2. t o be estimated with a considerable degree of accuracy. w. P. s. Some Algerian Olive Oils. L. 'Arehbutt. (Journ. SOC. Clzenz. I d . , 1907, 26, 1185-1186.)-The following results were obtained on the analysis of twelve authenti- cated*saniples of Algerian olive oil : Specific gravity, at 15.5" c., 0.9165 to 0.9178 ; free acid (as oleic), 0.4 to 4.5 per cent, ; saponification value, 18.90 to 19.13 ; iodine value (Wijs), 82.4 to 90.4; unsaponifiable matter, 0.72 to 0-98 per cent.No arachidic acid was found in the samples. When shaken with nitric acid (specific50 THE ANALYST, gravity 1.375), the oils gave no coloration immediately ; but, after standing for one hour, one oil turned greenish-brown, another developed a dark greenish, and the remainder pale brownish tints. The iodine values of some oils from named varieties of olives are also given. Whilst exceptionally high values are given by a few varieties grown in certain districts, the oils from other varieties yielded normal results. For example, the variety Chemlali-Sfax (Tunis) gave a value of 80.2 ; Chetui Bizerte (Tunis), 91.1 ; Chetui Mornag, 94.7 ; Rousette (Algeria), 90.1, etc.(Compare ANALYST, 1907, 32; 257.) Tvv. P. s. Niam Fat. J. Lewkowitsch. (Joz~rn. SOC. Chcm. Ind., 1907, 26, 1265-1266.) -The author has investigated the fruits of Lophira alatn from Sierra Leone. They yielded 61.5 per cent. of kernels and 38.5 per cent. of husks. The kernels, when extracted with ether, gave 0.8 per cent. of a black resinous body, which separated from the fat after evaporating off the ether. The fat freed from resin amounted to 41.19 per cent. of the kernels, or 19.18 per cent. o€ the whole seeds. I t is a soft buttery mass melting at 24' C., known in West Africa as Niam fat " or (' Meni oil." I t has an unpleasant taste, due probably to traces of dissolved resin, and is used by the natives for culinary purposes and as a hair-oil, Below are some of the characters of two samples : Specific gravity at 40" C.(water at 40' C. = 1). .. Saponification value ... ... ... ... Unsaponifiable matter ... ... ... ... Mean molecular weight of fatty acids ... ... Solidifying point of the fatty acids (titer test). .. Acid value ... ... ... ... ... ... Iodine value ... ... ... ... ... Fat extracted from Kernels. 0.9105 18.54 195.6 1.49 per cent. 68.4 - Fat prepared by Natives. 0.9063 5.78 190.1 1.38 per cent. 78.12 283.7 42.5" C. J. F. €3. Application to Solid Fats of Renard's Test for Peanut (Earthnut) Oil. W. B. Smith. (Jozwn. dnzer. C h m . SOC., 1907, 29, 1756-1757.)-Tolman's modifica- tion of this test consists in saponifying at least 20 grams of the sample with alcoholic potash, and treating the resulting soap with lead acetate, when the extraction of the lead soap with ether dissolves the lead oleate, linoleate, etc., and leaves the lead stearate, palmitate, and arachidate behind.On acidifying the insoluble portion with hydrochloric acid, the fatty acids are freed, and are separated and dried, dissolved in hot alcohol (90 per cent;.), and the solution cooled to 15" C. The arachidic acid crystallises out, is weighed, and its melting-point determined ( = 75" C. for the pure acid). The weight of arachidic acid, multiplied by 20, gives the approaimate amount of peanut oil present. I n using this method for the examination of solid fats (such as lard) containing large percentages of fatty acids, a precipitate is invariably obtained from alcohol,THE ANALYST.51 though it is frequently gelatinous and quite unlike the crystalline arachidic acid. Pure lard gave, by the above test, crystals melting at 54.3' C., while when mixed with 10 per cent. of peanut oil, the crystals obtained melted at 55" C., and the test thus failed to detect this proportion of peanut oil. When, however, the crystals first obtained were dissolved in alcohol and recrystallised, the melting-points of these products were 55' C. and 77" C. respectively, the latter evidently consisting chiefly of arachidic acid. I n the case of solid fats, therefore, the first crystals from alcohol should always be recrystallised until a constant me1 ting-point is obtained. A. R. T. Composition of Camembert Cheese. P. Buttenberg and F.Guth. (Zeit. Untemzich. Nahy. GenzLssm. , 1907, 14, 677-682.)-Analyses of twenty-two brands of Camembert cheese are recorded, froiii the results of which it is seen that this cheese is usually manufactured from full milk. I n fifteen of the samples the ratio of the fat to the fat-free dry solids varied from 1 : 0.86 to 1 : 1.76 ; in five samples (probably made from partially skimmed milk) the ratio was from 1 : 2 to I : 3 ; two other samples, obviously made from skimmed milk, contained 8.48 and 9.13 per cent. of fat respectively, the ratio varying from 1 : 1-32 to 1 : 1.41. I n only five of the samples was the amount of water below 50 per cent.; one of the above-mentioned skim-milk cheeses contained 61.6 per cent,. of water. w. P. s. The Composition of Extract of Crab.D. Ackermann and F. Kutscher. (Zed. I/'nterszcch. Nahr. Cfewss. , 1907, 14, 687-691.)-1n addition to the substances mentioned previously (ANALYST, 1907, 32, 256) as occurring in extract of crab, the authors have separated and identified the following bases : Crangitine (C,3H,oN,0,), crangonine ( C13H,,N,0,), neosine, and methylpyridine-ammonium hydroxide. The presence of the latter is worthy of note ; hitherto this base has been deemed peculiar to the vegetable kingdom. It has certainly been found in human urine (probably derived from vegetable foods containing pyridine bases), but never in meat extracts. w. P. s. The Application of Folin's Creatin and Creatinin Method to Meats and Meat Extracts. A. D. Emmett and H. S. Grindley. (JOWZ. Biol.Chem., 1907, 3, 491-516.)-1n reply to criticisms of Hehner (Phnrm. Jown., 1907, 78, 683) on Folin's method, the authors describe experiments in detail, from which they conclude that the method, when suitably modified, gives as accurate results with meat and meat extracts as with urine. They find that an increase in the amount of picric acid does not affect the estimation of the original creatinin, but that as a rule it does produce a difference when the converted creatin is also present. The quantity of picric acid solution (1.2 per cent.) should therefore be increased to 30 C.C. in estimating the dehydrated creatinin, but the 15 C.C. recommended previously (ANALYST, 1907, 32, 171) should be retained for the original creatinin estimation. Contrary to Hehner's experience, they find that variations, in the proportion of 10 per cent.alkali, make but; little difl'erence (though slightly lower results are obtained with 5 C.C. than with 10 or 15 c.c.) in the estimation of the original52 THE ANALYST, creatinin ; whilst in the case of the converted creatin 10 C.C. give better results than 5 c.c., but no better than those obtained with the large excess of 15 C.C. The method now used in the authors' laboratory has been modified as follows : The estimation of the ready-formed creatinin is made in the Bame way as described (Zoc. cit.). Aliquot portions of the solution are then made up to 10 C.C. (or evaporated if necessary), mixed with 10 C.C. of N-hydrochloric acid, and heated for thirty minutes in an autoclave at 117" to 119' C.They are next cooled and made up to 100 c.c., and aliquot portions transferred to 500 C.C. flasks, and treated with 30 C.C. of the picric acid solution and 10 C.C. of 10 per cent. sodium hydroxide solution, the colour produced being matched with $ bichromate solution, as before described. In experi- ments with solutions of pure creatin, the results of six colorimetric estimations ranged from 94.2 to 95.8 of the theoretical quantities. C. A. M. Characteristics of Segura Balsam. Utz. (Chem. Rev. Fett.-u. HCLYX. I?d, 1907, 14, 295-296.)-1t is stated that copaiba balsam is no longer being adulterated with gurjun balsam alone, but with segura balsam, or a, mixture of the latter with gurjun balsam. The sample of segura balsam examined was a dark-brown, sticky, viscous mass resembling Peru balsam. On warming it became very mobile, and emitted yellow vapours when strongly heated.I t was soluble in chloroform, benzene, petroleum spirit, and carbon tetrachloride, partially soluble in alcohol, and formed a dirty-green emulsion with ammonia solution. A dark red-brown coloration was produced on adding concentrated sulphuric acid to its solution in one of the above solvents, whilst with nitric acid (specific gravity 1.40) a yellowish-green coloration was obtained. Vanillin and hydrochloric acid gave a red-brown coloration, and stannous chloride a light-brown colour. I t had the following analytical values: Specific gravity at 15' C., 1,0337; acid value, 14.04; and saponification value, 92.66. The addition of segura balsam to gurjun balsam would raise the specific gravity and ester value, and lower the acid and saponification values.The values of Para copaiba balsam would be similarly affected, except that the saponification value (cold method) would be somewhat increased. The dis- tillation of segura balsam yielded about 5 per cent. of water, followed by 30 t o 40 per cent. of a light-brown ethereal oil of pleasant odour, and having the following constants : Specific gravity at 15" C., 0.9451 ; polarisation in 200-mm. tube, - 19.00 ; and refractive index, 1.4992. This oil behaved like the original balsam towards the above-mentioned reagents. This distilled oil is probably used in admixture with segura balsam, so as to prevent the latter affecting the values and the colour of copaiba balsam too much.I t had a pleasant aromatic odour. c. A. N. The Constituents of the Essential Oil of Nutmeg. F. B. Power and A. H. Salway. (Proc. Chem. Soc., 1907, 23, 285.)-The material employed in this investigation consisted of an oil which was distilled from unlimed Ceylon nutmegs of good quality, and was obtained in a yield of 6.94 per cent. I t had d 15"/15"=0*8690; a,, + 38'4' in a 1-decim. tube ; acid value, 0-81 ; ester value, 3.15. The more complete examination of the oxygenated constituents of the oil was accomplished by means of a product, designated heavy oil of nutmeg, from which the terpenes had been to aTHE ANALYST. 53 large extent removed. This had d 2O0/2Oo=1*102; a,+1°17’ in a I-decim. tube; saponification value, 6-10. Essential oil of nutmeg contains the following substances : (1) Eugenol and (2) isoeugenol (about 0.2 per cent.); (3) d-pinene and (4) d-camphene (about 80 per cent.) ; ( 5 ) dipentene (about 8 per cent.) ; (6) d-linalool, (7) d-borneol, (8) i-terpjneol, arid (9) geraniol (about 6 per cent.); (10) a new alcohol, yielding on oxidation a diketone, C,H,,O, (a very small amount); (11) a trace of an aldehyde resembling citral, but yielding a P-nap~~thacinchoninic acid derivative melting at 248” ; f12) safrole (about 0% per cent.); (13) rnyristicin, C,,H,,O, (about 4 per cent.); (14) myristic acid, in a free state (about 0.3 per cent,), and apparently a small amount in the form of esters; (15) formic, acetic, butyric, and octoic acids, and a new monocar- hoqjZic acid, C,3H,803, all in the form of esters, and in relatively small amount.This investigation has also shown that the portion of nutmeg oil which has hitherto been designated myristicol ” is it mixture of alcohols, of which terpineol appears to be the predominating constituent. Application of Lovibond’s Tintometer to the Analysis of Spirits, Etc. E. Westergaard. (Jozmt. Soc. Chem. Id., 1907, 26, 1226-1228.)-The author has employed Lovibond’s tintometer for the colorimetric estimation of the aldehydes and furfural in whisky, The usual standard solution of aldehyde was prepared and mixed at various dilutions with the magenta-sulphurous-acid reagent. The mixtures were placed in a, water-bath at 25” C. for fifteen minutes, and then examined in the $-inch cell in the tintometer. I t was found to be impossible to match the colours satisfac- torily, but good results were obtained by neutralising the colours with yellow and blue glasses until no colour was visible in the tintometer. I n the case of the magenta colours it was found that the quantity of yellow required was always double that of the blue. The results are calculated from the empirical equation y = 0-251 4x1*lG3, where y = the value of the yellow glasses, and x=cgm. of aldehyde per litre. In an exactly similar manner the colours produced by furfural and aniline acetate were estimated by neutralisation, but in this case the blue glasses required were in excess of the yellow. The equations were determined-for the blue y = 1.8138xU !‘2fi!‘4, and for the yellow y=1*5805zO*SS~, where x=mgm, of furfural per litre. The success obtained in thus recording numerically the colour reactions of aldehyde and furfural led the author to make preliminary investigations with two other colour-tests-viz., ammonia and Nessler’s solution and the nz-phenylenediamine reaction for nitrites. Both these colours could be successfully neutralised by blue and red glasses; the estimations were made in 1-inch cells, but a still deeper cell would be desirable. In performing all these colour-tests against numerical standards, the great influence of temperature and time on the intensity of the colours and the standard conditions adopted must be rigorously observed. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9083300048

