摘要:

MAY, 1913. Vol. XXXVIII., No. 446 THE ANALYST. OBITUARY. J O H N H E R O N . JOHN HERON was born in Bandon, co. Cork, on May 8,1850. He studied engineering at Queen’s College, Cork, and obtained the B.E. degree in 1871, but soon afterwards decided to make chemistry his career, and entered the Royal College of Chemistry under Professor Edward Frankland. In 1876 he left the college to take charge of a guncotton factory in Wales, but early in 1877 resigned that appointment to go to Worthington’s Brewery at Burton as assistant chemist under Dr. Horace Brown.I n 1883 he went as chemist to the Anglo-Bavarian Brewery at Shepton Mallet, and in 1885 was appointed chemist to the Invert Sugar Works of Messrs. Garton, Hill and Go. Here he remained till 1895, when he set up in London as brewers’ chemist and consultant, remaining in practice till his death. He died on March 29, leaving a widow and a family of three sons and seven daughters. Always keenly interested in chemical research, Heron contributed many valuable papers, mainly connected with the chemistry of brewing and of sugar, to various scientific societies.Of these, the first was the valuable research, made jointly with Horace Brown, ‘I Contributions to the History of Starch and its Transformations,” read before the Chemical Society.Of his others we can here only mention his important papers on the use of the polariscope in brewing practice and analysis, those on the manufacture and analysis of invert sugar, and his numerous researches in the chemistry of brewing, malting, and hops. He was an original member of the Laboratory Club, which developed into the Institute of Brewing, and also of the Society of Chemical Industry, and filled many important offices in both these societies. A man of great ability and genial character, his death will be felt amongst a large circle of scientific and social friends. L. T. THORNE.

ISSN:0003-2654    

DOI:10.1039/AN9133800185

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年代:1913

数据来源: RSC

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186 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS THE VALUE OF THE GUAIACUM TEST FOR BLOODSTAINS. BY HERBERT S. SHREWSBURY, F.I.C. (Read a t the Meeting, December 4, 1912.) ALTHOUGH Sutherland, in his monograph on bloodstains," agrees with many other authorities in condemning the guaiacum test for bloodstains, much experience in the use of it fully emphasises its value when properly carried out.It should never be relied upon without the application of confirmatory tests, but should be regarded as a, sorting test. Preparation of the Solution.-About 1 grm. of the resin is washed three times with rectified spirit, and the residue is then shaken with 100 C.C. of the same solvent until a pale straw-coloured extract is obtained. The solution must be freshly pre- pared ; when only twenty-four hours old it gives poor results, and when sixteen days old gave no reaction with a bloodstain a year old which reacted well with a freshly- prepared solution.The following details describe the method used by the author : * '' Bloodstains," by Major W. D. Sntherland, p. 24. BailliBre, Tindall, and Cox, 1907.THE VALUE OF THE GUAIACUX TEST FOR BLOODSTAINS 187 Application and Interpretation of the Test.-A small portion of the fabric to be tested is placed on a 4-cm.Dreverhoff ash-free filter, laid fiat in a white flat-bottomed porcelain dish and moistened with two or three drops of distilled water. The surrounding filter is examined for any red stains which may be extracted; if the stain is on a weapon or other article, it is gently rubbed with the moistened filter.When the fabric is moistened, one or two drops of the guaiacum solution are added, and if no colour is produced within a few seconds, a drop or two of hydrogen peroxide (20 vols.) is added. If blood only is present, no coloration is produced after addition of the guaiacum solution alone, but a characteristic blue colour is produced within one second of the addition of the peroxide.Blood never reacts with guaiacum alone, whereas some substances, such as the oxidases, do. The immediate reaction with guaiacum in presence of peroxide is a most impor- tant condition, the neglect of which has largely caused Sutherland to condemn the test. The reaction must occur within the second, and later colorations, which invariably develop, are to be disregarded.Guaiacum solution and hydrogen peroxide alone, if left to evaporate on a clean glazed tile, will gradually develop a faint blue coloration. No case has so far been met with in which the test carried out as above has indicated blood, and further tests have failed to confirm its presence. If a negative result is obtained, it is useless to search further unless the circum- stances are exceptional. Specific Nature of Test.-Sutherland (Zoc. cit.) quotes a list of thirty substances which all give the characteristic colour,” but the real question is, Do they give a blood positive reaction-viz. : (a) A red aqueous extract ; (b) a blue coloration within one second after peroxide is added; and (c) no blue coloration without it? All the thirty substances mentioned by Sutherland (with the exception of quinone) have been examined by the test applied as already described, and are taken in Sutherland’s order.A few preliminary tests with the reagents themselves may first be described. The guaiacum solution alone spontaneously evaporated to a, residue which remained white. Guaiacum solution and hydrogen peroxide developed a very faint violet colour in sixty seconds.This colour changed to a very faint blue, and remained constant in intensity. Distilled water, guaiacum solution, and hydrogen peroxide, gave the same very faint blue colour. The same reagents tried with human blood on cotton fabric, a bloodstain four months old, gave a vivid blue coloration in one second after the addition of hydrogen peroxide.The first ten substances gave an immediate vivid blue with guaiacum solution alone, and therefore gave a negative blood reaction. The substances were, potassium permanganate, manganese dioxide, lead peroxide, chlorine, iodine, bromine, nitrous acid, bleaching-powder, ferric chloride, potassium ferro- and ferri-cyanides. These substances, being strong oxidising agents, react with guaiacum alone.With regard to the bleaching-powder, it should be mentioned that, of the three samples tested, two of them were old, and these two gave a perfect blood- reaction (exclusive of the aqueous red extract), guaiacum alone giving no colour. Gum acacia, gluten, and milk, gave negative results, milk giving a colour after several minutes. Raw potato gave a faint blue after two seconds with guaiacum alone, and188 SHREWSBURY : a positive reaction on the addition of the peroxide.The substancea reacting are doubtless enzymes, but it is possible that the vegetable enzymes lose the power of reacting with guaiacum during the drying of vegetable stains on clothes. Pus gave a negative reaction unless accompanied by blood. Ammonium chloride gave a positive reaction, and sodium chloride, sweat, and chromium salts, all negative reactions.Salt solution of 10 and 14 per cent. concentrations required, respectively, 5 and 6 -_. Stain . Author’E blood on cambric ;: t w e n t y days old. As in Experj ment 1. A u t h o r ’ s blood on cambric ; fresh. As in Experi ment 3. As in Ex- perimentf 1 and 2. Washing. Incomple telj under tap ; air-dried.As completelj as possible under tap; air-dried. Immediately after shed- ding; three r i n s i ngs under tap ; air-dried. Five minutes a f t e r shedding ; thorough washing under tap. As in Experi- m e n t s 1 and 2. Description of- Washed Stain. Distinct pale y e l l o w - o r a n g e brown; re- s e m b l e d s l i g h t l y scorched linen. A s above, but much paler.I nv i s i b le ; very faint indication by t r a n s - m i t t e d light. As in Experi ment 3. As in Experi m e n t s 1 and 2. Test. Moistened with water ; applied guaiacum solu- tion, followed by hydrogen peroxide. As in Experi- ment 1. Soaked one hour i n d i s t i l l e d water ; applied guaiacum solu- tion, followed by h y d r o g e n peroxide. As in Experi- ment 3.No moistening with d i s t i l l e d w a t e r ; guaia- cum s o l u t i o n and hydrogen peroxide ap- plied. Reaction. Immediate blue coloration. As in Experiment 1. I m m e d i a t e f a i n t blue, rapidly de- veloping -to sky blue ; stains white against blue back- ground of fabric, corpuscles having apparently b e en washedfromstains into fabric. As in Experiment 3. Immediate b l u e coloration.THE VALUE OF THE GUATA.CUM TEST FOR BLOODSTAINS 189 five and three seconds for the development of the blue colour.A 16 per cent. solution gave a faint positive result. Sutherland’s suggestion, that the presence of salt in sweat and urine vitiated the test, is thus groundless. Sweat required thirty seconds t o give a faint colour. Rust required two minutes, the colour even then being very faint, but salts of copper and many plant extracts gave positive results.As regards these last, it is to be remembered that the reaction is characteristic of enzymes; but fortunately in practice, for reasons already suggested, these do not usually interfere with the test. Decoctions of leather, flannel (both old and new), and some kinds of filter-paper, were all negative.Four varieties of leather were tried, including oil, bark, and chrome tannages. Eleven kinds of filter-paper were experimented with, the best of all being Dreverhoff’s ashless 400. Wheat and maize flour contained enzymes, and gave no colour with guaiacum solutions alone, but gave the blue colour with hydrogen per- oxide. One part of copper sulphate in 10,000 was found to be negative, while 1 in 1,000 and 1 in 100 were positive; but it is inconceivable that distilled water would contain these latter amounts.Reactions with Washed Bloodstains.-The experiments tabulated on p. 188 show that the guaiacum test will reveal the presence of a bloodstain that has been thoroughly washed. It is not probable that clothing could be thoroughly washed within five minutes of a murder, so that Experiment 4 indicates the probability of the detection of a washed bloodstain by the guaiacum reaction.There are few, if any, stains except blood which will reaot to guaiacum after thorough washing. With a washed garment, therefore, a positive guaiacum reaction is highly characteristic of the presence of blood. The test does not, of course, indicate human blood; but the possibility of any other source is frequently excluded by other considerations, the very fact of clothing having been washed being suspicious in certain circumstances.Spring waters will react if they contain ferric chloride. Distilled water containing copper is mentioned by Sutherland. GOVERNMEET LABORATORY, TP.INID$D, B. w-. I. DISCUSSION. Dr.WILLCOX said that this paper was an interesting one, and put very fairly the position that the guaiacum test was entitled to hold. It was a very delicate test, but its delicacy depended upon the reagents being good-the guaiacum must be fresh and the peroxide pure and of the proper strength. As Mr. Shrewsbury had mentioned, it could only be regarded as a sorting test, not capable of proving with certainty that blood was present ; but there was a very strong presumption as to the presence of blood if the reaction was given quickly, this being the most important point.Some of the fine distinctions mentioned in the paper did not always hold good in actual practice. In medico-legal work the articles to be examined were often in a very dirty condition, and themselves yielded coloured solutions, so that the only thing that really enabled one to decide was whether a blue colour was given quickly or not.HeI90 KINGZETT AND WOODCOCK : could not quite agree with Nr. Shrewsbury’s observation that the reaction was not given quickly by any substance but blood. He had frequently found that in the case of boots which were very dirty, and perhaps covered at the bottom with a sort of manure, including pieces of straw, grass, etc., the guaiacum reaction was given by the deposit on the soles almost as quickly as in the caee of blood, although probably no blood was present.He ought perhaps to say that he had almost given up using the gusiacum test for medico-legal work, because he had found the recently introduced benzidine test to be more delicate and reliable as a sorting test, The reagent was a, saturated solution of benzidine in glacial acetic acid, diluted with four times its volume of 10 per cent.hydrogen peroxide. When this mixture was placed upon a, bloodstain, a magnificent blue colour was produced, like that obtained in the guaiacum test, but deeper. The benzidine test had the advantage over the guaiacum test that the reagents were not so liable to go wrong, but caution was necessary in regard to one point-namely, that the hydrogen peroxide must be perfectly pure and must con- tain no free acid. Of course, as Mr. Shrewsbury had pointed out, the indications of such preliminary tests must be confirmed by spectroscopic examination, by obtaining haemin crystals, and, if possible, by the application of the serum test to ascertain from what animal the blood came ; but when the articles to be examined were numerous the utility of these preliminary sorting tests was obvious. I t sometimes happened that, owing to the minuteness of the quantity of material available, only the guaiacum or benzidine tests could be applied, and in such cases the evidence must remain corres- pondingly doubtful, unless there were other circumstances to confirm the indications of the test. c B . P @ @ @