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

54 THE ANALYST. ORGANIC ANALYSIS. Analytical Values of African Semi-Hard Copals. C. Coffignier. (Bull. SOC. Chiin., 1907, [ 4 3, 1, 1131-1143.)-The following table summarises the results obtained with samples of the so-called semi-hard African copals : Specific gravity ... Melting-point . . . Acid value . . . ... Saponification value . . . Insoluble in boiling- Ethyl alcohol ... Methyl alcohol ... Amyl alcohol ... Ether ... ... Chloroform . . . ... Benzene ... ... Acetone ... .. Turpentine oil ... Benzaldehyde . . . Aniline ... ... Amyl acetate Carbon tetrachloridk' ' Benguela. 1.058 at 16" C. 165" C. (soft at 65" C.) 123.1 157.1 Per Cent. 16.50 46-90 0.90 43-70 47.30 65.60 24.80 68-80 14-10 0.90 1.20 74-00 Angola, White. 1.055 at 17" C. 95" c. (soft at 45" C.) 127-0 159.9 Per Cent.15.10 46.70 1-40 27-30 43.70 50.50 5-40 69.40 4.30 3.50 2.70 61-30 Angola, Red. 1.066 at 17" C. Above 300" C. (soft at 90" C.) 128.3 131.8 Per Cent. 38.60 68-00 7.00 51.20 65.70 70.00 5.50 77-00 Soluble 2.30 4.20 77-70 Congo. 1.061 at 17" C. 195O C. (soft at 90" C.) 132.3 131.8 Per Cent. 25.30 35.30 2.20 48.30 59.60 60.10 45.80 68.20 48.70 Soluble 0.90 66.10 Sierra Leone. 1.072 at 19" c. 130" C. (soft at 60" C.) 110.2 123.4 Per Cent. 62.30 49 -20 4.80 47.80 52.40 56.90 40.30 71.40 1.50 0.70 Soluble 70.90 The three hard copals : Zanzibar, Madagascar, and Demerara copals are not com- pletely soluble in any of the above-mentioned solvents, The author finds that Angola copal is largely soluble in cajeput oil, but is unable to confirm Livache's statement that it is completely eoluble.Thus, white Angola copal left 9.90 per cent. of insoluble matter, and red Angola 15.60 per cent. (cf. ANALYST, 1906, 31, 120 and 370; 1907, 32, 54). C. A. M. The Affinity Constants of Bases as determined by the Aid of Methyl- orange (Preliminary Note). V. H. Veley. (Proc. Chem. SOC., 1907, 23, 284-285.) -The author has previously shown (Trans. Chem. SOC., 1907, 91, 155) that if x be the units of 0.1 C.C. hydrochloric acid added to an N/40,000 solution of methyl-orange, and y be the heights of a variable tintometer column, expressed in cm., required to produce the required match in tint, then y = kx - b. In this expression k is the essential factor (or constant) of y in terms of x, and b is accidental. Certain values of k were obtained for hydrochloric acid, as also for the hydro- chlorides of some aminocarboxylic acids.THE ANALYST.55 As it was thought that such values might serve to determine the amount of free hydrochloric acid, and hence the degree of hydrolysis of the hydrochlorides of bases, preliminary experiments were made without any special care with a sample of m-phen ylenediamine hydrochloride. It was then found with aqueous solutions of this salt containing an equi-acidic quantity of this acid, whether free or combined, that the ratio k [+C,H4(NH,),,2HC1]/k[HCl] = 0.5 approximately, I n other words, 50 per cent. of the salt is hydrolysed into the free base and acid. As the result is identical with that obtained by Bredig (Zeitsch. physiknl. Chem., 1894, 13, 214), it was thought that this very simple line of investigation might he pursued further.So far the hydrochlorides of about 40 bases of various degree of complexity, ranging from hydroxylamine to cinchonidine, have been examined. Several results are found to be in accordance with the expression of Arrhenius, kblk, = (1 - z)v/x2 (Zeitsch. physikal. Chem., 1881,5,17), even at the great dilutions examined, whilst in the case of bases of analogous composition the ratio of the hydrolysis values found is nearly equal to the ratio of the heats of neutralisation with hydrochloric acid. The Characterisation of Mercerised Cotton. J. Hiibner. (Proc. Cliem. Soc., 1907, 23, 304.)-The author has studied the action of a number of reagents on cotton, both before and after mercerisation, and finds that the following methods afford a certain means of distinguishing between mmcerised and non-mercerised cotton, and also enable the degree of mercerisation to be approximately ascertained.The cotton to be examined is steeped in a saturated solution of potassium iodide containing iodine; after a few seconds’ immersion, the sample is withdrawn and washed five or six times in a 2 per cent. potassium iodide solution. After this treat- ment, mercerised cotton is found to have acquired a brownish-black colour, whilst unmercerised cotton remains white ; on then treating the samples with water, the mercerised cotton turns bluish-black, and the unrnercerised sample remains quite white. Another convenient method for distinguishing between mercerised and untreated cotton consists in steeping the samples in an aqueous solution, 100 C.C.of which contain 93.3 grams of zinc chloride and about 0.005 gram of iodine ; in this liquid, non-mercerised cotton remain8 practically white, whilst the mercerised material becomes of a dark navy-blue colour. (Cf. Schwalbe, Ber. d e u t . Chenz. Ges., 1907, 40, 4523.) Emulsions. S. Pickering. (PYOC. Chem. SOC., 1907, 23, 256.)-Paraffin oil, when churned with solutions of soap, glue, starch, albumin, etc., forms an emulsion which rises, like cream, to the surface of the excess of water, and contains from 65 to 82 per cent. by volume of the oil. Close packing of uniform globules would give an emulsion containing 74 per cent. The percentage of oil can be increased to 99 per cent., the emulsion then being practically solid.Emulsification seems to depend on the separation from the liquid of very minute, solid particles which are attracted by, and surround, the oil globules, thus preventing them from coalescing. Any pre- cipitated substance which is sufliciently finely divided will act as an emulsifying agent, but, after becoming agglomerated by drying, it loses this property. The basic56 THE ANALYST. sulphates of iron and copper are conspicuously good emulsifiers: and, when they are used instead of soap, it is possible to mix with the emulsions substances which could not be added if soap had been used-for example, sodium hydroxide. Solids which are not sufficiently fine-grained to make true emulsions with oil will sometimes make quasi-emulsions, in which the oil globules are merely entangled with the solid particles.I n this case, dilution with water separates the oil from the solid, which is not the case with true emulsions. Polarimetric Determination of Gliadin. G. W. Shaw. ( JOUWZ. Anzey. Chew. SOC., 1907, 29, 1747-1750.)-A comparison of the polarimetric method with determinations made in the ordinary way with the Kjeldahl-Gunning process has shown that the former is capable of affording results sufficiently accurate for technical purposes, while allowing of a considerable saving of time. The solution of the gliadin was obtained by cold digestion of 15.97 grams of the material (wheat-meals, flours, etc.) with 100 C.C. of 70 per cent. alcohol. The digestion-flask was shaken at intervals of half an hour for two hours, avoiding excessive agitation, and left over- night before filtration.The polarimetric observations are carried out directly on this alcoholic solution, and also after precipitating the protein substances by means of concentrated mercuric nitrate solution. The latter observation gives the rotation due to '' non-gliadin rotatory substances," and this reading should be subtracted from the direct reading to obtain the true gliadin reading. 1-00 per cent. on the sugar scale is equivalent to 0.20 per cent. on the gliadin scale, so that, unless extreme accuracy is required, this correction may frequently be omitted, especially in the case of flours. The average difference in the results obtained polarimetrically as com- p r e d with the Kjeldahl figures is only 0.03 per cent.of gliadin nitrogen. A. R. T. Method for the Rapid Estimation of Water in Gluten. W. Bremer. (Zeit. Ui~tersuch. Nalzr. Genz~ss??~., 1907, 14, 682-686.)-The cake of moist gluten, obtained from a sample of flour in the usual way, is pressed between slabs of grey slate in order to remove most of the adherent water. The thin film of gluten is now transferred to the surface of a piece of perforated porcelain, semi-cylindrical in shape, and placed in an oven having a, temperature of 105" to l l O o C. The ends of the porcelain cylinder are open, so that the hot air is able to reach the under side of the gluten through the perforations, and the process of drying is usually complete in about four hours. The dry gluten is weighed on the cylinder in a suitably shaped weighing-bottle, w.P. s. Use of Barfoeds Solution in distinguishing Glucose from Maltose, Lactose, and Sucrose. F. C. Hinkel and H. C. Sherman. (Joz6m. Anzer. Chem. SOC., 1907, 29, 1744-1747.)--The authors find Barfoed's reagent capable of detecting 0.4 ugm. of glucose, either alone or in presence of not more than 0.02 gram of maltose, lactose, or sucrose. The reagent is prepared by dissolving 45 grams of crystallised neutral cupric acetate in 900 C.C. of water, adding 1.2 C.C. of 50 per cent. acetic acid to the filtered solution, and diluting to one litre. This solution, theTHE ANALYST. 57 efficiency of which should be tested by each worker, should show no change after ten minutes’ heating at 100” C. To obtain the best results, the following process should be followed.The sugar solution to be tested is added to 5 C.C. of the reagent in a test-tube, which is then placed in a water-bath of sufficient depth to surround the tube with boiling water to at least the level of the liquid in the test-tube. After three and a half minutes the solution in the tube is examined for precipitated cuprous oxide by viewing it against a black background in a good light. If no reduction is observed, the tube is allowed to stand at room-temperature for five to ten minutes, and the contents re-examined. A reduction due to disaccharide occurs if the heating be too prolonged, or if the amount of sugar or of acid present be too large. The volume of the sugar solution added is not important, but the total sugar present in any one test should not exceed 0.02 gram, In order to effect complete destruction of the glucose, so that the filtrate may be examined for maltose or lactose, not more than 2 mgm.of glucose per 5 C.C. of the reagent should be present. A. R. T. Quantitative Estimation of Glycuronic Acid and its Colour Reactions. K. U. LefQvre and B. Tollens. (Ber. deut. Chem. Ges., 1907, 40, 4513-4523.)- The anhydride of glycuronic acid, glycurone, like the pentoses, yields furfural when distilled with hydrochloric acid of specific gravity 1.06, but, unlike the pentoses, it give8 simultaneously carbon dioxide, thus : C,H,O, = C,H,O, + CO, + 2H20. The authors have standardised the furfural method for the estimation of glycurone in euxanthic acid and ‘( purree ” (Indian yellow).The distillation is carried out in the same manner as for the pentoses, but the decomposition of the glycuronic acid takes place more slowly, and consequently the yields of furfural are low owing to the secondary resinifpation of this aldehyde. A number of concordant results showed that the weight of furfural phloroglucide obtained, multiplied by 3, gives as nearly as possible the quantity of glycurone in the substance. Tested in this way, a sample of ’‘ purree ” was found to contain 18.3 to 18.8 per cent. of glycurone. The glycurone may also be estimated by determining the quantity of carbon dioxide evolved under the same conditions. The substance is boiled with the acid under a reflux condenser for three and a half hours. The upper part of the condenser is bent round and delivers the gas through two small Peligot tubes containing water, then through a calcium chloride tube, and lastly through a weighed potash apparatus.A slow stream of purified air is aspirated through the apparatus during the operation. The quantity of carbon dioxide obtained corresponds closely with the theoretical amount, 25 per cent., indicated in the above equation. By combining these two methods it is possible to estimate separately the quantities of glycurone and pentoses present in mixtures. Glycuronic acid shows qualitatively the same colour reactions as the pentoses, the only difference being the time required for the coloration to appear. Bial (Chem. Zentralb, 1902, II., 295, and 1903, II., 1021) employs for the detection of pentoses in urine a solution of orcin and a trace of ferric chloride in strong hydro- chloric acid.If the heating be carried out exactly according to Bial’s directions, xylose gives a green colour and glycuronic acid gives nothing, but if the boiling be58 THE ANALYST. continued the same green colour appears with glycuronic acid. Arabinose is 1858 sensitive than xylose, though still rather more sensitive than glycuronic acid. This test possesses a certain utility, but in view of the above observations, and of the fact that the time required will depend also on the concentration of the substance sought for, no great reliance must be placed on it. J. F. B. Estimation of Indigotin in Indigo-yielding Plants. C. Bergtheil and R. V. Briggs. (Journ. SOC. Chem. Ind., 1907, 26, 1172-1174.)-As the result of their investigations, the authors consider that neither of the methods suggested by Orchardson, Wood, and Bloxam (ANALYST, 1907, 32, 99) for the estimation of the indigotin obtainable from the leaf can be used in practice, both leading to entirely erroneous results unless the exact indican-content of the sample be known previously and the methods adjusted accordingly.Due regard being given to the purity in indirubin of the precipitate obtained in the isatin method, this method does not yield higher results than the persulphate method, as stated by Orchardson, Wood, and Bloxam. w. P. s. Analysis of Indigo (Part 111.) and of the Dried Leaves of Indigofera Arrecta and Indigofera Sumatrana. R. Gaunt, F. Thomas, and W. P. Bloxam. (Journ. Xoc.Chem. I n d . , 1907, 26, 1174-1182.)-Experimental proof is given that the isatin method (ANALYST, 1907, 32, 99) is at present the only trust- worthy one for the analysis of the leaves of indigofera. The product obtained by the method is shown to be almoRt chemically pure indirubin, and, as this substance can only originate from the indoxyl liberated from indican on hydrolysis, it must be a true expression of the amount of the substance present. The isatin method con- sists essentially in boiling a quantity of the leaf extract containing about 0.1 gram of indirubin with 0.1 gram of isatin in an atmosphere of carbon dioxide. After the boiling has been carried on for ten minutes, 20 C.C. of pure hydrochloric acid are slowly run into the mixture. The whole is then boiled for a further thirty minutes, cooled, and the precipitate is collected on a weighed filter, washed thoroughly with 1 per cent.sodium hydroxide solution at a temperature of 70" C., then with 4 per cent. acetic acid, dried at 100' C., and weighed. w. P. s. Estimation of Naphthalene in Coal Gas and in Spent Oxide of Iron. C. J. D. Gair. (Joz~rn. SOC. Chem. Ind., 1907, 26,1263-1264.)-1n a previous paper (ANALYST, 1906, 31, 54) the author showed that naphthalene may be absorbed from coal gas, for purposes of estimation, by passing the gas through acetic acid of 1.044 specific gravity. A volumetric modification of this method is now described. The quantity of acetic acid taken varies, according to the richness of the gas, from 200 C.C. for gas containing 5 to 15 grains per 100 cubic feet to 500 C.C.for gas con- taining 80 grains. The absorption of the naphthalene takes place in three Dreschel's bottles, two of which contain acetic acid, whilst the last contains 150 C.C. of a strong solution of picric acid as a guard. If the gas contains ammonia, it is first passed through a solution of oxalic acid, The quantity of gas treated should not exceed 10 cubic feet, and it is passed through the apparatus at the rate of about 0.75 cubicTHE ANALYST.. 59 foot per hour. The contents of the absorption bottles are mixed together and treated with 500 C.C. of strong picric acid solution. After standing for five to thirty minutes the whole of the naphthalene separates as picrate, which is then filtered off and washed with 300 to 500 C.C.of picric acid until free from acetic acid. The precipitate is transferred to a beaker with water, and is boiled for ten minutes with excess of +& sodium hydroxide solution; excess of & picric acid is then added, and the liquid is titrated back with sodium hydroxide in presence of lacmoid : 1 C.C. of FG sodium hydroxide consumed is equivalent to 0.0128 gram or 0.197 grain of naph- thalene. According to another method, called the (‘ reprecipitation ” method, the naphthalene is absorbed in picric acid solution, and the precipitate, which is a mixture of naphthalene and its picrate, is filtered off and transferred to a flask with a small quantity of strong picric acid solution. Absolute alcohol is added until the precipitate is dissolved and the naphthalene is reprecipitated in the form of pure naphthalene picrate, by adding ,a sufficient quantity of strong picric acid solution.The picrate is then filtered off, decomposed by sodium hydroxide, and estimated as above. This latter method may be applied to the case of spent oxide of iron, by extracting the naphthalene by means of 80 per cent. alcohol, and precipitating the naphthalene from the filtered extract by picric acid. J. F. B. Some Properties of Pine-Wood Oils. 0. Kress. (School of Mines Qzbarterly, 1907, 29, 46-53.)