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DOI:10.1039/AN913380186b

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年代:1913

数据来源: RSC

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I90 KINGZETT AND WOODCOCK : THE BACTERIAL TESTING OF DISINFECTANTS : A PRACTICAL CRITICISM. BY C. T. KINGZETT, F.T.C., AND R. C. WOODCOCK, F.I.C. (Read at the Meeting, March 5, 1913.) IN our paper (Pharm. J., 1910,85,157) on Bacteriological Testings of Certain Disin- fectants, and the Results as affected by Varying Conditions ” of time and temperature, we clearly demonstrated by experiments the fact that, while the Rideal-Walker test is serviceable for ascertaining the comparative germicidal values of coaEtar disinfectants under the particular conditions of that test, it is perfectly useless for determining the real disinfectant values of these and other preparations for practiczal application. For example, if peroxide of hydrogen of so-called 10 volumes strength, and formaldehyde of about 40 per cent.strength, be severally examined under the ordinary conditions observed in conducting that test, it appears that they are both of insignificant value as disinfectants, whereas it is a matter of common knowledge and beyond dispute that for many applications they are, in fact, more valuable than pure phenol and some of those other coal-tar preparations which, being peculiarly amenable to the Rideal-Walker test, appear in the light of that test to be superior.THE BACTERIAL TESTING OF DISINFECTANTS Boric acid ...C h r om i c acid, CrOs (anhydride) Nitric acid ... Sulphuretted hy- Hydriodic acid ... Hydroohloric acid Sulphuric acid ... Sulphurous acid drogen Bleaching powder Bromine ... ... Chlorine ... ... Iodine ...... 191 100 grms. of water at 20" C. dissolve A saturated solution a t 18" C. containe 4 grms. of the acid 62.45 per cent. - - - 100 C.C. of water at 20" C. dissolve 0.4 grm. - Available chlorine, 32.6 per cent. (A clear solution was used.) A solution was made in distilled water; it contained 3 per cent. of bromine. A saturated solution a t 25" C. is said to contain 3.07 to 3-48 per cent.of bromine A solution was made in distilled water; it contained 0-22 per cent. of chlorine. A saturated solution at 25" C. is said to contain 0.641 per cent. of chlorine A solution in distilled water was used containing 0.023 per cent. of iodine. A saturated solution at 25O C. is said to contain 0.0279 to 0-034 per cent. of iodine TABLE. I ... ... ... ... ... ... ...... ... Name. - Using a solution known to contain In another experiment ... ... Very soluble ... ... ... ... 100 grms. water at 20' C. dissolve Very soluble ... ... ... ... 100 C.C. of water at 20° C. dissolve 0.263 grm. per 100 C.C. (i.e., saturated at 18°C.) - - 1-11 grms. - 0.18 grm. General Remarks. I Acetic acid Benzoic acid Citric acid Formic acid Lactic acid Picric acid Prussic acid P yrogallol Salicylic acid Dilution required to kil B.Typhosus i an average of 73 minutes at 16O to 18" C. - 1 : 300 1 : 350 1 : 800 1 : 650 1 : 750 - 1 : 1,350 1 : 6,000 1 : 5,000 1 : 20,000 1 : 16,000 1 : 40 1 : 380 - 1 : 4 1 : 150 1 : 170 1 : 500 1 : 50 1 : 40 - Coefficient calculated upon the original material, unless otherwise stated. Nil 3 3.5 8 6.5 7.5 Nil 13.5 60 50 200 160 0.4 3.8 Nil 0 -04 1-5 1.7 5 0.5 0.4 Nil192 KINGZETT AND WOODCOCK : Name.Tannic acid . # Tartaric acid . I Borax crystals ... Copper sulp hat e crystals Ferric chloride ... Ferrous siilphate Mercuric chloride crystals Potash alum ... Potassium bichro- mate crystals Potassium bisul- phate Potassium per- manganat e Potassium per- mangenate Zinc sulphate ... Sodium bisulphite Sodium carbonate Sodium fluoride... Zinc chloride ... Zinc s u l p h a t e crystals Copper benzoate Copper formate ... Lead a c e t a t e Mercuric cyanide crystals Ortho-oxalic acid ester of phenol Quinine bisulphate Sodium salicylate General Remarks. Very soluble ... ... ... 1 ) ... ... ... Y! 100 grms. of water at 21*5O C. dissolvf 2.8 grms. of the anhydrous salt 100 grms.of water at 20" C. dissolve 20.7 grms. of the anhydrous salt No sharp reading obtainable 100 grms. of water at 20° C. dissolve 26.4 grms. of the anhydrous salt No sharp reading could be obtained. Sulphuretted hydrogen water wa8 added to the broth tubes 100 C.C. water at 15" C. dissolve 9.6 grms. A saturated solution at 20" C. con- tains 12 per cent. of the salt - 50 per cent.50 per cent. } . . . . . . ... .. 100 grms. of saturated solution at 18" C. contains 4.3 grms. LOO grms. of water at 15" C. dissolve 50.88 grms. of the anhydrous salt Very slightly soluble in water 9 saturated solution equals 1 in 8 of LOO grms. of water at 25" C. dissolve LOO C.C. of water dissolve 8 grms. at water 50 grms. of the anhydrous salt 15" C. .OO grms. of water at 25" C.dissolve 11.77 grms. Jery soluble ... ... ... ... Dilution required to kil B. Typhosws i i an average of 7+ minutes a t 1tio to 18" C. 1 : 14 1 : 5 - Up to 1 in 3( 1 : 8 - 1 : 1,500 to 1 : 2,000 - 1 : 15 1 : 450 1 : 6,000 1 : 1,500 - - - 1: 17 - - 1 : 10 - 1 : 200 1 : 520 - 1:Ei to 1: 10 Coefficient calculated upon the original material, unless otherwise stated. 0.14 0.05 Nil Nil to 0.3 0.08 Nil 15 to 20 Nil 0.15 4.5 60 15 Nil Nil Nil 0.17 Nil Nil 0.1 Nil 2 5.2 Nil 0.05 to 0.1THE BACTERIAL TESTING OF DISINFECTANTS Name.Strychnine sul phate Zinc benzoate .. Zinc boro-diortho hydroxy- benao. ate Zinc formate .. Zinc hydrogen bo. rodisalicylate . . Zinc salicylate .. Zinc sulpho. carbolat e Ammonia (NH,) Caustic soda .. Lime, slaked .. Lime-water (satu- rated) Aniline ...Nicotine . . . Pyridine . . . Strychnine . . Alcohol C,H,O H Ijr-naphthol . . Camphor. . . Chloral hydrate.. Chloroform . ., Eugenol ... F o r m a l d e h y d e (38-5 per cent.) General Remarks. Water dissolves 3.2 per cent. ... Very slightly soluble in water , .. Not very soluble in water ... ... 1 part dissolves in 24 parts oE water Fairly soluble in cold water .. . ... Soluble to about 2 per cent. in cold water Soluble in 2 parts of water . . , ... Tested directly in suspension . , . 100 grms. of water a.t 20" C. dissolve 0.125 grm. of CaO 100 C.C. water dissolve 3.481 C.C. Soluble in water in all proportions . . . German Government quality distill- ing 50 per cent. at 140' C., 90 per cent. at 160" C. Water dissolves 0.02 per cent.. . . aniline - A solution containing 5 per cent. of soda and 5 per cent. of p-naphthol was used, the coefficient likely to be due to the soda only Coefficient of the solution ... But coefficient calculated on the 1 part dissolves in 700 parts of water A saturated water solution was used ; 100 C.C. of water at 17.4" C. contain 0.71 grm. of chloroform Only slightly soluble in water .. . original P-napht hol Very soluble ... ... ... ... - Dilution required to kill B. Y'yphosus in an average of 7$ niinutes a t 16" to 18" C. - - 1 : 300 - 1 : 400 - 1 : 2 to 1 : 5 1 : 50 1 : 1,400 1 : 450 - 1 : 55 1 : 20 1 : 38 - 1 : 3 1 : 56 1 : 1,120 1 : 9 - - 1 : 900 1 : 35 193 Coeflicien t calculated upon the original material, unless Itherwise stated, Nil Nil 3 Nil 4 Nil 0.02 to0.05 .0.5 34 4.5 Nil 0.55 2.0 0.38 Nil 0.03 0.56 11.2 Nil 0.09 Nil 9 0.35194 KINGZETT AND WOODCOCK : Nsmc. Guaiacol ... . . I Hydrogen per- oxide Hydro-naphthol.. . Iodoform ... Menthol ... Nethylene blue (double zinc Resorcinol ... Sulphur, flowers salt) of Thyme oil (red oil of origanum) Thymol ... ... General Remarks. Soluble in 80 parts of cold water 10 vols.... ... ... ... ... The same results were obtained as 100 C.C. water at 25' C. dissolves Almost insoluble in water ... ... Soluble in about 30 parts water ... with P-naphthol above 0.01 grm. Very soluble ... ... ... ... Moistened with alcohol and an 8 per cent. solution of gelatin used instead of water to suspend it I n making the test, the oil was mixed with water and well agitated 1 part dissolves in 1,500 parts of cold water Dilution required to kill B.Z'yphosus in an average of 74- minutes a t 16" to 18" cl. 1 : 200 ' 1 : 4 1 : 30 - 1 : 2,800 1 : 2,400 Coefficient zalculsted upon the original material, unless therwise stated. 2 0.04 Nil Nil Nil 0.3 Under 0.1 28 24 The solubilities of substances given above have been taken from various books of reference.This criticism applies equally to the several modifications of the Rideal-Walker test as advocated by the Lancet and others. Illustr,ative of this conclusion, our experiments showed that one coal-tar disin- fectant, having a Rideal-Walker coefficient of 4, exhibits a higher value than another possessed of a Rideal-Walker 20 coefficient when examined by the Martin and Chick method of testing.Since then we have determined the Rideal-Walker coefficients of a great number of chemical substances, all of which are known to be possessed of either oxidant, antiseptic, disinfectant, preservative, corrosive, or lethal properties, and the results fully confirm our earlier conclusions, and suffice to establish the perfectly unreliable character and extremely limited capacity of the Rideal-Walker test for ascertaining the real disinfectant value of sanitary preparations.It will be observed that the halogens, chlorine, bromine, and iodine, in the pure state, have phenomenally high coefficients, while borax, boric, salicylic and benzoic acids, the sulphates of iron, copper, and zinc, acetate of lead, the chlorides of iron and zinc, and strychnine, have little or novalue in the light of this test, an obviously erroneous condemnation of value which is also shared by lime-water, menthol, iodoform, nicotine, camphor, chloroform, sodium fluoride, sodium bisulphite, and quinine bisulphate.THE BACTERIAL TESTING OF DISINFECTANTS 195 Again, the powerful oxidising agent, chromic acid, according to this criterion, has but the comparatively small coefficient of 3.Nicotine, prussic acid, and strychnine-three of the most lethal agents known to science-would appear to be practically devoid of the power to kill the common typhoid bacillus, and even mercuric chloride, which has in the past been generally credited with the highest germicidal power, is made to appear of smaller value than many coal-tar preparations when tested as described.Curious to relate, potassium permanganate, which is known to be a powerful oxidising agent, comes out with twenty times the value of chromic acid, while peroxide of hydrogen, which is a valuable disinfectant and oxidising agent, is made to appear possessed only of the paltry coefficient 0-04. The case of benzoic acid is worthy of a little special attention, bearing in mind more particularly the extent to which it is employed as a food preservative. I t is but slightly soluble in water, and, using a saturated solution in our investigation, it appeared in one experiment to be devoid of bactericidal value, whilst in a second test it gave a coefficient of 3.8.According to Rideal, it has a, coefficient of 5, but how this was determined is not known by us.I n any case, it is remarkable that on the one hand by the same test the same substance is made to have about four times the value of pure phenol as a germicide, while on the other it is made to appear valueless. What can be thought of a test that gives such divergent results? I t is also of some interest to note that according to the Rideal-Walker test as applied by us, sulphate of copper, which has always been regarded as a germicide of some value, and which is often used very successfully for the purification of water- supplies, is almost devoid of germicidal value.The truth is that the Rideal-Walker test has been credited with the most exaggerated capability, while it ignores the existence of chemical actions and con- ditions-in short, that ‘‘ total environment,” which is of the highest importance if proper appraisement is to be made of so many different articles which are known to exercise their chemical, bactericidal, and other actions in so many diverse ways.In the Rideal-Walker method the typhoid bacillus is generally employed as the test organism, but other organisms may, of course, be, and are often, used, and the results obtained, using these different varieties, vary very much ; in other words, the ratio of the killing power between carbolic acid and the disinfectant-the subject of test-varies to an enormous extent, Other investigators have already pointed this out, as illustrated by the following quotation from ‘‘ The Bacteriological Examination of Disinfectants,” by W.Partridge (1907) : ‘‘ Most disinfectants show diff’erent co- efficients when tested against different organisms. For example, a well-known dis- infectant has the following carbolic acid coefficients for the organisms specified : ... ... ... ... ... ... 11.0 9.3 B. typhosus Staphylococcus pyogenes aureus ... ... ... B. pestis ... ... ... ... ... ... 34-0 B. tuberculosis ...... ... ... ... ... 11.0 B. dysenteria ... ... ... ... ... ... 10.0 B. diphtheria ... ... ... ... .. ... 20.0 Vzbrio cholera ... ... ... ... ... ... 32.3 B. mallei ... ... *.. ... ... ... 15.0 ”196 KINGZETT AND WOODCOCK : That is to say, this particular disinfectant could be advertised as having it coefficiency of 9.3 or any of the other figures up to 34. It is further to be noted that the relative coefficients of a number of disinfectants in respect of the same individual organisms vary throughout the series.The Rideal-Walker test, then, stands condemned as a measure of value of dis- infectants aa a class, and the only gauge of utility of the various disinfectants available for public and sanitary employment is the extent to which, as shown by experience, they may be satisfactorily employed for the particular purposes for which they are advocated.If for foods, etc., preservative action be required, benzoic acid, borax, boracic acid, salicylic acid, and so forth, are available. If destructive action by oxidation be desired, peroxide of hydrogen, chromic acid, the manganates, permanganates, chlorine, etc., can be usefully employed. If coagulative effect be desired, carbolic acid, alum, and many other substances may be selected.If antiseptic action be the desired object, chloride of zinc, the sulphites and bisulphites, benzoic acid and the benzoates, will serve with others. If sterilisation by fumigation be aimed at, formaldehyde and burning sulphur in association with aqueous vapour will fully answer requirements. As to the first- named of these two substances, we have shown in our previous investigation that although formaldehyde exhibits a nominal Rideal- Walker coefficient of only 0.35, it shows a superiority of germicidal value in comparison with phenol when sufficient time be allowed and at a higher temperature. For example, in one and a quarter hours, at 15' to 18' C., it has almost the same killing power over B.typhosus as carbolic acid, and in one and a quarter hours at 37" C., 1 part in 550 of the 37 to 39 per cent. solution kills as compared with 1 in 320 of carbolic acid; in other words, the coefficient of formaldehyde then becomes 1.8 as compared with carbolic acid coefficient 1. As to burning sulphur, its utility is supported incidentally by our test, showing sulphurous acid to have the coeficiency of 13.5.For purification of the air, antiseptic washings of wounds, etc., and general sanitary requirements, many other preparations are available. It is worthy of observation that the Special Sanitary Commissioner of the Lancet (October 19, 1912), in his report concerning the International Congress of Hygiene and Demography, recently held at Washington, expressed the view that the chief difficulty experienced by the Congress was to the effect that '' the immense majority of members did not in the least understand what these labours should have aimed at," and this would certainly appear to be the case in respect of at least one of the resolutions which was passed thereat in the following terms : '( That the disinfectants used in different countries should be controlled by a simple bacteria test, capable of being easily effected, and that a Committee from this Congress confer with the Committee of the International Congress on Applied Chemistry to define such test." At any rate, this resolution has nothing but an abstract value, and even that is destroyed by the practical results of our investigation, as reported in this communi- cation, in view of which it is inconceivable that any such test can be devised.THE BACTERIAL TESTING OF DISINFECTANTS 197 I t may be noted that the coefficients of some of the substances referred to in this investigation have been previously determined by others (“A Dictionary of Applied Chemistry,” Thorpe, vol.ii., 1912, p.263), and the following table gives the results side by side with our own in those cases where they agree : Name. ... Absolute alcohol ... ... ... Acetic acid ... ... ... ... Boric acid ... ... ... ... Formaldehyde ... ... ... Lactic acid .I. ... ... Pyrogallol ... ... ... ... Resorcinol ... ... ... ... Zinc chloride ... ... ... ... ... ... ... ... ... ... Thorp’s Dictionary.Less than 0.1 0.6 Less than 0.1 0.55 1.8 0.22 0.3 0.15 Our Determination. 0.03 0.4 Nil 0.35 1-7 0.4 0-3 0.17 An important feature of our investigation is that all the determinations of coefficient value were made by the same investigators working in the same laboratory under absolutely identical conditions. We have pleasure in expressing our acknowledgment of the practical services given to us in this investigation by our assistant, Mr.J. E. Brimley, B.Sc. DISCUSSION. The PRESIDENT having invited discussion- Mr. W. PARTRIDGE said that, although the Rideal-Walker test had been subjected to a great deal of criticism, in his opinion it would still be found to be the most reliable for most cases. Since it was brought forward, however, a good deal more had been learned about B.typhoszis, and particularly the fact that this organism varied greatly in its power to resist the action of disinfectants. Indeed, there were so many varieties of it that it was not surprising that, even in the hands of the same worker, different coefkicients should be given by organisms from different sources. In view of this he had sometimes wondered whether it would not be better to use another organism.It might be noted that some of the substances included in the authors’ present in- vestigation were hardly of the nature of disinfectants. Iodoform, for instance, was a substance which it was perhaps hardly fair to test by the ordinary methods. I t became active, only when actually in contact with the surface to which it was applied, and its action was no doubt due bo the iodine liberated from it.The results recorded in the authors’ table, however, appeared to indicate that it had no disinfectant action at all. Mr. F. W. RICHARDSON said he had always found the great difficulty to be in regard to the nature of the bacterial culture used. B. typhosuus varied a great deal in character, and, as Mr. Partridge had indicated, it was almost impossible to get concordant results unless one could use a perfectly stable organism.He himself198 KINGZETT AND WOODCOCK : should prefer to use B. coli communis, and he suggested that an attempt should be made to ascertain what culture medium was best calculated to insure concordant results when this organism was used for such tests. Mr.CHASTON CHAPMAN asked whether the authors intended to draw any, and if so, what, distinction between antiseptics and preservatives. He noticed, for instance, that sulphites and bisulphites were not placed in the category of food preservatives, for which purpose they were, in fact, somewhat extensively used. If this was to be taken to mean that those substances had any marked bactericidal properties, he thought the authors were scarcely correct, as unless used in excessive proportions, they were only capable of acting as preservatives.Mr. RICHMOND thought that the fact that there were so many varieties of B. coli would militate against the adoption of Mr. Richardson’s suggestion. Mr. J. GOLDING said that his colleague, Dr. Williams, was in favour of the use of dried fzces rather than cultures of B.coli or 23. typhosus alone. Cultures of these organisms were not really very constant, and in using a material containing organic matter the conditions under which most preservatives and disinfectants were required to act would be more nearly approached. The PRESIDENT said that he felt some hesitation in contributing to the discussion, since the subject was of such a special character, and one with which he had only occasionally to deal; but he should like to ask why raw sewage should not be used for the purpose of these tests ? Whenever he had had to compare the action of one disinfectant against another, he had always used raw sewage, and the results obtained seemed to him to be just as good, from a comparative point of view, as were obtained when a specific organism was used.Dr. RIDEAL said that at the Washington Congress there were two debates on the testing of disinfectants, one in connection with the International Congress of Applied Chemistry, and the other in connection with the International Congress of Hygiene and Demography. The discussion in the chemical congress resulted in the formation of a committee, including representatives of France, Germany and America, with himself as the English representative, their instructions being as stated by Mr.Kingzett and Mr. Woodcock. Amongst the tests that had already been devised were the Rideal-Walker test, the test devised at the Lister Institute, and also the test devised by Dr. Sims Woodhead (the Lancet Commissioner) and Mr.Ponder. The Lancet test, however, after the discussion that took place at the British Pharmaceutical Conference at Cambridge, had not been heard of any more. Work had since been done on the subject in Smerica, and Dr. Anderson, the head of the Bureau of Hygiene at Washington, in conjunction with Dr. McClintick, had devised a new test which was a sort of compromise between the Lancet test and the Rideal-Walker test.The results of the application of this test to all the disinfec- tants on sale in America were published as a bulletin of the Bureau of Hygiene, and were under discussion just before the two International Congresses met. Unfortu- nately, however, the death of Dr. McClintick, the worker who was best acquainted with the technique of the test, prevented its full discussion.As to whether B. typho- szis or B. coli should be used, the amount of experience now available was greater with B. typhosus than with B. coli, and he thought the variations were less in theTHE BACTERIAL TESTING OF DISINFECTANTS 199 case of B. typhosus than in the case of B. coli. I t was certainly true that in the Lancet test, using tbe McConkey medium, it was easy to see whether the B.coli was alive or not, but E. coli was open to great objection on account of its being SO common. Accidents with B. coli were not at all unlikely, and, seeing that the organism was subject to great variations in strain, he should certainly advocate the continuance of the use of B. typhosus. He thought the authors would agree that a bacterial test, after all, did not really indicate whether proper disinfection was taking place.For this it was necessary to supplement the bacterial test by determining the chemical change. I n the course of the Lancet inquiry, some attempt was maae to show that that test had a direct relation to the chemical composition of the disinfec- tant, and the formula ~- - - Lancet figure was put forward.But in his criticism of that suggestion he had shown that, while an infinite disinfecting power would be assigned to carbolic acid, that assigned to tribromophenol would be nil. He agreed, however, with the present authors that the oxidising power of the disinfectant must be taken into consideration-i.e., not only the bactericidal effect, but the effect on the environment of the organism.He thought that the most remarkable fact brought out by the recent work on this subject was that, whichever test was used, the halo- gens invariably showed a very high coefficient, chlorine being, according to all the methods, the pre-eminent bactericide. The utility of bleaching powder and the hypochlorites in the sterilisation of water was now recognised, especially in America, where in many large cities the use of these agents was solely relied upon for main- taining the purity of the water-supply, while the use of bleaching powder, or of chlorine itself, for sterilising sewage effluents before their discharge into rivers, was also very extensive in America; so that the indications given by these bacterial tests as to the germicidal value of chlorine compounds had been fully borne out by the results of practical application on a large scale.Mr. E. K. RIDEAL said that Konig had shown that the acids, when subjected to a disinfecting test, showed coefficients varying according to their degree of ionisation, etc., thus bearing out the observations of the authors. The real question in these cases was whether the reaction was that of the substance itself or of its ions.In the case of phenol, the substance itself reacted, probably forming an emulsion; but in the case of, say, salicylic acid, which became partly ionised in solution, it did not seem right to assume that the salicyl ion would act upon an organism in the same manner as phenol, which was not necessarily ionised in solution, and this was no doubt the reason for the anomalous values shown by salicylic acid and benzoic acid and other compounds containing ions in solution.Substances which formed emulsions could no doubt be tested quite well by means of dried fzceg, but substances that were ionised in solution would be at a disadvantage, as the ions would be dis- charged on coming in contact with the small suspended particles contained in such a medium. The Rideal-Walker test itself did not treat several oxidising agents quite fairly, because many oxidising agents spontaneously discharge their ions, even in the absence of organic matter.A saturated solution of ozone, for instance, would be decomposed when it cameinto contact with glass beads, or even with the sides of the vessel itself.If ozone were brought into contact with micro-organisms, two actions 3200 TEE BACTERIAL TESTING OF DISINFECTANTS would take place, the organism being destroyed to a certain extent by the ozone, while at the same time on the surface of the organism the ozone would be catalyti- cally decomposed. So that two distinct methods of testing were redly needed, the one against an inorganic colloid and the other against the living organism itself, the two factors-namely, the ionic reaction and the coagulant (or rather surface tension) reaction-being made use of.Mr. PARTRIDGE desired to add that, when he suggested the use of an organism other than B. typhosus, he was not thinking of B. coli. The liability of the latter to variations was well known, and he thought that the first step towards the improve- ment of bacterial tests should be to ascertain what organism was least likely to vary.Both B. typhosus and 23. coli did vary, and very often to an extent suficient to upset the results. Mr. WOODCOCK said that iodoform had been included because it was used extensively as a surgical dressing, its action being at any rate antiseptic; and the table, of course, included other substances which had antiseptic properties, but which were not generally used as disinfectants.He did not think that the use of B. typho- suus afforded any ground for complaint, provided that the growth was satisfactory- and if anything were wrong in this respect it would be at once detected by anyone experienced in the use of the test. But special experience in the details of manipula- tion was of course essential. With regard to the use of the terms (( antiseptic ” and “ disinfectant,” they had used the term L L antiseptic ” as denoting not actual killing power, but merely the restraining of growth or prevention of decomposition. They regarded ‘‘ antiseptic ’’ and cc preservative ’) as having practically the same meaning. Mr. KINGZETT said that there was no intention on their part merely to attack the Rideal-Walker test. They agreed with Mr. Partridge that there was a great deal to be said in its favour up to a point, and there was no doubt as to its being the best test yet available for determining the relative value of coal-tar disinfectants. But they did say that it was of little value in the caae of preparations outside that class, because, owing to questions of environment, the substances were not really amenable to the test, seeing that no regard was had to chemical and physical conditionfl, which, as Mr. E. K. Rideal had pointed out, wereof soniuch importance in connider- ing this subject. The question of the use of facces instead of R. tpphosus had been discussed again and again, but if there was one substance more variable than another it was faxes, and it was the last thing that one would expect to give satisfactory results in a test of this kind.