-The light oil called ‘‘ turpyne,” obtained by the distillation of pine-wood, possesses solvent properties closely resembling those of turpentine ; it also resembles the latter in specific gravity and rate of expansion on warming. For the samples investigated by the author the influence of temperature upon the index of refraction was the same for turpentine and for turpyne,” but at any given temperature the refractive index of the latter was higher than that of the former ; in fact, the wood oil showed a higher refraction than the maximum limit (1.4699 at 25’ C .) specified by McGill (BuZleti.12, No. 79, Laboratory, Inland Revenue Depart- ment, Ottawa) for turpentine. A sample of pine-wood oil, which had been treated for the removal of its characteristic odour, showed a density and index of refraction practically coinciding with the maximum values found for genuine turpentine by McGill (loc. cit.). It also resembled turpentine in the rate of change of density and refraction on warming. When the ordinary ‘( turpyne ” was submitted to fractional distillation, the indices of refraction of the successive fractions increased with the boiling-points.The densities and refractive indices of the earlier fractions were within the limits of variation of turpentine. The portion distilling at 169” to 172’ C., showed the index of refraction of the original sample. Storage in full bottles protected from air, light and moisture, had no appreciable effect on the densities and refractive indices of turpentine and ( ( turpyne.” The iodine absorption methods gave exceedingly variable and uncertain results with all of the pine-wood oils. The end- point of the final titration was unsatisfactory, and was greatly influenced by the excess of the reagent added. J. F. B. Composition of Bees’ Resin (Propolis).P. Bohrisch. (Pharm Centralb., 1907, 48, 929; Chem. Zeit. [Rep.], 1907, 31, 647.)-The specimen examined was60 THE ANALYST, fractionated into-(1) p~o2iolis resin (43.6 per cent.), a darkjbrown, soft, very aromatic resin, insoluble in hot petroleum spirit, but soluble in 26 per cent. alcohol; (2) propolis balsam (8.7 per cent.), a golden-yellow, transparent, viscous liquid, having a bitter taste and strong aromatic odour; it dissolved in hot petroleum spirit and 70 per cent. alcohol; (3) propolis waz, a wax-like mass of dark yellow colour and strongly aromatic odour, consisting of a mixture of beeswax with another body of high acid value. I t had an acid value of 28.40 ; ester value, 68.75 ; and saponifica- tion value, 97.15. The propolis also contained 12.9 per cent.of impurities (insoluble in alcohol and petroleum spirit) and 6.9 per cent. of volatile constituents-water, ethereal oils, etc. (Cf. ANALYST, 1907, 32, 422.) C. A. M. Action of Nitrous Acid on Caoutchouc. 0. Gottlob. (Zeits. aizgezu. Chem., 1907, 20, 2213-2221.) -Referring to a paper (ANALYST, 1907, 32, 224) in which P. Alexander stated that the substance obtained by the action of nitrous acid fumes on caoutchouc was a ‘‘ nitrosate,” and not the “ nitrosite-c ” of Harries, the author points out that the conditions under which Alexander worked differed considerably from those prescribed by Harries. Alexander did not purify the caoutchouc except by mechanical washing ; he dissolved it in carbon tetrachloride instead of benzene ; he treated it with nitrous fumes, evolved by the action of starch on concentrated nitric acid, instead of those prepared from dilute nitric acid and arsenious acid; he took no steps to purify the product with ethyl acetate and ether, as prescribed, and he dried it in a current of hydrogen at 40” C.instead of in vacuo. The author has investigated these factors, and considers that they have been the cause of the divergent results obtained by Alexander. He concludes that by treating caoutchoucs of different origins in the raw or purified state with nitrous gases differing.in their contents of nitrogen peroxide, nitrosites are obtained whicb may differ more or less from each other in the crude state, but which may all be brought down to the same individual substance-viz., the (‘ nitrosite-c ” of Harries.Alexander’s view as to the existence of a “ nitrosate ” having the formula C,H,,N2Os does not appear to be sufficiently supported. In order to obtain the “ nitrosite-c ” in the pure state, it is necessary to adhere closely to the method described by Harries. I n using the method for technical analyses the composition of the nitrous gases employed does not appear to be of very much importance, but, in view of the more constant composition of the precipitate produced, it is preferable to evolve them from dilute nitric acid by the action of arsenious acid. J. F. B. The Analysis of Rubber. G. Fendler and 0. Kuhn. (Gumnzi-Zezt., 1907, 22, 132-134, 160-163, 215-219, 249-252.)-1t is shown that rubber is not completely dissolved by solvents, such as benzene, petroleum spirit, and carbon tetrachloride, in the cold, the amount taken up varying with the state of division of the rubber, the temperature, the frequency of shaking, the duration of the action of the solvent, and the treatment to which the rubber has previously been subjected.Thus rubber is rendered more soluble by heating, and the solution is less viscous. By heating the rubber with the solvent more is dissolved, but solution is still incomplete. Hence the authors conclude that the results obtained by the methods in which the rubberTHE ANALYST. 61 is precipitated from ts solutions by the addition of alcohol cannot be regarded as invariably 'trustworthy. Toluene will effect complete solution of rubber, but the re-precipitation with alcohol is unsatisfactory.The authors were also unable to obtain good results by the nitrosite method (ANALYST, 1907, 32, 224) or by Budde's original tetrabromide method (Gzcmmi-Zeit., 1907, 21, 1205) ; but the following modification of the latter method, in which toluene is substituted for carbon tetra chlpride, proved very satisfactory : One gram of the finely-divided sample is heated on the water-bath with 60 C.C. of toluene, the flask being vigorously shaken at intervals until solution is complete. The liquid is then cooled, made up to 100 C.C. with toluene, and filtered through cotton-wool, 10 C.C. of the filtrate evaporated, and the residue dissolved in 50 C.C. of carbon tetrachloride. This solution is treated with 50 C.C. of bromine solution (6 C.C.of bromine and 1 gram of iodine in 1,000 C.C. of carbon tetrachloride), and set aside for twenty-four hours, after which 50 C.C. of absolute alcohol are added, the mixture thoroughly shaken, and the precipitated caoutchouc tetrabromide collected, washed first with a mixture of carbon tetra- chloride and alcohol (2: 1) and then with absolute alcohol, dried at 50" to 60" C., and weighed. The weight of tetrabromide multiplied by the factor 0.298 gives the amount of caoutchouc precipitated. C. A. 31. Solubility of Stearic Acid in Ethyl Alcohol at 0" C. W. H. Emerson. (Jozcrn. Amer. Clzenz. SOL, 1907,29,1750-1756.)-1n determining stearic acid by Hehner and Mitchell's method (ANALYST, 1896, 21, 316), some difficulty was experienced in obtaining a definite saturated solution of stearic acid in alcohol; and as the prepara- tion of such a solution is essential to the accuracy of the method, the author studied the solubility at 0" C., using a purified steario acid melting at 69.1" to 69.4" C.The following results were obtained : Strength (per Cent. by Volume) of Alcohol used. 95.7 95.5 95.1 94-5 94.3 Stearic Acid dissolved i n 100 C.C. at 0" C. 0.1246 gram. 0.1223 ,, 0.1139 ,, 0.1035 ,, 0.0996 ,, The solubility of stearic acid may be considered as practically constant for a wide range in the amount of acid, if more than 0-7 gram is used with 100 C.C. of alcohol of 94 to 95 per cent (by volume), and more than about 0.5 gram with 50 C.C. of solvent. Hehner and Mitchell (Zoc. cit.) found the solubility to be 0.15 gram of stearic acid per 100 C.C. of 94.4 per cent. alcohol. Stearic acid, after evaporation with alcohol, has an increased solubility in this solvent, possibly due to the forma- tion of some ethyl stearate. The increase amounts to about 1.5 per cent. of the stearic acid used. I t is necessary to bear this in mind in determining stearic acid in a mixture which has been recovered from alcoholic solution. I n order to determine small amounts of stearic acid accurately by the above method, therefore, the author considers it necessary to add a knowniamount of the pure acid sufficient to bring up the total to at least 0.7 gram per 100 c.c., or 0-5 gram per 50 C.C. of alcohol. A. R. T.62 THE ANALYST. Sheep Dips. 0. Quibell. (Jozmn. SOC. Chem. Ind., 1907, 26, 1266-1268.)-1n a paper on the parasitic diseases of sheep and their prevention and cure, the author quotes the following analyses of typical dips : Sulphur-arsenic Type.- Arsenic trioxide, 21-90 ; alkali, 2.86 ; moisture, 6-70 ; sulphur, 68.54 per cent. : 1 pound of it is diluted with 11 gallons of water. Carbolic Type.-(a) Emulsifying dip : Phenols, 16.30 ; hydrocarbon oils, 60.16 ; bases, 2.10; fatty acids, 14.08; alkali and water (by difference), 7.36 per cent. : 1 gallon is diluted with 50 gallons of water. ( b ) Soluble dip : Phenols, 60.1 ; hydro- carbon oils, 2.0 ; fatty acids, 23.0; alkali, 4.1 ; water, 10.8 per cent. : 1 gallon is diluted with 100 gallons of water. Combined Arsenical and Carbolic Type.--Tar acids, 13.32 ; fatty acids and glycerides, 22.48 ; hydrocarbons, 32.72 ; bases, 1-03 ; arsenic trioxide, 8.05 ; alkali, 5.83 ; water (by difference), 16.57 per cent. J. F. B.