ISSN:0003-2654    

DOI:10.1039/AN9133800190

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

COCOA BUTTER AND “ GREEN BUTTER ’’ 201 A SIMPLE TEST FOR DIFFERENTIATING BETWEEN COCOA BUTTER AND ‘‘ GREEN BUTTER.” BY CECIL REVIS AND E. RICHARDS BOLTON. (Bead at the Meeting, April 2, 1913.) As at the present time products of varying composition known as “ green butters ” are frequently used as cocoa butter substitutes, and so may be found in chocolates either alone or, more generally, mixed with ’genuine cocoa butter, a reliable method of distinguishing these fats, or detecting them in the presence of one another, is necessary, and more particularly so on account of the extreme and Jsnally exact similarity of the analytical figures of these fats to genuine cocoa butter.I n addition to the analytical figures, these butters also conduct themselves like cocoa butter towards Bjorklund’s test and other solubility tests so nearly that they do not admit of differentiation.As the authors feel that this difficulty may have pressed as heavily on some other analysts as it has on themselves, they venture to put forward the following method, which has been of great assistance to them; though, on account of the great varieties of ( 6 green butter ” which occur, they feel a certain amount of diffidence in regard to its universal application, though believing that in the majority of cases it will give information which cannot be obtained in any other way.I t must be clearly under- stood that this test is not intended to supersede the determination of the ordinary analytical constants, but is to be used in those cases in which the analytical results fail to indicate fats other than cocoa butter.The test is really a modification of one published by Halphen (J. Pharm. Chim., 1908, 28, 345). The test as described by him is as follows : One grm. of the abso- lutely clear filtered fat is dissolved in 2 C.C. of carbon tetrachloride; to 2 C.C. of this mixture is added a solution of bromine in carbon tetrachloride (made by adding bromine to an equal volume of carbon tetrachloride) drop by drop until the colour of the bromine is just permanent; to the mixture are added 3 C.C.of petroleum (sp. gr. 0-700), and the tube stoppered, and allowed to stand twenty-four hours at ordinary room temperature. Halphesl states that under these circumstances a solution of COCOR butter remains perfectly clear, whilst “green butters ” give a flocculent precipitate, and that in this way 5 per cent.of “green butter ” can be detected in cocoa butter. The authors’ experience of this test has not been satisfactory, as several ‘( green butters ” gave practically no precipitate at all. It was noticed, however, that on the addition of the bromine to the solution of cocoa butter in carbon tetrachloride, the mixture immediately became turbid, while with ‘( green butters ” it remained perfectly clear, and that this turbidity was not soluble in petroleum ether, whereas it is in the petroleum suggested by Halphen.202 REVIS AND BOLTON: SIMPLE TEST FOR DIFFERENTIATING By making a slight modification in the fat solvent, etc., we have found that this method will absolutely differentiate between “green butters ” (at least in the case of the many that we have tried) and genuine cocoa butter, and will detect the presence of 10 per cent.of cocoa butter when mixed with “ green butter.” The modified test is as follows : One grm. of the clear filtered fat is dissolved in 2 C.C. of a mixture of equal parts of carbon tetrachloride and petroleum ether (distilling below 40” C.), and 2 C.C.of this solution are placed in a test-tube about 6 inches long and 4 inch in diameter. This tube is cooled in water, and the solution of bromine in carbon tetra- chloride (see above) added drop by drop, with constant shaking, until the colour of the bromine is permanent. The greatest care must be taken that only one drop in excess is allowed.The tube is then corked and allowed to stand. If, after the expiration of fifteen minutes, the solution is perfectly clear, cocoa butter is not present, or there is less than 10 per cent, If the solution shows any turbidity, the presence of cocoa butter is indicated, except in the case of one-somewhat rare- cocoa buttek substitute obtained from a species of Gutta nut. This one exception, however, does not give quite the same turbidity as cocoa butter, and can easily bo distinguished as described below.The method can be made roughly quantitative by making mixtures of cocoa butter and some solid fat of low iodine value (such as cocoanut oil or cocoanut ‘ 4 stearine ” if an actual ‘( green butter ” is not to hand), and comparing the turbidities produced by these mixtures and tho sample under examination.After the turbidity has been compared, 2 C.C. of petroleum ether are added to the tubes, which, after mixing by inversion, are allowed to stand all night, when the cocoa-butter turbidity settles out as a very fine canary-coloured precipitate, easily distinguished from the slight flocculent precipitate which “ green butters ’I under these circumstances usually throw down.I t is to be also noted that cocoa butter is completely soluble in the carbon tetrachloride-petroleum-ether mixture in the strength given above, whereas (‘ green butters ” usually become turbid almost immediately, and on standing for two hours usually throw down a considerable precipitate. Care must therefore be taken that the solation used for the test is quite clear.The fat mentioned above, which might possibly be mistaken for cocoa butter, may be distinguished from true cocoa butter as follows: The solution of the fat, after treatment with the bromine, is allowed to stand for fifteen minutes, and the turbidity is then carefully examined by transmitted light. The turbidity due to cocoa butter is absolutely non-flocculent, arid any appearance of flocculent particles is characteristic of this other fat.If now to the brominated solution are added 2 C.C. of petroleum (fraction of motor spirit distilling between 90” and looo C.) and the whole mixed, any turbidity due to cocoa butter entirely dissolves, whilst the turbidity due to this other fat remains quite insoluble. By this means 5 per cent.of this fat may be detected in admixture with 95 per cent. of cocoa butter or “ green butter.” More than 10 per cent. of this fat produces such a heavy flocculent precipitate that it could not possibly be mistaken.BETWEEN COCOA BUTTER AND “ GREEN BUTTER ” 203 DISCUSSION. Dr. DYER asked what were the names of the seeds that yielded green butter.” Mr. A. E. PARKES, referring to the authors) observation that samples of cocoa butter did not invariably react with Halphen’s test, suggested that possibly this difference might be due to variations in the composition of samples from different countries.From the authors’ description of the reaction it seemed as though the precipitate were probably a bromine compound of a, similar nature to that obtained in the hexabromide test.The PRESIDENT asked what was the cause of the colour of “green butter.” Mr. BOLTON said that he did not know exactly what the green colour was due to-it was probably chlorophyll-but there were on the market so-called “ green butters ” which consisted entirely of other fats coloured with an aniline dye. The colour of ‘‘ green butter ” was now, however, frequently taken out in refining, and some of the tasteless products now sold were either colourless or coloured yellow.The origin of the substance was somewhat of a manufacturer’s secret, but it was a type of vegetable tallow. The particular type of vegetable tallow that was con- sidered to be the most suitable was now rather scarce, but would probably be more abundant in the near future.The fruit was obtained from the trees only about once in three years. Mr. REVIS said that the great difficulty in this matter lay in the fact that many cocoa butter substitutes were not cocoanut-oil products. This test, based on that devised by Halphen, was the only one that afforded any assistance, but it must be borne in mind that what it really did was to detect cocoa butter.They hoped that the process would be tried by others, because, although it had proved successful with such samples as they bad been able to obtain, that experience might possibly not be universal. As Mr. Parkes had mentioned, cocoa beans and cocoa varied con- siderably in composition, but in spite of this the composition of cocoa butter was fairly constant. He did not know what the turbidity was due to, but imagined that it must be caused by some action of the bromine on the unsaponifiable matter.Mr. BOLTON remarked that ‘‘ green butter” was liable to vary a good deal in composition, because if there were not enough of the kind of fat usually used other fats would be added, He had known shea-nut “stearine ” to be sold as ( ( green butter,” but that would be readily detected in other ways. He should like again to emphasise the fact that it was only necessary to apply this special test when the usual constants were exactly the same as those of cocoa butter. The PRESIDENT asked whether ‘‘ green butter” was as wholesome as cocoa butter. Mr. BOLTON said that it seemed to be perfectly wholesome and harmless, and there was no reason whatever to suppose that it contained anything deleterious, With regard to the question of its comparison with cocoa butter, it must be remem- bered that ‘‘ green butter ” was subjected to all the processes of the modern refiner and was usually tasteless, whereas cocoa butter was simply pressed out, of the beans, filtered or not, as the case might be, and clarified.