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年代:1908

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62 THE ANALYST. INORGANIC ANALYSIS. The Chemistry of Bordeaux Mixture. S. Pickering. (Proc. Chem. Soc., 1907, 23, 261-262.)-The substances formed on. the addition of lime to copper sul- phate, as in the preparation of Bordeaux mixture, are dependent on the proportions of lime used, and may be either (1) 4Cu0,S0,,0*06CaS04 ; (2) 4CuO,SO3,O~25CaSO, ; (3) 10Cu0,S0,,1-3CaS04 ; (4) 10CuO,S0,,4CaO,SO, ; (possibly 5 ) lOCuO,SO,, lOCaO,SO,, or (6) Cu0,3CaO ; that present in most cases probably being (4). The fungicidal action of Bordeaux mixture seems to depend on the liberation of normal copper sulphate by the action of carbon dioxide on the basic sulphate. The action begins only after a certain lapse of time, the basic calcium sulphate having to be decomposed before the basic copper sulphate is attacked.By using only sufficient lime to form 4CuO,SO,, the presence of basic calcium sulphate and the consequent delay in the action is avoided ; in addition to this, the amount of normal copper sul- phate liberated (for a given amount of copper sulphate taken) and the insecticidal value of the mixture will be two and a half times as great as when it consists of 10Cu0,S03,4Ca0, SO,. The basic sulphates, when precipitated by lime in presence of excess of sodium sulphate, contain sodium sulphate as well as calcium sulphate. The formula of the most basic sulphate is 10CuO,SO,,(Na,Ca)SO,. When precipitated by soda, they contain no appreciable amount of sodium sulphate, unless a large excess of the latter is present in the liquid. Nickel sulphate with lime gives a basic sulphate containing a very little calcium sulphate, but, if the lime is at all times in excess, the basic sulphate is deprived of most of its acid, the precipitate consisting essentially of a double oxide.Estimation of Carbon Dioxide in Electrolytic Chlorine. P. Philosophoff. CIzcm. Zczt., 1907, 31, 1256-1257.)-The mixed gases, stored over concentrated sodium chloride solution saturated previously with the gases, are brought into a Bunte burette containing mercury and connected with a graduated levelling tube.THE ANALYST. 63 The diminution due to the absorption of the chlorine by the mercury is measured by readjusting the level of the mercury in the graduated tube. The carbon dioxide is absorbed subsequently by potassium hydroxide.w. P. s. Estimation of Hydrofluosilicic Acid. S. Honig-Szabadka. (Chem. Zed., 1907, 31, 1207-1208.)-The following simple acidimetric method for the estimation of hydrofluosilicic acid, though not theoretically exact, owing to the slight hydrolytic dissociation of sodium fluosili,cate, is sufficiently accurate for industrial purposes, particularly for rapid control of the manufacture of the salts. It consists of a differential titration, first in presence of methyl orange, and then, near the boiling- point, in presence of phenolphthalein. At the neutral point, with methyl orange, all the foreign mineral acids have been neutralised, and the hydrofluosilicic acid has been converted into its sodium salt, thus : H,SiF, + 2NaOH = Na,SiF, + 2H,O. The solu- tion is then heated to boiling, phenolphthalein is added, and normal sodium hydroxide solution is run into the hot liquid until a pink colour is produced.At this stage the following reaction has taken place : Na,SiF, +4NaOH= 6NaF+ Si(OH),. From the result of the latter titration, the quantity of hydro- fluosilic acid may be calculated ; any sodium fluosilicate originally present would, however, be included in the result. J. F. B. A Colorimetric Method for the Determination of Small Percentages of Iron in Copper Alloys. A. W. Gregory. (Proc. Chem. SOC., 1907, 23, 306-307.) -The method is based upon the colour reaction given by salicylic acid and ferric chloride. This reaction is modified by using a solution of salicylic acid in acetic acid, and the test is carried out in the presence of sodium acetate. Under these conditions a deep red colour is produced, which is used as a colorimetric test for iron in small quantities.The interfering action of the blue copper salts is overcome by the addition of a weak solution of potassium cyanide, which results in the formation of the colourless complex cyanide of copper and potassium. Zinc and antimony do not interfere with the reaction, but lead must be removed as sulphate. This method has been found to give very accurate results in cases where the per- centage of iron in the copper alloys is so low that the ordinary gravimetric methods of estimation involve the use of a, large quantity of the alloy. Precipitation of Iron by Ammonia in Presence of Tartaric Acid. W. Strecker. (ClLem. Zeit., 1907,31, 1217.)-The author confirms the statement of Grossmann and Schiick (ANALYST, 1907, 32, 394) that on heating, sodium hydroxide precipitates iron completely from solutions containing tartaric acid.He also shows that animonia causes complete precipitation of the iron on heating, provided that the liquid does not contain more than one molecule of tartaric acid for every 2.5 atoms of iron present. If the quantity of tartaric acid added is increased beyond this pro- portion, precipitation is delayed, becomes incomplete, and finally ceases altogether. Attempts to isolate definite complex compounds of tartaric acid, iron, and ammonia, failed. A. G. L.64 THE ANALYSTo Detection and Estimation of Traces of Manganese. M. Duyk. (Ann. dc Chim. Anal., 1907, 12, 465-466.)-0n adding a trace of a manganese salt to a moderately alkaline 10 per cent.solution of potassium hypochlorite, and then one drop of a 10 per cent;. solution of copper salphate, a precipitate of cupric oxide is produced, and on heating the liquid for a few seconds the manganese dissolves com- pletely, and colours the supernatant liquid violet. This reaction, which is to be attributed to the formation of potassium permanganate, is capable of detecting 0.25 mgrm. of manganese in 4 to 5 C.C. of the hypochlorite solution. As the depth of the colour is proportional to the amount of manganese, the reaction may be made the basis of an exact colorinietric method of estimation. The hypochlorites of sodium or calcium may take the place of the potassium hypochlorite.C. A. M. The Detection of Traces of Mercuric Chloride. K. Kof and H. Haehn. (Arch. der Pharm., 1907, 245, 529-533.)-1f a photographic plate be placed film downwards upon a beaker containing a 2 per cent. solution of mercuric chloride, the surface of which is within 5 to 10 mm. of the film, radiation occurs, which retards the subsequent development of the plate, after at least thirty minutes’. exposure in the dark-room. By placing a strip of glass between the film and surface of the liquid, it is possible to obtain an image of this diaphragm after sufficient exposure. The effect of the mercuric chloride vapour upon the plate may be prevented by adding sodium chloride in excess of saturation to the solubion, but if stannous chloride solution then be added; reaction radiation begins, though it now accelerates the reduc- tion, so that the image of a diaphragm appears as a positive instead of a negative. The radiation reaction is given by solutions containing 0.01 to G per cent.of mercuric chloride, but not by a 0.001 per cent. solution. Solutions of the salt in alcohol, benzene, or toluene also affect the plate, but solid mercuric chloride has no action at a distance of 5 to 10 mm. The vapours from a solution may also be received upon moistened filter-paper, and a colorimetric estimation made by means of hydrogen sulphide. By comparing the stains obtained on a square of filter- paper of equal size (17.3 sq. cm.), impregnated with solutions of mercuric chloride of known strength, it was found that at 13’ C., at a pressure of 763 mm., about 0.00008 gram of mercuric chloride evaporated from a 2 per cent.solution in 165 hours, corresponding to0*000000011 gram per sq. cm. of paper in thirty minutes. If a drop of a 0.01 per cent. solution (0*000005 gram of mercuric chloride) be introduced into a cavity in an object-glass, thin glass strips placed to the right and left to support a photographic plate film downwards, and the whole left for twenty-four hours in the dark-room, the image of the drop will appear as a white spot when the plate is sub- sequently developed. C:A. M. The Use of Nitron for the Estimation of Nitric Acid in Soils and Plants. J. Litzendorff. (Zeits. angcw. Chem., 1907,20, 2209-2213.)-The ‘ I nitron ” method (ANALYST, 1905, 30, 256 ; 1906, 31, 267 ; 1907, 32, 349) is applicable for the estima- tion of nitrates in soil extracts containing about 5 mgms.per 100 C.C. The extracts are prepared by the method of Buhlert and Fickenday by shaking 2 kilogms. of soil with 4 kilogms. of water for half an hour. The extract is then evaporated to aTHE ANALYST. 65 suitable concentration with the addition of magnesium oxide, or else the extract may be filtered cold through a long filter-bag, such as is used for filtering wines, and further quantities of the soil shaken with the same liquid. To 100 C.C. of the solu- tion, heated to boiling, are added 5 to 10 C.C. of a 10 per cent. solution of nitron ” acetate, and the liquid is allowed to stand for several hours in the ice-box; the “ nitron ” nitrate is collected in a Gooch crucible, washed with ice-cold water and dried at 110’ C.I n soils containing not less than 2 to 3 mgms. of nitric acid per 100 grams, the ‘( nitron ” method gives accurate results. With poorer soils, the extracts of which have to be considerably concentrated, difficulties are experienced owing to the accumulation of substances which prevent the crystallisation of the nitron ” nitrate. Similar inhibiting impurities occur in soil extracts which have been sterilised by heat. These substances may be eliminated by means of hydrogen peroxide, which is added repeatedly to the liquid during evaporation. When sufficiently concentrated, the liquid is transferred to a measuring flask and is heated in a boiling water-bath for several hours, further additions of peroxide being made from time to time until the extract is colourless.The (‘ nitron ” method has also been employed for the estimation of nitrates in plants such as mustard. The aqueous extract of the dried plant is clarified with basic lead acetate before precipitating the nitrates. I t would appear that the older methods of estimation, when applied to plant extracts-at any rate, if basic lead acetate be not used-tend to give results which are too high. A correction is made for the solubility of the (( nitron ” nitrate. J. F. B. The Estimation of Phosphorous Acid. C. Marie and A. Lucas. (Comnptes Re?tdzis, 1907, 145, 60-62.)