ISSN:0003-2654    

DOI:10.1039/AN9133800201

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

204 ABSTRACTS OF CHEMICAL PAPERS ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. Use of H. Rosset. FOOD AND DRUGS ANALYSIS. Miscibility Curves in the Examination of Spirits of Camphor. (Ann. Chim. anal., 1913, 18, 49-56.)-The author has extended the methods described previously by Louise (ANALYST, 1907, 32, 365; 1910, 35, 322; 1911, 36, 556) to the analysis of alcoholic solutions of camphor, and shows that it is possible to estimate both the camphor and the alcohol from the miscibility curves obtained.The alcohol is found from curves plotted from the results given by mixtures of alcohol and standard petroleum spirit, and the amount of camphor from the miscibility curves of mixtures of alcohol and nitroben zene. w. P. s. Polenske ‘‘ Difference Value ” for the Detection of Certain Animal Fats and its Theoretical Basis.A. Bomer and R. Limprich. (Zeitsch. Unter- such. Nuhr. Genussin., 1913, 25, 367-386.)-The method described by Polenske (ANALYST, 1907, 32, 382; 1908, 33, 476) is of use for the detection of beef or mutton fat in lard when the quantity of the former is not less than from 15 to 20 per cent., and the method depends on the difference in composition of the glycerides of lard and beef fat.The value is chiefly affected by the palmitodistearin present in the fats, the a-palmitodistearin of lard giving the fat a “difference value” of 18-4, whilst P-palmitodistearin is the source of the ( ( diiference value ” of 11-8 in the case of beef or mutton fat. No advantage is derived from determining the ‘‘ difference value ” of mixed glycerides which crystallise from an ethereal solution of the fats.RT. P. s. Mixed Glycerides of Palmitic and Stearic Acids Present in Lard. A. Bomer. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 25, 321-353.)-By repeated fractional precipitation and crystallisation of lard from ether, the author has isolated the saturated glycerides of this fat. Tristearin is not present in lard, and in tbis respect the latter differs from beef and mutton tallows.The insoluble glyceride obtained from lard is palmitodistearin and not heptadecyldistearin, as stated by Kreis and Hafner (ANALYST, 1904, 29, 259). Heptadecyldistearin could not be detected in lard. As the palmitodistearin obtained from lard differs in its melting- point and crystalline form from the palmitodistearin derived from mutton tallow, it is probable that the former is a-palmitodistearin and the latter P-palmitodistearin, Lard was also found to contain a second saturated glyceride-namely, stearodipalmitin.The lard used in the experiments yielded about 3 per cent. of a-palmitodistearin, melting-point, 68-5’ C., and about 2 per cent. of stearodipalmitin, melting-point 58.2” C.w. P. s.FOOD AND DRUGS ANALYSIS 205 Lecithin Preparations and the Estimation of Lecithin. R. Cohn. (Zeitsch. offentl. Chem., 1913, 19, 54-62 ; through Chem. Zentralbl., 1913, I,, 1129- 1130.)-The estimation of lecithin may be divided into three parts-namely, the extraction of the lecithin, its purification, and the estimation of the phosphorus in the product.For the extraction of the lecithin from 1 to 2 grms. of commercial preparations of lecithin, or from 5 to 20 grms. of a food material containing lecithin, are extracted for several hours with two successive quantities of 100 C.C. of 96 per cent. alcohol, the first extraction being carried out at the ordinary temperature and the second a t the boiling temperature of the alcohol, a reflux apparatus being used in this case.The residue is then ground up with sand, extracted once more with alcohol, and then boiled for two hours with about 100 C.C. of chloroform. When dealing with fatty substances, the chloroform extraction may be made with advantage immediately after the first extraction with cold alcohol. The ease with which lecithin may be extracted from a preparation depends largely on the treatment to which it has been subjected during manufacture ; prolonged heating or lengthy storage renders the lecithin less soluble, and in certain cases, the extraction with hot alcohol must be continued for, say, twenty hours, before phosphorus compounds cease to be extracted.After the alcohol and chloroform extracts have been evaporated, the residue obtained is boiled for two hours with 100 C.C.of chloroform in order to separate the lecithin from glyceryl-phosphoric acid and free phosphoric acid; the chloroform solution is then filtered and evaporated. The quantity of phosphorus in this residue is then estimated by oxidising it with nitric acid and sulphuric acid, or igniting it with the addition of magnesium oxide, or a mixture of sodium carbonate and potassium nitrate, precipitating the resulting phosphoric acid with molybdic acid solution, and converting the molybdate precipitate into ammonium magnesium phosphate in the usual way.Commercial preparations of lecithin frequently contain less than the guaranteed quantity of lecithin; the author considers that a substanco sold as pure lecithin should contain, at the least, from 90 to 95 per cent.of lecithin, and that the quantity of the latter in any preparation should be within 10 per cent. of the amount claimed by the manufacturers to be present. The quantity should be expressed as lecithin itself, and not as lecithin-albumin or lecithin-protein, as these are of variable composition, and may contain from 5 to 30 per cent.of lecithin. The author does not attempt to solve the question whether yolk of egg contains lecithin in chemical combination, but points out that, as lecithin may be almost com- pletely extracted from yolk of egg by means of cold alcohol, the presence of combined lecithin is improbable. The insolubility of lecithin under certain conditions is possibly due to adsorption by proteins.w. P. s. Effect of Boiling on the Physico-Chemical Behaviour of Human Milk, Cow’s Milk, and Buttermilk. P. Grosser. (Biochem. Zeitsch., 1913,48, 427-432.) -The experiments were undertaken to determine whether the two kinds of milk are affected differently by boiling, and if it is possible to find a difference between raw and boiled milk by physico-chemical methods. The milk, from which the cream was removed by means of a separator, was filtered through a Bechold ultrafilter by206 ABSTRACTS OF CHEMICAL PAPERS means of compressed nitrogen at 6 atmospheres. The filtrate, which was free from colloids, was examined with regard to depression of freezing-point, and nitrogen, phosphorus, and lime content. The results indicate that boiling does not aftect the freezing-point, and in the case of cow’s milk scarcely affects the phosphoric acid and nitrogen.In human milk the phosphorus and nitrogen sink considerably on boil- ing. The lime content of the ultrafiltrate of both milks diminished on continued boiling, the diminution being greater in human milk, In the case of butter milk, boiling produced no change in the values determined.E. W. Detection of Saffron in Confectionery. C. Martini. (Staz. sperim. agrar. ital., 1912, 46, 18-24 ; through Chem. Zentralbl., 1913, I., 1068.)-The finely powdered confectionery is extracted for twenty-four hours in the cold with 70 per cent. alcohol with frequent agitation. Fifty grms. of the powdered residue are then boiled for fifteen minutes with 100 C.C. of 70 per cent.alcohol under a reflux con- denser on the water-bath. After filtration, the residue is again boiled with fresh alcohol, the united extracts are concentrated on the water-bath ; it is then exhausted with ether. The extract, after evaporating the ether, is boiled with 98 per cent. alcohol, and the latter solution evaporated. The product is then tested by the well-known colour reaction for saffron, with sulphuric and nitric acids. J.F. B. Chemical Composition of Authentic Vanilla Extracts, together with Analytical Methods and Limits of Constants. A. L. Winton and E. H. Berry. (US. Dept. Agric., Bureau of Chem., Bull. No, 152.)-After a discussion of the com- mercial origin of various kinds of vanilla beans, and the processes of manufacture of vanilla extract, methods of analysis are fully described, including the determination of vanillin and coumarin by the modified Hess and Prescott method (J.Amer. Chem. SOC., 1899, 21, 256 ; ibid., 1902, 24, 1128 ; ibid., 1905, 27, 719 ; U,S. Dept. Agric., Bureau of Chem., Bull. 132, p. 109, and Bull. 137, p. 120) ; the normal lead number (Winton and Lott method, U.S. Dept. Agric., Bureau of Chem., Bull.132, p. 110, and Bull. 137, p. 120); the colour value of the extract ; the residual colour after precipita- tion with lead acetate ; and the colour insoluble in amyl alcohol (Tolman and Hillyer, BUZZ. 122, p. 206; Bull. 132, p. 90). A large number of samples of known origin were examined in the laboratory by preparing extracts from them, following the method employed by the U.S.Pharmacopoeia, in order to learn the influence of variety, grade, and length of bean on the composition of the vanilla extract. In discussing the results of these analyses (all the figures of which are recorded) it is observed that the extracts from Ceylon beans were so abnormal and variable in composition as to indicate either unusual curing or previous extraction. Vanillin.-The range in vanillin content ran from 0.11 to 0.31 grm.per 100 c.c., and is somewhat greater than has usually been thought possible ; but the figure 0.25 stated by Leach to be regarded with suspicion refers to extracts on the commercial scale and not in the laboratory. The minimum figure (0.11) waB found in Tahiti extracts prepared from undried beans.FOOD AND DRUGS ANALYSIS 207 Nomital Lead Nunzber.-The variation in this value (0.4 to 0.74) is less than that of any other constant.The constituents yielding the precipitate appear to be more easily soluble than the vanillin and the colour. This determination not only serves to distinguish a true extract from a solution of vanillin, but is also of value taken along with a coumltrin estimation as a means of detecting the presence of Tonka extract.Coloz~r Values of Extract and Lead Filtrate.-The colour is the most variable and diEcultly extractable constituent. As a means of detecting caramel, the percentage of colour left in the lead filtrate is most significant. The maximum found in these samples (excluding Ceylon) was 8 per cent. red and 10 per cent. yellow, these figures being far surpassed by caramel-coloured ex tracts.As regards length of bean, the differences found, although not marked, point to a, slight inferiority of the shorter beans. The next section deals with vanilla extracts prepared with different solvents and solvent mixtures in the laboratory, the standard solvent being 60 per cent. alcohol and sugar, the other solvents examined being (1) 60 per cent, alcohol alone; (2) 60 per cent.alcohol and glycerol; (3) 35 per cent, alcohol alone ; (4) 35 per cent. alcohol and sugar ; (5) 35 per cent. alcohol and glycerol. The 35 per cent. extracts were highly unsatisfactory, owing to the extraction of gelatinous material which clogged the percolators. With the same strength of alcohol the only noteworthy difference was found to be that the glycerol extracts were more strongly coloured, thus explaining the popularity of glycerol for commercial extracts.Standard VapiZlcL Extract.-The following tentative limits of composition for standard vanilla extract (10 grms. of beans to 100 c.c.) appear to be warranted by the results obtained : Vanillin, 0.10 to 0.35 grrn. per 100 C.C. Normal lead number, 0.40 to 0.80.Per cent. of total colour in lead filtrate, not more than 10 per cent. red, or Ratio of red to yellow in the extract, not less than 1 : 2.2. Colour insoluble in amyl alcohol, not more than 40 per cent. (Cf. 0. Folin and W. Denis, ANALYST, 1912, 37, 501.) 12 per cent. yellow. H. F. E. H. Direct Estimation of Water in Foods, etc., by Distillation. F. Michel. (Chem.Zeit., 1913, 37, 353-355.)-This method has been described previously by Aschmann and Arend (ANALYST, 1907, 32, 21) who have employed it for the estimation of water in butter and other fats, and the author now shows that it may be applied to almost all classes of foods. He recommends the use of a mixture consisting of 1 volume of toluene and 2 volumes of xylene, about 150 C.O. of this mixture being employed for 20 grms.of the substance under examination. Ordinary parafin, having a boiling-point above looo C., may also be used. The distillate is collected in a narrow graduated cylinder, and, at the end of the distillation, any drops of water remaining in the condenser may be transferred to the receiver by mean8 of a, rubber-tipped rod or feather dipped in xylene. In order that the volume of the208 ABSTICAC'l'S OF CHEMICAL PAPERS water in the receiver may be determined accurately, the contents of the receiver may be submitted to centrifugal action. A correction must be made on the volume of water observed owing to the change of meniscus caused by the hydrocarbon layer above the water layer ; for instance, if a quantity of xylene be poured on the surface of 5 C.C. of water contained in a narrow cylinder, the water will then show an apparent volume of 4.85 C.C. Consequently, 0.15 C.C. is added to the volume of water found. The author finds that a further quantity of 0.03 C.C. must be added for each C.C. of water collected in the receiver in order to allow for loss during the distillation. When these allowances are made, the error of the method is not greater than kO.2 per cent. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800204