-The method depends upon the oxidation of the phosphorous acid by means of alkaline permanganate solution, the excess of which is titrated back with standard ferrous ammonium sulphate solution.A sufficient quantity of potassium carbonate to give an excess of 3 grams per 100 C.C. of the final solution is heated to 80° C. on the water-bath with 50 C.C. of $; potamium permanganate solution, the solution of the phosphorous acid or phosphite (0.2 to 0.3 gram) introduced, and the temperature maintained at about 80’ C. for fifteen minutes. A standardised solution of ferrous ammonium sulphate containing 10 per cent. of sulphuric acid is then introduced, and the excess of ferrous salt titrated back with the standard permanganate solution. A convenient method of standardising the latter is to heat it on the water-bath with alkali carbonate and a weighed quantity of calcium formate as in the phosphite estimation, the process of oxidation being as follows : 4KMn0, + 3(HC02),Ca = 4Mn02+ 3CaC0, + K2C0, + SKHCO, + 2H,O.C. A. M. The Analysis of Sodium Peroxide. R. Niemeyer. (Chem. Zeit., 1907, 31, 1257.)-Although the gasometric method for estimating the available oxygen in sodium peroxide (ANALYST, 1906, 31, 313) gives results which are about 0.8 per cent. higher than those obtained by the permanganate method, the author considers that the latter method, on account of its simplicity, is to be preferred. The estimationTHE ANALYST. should be carried out as follows : About 0.2 gram of the sodium peroxide is placed in a small capsule (made from the bottom of a test-tube) contained in a stoppered weighing bottle, and the whole is weighed. The weights of the capsule and bottle are ascertained previously.The capsule is then removed from the bottle by means of a pair of forceps and introduced into a beaker containing 500 C.C. of water, the capsule being held in a sloping position, so that it sinks to the bottom of the beaker. Care must be taken that no particles of the peroxide come to the surface of the water. An excess of eulphuric acid is added, with stirring, and the solution is titrated with -& perinanganate solution. w. P. s. Estimation of the Strength of Concentrated Sulphuric Acid. E. Buch- wald. (Chem. Zeit., 1907, 31, 1256.)-In the volumetric estimation of sulphuric acid the accurate standardisation of the alkali solution used is of the utmost importance, especially in the analysis of concentrated sulphuric acid, where any slight error is multiplied to a considerable extent in the subsequent calculation.The author recommends that the alkali solution be standardised on an acid solution the strength of which has been ascertained by titrating the iodine liberated from a mixture of potassium iodide and iodate by a known volume oE the acid. This iodine is titrated with a thiosulphate solution itself titrated against pure iodine. The standardisation of the acid may also be checked by titration on a known weight of Iceland spar, and, furbher, if hydrochloric acid be employed, a known volume may be precipitated by the addition of silver nitrate and the silver chloride weighe'd. I t is preferable to treat the alkali solution with barium hydroxide to remove carbonates, the excess of barium being afterwards precipitated by means of sulphuric acid, aud to use phenolphthalein as indicator in the titration of the sulphuric acid under examination.w. P. s. Separation of Thorium, Titanium, and Zirconium from Iron. M. Dittrich and S. Freund. (Zeits. Anal. Chena., 1907, 56, 348-352.)-The mixed oxides are fused with potassium bisulphate, the melt is dissolved in cold water and saturated with sulphuretted hydrogen. The filtered liquid is diluted to 600 c.c., sodium acetate is added, and the whole boiled for some time in a flask through which carbon dioxide is passed, the water lost by evaporation being replaced from time to time. The precipitated hydroxides are ignited, weighed, and converted into nitrates by fusion with potassium bisulphate, precipitation of the aqueous solution by ammonia, and solution of the hydroxides in nitric acid.In this solution, zirconium and thorium are separated from titanium by means of ammonium salicylate (see p. 67). The precipitated hydroxides of zirconium and thorium are ignited, weighed, and fused with potassium bisulphate. The melt is dissolved in cold water, and ammonium oxalate added until the oxalates precipitated at first are completely redis- solved. The clear solution is heated to boiling, and thorium oxalate precipitated by adding boiling concentrated hydrochloric acid, and heating on a water-bath for another two hours. The precipitate is washed with a 5 per cent. solution of ammonium oxalate in dilute hydrochloric acid (1 : 4). Zirconium may be precipitatedTHE ANALYST. 67 with ammonia in the filtrate, after destruction of the oxalate with sulphuric.acid. Test results quoted are satisfactory for all four metals. A. G. I;. Simultaneous Precipitation of Titanium and Zirconium in Presence of Iron. M. Dittrich and S. Freund. (Zeits. Anal. Chem., 1907, 56, 337-343.)-Four slightly different methods are described, all depending on the precipitation by prolonged boiling of titanic acid and zirconium hydroxide from nearly neutral solutions containing the iron in the ferrous state. In three of the methods the mixture of the three oxides, obtained as usual, is fused with potassium bisulphate, the melt is dissolved in water, and sulphuretted hydrogen is passed through the liquid until any platinum (from the crucible) present is precipitated, and the iron is completely reduced.The liquid is next filtered into- a large flask, neutralised with sodium carbonate, and made slightly acid with sulphuric acid. Sulphuretted hydrogen is passed into the flask, the excess being removed by heating and passing a stream of carbon dioxide through the liquid. A solution of about 5 grams of sodium acetate, sodium thiosulphate, or, preferably, ammonium sulphate, is then added from a tap-funnel, and the boiling in the current of carbon dioxide is continued for another one or two hours, when the precipitate, which should be quite white, is filtered off, washed, ignited, and weighed. Any oxides adhering to the flask may be brought into solution by warming with strong sulphuric acid and hydrogen peroxide ; the solution obtained is diluted, precipitated with ammonia, and the hydroxides added to the main precipitate.The fourth method consists in dissolving the bisulphate melt in water and hydrochloric acid, reducing the iron by means of sulphur dioxide, nearly neutralising the liquid with ammonia, adding an aqueous solution of sulphur dioxide and precipitating the hydroxides of titanium and zirconium by boiling in a current of carbon dioxide as above. In all cases iron can be directly determined in the filtrates as usual. Titanium is determined colorimetrically, and zirconium is taken by diffarence. Test results quoted are satisfactory. A. G. L. A New Separation of Titanium and Zirconium. M. Dittrich and s. Freund. (Zeits. Anal. Chewz., 1907, 56, 344-345.)-The dilute solution of titanium and zirconium nitrates is nearly neutralised with sodium carbonate, and is then added drop by drop to a boiling solution of 10 grams of ammonium salicylate in 50 C.C.of water. Boiling is continued until the volume of the solution has been reduced to 150 to 200 c.c., when the precipitated zirconium salicylate is filtered off hot, washed with a boiling solution of ammonium salicylate until perfectly white, ignited, and weighed as ZrO,. The oxide should be tested for titanium with hydrogen peroxide, and the separation repeated, if necessary. The results quoted are satisfactory. Titanium and thorium can be separated in the 8ame way. A. G. L. Rapid Electrolytic Estimation of Zinc. F. C. Frary. (Zeits. afzgew. Chem., 1907, 20, 2247-2250.)-The author questions the accuracy of the estimations of zinc made by Exner and Ingham, and by Langness (ANALYST, 1907, 32, 269), with the aid of a rotating anode, chiefly on the ground that apparently the liquids left atTHE ANALYST+ the epd of each experiment were not tested for the presence of zinc. Using his own method of electro-magnetically rotating the liquid, and testing for zinc at the end of each experiment, he finds that 0.1 gram of zinc can be completely deposited from alkaline solutions in thirty minutes, with a current of 4.5 a m p h s , at about 4 to 5 volts. For quantities of zinc of 0.2 gram a current of 4 to 5 amperes was used for the first fifteen minutes, and then 1.5 amperes for another twenty minutes, when deposition was complete. I n each case the volume of the electrolyte was 100 to 125 c.c.; it contained eight grams of sodium hydroxide, and was cooled by an external lead coil, through which water circulated. The cathode consisted of a cylinder of nickel gauze, closely fitting the beaker ; the deposited zinc was removed by means of dilute sulphuric acid, the cathode losing up to 0.01 gram (average, 0-001 gram) in weight by this operation. The author noticed the formation of a yellow substance, apparently an oxide of platinum, in very small quantity, on the platinum spiral used 8s anode in his experiments (cf. ANALYST, 1908, 30). A. G. L.