出版商:RSC    

年代:1913

数据来源: RSC

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208 ABSTICAC'l'S OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Analysis of Human Bile. E. v. Czyhlarz, A. Fuchs, and 0. v. Furth. (Biochem. Zeitsch., 1913, 49, 120-130.)-About 30 C.C. bile are required. This is divided into three portions : for the determination of moisture, the bile pigment, and the bile acids-mucin, fatty matter, and cholesterol. The moisture is determined on 3 C.C.by drying at 100' C. until constant weight. For the determination of bile pigment, 5 C.C. are heated with 5 C.C. 10 per cent. sodium hydroxide solution on the water-bath for half an hour, whereby the bilirubin is converted into biliverdin. Thirty C.C. of 95 per cent. alcohol are then added to the hot liquid, the precipitate filtered off, and to the filtrate dilute hydrochloric acid is added drop by drop until there is a slight acidity.The clear and intensely emerald green-coloured liquid thus obtained is compared colorimetrically with a 0.02 per cent. alcoholic biliverdin solution in a Dubosq colorimeter. The third portion (about 22 c.c.) is extracted three times with ether. A small quantity of alcohol may be added to suppress emulsification, which may be very troublesome, and it is some- times necessary to wait several hours to obtain a clean separation.The extract is freed from ether, the residue evaporated on the water-bath with 20 C.C. of freshly prepared sodium ethylate solution, dissolved in water, and extracied with ether to separate cholesterol from the soaps. The ethereal layer is then evaporated, and the residue dissolved in 10 C.C. pure chloroform.Should there be any residue, it is taken up with a little water and added to the soap fraction. The cholesterol in the chloroform solution is determined colorimetrically by the method of E. Schulze (Zeitsch. physiol. Chem., 1890, 14, 503), and Grigant (Compt. rend. SOC. Biol., 1910, 68, 827), for which purpose 10 C.C. of the chloroform solution are treated with 2 C.C. commercial acetic anhydride (reaction not given by pure substance), and 10 drops concentrated sulphuric acid, shaken and allowed to stand a few minutes.This liquid is then compared colorimetrically with a 0.05 per cent. cholesterol solution treated in a similar manner. For the estimation of the higher fatty acids, the aqueous soap solution (see above) is acidified with sulphuric acid, extracted with ether, the ether extract evaporated, and the residue dried at 100" C.and weighed. This is treated Mucin is estimated in the aqueous portion of the main fraction.BACTERIOLOGICAL, PHYSIOLOGICAL, ETC, 209 with 80 C.C. 95 per cent. alcohol, and the precipitated mucin collected on a hardened filter, and washed with alcohol. If the mucin precipitate is large, it can be removed from the filter while still moist, dried at 100" C., and weighed ; otherwise the nitrogen is estitnated by Kjeldahl's method, the nitrogen content of mucin being taken as 16.14 per cent.The alcoholic filtrate is evaporated on the water-bath ; the residue, taken up in 20 C.C. water, is transferred to a large pressure bottle, decomposed with two and a half times its weight of 60 per cent.caustic potash, and the closed bottle heated for forty-eight hours in a boiling water-bath. After cooling, the contents of the bottle are transferred to a beaker, diluted with twice its volume of water, and made strongly acid with concentrated hydrochloric acid, and allowed to stand for one day. The cholic acid precipitate is then collected, washed well with water, and then dissolved from the filter by means of hot 95 per cent.alcohol. The alcoholic solution is evaporated to dryness, and the residue dissolved in a small quantity absolute alcohol, and filtered to remove any inorganic salts, and the filtrate evaporated to dryness, dried at 100" C. and weighed. The author gives numerous results obtained by the above methods with abnormal biles.E. W. Study of the Oxydation Products of Cholesterol. I. Lifsehutz. (Biochem. Zeitsch., 1913, 48, 373-410.)-The author finds that in various diseases the oxycholesterol content of the blood differs from that of the normal tissue. Thus the blood-fat of a man in a comatose condition contained no trace of oxycholesterol, whilst in cases of diabetes and syphilis the content was below the normal; and of several blood sera of insane, oxycholesterol was absent in two and present only in small quantity in the- remainder.The oxycholesterol is detected by the coloration produced on adding sulphuric acid to an acetic acid solution, and is determined quantitatively by comparing this colour spectrometrically with that produced in a, standard solution of known oxycholesterol content.The standard solution is prepared by diluting 1 C.C. of a 0.1 per cent. solution of oxycholesterol in chloroform with 2 C.C. glacial acetic acid. The material to be examined is similarly dissolved, the amount employed varying with its oxycholeskierol content ; for unsaponifiable matter the author recommends a 0.4 to 0-6 per cent. chloroform solution.To each solution 7 to 8 drops of strong sulphuric acid are added, the liquids mixed, and after standing ten to fifteen minutes, 1 to 2 drops of a 5 per cent. solution of ferric chloride in glacial acetic acid are added. The two liquids are then examined by the spectroscope, and the more concentrated solution diluted until the two liquids yield spectra of equal intensity. The oxycholesterol can be prepared by treating a solution of 2 grms.cholesterol in 100 C.C. glacial acetic acid with 2 grms. benzoyl peroxide, and boiling until the light yellow liquid assumes a slight brownish tint. The cooled liquid is poured into water, the reaction product separated, repeatedly boiled with water, and then boiled with 50 C.C. $ potassium hydroxide for forty-five minutes.The liquid is then diluted with water and extracted with ether. The oxycholesterol thus obtained is stable if protected from light and moisture, and is a suitable standard for spectrometric purposes. E. W.21 0 ABSTRACTS OF CHEMICAL PAPERS Determination of Pepsin Activity. S. V. Bogdondy. (Zeitsch. physiol. Chem., 1913, 84, 18-29.> - Sixty C.C.of a casein solution prepared by mixing 17.5 grins. casein with 250 to 300 C.C. water, adding 27.5 C.C. $ hydrochloric acid, diluting to 500 C.C. and heating to 40" C. to obtain perfect solution, are mixed with the pepsin, heated to 40" C. for a known time, and the unchanged casein precipitated by adding 30 C.C. of a reagent containing 150 grms. sodium sulphate, 50 grms. magnesium sulphate, and 100 C.C.96 per cent. alcohol per litre. The mixture is made up to 100 C.C. with water, filtered, grid the rotatory power of the filtrate measured. This rotatory power, though admitted to be not exactly proportional to, is yet a measure of, the activity of the pepsin, and the results obtained agree well with those given by known methods, E. W. Application of Precipitin Reactions to Seed Identification. Zade.(Bull. Agric. Intell. and of Plant Diseases, 1913, 4, 200-20l.)-It is not possible to distinguish, without previous cultivation experiments, a winter from a summer wheat, nor an awned from an awnless variety; the nature of the seeds of leguminous fodder crops also is only ascertained, and then not with absolute certainty, from the impurities found among them.Relander has experimented with the object of adopting the precipitin method for seed identification. The manner of proceeding is as follows: A sample of wheat, for instance, is reduced to a, fine powder and treated with a given volume of physiological salt solution. The extract is filtered and injected in small quantities, repeated at fixed intervals (three to ten days) into the blood of the animal which is the subject of the experiment.,4 small amount of the blood of the animal is then taken, the immunised serum separated by centrifug- ing, and filtered perfectly clear. On adding to the filtrate some drops of the original wheat extract, a precipitate is obtained which is not produced if extracts are injected which have been prepared from other seeds.Relander by this method found that the serum of a rabbit which had been injected with an extract of two-rowed barley reacted in the presence of a similar extract (the reaction being more energetic for the same variety than for different ones), while there was no reaction in the case of six-rowed barley. The same method rendered it possible to distinguish Italian and American clover-seed from Finnish and Norwegian, but the two latter are indistin- guishable from one another.EL. F. E. H. Biological Considerations in Relation to Seed-Testing. D. Sehaffnit. (Bull. Agric. Intell. and of Plant Diseases, 1912, 3, 2403.)-The usual method of testing seeds determines only the germinating power when placed under favourable conditions. Many seeds which will germinate are deficient in '( shooting power " (Triebkraft)-that is to say, they fail to emerge above the surface of the soil when grown at a depth of from 3 to 8 cm.Some seeds showing 100 per cent. germin- ating capacity often yielded 60 per cent. or less of shooting power, thus explaining the bad result after sowing in the field of seeds which by laboratory tests have been found faultless.Such weakness is a special characteristic of small seeds which have at their disposal a less quantity of vital energy and a proportionately smaller quantity of reserved substances. Failure to emerge from the surface of the soilORGANIC ANALYSIS 211 after germination may be due to the attacks of fusarium and other micro-organisms. Chemical substances such as sulphate of copper or formaldehyde, or excessive heating in the destruction of smut (ustilago), will also bring about a similar result. To obtain uniform results in the testing of shooting power, the following constant conditions of cultivation are necessary : (1) Regularity and uniformity of the medium in which sowing is effected ; (2) determined depth of sowing ; (3) constant quantity of water in the medium ; (4) constant temperature. The best medium was found to be coarse brick-powder freed from the fine dust by sifting. Each time before use it is heated for two hours to 150' C., then cooled, and mixed with 20 per cent. of water. Cereal seeds should be sown at a depth of 3 cm. The germinating boxes are covered with a glass bell jar, thus insuring a constant moisture content. The temperature should be kept at 1 5 O C. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9133800208

出版商:RSC    

年代:1913

数据来源: RSC

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ORGANIC ANALYSIS 211 ORGANIC ANALYSIS. Determination of Chlorides and Bromides in Organic Liquids. S. v. Bogdondy. (Zeitsch. physiol. Chem., 1913, 84, ll-l5.)-The substance is decom- posed by heating with a mixture of concentrated and fuming sulphuric acid, as used in Kjeldahl’s determinations, to which 10 grms. copper sulphate and 80 grms, potassium sulphate are added per 250 C.C. The decomposition is carried out in a flask connected with two suitable absorption vessels containing silver nitrate dissolved in 20 per cent.nitric acid. A current of air is drawn through the apparatus, and the heating continued until the residue becomes transparent and blue. The silver pre- cipitates are then treated in the usual manner. E. w. Aceuracy and Limitations of Coal Analysis.A. C. Fieldner. (Chem. Engineer, 1913, 17, 50-65.)-A paper communicated by permission of the Director of the United States Bureau of Mines, and supported by statistics from the laboratory records of that department. I t is stated that duplicate determinations of ( ( moisture ” seldom vary by more than 0.15 per cent., when the &inch mesh sample is air dried at 30’ to 40’ C., and the air-dried sample reduced to 60 mesh in a ball mill, and 1 grm.dried for one hour at 105’ C. Duplicate determinations of (‘ ash ” will agree within 0.2 per cent. if a standard temperature be adopted, but the difference between a low and a bright red heat may lead to differences of more than 1 per cent. Determina- tions of “volatile matter” made by the same analyst in the same laboratory may differ by 0.5 per cent., but between the results of different laboratories the difference may rise to nearly 3 per cent., and these wide differences most often occur on samplee of anthracite, in which the amount of volatile matter is so small that the two numbers returned may approximate the ratio of 2 : 1.With soft coals such wide differences are less common and are less serious as the figure to be returned is of the order of 30 per cent., but for anthracites the adoption of a standard tempera- ture is essential if the figures are to possess any value at all.A temperature of 950’ to l,OOOo C. is recommended for all coals. Carbon can be determined with an error not exceeding 0.3 per cent., hydrogen with an error of less than 0.05 per cent., and nitrogen within 0.03 per cent., but the212 ABSTRACTS OF CHEMICAL PAPERS value of the results of ultimate analysis as a means of calculating the calorific value is reduced by the uncertainty attaching to the figure for oxygen.This figure has to bear the sum of ail the errors incurred in the determination of carbon, hydrogen, nitrogen, sulphur, and ash. Of these errors, by far the most serious is that due to the difference between the ‘‘ ash ” as determined, and the mineral matter as it occurs in the coal.I n spite of this it is shown that the application of Dulong’s formula to true coals rarely leads to values which differ by inore than 1.5 per cent. from the values determined by the bomb calorimeter. With lignites and peat, Dulong’s formula leads to results much below the truth.The limit of accuracy of carefully conducted work with a bomb calorimeter is not put above 0-5 per cent., but it is stated that this is less than the usual error of sampling, which, without special pre- cautions, may be 1 per cent, I n the case of coal from one mine and seam, a fairly accurate calculation of the calorific value can be made from the percentage of ash and moisture in the sample under consideration, and the calorific value of the ‘‘ coal substance” of that seam of coal as determined previously.The error of such a calculation rarely amounts to 1 per cent. For the fine grinding of coal samples, the use of a porcelain ball mill is strongly recommended. The abrasion of the pebbles is negligible in its influence on the per- centage of ash (0.004 per cent.), but the porcelain cylinders suffer abrasion to an extent which makes it advisable to grind as much as 500 grms.of the sample, so as to reduce the percentage error to 0.04 per cent. or less, which is negligible. These figures are supported by results representing the grinding of nearly half a ton of coal (more than 1,000 samples).The use of a tool steel diamond mortar may lead to the over-estimation of the ash of a hard foundry coke by more than 1 per cent., whilst the use of a chilled cast-iron bucking-board may lead to errors in excess of 4 per cent. G. C. J. Chemical Examination of Liquid Fuels. W. H. Paterson. (J. SOC. Chem. Ind., 1913, 32, 218.)-An 6‘ oil fuel,” or oil for internal combustion engines, must be volatile, and must not cause corrosion or other difficulties in the cylinder.For a “ fuel oil,” or oil to be used in firing boilers, cheapness, comparatively high flash- point, and high calorific value are more important. I n addition to petrol, alcohol and benzene, or mixtures of them, may be used in certain internal combustion engines ; but in competition with coal only crude petroleum, or petroleum residues, tar oils, products from animal or vegetable sources, and oils from lignite, peat, wood, or shale, can be considered. A list of eighteen liquid fuels, none exceeding 63 per ton in price, with their sp.gr., carbon hydrogen, sulphur, oxygen and nitrogen, gross, net, and calculated calorific values, open flash-point and burning-point, and a table of fractions obtained at various temperatures, are given.Some of these oils have been successfully used in the Diesel engine, and most of them are probably suitable. The impor- tance of the corrections for the latent heat of steam and for acid in obtaining the net from the gross calorific value is emphasised. The viscosity is an important factor, especially in oils for the Diesel engines, as too mobile an oil leaks through the valves.At low temperatures the fluidity of some oils increases rapidly with the As fuel oils, their efficiency depends on their calorific value.ORGANIC ANALYSIS 213 temperature. sp. gr., low flash-point, high hydrogen content, and low boiling-point. For petroleum products there is a general correlation between low 0.E. M. Nex German Regulations for the Official Examination of Inks. I?. W. Hinrichsen. (Chem. Zeit., 1913, 37, 265-267.)-According to the official German regulations of May, 1912, '' documentary ink " is an iron gall ink containing at least 27 grms. of anhydrous gallotannic and gallic acids, and not less than 4 grms. or more than 6 grms. of iron per litre (ratio 4-5 : 1 and 6-75 : 1).It must keep at least fourteen days in the inkpot, without deposit, etc., must flow readily from the pen, and produce writing which, after eight days' exposure to light and air, remains deep black when washed with water, 85 per cent. alcohol, and 50 per cent. alcohol. An ordinary iron-gall writing-ink must answer the same requirements, but may contain less tannin (18 grms.), with not less than 2.6 grms.or more than 4 grms. of iron per litre (ratio as before). Gallotannic and gallic acids are estimated by shaking the ink with ethyl acetate, evaporating the extract, and weighing the residue. The latter is regarded as consisting of gallotannic and gallic acids when 0.1 grm. thereof absorbs at least 0.5 grm. of iodine in the presence of 2 grms. of sodium bicarbonate.The method of Rothe and Hinrichsen is suitable for the estimation : Ten C.C. of the ink are treated with 10 C.C. of concentrated hydrochloric acid, and shaken with successive portions of 50 C.C. of ethyl acetate, preferably in a shaking apparatus, until the aqueous layer when neutralised with sodium carbonate gives no reaction for gallotannic or gallic acids with ferrous sulphate and ferric chloride.The united extracts are shaken several times with fresh portions of 10 C.C. of a semi-saturated solution of potassium chloride, to remove any dissolved iron salts, and are then evaporated in vacuo and the residue transferred by means of water to a tared crucible, and dried at 105" to l l O o C., or, better, in vacuo at 60" C., until con- stant in weight.I n estimating the iodine absorption, 0.1 grm. of the residue is mixed in a stoppered flask with 2 grms. of sodium bicarbonate and a measured quantity (25 to 50 c.c.) of standard iodine solution (about 50 grms. per litre). Simultaneously a blank estimation is made, and the next day the contents of both flasks are titrated with sodium thiosulphate solution. Iron is estimated by igniting the residue from 10 C.C.of the ink until free from carbon, and then heating it with 1 to 2 C.C. of concentrated hydrochloric acid (sp. gr. 1.124) in a covered crucible on the sand-bath until dissolved. From 1 to 2 C.C. of chlorine-water are next added, the solution evaporated to dryness, the residue dissolved in about 0.5 C.C. of warm strong hydro- chloric acid, and the solution diluted with about 20 C.C.of water. About 1 grm. of potassium iodide is then added, and the separated iodine immediately titrated with thiosulphate solution, whilst the liquid is meanwhile heated to 55' C., to promote the further separation of iodine. I n testing the permanency of the writing, the ink is made to flow over standard paper fixed in a frame inclined at an angle of 45", the pipette being placed in a rest so that it is held at a definite angle towards the paper.Similar colour bands are made upon the same paper with Schluttig and Neumann's standard ink. This contains 23.4 grms. of tannin, 7.7 grms. of crystalline gallic acid, 30 grms. of ferrous sulphate, 10 grms. of gum arabic, 2.5 grms. of hydro- chloric acid, and 1.0 grm. of carbolic acid, per litre.It is allowed to stand for four224 ABSTRACTS OF CHEMICAL PAPERS days at 10" to 15" C., and then decanted from the slight sediment. For comparison with any given ink, it is coloured with a suitable provisional dyestuff to match the sample. The papers with the coloured bands of standard ink and the ink under examination are exposed to the air for eight days in diffused light, and are then cut horizontally into strips.One of these is immersed in water, a second in 85 per cent. alcohol, and a third in 50 per cent. alcohol. None of the bands of ink should appear perceptibly fainter after being treated in this way for several days. C . A. M. Red Cabbage Extract as Indicator for Measuring Hydrogen Ion Concen- tration. L. E. Walbum (Riochem.Zeitsch., 1913, 48, 291-29G.)-The indicator is prepared by forty-eight hours' extraction of 500 grms. finely-cut red cabbage with 500 grms. 96 per cent. alcohol, and subsequent filtration through paper. The author measured the hydrogen ion concentration of a number of protein solutions by means of this indicator, and compared the results with those obtained electrometrically and those obtained by a number of indicators of the ax0 group, and found that thecolori- metric estimation by means of red cabbage extract gives values agreeing satisfactorily with those found electrometrically.The indicator can be used for hydrogen ion concentrations ranging from PH*= about 2.0 to PH. = about 4.5. The indicator gives satisfactory results even in presence of considerable quanti- ties of proteins. Neutral salts (up to 0.5 molecule sodium chloride), toluene, and chloroform, exercise no disturbing action.E. W. Nomenclature of Mixed Glycerides and the Synthetic Preparation of a-Distearin and P-Palmitodistearin. A. Bomer and R. Limprich. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 25, 354-366.1-1t is suggested that, in the case of mixed glycerides where different fatty acid radicles are combined with the glyceryl radicle, the position of the acid radicle should be denoted.For instance, the two isomeric glycerides containing one palmitic and two stearic radicles may be described as follows : a-position : CH,.O.C,,H,,O I P-position : bH.0.C,,H350 I I y-position : CH,.O.C1,H,,O a-palm i t o-P y -dis t ear in. 1 @position : bH.0.C16H3,0 I y-position : CH,.0.C1,H3,0 p-palmito-ay-distearin. As the a and y positions are of the same value, it is sufficient to term these two glycerides a-palmitodistearin and P-palmitodistearin, respectively.When three different fatty acid radicles are present in the same molecule, their position may be denoted in the same manner. The authors have prepared a-distearin from a-dichlorhydrin and potassium stear- ate, using Guth's method (cf.ANALYST, 1903, 28, 152, 359), and found that a consider- able quantity of tristearin was produced at the same time; the a-distearin had a melting-point of 78.5' C. Tristearin, and possibly stearodipalmitin, was also formed when P-palmitodistearin was prepared synthetically from a-distearin and palmiticORGANIC ANALYSIS 215 acid.other respects with the palmitodistearin isolated from mutton tallow. The synthetic P-palmitodistearin melted at about 6 3 O C., and corresponded in W. P. S. Effeet of Certain Pigments on Linseed Oil. Manganese Content of Raw Linseed Oil. E. W. Boughton. (U.X. Dept. Agric., Burea?A of Chem., Circular No. 111, February 15, 1913.)-In order to determine the effect of pigments, without driers, upon raw linseed oil, mixtures were made and exposed to diffused light in stoppered jars for periods of one and two years, samples of the mixtures being examined at the end of each period. The oil used contained 0.13 per cent.of ash, and had a sp. gr. of 0.934 at 15.6' C. ; acid value, 1.7, and iodine value, 179.6. It was mixed with the following pigments : White lead, kaolin, Indian red, flaked graphite, magnetic oxide (black), zinc yellow (chromate), artificial graphite, zinc white, chrome yellow, chromium oxide (green), and lampblack, the proportions rang- ing from 16 per cent.(lampblack) to 72 per cent. (white lead). The oils separated from the paints showed slightly reduced iodine values in most cases, the greatest reductions being observed with the so-called (' inert " pigments, kaolin and Indian red.I n no instance, however, did the iodine value fall below that sometimes given by genuine samples of linseed oil, the minimum value obtained being 171.6 with the oil from the kaolin mixture after two years. The ash yielded by the separated oils did not indicate that any appreciable amount of pigment had been dissolved, except in the case of the white lead paint, the oil of which yielded 0.35 per cent.of ash after one year, and 0.40 per cent. after two years. The sp. gr. of most of the oils showed a decided increase, the highest values, 0.939 to 0.940, being obtained with oils from the mixtures containing white lead, Indian red, kaolin, and artificial graphite. The values obtained after two years, however, were but little lower than those given after one year, and from this it would seem that the air in the jars had but little influence. I n many of the samples the sp.gr. exceeded the upper limit for raw linseed oil of 0.936 at 1 5 6 O C. (Proc. Amer. SOC. Test. Mat., 1909, 9,164), and this indicates that if the oil separated from a mixed paint after storage shows a sp.gr. approximating the lower limit for pure linseed oil (0.932) it may suggest the presence of other oils of lower specific gravity. Some bleaching of the linseed oil had been effected by,white lead, Indian red, chrome yellow, and chroniium oxide, and particularly by kaolin, but the other pigments had caused no appreciable change in the colour of the oil.Similar analytical results were obtained in the examination of oil from mixtures containing sufficient white lead to form a paste, but here also no driers or thinning agents had been used. I t was found that white lead apparently entered more closely into combination with the oil than lead chromate. Manganese in Raw Linseed Oil.