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年代:1908

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68 THE ANALYST+ APPARATUS, ETC. A Water-Jet Blower of Simple Construction. S. M. Revington and I. G. Rankin. (Chenz. News, 1907, 96, 259.) - .4 bottle of 4 litres capacity is fitted with a tight cork having four holes, as shown in the figure. The tube A is constricted in the centre, and the water-jet delivers into it diagonally on to the constricted part. B is a syphon-tube, the flow from which is regulated by a, screw-clip ; and C is a safety-tube about 2 feet 6 inches high. Air passes out at D, which has a diameter of 2 inch. By turning on the water and closing the exit D, the pressure soon starts the syphon, and air and water escape by the safety-tube. The blast will then be found to be strong and steady. If A be provided with a side-tube, and the jet connected to A with rubber tubing, the apparatus can be used for circulating gas.The position of the jet may be adjusted by noting the height of water in the safety-tube, and the same holds in con- trolling the outfall by means of ;the clip, care being taken that the bottle does not begin to fill. A. R. T. Laboratory Apparatus for the Evaporation of Liquids by Radiation from above. H. J. S. Sand. (Jozmz. SOC. Chem. Ind., 1907, 26, 1225-1226.)-An im- proved substitute for a water-bath for the evaporation of liquids consists of a plate of fused silica, which is held above the basin containing the liquid by means of a clamp,THE ANALYST. 69 the cork linings of which have been replaced by.pieces of asbestos board. The silica, plate is heated to a high temperature by means of a small blast-burner with a spreader giving a flat flame.The burner is held on the same stand as the basin, but in a different plane, by means of a clamp attached to a short iron rod extending from the stand horizontally. The rate of evaporation, in the case of pure water, is about 50 per cent. faster than with water-bath with a good draught. For liquids of higher boiling-point, such as solutions containing sulphuric acid, the comparison is still more favourable. Liquids from which large quantities of crystals separate show a tendency to creep up the sides, and if the crusts of crystals be not con- tinually removed losses may occur by spirting. J. F. B. A Gas-Generating Apparatus. E. Muller. (C?t,em. ,%it., 1907, 31, 1257.)-The apparatus consists of a U-tube provided with glass stoppers and a side-tube, as shown in the illustration.The stopper a forms a small washing chamber for the evolved gases, which are discharged into the solution to be treated through the side-tube. The volume of the gas, and to some extent its pressure, may be regulated by operating the stopper b. w. P. s. A Filter-Tube. Porter W. Shimer. (Chem. Engineer, 1907, 6, 197-198.)- This consists of an ordinary carbon-tube 1 inch in diameter, and is provided I' a with a device for supporting the filter and pushing it out of the tube. This device is a glass tube, which passes through the stem of the filter-tube, and has a flattened, perforated bulb at its upper end (see figure). This flattened top is covered with a close-fitting disc of piano- or filtering-felt, on which paper-pulp is deposited. This pulp is readily prepared by acting on unwashed Swedish filter-paper, in a cerasin vessel, with hydro- chloric acid (specific gravity, 1.18) containing a little hydrofluoric acid. The resulting pulp is stirred up with distilled water, and is deposited under diminished pressure on the filter-felt in the tube. The filter is very effective and rapid even for fine precipitates, but is un- suitable for large precipitates of oxide of iron and alumina. It is useful in the washing of oxidisable precipitates, as air can be excluded. Where rubber is unobjectionable, the filter support may be made from sheet-rubber, ++ inch thick, and perforated with five small holes. A central hole then holds a glass rod long70 THE ANALYST. enough to use for pushing out the. filter. Three-quarter inch tubes are used for carbon filtrations, the felt and pulp being replaced by glass-wool and finely-divided asbestos. A. R. T. % * * * a +

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70 THE ANALYST. REVIEW. DESCRIPTIVE: BIOCHEMIE RIIT ~ESONDERER BER~JCI~SICHTIGUNG DER CHEMISCHEN AEBEITSMETHODEN. By Dr. SIGMUND FRANKEL. Published by J. F. Berg- mann, Wiesbaden, 1907. Pp. x+639. Price 17 M. The work under notice gives as complete a description of the substances which occur in the animal organism, or which result from the hydrolysis of proteins, as the space permits. And the space is made to contain a very large amount of material, for small type is used in descriptions of analytical processes, and the abbreviations to which the Zeiztralblatt has accustomed us are generally employed. In the preface the author states that the work is intended as an aid for those occupied with physio- logical chemistry, and that methods of preparation and estimation are set forth in such a manner that anyone should be able to use them, provided that he is intimate with chemical methods.To attain this result the author has divided his work in a very systematic manner, and the thirty-four chapters are assigned to the following subjects : Fats and fatty acids ; polycarboxylic acids ; hydrocarbons, alcohols, and ketones ; carbohydrates ; sulphur derivatives ; aliphatic bases ; guanidine and derivatives ; urea and derivatives ; amino-fatty acids ; pyrimidine derivatives ; the purine group ; nitrogenous substafices of unkaown constitution ; lipoids : nucle'ic acids ; sulphonic acids ; substances containing iodine ; hydro-aromatic compounds ; conjugated gallic acids ; aromatic compounds ; aromatic derivatives of glycine ; quinoline compounds ; aromatic bases ; acids from urine ; proteins ; products of protein hydrolysis ; method of examination and isolation of the hydrolysed products ; proteins from a systematic standpoint ; alburnenoids ; proteins with prosthetic groups ; hzmoglobin ; albumoses, peptones, peptides, etc.; colouring matters ; fer- ments ; and finally chemistry of the organs, secretions and excretions. To review a work of this size shortly, but fairly, is a difficult task, and the reviewer, having enumerated the subjects treated by the author, considers that the best way will be to show how the subject-matter is treated. A good example to take is the chapter on purine derivatives (Chapter XI., pp. 117-143), in which we are first introduced to glyoxaline (iminazole), and then to purine and the way in which the ring is numbered.The general reactions of compounds of the purine group follow, and then comes the method of Kriiger and Salornon for separation of purine bases from urine, the estimation of uric acid and purine bases in urine, the estimation of purine bases in organs and excrement, and then Schindler's process for the quantita- tive separation of adenine, hypoxanthine, guanine, and xant hine. Special descriptions now follow of the individual purine derivatives of physiological interest ; the sub- stances so treated being hypoxanthine, adenine, guanine, epiguanine, episarcine, xanthine, I-methylxanthine, heteroxanthine, paraxanthine, uric acid, and finally purine bases of unknown constitution. Under each individual substance we are informed as to its occurrence, physical properties, and chief reactions and derivatives, synthesis and practical preparation from animal or vegetable material.THE ANALYST. 7 1 The systematic arrangement of the chapter under consideration is characteristic of the whole work, and when one adds that the printing and paper are good, and that the work is provided with excellent indexes, arranged both as to subjects and authors, the great use that this work should be to those occupied with physiological chemistry is at once apparent. References are given in footnotes, and the literature of the subject has been examined up to the latter part of 1906. Both author and publisher are to be congratulated on the work. + * * * - I ? J. T. H.

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DOI:10.1039/AN9083300070

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年代:1908

数据来源: RSC

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THE ANALYST. 71 GENERAL RESULTS OF THE INVESTIGATIONS SHOWING THE EFFECT OF SULPHUROUS ACID AND SULPHITES UPON DIGESTION AND HEALTH. BY H. W, WILEY. Circular No. 37 of the United States Depaytmeitt of dgriczilt w e . THE methods pursued in this investigation were practically identical with those described in tha report on the effect of borax (ANALYST, 1904, 29, 357) and salicylic acid and salicylatles (ibid., 1907, 32, 19) when administered with food. The effect of sulphurous acid as well as sulphites was studied. From a consideration of the data in the individual cases and the summaries of the results, it appears that the administration of sulphurous acid in the food, either in tbe form of sulphurous acid gas in solution or in the form of sulphites, is objectionable, and produces serious disturbances of the metabolic functions and injury to digestion and health, This injury manifests itself in a, number of different ways, both in the production of clinical symptoms, which indicate serious dis- turbances, malaise, or positive suffering, and also by inducing certain changes in the metabolic processes which are not manifested in the way of ordinary clinical symptoms, and are only detected by careful chemical and microscopical study of the excretory products.The assimilation of food materials containing organic phosphorus is retarded, while there is evidence of increased sulphur catabolism. The sulphur balance-sheets show that a great burden has been added to the already overworked kidneys, which are called upon in this case to remove nearly all, if not quite all, of the added sulphur from the body, previously converted in great part to sulphuric acid.I t is not possible that placing upon the kidneys this increased work of excreting sulphur can result in anything but injury. The fact that the microscopic crystalline and amorphous bodies in the urine are increased in number under the influence of the added sulphur is another indication of the extraordinary demands made upon the kidneys in such circumstances. This increase is interesting in respect of the effect which the continued exhibition of sulphurous acid must eventually have upon the structure of the kidney. It is reasonable to suppose that the continued use of a body which produces such results would cause lesions of a histological character that eventually would develop con- ditions which would give serious apprehension. The further observation that there is a marked tendency to the production of albuminuria, although of an incipient character, is an indication of the unfavourable results of the administration of the sulphurous acid.It is therefore evident that, by increasing the burden upon the excretory organs, the administration of sulphur in the form mentioned is highly detrimental to health.78 THE ANALYST. Another effect which the administration of the sulphur produced, and one of a more serious character still, is found in the impoverishment of the blood in respect of the number of red and white corpuscles therein. The administration of a substance which diminishes by a notable percentage these important component particles of the blood must be regarded as highly prejudicial to health.The bleaching effect of the sulphurous acid upon the colour of the blood is a, matter of less consequence, and no great effect is produced upon the haemoglobin, but the diminu- tion of the number of red and white corpuscles is a matter of serious concern. The variations of the metabolic processes from the normal, as indicated in the experiments, were never of a character favourable to a more healthy condition of the system, but, on the other hand, all these variations, in so far as the effect of the changes could be distinguished, were of a prejudicial character. There is no evidence that the sulphur, added to the foods in the form of sulphurous acid or sul- phites, takes any part in the nutrition of the tissues of the body containing sulphur -namely, the proteids-hence no claim of food value can be established for these bodies.The evidence all points to the fact that they are purely drugs, devoid of food value, having no favourable effects upon the metabolic processes, but, on the other hand, exerting deleterious and harmful effects. The verdict which must be pro- nounced in this case is decidedly unfavourable to the use of this preservative in any quantity or for any period of time, and shows the desirability of avoiding the addition of any form of sulphurous acid to products intended for human food. INSTITUTE OF CHEMISTRY OF GREAT BRITAIN AND IRELAND. PASS LIST OF THE JANUARY EXAMINATIONS, 1908. OF twenty-three candidates who presented themselves for the Intermediate Examination, the following fourteen passed : W. Cameron, F.Challenger, B.Sc. (Lond.), P. W. Copeland, B.Sc. (Lond.), G. A.M. Cunningham, H. Davies, J. G. Hay, A. Hepburn, H. R. Jensen, B.Sc. (Liverpool), C. H. Kirkaldy, F. W. Linch, W. A. Riley, V. J. Tilley, R. Unwin, and C. H. Warner. I n the Final Examination for the Associateship, of four candidates who presented themselves in the branch of Mineral Chemistry, the following three passed : S. L. Archbutt, C. P. Matthews, B.Sc. (Lond.), and L. A. Levy, B.A. (Cantab), B.Sc. (Lond.). One candidate presented himself in Physical Chemistry, and passed : N. P. Campbell, B.A. (Oxon). Of six in Organic Chemistry, three passed : T. P. Hilditch, B.Sc. (Lond.), B. D. Porrit, B.Sc. (Lond.), and H. E. Watson, B.Sc. (Lond.). Eight candidates presented themselves in the Chemistry of Food and Drugs, of whom the following seven passed: A. P. Davson, Assoc.R.C.Sc. (Lond.), A. G. Harrington, H. Mansfield, B.Sc. (Lond.), R. D. Masson, P. Murphy, B. F. Sawbridge, B.A. (Oxon), and J. M. Wilkie, B.Sc. (Lond.). W. P. Hayworth, A.T.C., also passed this examination in order to obtain the special certificate recognised by the Local Government Boards. Four candidates presented themselves for examination for the Fellowship, and the following three passed : W. Barbour, M.A., B.Sc. (St. Andrews), in the branch of Organic Chemistry; P. V. DuprB, A.C.G.I., in Mineral Chemistry; and A. C. Franklin, in Metallurgical Chemistry.

ISSN:0003-2654    

DOI:10.1039/AN9083300071

出版商:RSC    

年代:1908

数据来源: RSC