--The proportion of ash and manganese in sixteen samples of oil of undoubted purity was estimated, the latter by the bismuthate method.The ash ranged from 0-02 to 0.21 per cent., and the manganese from a faint trace to 0.0008 per cent. of the oil. C. A. M. Permanganate [Alkaline] in the Estimation of Some Organie Com- pounds. ( J . Ind. and Eng. Chem., 1913, 5, 218-220.)-1n alkaline solution, phenol, pyrocatechol, resorcinol, quinol, salicylic acid (but not benaoic acid), C.M. Pence.216 ABSTRACTS OF CHEMICAL PAPERS and salol are completely oxidised by permanganate to carbon dioxide and water. The following method is recommended for the estimation of any one of them in absence of any other sabstance which reduces permanganate : A suitable quantity of the substance, brought into solution if necessary by means of 4 sodium hydroxide, is added to 50 C.C. of .& permanganatecontaining 3 or 4 grms.of sodium bicarbonate in solution. The mixture is boiled for five to ten minutes, cooled to about 60" C., acidified with dilute sulphuric acid, allowed to stand about two minutes, and then cooled to room temperature. To the cool and diluted solution about 1 grm. of potassium iodide is added, and the excess of permanganate taken is calculated from the amount of & thiosulphate required to reduce the liberated iodine. The extreme error of the method is rtO.5 per cent.on the amount of phenol or other reducing substance present. G. C. J. Direct Estimation of Oxygen in Organic Compounds. M. C. Boswell. ( J . Arner. Chem. SOC., 1913, 35, 284-290.)-The method is based upon the fact that when an organic substance is heated in a, quartz tube in a current of pure hydrogen, and the products of the reaction are passed over charcoal at a white heat, the whole of the oxygen in the original compound is converted into water, carbon dioxide, and carbon monoxide.The water is absorbed in tubes containing pumice moistened with sulphuric acid, the carbon dioxide in soda-lime, whilst the carbon monoxide is estimated by passing the residual gas through iodine pentoxide, and absorbing in soda-lime the carbon dioxide thus produced (ANALYST, 1912, 37, 106).The quartz tube for the combustion is about 980 mm. long by 13 mm. internal diameter, and it is lightly packed with fragments of charcoal for a length of 400 mm. from a point 135 mm.from one end. This tube is heated in an ordinary corn- bustion furnace from which the iron trough and tiling have been removed, and, further to prevent transference of heat to the substance during the preliminary heating of the charcoal, two guards of asbestos board are fitted across the furnace, one 15 nim. from the end of the charcoal layer, and the other 30 mm. from the first.The hydrogen is generated electrolytically, and oxygen is removed by passing the gas through a quartz tube (360 mm. x 13 mm.) containing a tightly wound coil of copper gauze which is heated to white heat. After leaving this, the hydrogen is dried by passing through calcium chloride, then through sulphuric acid, and finally through phosphorus pentoxide, after which it enters the combustion tube.The tared and other absorption-vessels are arranged in the following order : (1) A U-tube with sulphuric acid on pumice ; (2) soda-lime tube; (3) U-tube with sulphuric acid on pumice to retain moisture carried over from (2) ; (4) modi- fication of Levy's iodine pentoxide apparatus, which during the estimation is heated in an oil-bath at 160' to 170" C. ; (5) U-tube with sulphuric acid on pumice to absorb any moisture liberated when any iodic acid is reduced by the carbon monoxide; (6) soda-lime tube; (7) U-tube with sulphuric acid on pumice; and (8) straight guard tube of calcium chloride.About 0.3 grm. of the substance is weighed into a silica boat, which has previously been heated in a blast flame and cooled in a desiccator. This boat is introduced into the combustion tube at a distance of not less than 60 mm.from the nearer asbestos board. After the tube has beesORGANIC ANALYSIS 217 swept out with a current of purified hydrogen, the absorption vessels are connected, the portion of the tube containing the charcoal then heated, and the heat subsequently extended very gradually to that part containing the silica boat.The hydrogen current is continued for about fifteen minutes from the time when full heat has been applied to the substance, and its rate is increased during the last ten minutes SO as to drive over all the gaseous products of the reaction. At the end of the combustion (one and a half to one and three-quarter hours in all) the five tared absorption vessels are detached, and dry air (free from carbon dioxide) passed through them for about ten minutes, after which they are separated, allowed to stand for an hour, and repeatedly wiped with a cloth until constant in weight.In calculating the increase in weight in the tubes following the iodine pentoxide apparatus, a deduction of 50 per cent. is made for the oxygen derived from the iodine pentoxide, and not from the substance.The tabulated results show that the method is as accurate as the usual combustion method of estimating carbon and hydrogen. In the possible case of substances yield- ing stable compounds of carbon and hydrogen which would partially condense in the absorption vessels and vitiate the results, it would probably be practicable to eliminate such source of error by mixing a weighed quantity of a, pure oxidising agent, such as potassium permanganate, with the substance in the boat.C. A. M. Detection of [Commercial] Invert Sugar by Means of /%Naphthol. F. M. Litterseheid. (Chem. Zeit., 1913, 37, 321.)-The test proposed depends on the presence of traces of furfnral derivatives in commercial invert sugar, and on the fact that these derivatives yield a red coloration when treated with ,&naphthol and sulphuric acid.For the detection of invert sugar in honey, about 20 grms. of the sample are stirred with 10 C.C. of ether, the ethereal solution is decanted, and the extraction is repeated. The ethereal extracts are now, without filtration, transferred t o a, porcelain basin, and after the addition of a crystal of /I-naphthol the ether is allowed to evaporate at the ordinary temperature, The residue is then treated with 5 C.C.of 88 to 90 per cent. sulphuric acid, the latter being added carefully so that it flows over the whole surface of the residue. Should the honey contain not less than 5 per cent. of commercial invert sugar, a Bordeaux-red or blue-violet coloration will develop within thirty minutes ; the blue-violet coloration is usually noticed at the outer edge of the mixture.Natural honey yields a dirty yellow coloration with the test, a faint pink tint being noticed in many cases. The sulphuric acid employed should be chemically pure, and its concentration should be within the limits mentioned. w. P. s. Influence of Ammonium Sulphate on the Polarimetric Estimation of Lactose.G. Jahnson-Blohm. (Zeitsch. physiol. Chem., 1913, 83, 441-444.)- The author finds that the presence of ammonium sulphate in quantity equal to that employed in E. Salkowski’s method (ANALYST, 1912, 37,350) for determining lactose in milk produces a small decrease in the rotation. For a lactose content of 4 to 6 per cent. the results are 0.10 per cent. low, and the author recommends the application of this figure as a correction.E. W.218 ABSTltACTS OF CHEMICAL PAPERS Method of Estimating Sugar. I. Bang. (Biochenz. Zeitsch., 1913, 49, 1-19.) -A copper solution is prepared by dissolving 160 grms. potassium bicarbonate, 100 grms. potassium carbonate, and 66 grms. potassium chloride, in about 700 C.C. water, adding 4.4 grms. copper sulphate and diluting to 1 litre.Of this solution, 300 C.C. are diluted with a saturated potassium chloride solution to 1 litre. I n preparing these solutions, it is necessary to avoid vigorous shaking, as this causes the absorption of too much air. Fifty-five C.C. of this solution are added to the sugar solution contained in a 100 C.C. Jena flask to the neck of which is attached a thick rubber tube.The mixture is boiled for three minutes, the flask then closed by means of a strong pinchcock, and immediately after closing removed from the flame and cooled in a stream of water. It is essential to avoid access of air during cooling, to prevent oxidation of reduced copper. When cold the flask is opened, starch solution added, and reduced copper estimated by titration with standard iodine of convenient strength (Fn to &).The following reaction occurs : CuCl+ I + K,CO, = CUCO, + KCI + KI. Tables are given showing the quantities of $!!, and &- iodine which correspond with quantities of 1 to 10 mgrms. dextrose. It is claimed that the results agree well with those obtained polarimetrically, and that the new copper solution is superior to the older ones in not being so readily reduced by substances other than sugar, which is of special advantage in determining sugar in blood and urine.E. W. Estimation of Sugars by the Kjeldahl-Bertrand Method. P. Beyers- dorfer. (Zeits. ges. Brauw., 1912, 35, 556-559, 569-572, 582-585 ; through Chem. Zentralbl., 1913, I., 1066-1067.)-According to Kjeldahl, two different sugars may be estimated in presence of each other by determining the reducing power of different quantities of the sugar solution towards different quantities of Fehling’s solution.The cupric reducing power is not an exact additive function in the sense assumed by Kjeldahl, and the solution of a mixture of sugars does not behave towards different quantities of Fehling’s solution as a solution of a single sugar.This principle may be applied for the qualitative detection of a mixture of two sugars. If with the same quantity of the solution to be examined different cupric reducing values be found with different quantities of Fehling’s solution, the substance is a mixture of two or more reducing bodies. From the optical activity and the dry substance of a solution containing only two sugars, the quantity of each sugar mpy be calculated approximately, but this is not valid if a third substance which is inactive be also present.In such cases the cupric reducing value of the solution-which, however, must not contain more than 1 per cent. of reducing substance-affords the necessary data. For the hydrolysis of beer extract the author employs, instead of hydrochloric acid, a solution of sulphuric acid (1 : 3), heating the mixture for five to six hours ; the acid may then be easily removed by barium carbonate, and the hydrolysed products fermented by yeast. Nevertheless the barium carbonate acts upon the dextrose, possibly on rtcoount of its alkaline reaction, and this action has an influence on the optical rotation of the inverted extract.The fermentable sugar in wort and Such estimation, however, is not in fact possible.ORGANIC ANALYSIS 219 beer could not be estimated by the quantity of carbon dioxide evolved on fermenta- tion, owing to experimental difficulties; it was determined from the specific gravity before and after fermentation. J. F. B. Estimation of Reducing Sugars by Lehmann’s Method.L. Grimbert. (BUZZ. SOC. Chim., 1913, 13, 11 7-120.)-The various modifications of Lehmann’s method (iodimetric estimation of copper remaining in solution after treatment with excess of Fehling’s solution) are discussed, and that of Bertrand (Bzdl. SOC. Chim., 1906, 35, 1285) is recommended. The use of Bertrand’s copper solution and alkali tartrate solution (Zoc. cit.) are recommended. The & iodine solution is standardised by means of arsenious acid, and the thiosulphate solution is adjusted to be exactly equivalent to the iodine solution under the conditions obtaining in a titration of the acidified filtrate from a copper reduction experirnent-that is to say, in presence of 50 C.C.of 6 per cent. sulphuric acid. The copper solution is standardised by taking 20 C.C.together with 20 C.C. of the alkali tartrate solution, diluting to 200 c.c., withdrawing a portion of 50 c.c., adding 8 C.C. of dilute (1 : 1) sulphuric acid and 10 C.C. of 20 per cent. potassium iodide. After a few minutes 10 C.C. of thiosulphate solution is added, and the excess of thiosulphate titrated with iodine in presence of starch solution. In estimating reducing sugars, one takes 20 C.C.each of copper solution and alkali tartrate solution, not more than 0.1 grm. of sugar, and enough water to make the total volume 60 c.c., and boils for exactly three minutes. The mixture is cooled, made up to 200 c.c., filtered, and 50 C.C. of the filtrate is acidified, treated with potassium iodide, and titrated as already described.The difference between the volume of iodine solution required in the final titration and that required in standardising the copper solution is the measure of the sugar present, and its amount is given directly by reference to Bertrand’s tables (Zoc. cit.). The author has checked many of Bertrand’s figures for dextrose, and in no case do his numbers differ from those of the ear1,ier author by as much as I per cent.G. C. 5. Accuracy of the Estimation of 1. Tyrosine in Proteins. E. Abder- halden and D. Fuchs. (Zeitsch. physiol. Chem., 1913, 83, 468-473.)-The colorimetric method for determining tyrosine described by 0. Folin and W. Denis (J. BioZ. Chem., 1912,12, 245) yields results which are too high because similar colours are produced by oxytryptophane and tryptophane.The authors agree with Folin and Denis in finding it frequently exceedingly difficult to separate quantitatively tyrosine by simple crystallisation. The cause of this has been traced in certain cases to absorption of acid or ammonia fumes from the atmosphere during evaporation in open basins. Much better results are obtained if the evaporation be conducted under reduced pressure.A more interesting reason for quite considerable quantities of tyrosine failing to crystallise is the formation of salt-like compounds with the basic constituents of proteins, such as the compound of tyrosine with lysine observed by E. Fischer and E. Abderhalden. In view of this experience, tests were made to determine whether it is possible to quantitatively recover tyrosine added to gelatine. Tyrosine-free gelatine was dissolved in five times its weight of 25 per cent. sulphuric acid, a known quantity of tyrosine added, and boiled for twenty hours. Baryta was220 ABSTRACTS OF CHEMICAL PAPERS then added to remove the sulphuric acid, and the barium sulphate extracted with boiling water until the extract no longer gave a violet colour with a 1 per cent- aqueous solution of triketohydrindenehydrate (Ninhydrin). This reagent proved much more delicate than Millon’s reagent. By concentrating the combined filtrates at 45” C., it was possible to recover as much as 90 per cent. of the added tyrosine ; in certain cases, however, the yield amounted to only 60 to 70 per cent. I t was found possible to recover the tyrosine almost quantitatively by the following method : The liquid after hydrolysis is diluted until it contains 2.5 per cent. sulphuric acid. A 10 per cent. solution of phosphotungstic acid is then added with constant stirring, great care being taken to avoid the addition of any excess. The precipitate is filtered off and washed, and the filtrate treated with baryta, to remove phosphotungstic acid and filtered. To this filtrate the exact amount of sulphuric acid needed t o remove the excess of baryta is added and the barium sulphate extracted with boiling water until no coloration is given by “Ninhydrin.” The filtrate was then con- centrated at 40’ C. under reduced pressure until the mother-liquor gave no reaction with Millon’s reagent. The crude tyrosine which separated was purified by boiling with animal charcoal and fractional crystallisation from water until a sample on analysis yielded figures agreeing with pure tyrosine. E. W.

ISSN:0003-2654    

DOI:10.1039/AN9133800211

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

220 ABSTRACTS OF CHEMICAL PAPERS INORGANIC ANALYSIS. Analysis of Aluminium Alloys. W. E. von John. (Chem. Zeit., 1913, 37, 363.)--In the analysis of alloys in which aluminium predominates, the separation of the aluminium is often tedious and apt to be attended by loss of the minor constituents. The following method of analysis is recommended as simple and yet capable of yielding results of a satisfactory degree of accuracy: The drillings (1 grm.) are dissolved in hydrochloric acid, and the usual trace of silica separated by evaporation to dryness.In the filtrate from the silica, lead and tin, if present, are separated by means of sulphuric acid and nitric acid. To the filtrate-now free from silica, lead, and tin-bromine water, and then caustic alkali are added.The mixture is heated to boiling, let stand overnight, and then filtered. The precipitate, which contains all the copper, iron, manganese, and magnesium, is washed and dissolved in dilute sulphuric acid, the copper separated as sulphide, and the filtrate boiled to expel hydrogen sulphide, and treated with bromine to oxidise iron. The excess of bromine is expelled by boiling, and iron precipitated by ammonia, the manganese in the filtrate from the ferric hydroxide being precipitated by means of bromine or hydrogen peroxide.In the filtrate from manganese, the magnesium is precipitated as mag- nesium ammonium phosphate. The filtrate from copper, iron, manganese, and magnesium, which contains all the zinc as well as the aluminium, is treated with ammonium sulphide, and the zinc sulphide filtered off and ignited with sulphur in a current of hydrogen.The zinc sulphide is dissolved in hydrochloric acid, and the solution tested for the presence of aluminium, which, if present, must be precipitated as hydroxide, and its weight deducted from the weight previously recorded as due to zinc sulphide. The test numbers are good. G. C. J.INORGANIC ANALYSIS 221 Detection of Arsenic by Means of Bettendorf’s Reagent.L. W. Winkler. (Zeitsch. angew. Chem., 1913, 26, 143-144.)-Statements have been made that Bettendorf’s reagent (stannous chloride) reduces sulphates on heating, and that, con- sequently, the solution to be tested for arsenic must not be warmed after the addition of the reagent if the solution contains sulphates or sulphuric acid.The author finds that this is not the case ; no reduction occurs on heating the mixture, and the presence of sulphuric acid is even of advantage, as it acts as a dehydrating agent. The reagent is best prepared by dissolving 100 grms. of stannous chloride, SnC1,,2H20 (the crystals should be quite transparent), in 1 litre of concentrated hydrochloric acid (36 to 38 per cent.HCI). Usually traces of arsenic are present in the acid, and cause the solution to become light brown in colour; if, however, about 1 grm. of finely powdered glass is added, and the whole is kept in a warm place for from twenty-four to forty-eight hours, the arsenic will be precipitated and the clear, colour- less solution may he decanted and stored in stoppered bottles.In carrying out the test, the solution of the substance under examination (preferably in hydrochloric acid) is mixed in a test-tube with five times its volume of the reagent, the mixture is heated just to boiling, and then placed aside for thirty minutes. Arsenic may be detected in concentrated sulpliuric acid by mixing 1 C.C. of the acid with 1 C.C. of water, and adding 10 C.C.of the reagent. The minimum quantity of arsenic which can be detected by the test is about 0.001 grm. of arsenic trioxide per litre of solution, when 2 C.C. of the latter are used for the test. w. P. s. Factors influeneing the Estimation of Arsenic in Soils. J. E. Greaves. (J. Amer. Chem. Soc., 1913, 35, 150-156.)-0n account of its extensive use as an in- secticide, arsenic may accumulate in soils to such an extent as to become injurious to vegetation; it also occurs in many virgin soils.The author confirms the work of previous investigators on the retarding effect which the presence of iron exerts upon the arsenic liberated by the Marsh method. Working with 1 mgrm. of arsenic, 1 mgrm. of iron, 25 grms. of zinc, and dilute sulphuric acid, it was found that one quarter of the amount of arsenic was retained.I t is shown that the retarding action of 1 mgrm. of iron can be overcome by the use of 200 mgrms. of stannous chloride, and that for 0.5 grm. of iron 1 grm. of stannous chloride suffices. Since arsenic tri- chloride is volatile at comparatively low temperatures, tests were made with 10 grms. of soil, containing varying amounts of sodium chloride and 1 mgrm.of arsenic, in all cases using 2 grms. of stannous chloride. The result showed that no appreciable quantity of arsenic is lost, even when the percentage of chloride in the soil reaches 3 per cent. The method which has given the best results is as follows : To 10 grms. of soil are added 25 C.C. of concentrated nitric acid and the mixture heated for thirty minutes.While still moderately hot, 10 C.C. of concentrated sulphuric acid are added, and the whole heated for thirty minutes. The soil is thoroughly washed with hot distilled water, the filtrate evaporated to dryness, and heated until free from nitrates. The residue is then treated with dilute arsenic-free sulphuric acid to which has been added 20 C.C. of 10 per cent.stannous chloride solution. The solution is slowly introduced into a Marsh apparatus, the glass tube through which the hydrogen was conducted being heated by means of an electric222 ABSTRACTS OF CHEMICAL PAPERS combustion furnace, the temperature of which was maintained just below the melting- point of hard glass by means of a rheostat. The tube and deposit of arsenic obtained after the apparatus has been running two hours is then carefully weighed on a fine analytical balance, the arsenic being dissolved out by dilute nitric acid, the tube washed in water, alcohol, and ether, dried, and then weighed as before.H. F. E. H. Determination of Copper in White Metal Alloys. F. Ibbotson and L. Aitchison. (Chem. News, 1913, 107, 121.)-The drillings (0.5 grm.) are dissolved in 10 to 15 C.C.of aqua regia, an equal volume of water is added, and the solution cooled. If lead chloride separates, it is filtered off' on a pulp filter, which is washed with cold water. About 1 grm. of tartaric acid is added, and, when this has dissolved, the solution is nearly neutralised with sodium hydroxide, heated to boiling and added, drop by drop from a separating funnel, to a boiling solution containing 20 grms.of sodium hydroxide and 2 to 3 grms of hydrazine hydrochloride in 250 to 300 C.C. of water. The latter solution is agitated vigorously during the operation. After digesting the mixture for about fifteen minutes, the precipitate of metallic copper is filtered off on a filter of ashless paper pulp, washed with hot water, dissolved on the filter by means of dilute nitric acid (sp.gr., lei), the filter washed, and the filtrate of copper nitrate evaporated to pastiness. On taking up in water and a few drops of nitric acid, it should be free from any opalescence which would be caused by unseparated stannic oxide, and the weight of the filter ash should be negligible. Sodium carbonate solution is next added to the copper solution until it is alkaline, then acetic acid in slight excess, and the solution is boiled.When cold, potaseium iodide is added, and the liberated iodine is titrated with thiosulphate, of which 1 C.C. = 1 mgrm. copper. The method is accurate with alloys Containing 80 per cent. of lead, together with tin and antimony, and also wihh alloys in which tin predominates.The small quantities of zinc which occur in these alloys are completely separated from copper, and the minute quantities of iron unavoidably present in white metals are without appreciable effect on the results. G. C. J. Eleetrolytie Estimation of Copper in Ores containing Arsenic, Anti- mony, or Bismuth. D. J. Demorest. (J. Id. and Eng. Chem., 1913, 5, 216.) -The following method is less tedious than methods in which the metals are first precipitated as sulphides, arsenic and antimony removed by means of sodium sulphide, and copper separated from bismuth by means of cyanide.One grm., or more if the sBmple is low in copper, is decomposed by heating with 7 C.C. of hydrochloric acid and 7 C.C. of nitric acid, and the mixture is evaporated with 5 C.C.of sulphuric acid until it fumes. About 30 C.C. of 10 per cent. tartaric acid solution is added, the mixture heated till all soluble matter is dissolved, allowed to cool somewhat, made alkaline with ammonia and then acid with sulphuric acid, of which about 1 C.C. more is used than is necessary to neutralise the ammonia, TQ the hot solution, 2 grms. of sodium sulphite is added, and the mixture stirred until solution is complete.Then a strong solution of potassium thiocyanate, containing about 1 grm. of the salt, is added, the solution stirred vigorously, heated to boiling,INORGANIC ANALYSIS 223 and the precipitate given a few minutes to subside. The precipitate is filtered off on a paper of close texture, and washed several times with a solution containing 1 per cent, of thiocyanate and 1 per cent.of tartaric acid. It may then be ignited with the paper, dissolved in 5 C.C. of nitric acid, diluted and electrolysed, or, preferably, it is dissolved on the filter with 18 C.C. of dilute (1 :2) nitric acid, the funnel being covered to avoid loss, the filtrate is heated to boiling, and passed once more through the filter, which is washed with about 100 C.C.of water, and the filtrate and washings are boiled vigorously for five minutes to destroy thiocyanic acid, the bulk adjusted to about 125 c.c., and the solution electrolysed, using a gauze cathode, a drop of potential of 3 volts and a current of 3 amperes. Precipitation is complete in thirty to sixty minutes, and the deposit is firmly adherent if the boiling to destroy thio- cyanic acid was sufficiently prolonged.Copper (0.15 grm.) may be determined in presence of an equal weight of arsenic, antimony, bismuth, iron, and lead, with an error not exceeding - 0-5 mgrm. The test numbers show no example of over- estimation of copper. G. C. J, Thioeyanate-Permanganate Method for Copper in Ores. D. J. Demorest. ( J . Ind. and Eng. Chew., 1913,5,215-216.)-1n Guess’s method for the determination of copper, the cuprous thiocyanate is decomposed on the filter by means of sodium hydroxide, and the resulting solution of sodium thiocyanate is acidified and titrated with permanganate.Theoretically 5Cu = 5HCNS = GKMnO,, but under the con- ditions prescribed by Guess the reaction does not proceed quantitatively, and an empirical factor (about 1-05 the theoretical) has to be determined by the operator (see Low’s ‘( Technical Methods of Ore Analysis ” ; also Grossmann and Holter, ANALYST, 1909, 34, 244). The reaction may be made approximately quantitative and the use of an empirical factor dispensed with by adding the bulk of the permanganate to the alkaline solution and only adding sulphuric acid when the thiocyanate reaction has nearly disappeared.The ore is heated for several minutes with 5 C.C. of strong hydrochloric acid, 10 C.C. of nitric acid are then added, and the digestion continued until the ore is completely decomposed. After addition of 10 C.C. of dilute (1 : 1) sulphuric acid, the mixture is evaporated until it fumes, allowed to cool, and then warmed with 50 C.C.of 6 per cent. tartaric aeid solution until all soluble salts are dissolved. Ammonia ie added until the appearance of a deep blue colour, then sulphuric acid until the reaction is acid, and then a further 1 C.C. of acid. After addition of 20 C.C. of 5 per cent. sodium sulphite solution, the mixture, is heated nearly to boiling, and 20 C.C. of 5 per cent. potassium thiocyanate is added slowly with vigorous stirring.The mixture is maintained at a temperature near the boiling- point for several minutes, allowed to cool somewhat, and then filtered through asbestos contained in a Gooch crucible. The precipitate is washed with water, the pump-flask changed, and 30 C.C. of hot 10 per cent. sodium hydroxide poured through the filter, which is washed with water.The filtrate is heated to about 50” C and permanganate run in from a burette until a drop of the solution, when tested on a white plate with a drop of a strongly acid solution of ferric chloride, shows only a faint coloration, About 30 C.C. of dilute sulphuric acid are then added to the contents of the titration flask, which are shaken until the manganese dioxide all dissolves,224 ABSTRACTS OF CHEMICAL PAPERS and the titration is completed in acid solution.is required at this stage, the error of the method does not exceed 1 per cent. element, except silver, interferes. If only about 1 C.C. of permanganate No G. C. J. Electrolytic Separation of Copper from Tungsten and Molybdenum. W. D. Treadwell. (Zeitsch. Electrochem., 1913, 19, 219-221.) - The use of potas- sium cyanide to effect this separation is objectionable, and its effectiveness in the case of molybdenum doubtful.Copper may be readily separated from tungsten as follows : The solution (150 c.c.), containing the tungsten as alkali tungstate and the copper as chloride, nitrate, sulphate, phosphate, or acetate, is made strongly alkaline by addition of 15 to 20 C.C. of strong ammonia, and 3 to 5 grms.of ammonium sulphate are also added. The solution is then electrolysed by connecting the electrodes direct to the terminals of a single lead accumulator. As much as 0.2 grm. of copper can be deposited in three hours, or in twenty minutes if a rotating electrode be employed. As the results are unaffected by leaving the cell connected to the accumulator after all the copper is out of solution, it is convenient when using stationary electrodes to allow the electrolysis to proceed overnight.The above process cannot be applied without modification to the separation of copper from molybdenum, since, at 1.8 to 2 volts, alkali molybdates are reduced to salts of molybdenum, and ultimately molybdenum hydroxide is deposited on the cathode.If, however, the difference of potential between the terminals be not allowed to exceed 0.9 volt, if the deposition of the copper be facilitated by the addition of a suitable reducing agent, and if certain precautions be taken, a quanti- tative separation of these metals is possible. The reducing agent recommended is sodium bisulphite, at the rate of 15 to 30 C.C. of the commercial solution to 150 C.C.of electrolyte, to which 15 to 20 C.C. of ammonia, is also added. Agitation of the electrolyte is essential to success, the cathode deposit must remain covered with liquid to avoid oxidation of the copper, and the current must be broken without delay when all the copper is out of solution. The rapid falling off of the current indicates the completion of the deposition, but, if there is no ammeter in the circuit, it sufices to break the current five minutes after the solution has ceased to possess a perceptible blue colour.As much as 0.25 grm. copper can be deposited in thirty minutes with an error not exceeding 2 0.5 mgrm. G. C. J. Estimation of Hypochlorites. H. G. Williams. (Chem. News, 1913, 107, 109.)-Roncali and Roberts (Chem.Central, 1904,1, 1294) suggest the estimation of hypochlorites by adding (slowly) a known volume of the hypochlorite solution to a boiling solution of hydrazine sulphate in dilute sulphuric acid and measuring the volume of nitrogen liberated, ‘‘ the available chlorine ” being double this. The following method is simpler and sufficiently accurate : The hypochlorite is titrated with a solution of hydrazine sulphate containing 3.2535 grms.per litre (each C.C. = 0.0008 grm. of oxygen = 0.003546 grm. of chlorine), the end-point being determined by iodide-starch paper. If the alksIi always present with hypochlorites is not sufficient to neutralise the sulphuric acidIN ORGANIC ANALYSIS 225 liberated, sodium bicarbonate in sufficient quantity must be added.appears to be- Results are recorded in which sodium hypoohlorite and bleaching powder are tested by the above method against a titration with & arsenious acid, the average difference with the hypochlorite being 0.075 per cent., and with the bleaching powder 0.11 per cent. A solution of hydrazine sulphate is much easier to prepare than $% AspO6, and appears to keep better.Browne and Shetterly (J. Chem. Amer. Chem. Soc., 1908, 30, 53) find that when hydrazine sulphate is oxidised by chlorates or by free chlorine, ammonia and hydrazoic acid are formed, but no trace of these can be detected in the mixtures after titration (cj. ANALYST, 1908, 33, 24). The action N2H4 + 2(MOC1)= N, + 2H20 + 2(MCl). H. F. E. H. Estimation of Manganese in the Presence of Iron.M. E. Pozzi-Escot. (Ann. Chim. anal., 1913, 18, 56-58.)-An iodimetric method is recommended. The solution containing iron and manganese is heated to boiling and treated with an ~ ~ ~ e s s of sodium hydroxide and about 1 grm. of sodium persulphate; the precipi- tated hydroxides are washed by decantation, then collected on a small filter, and washed until the filtrate is neutral.The filter and precipitate are now transferred to a flask of about 200 C.C. capacity, the neck of which is closed with a hollow ground-in stopper. This stopper is provided with a side tube which is extended to form a series of five absorption bulbs, and a second tube passes through the stopper t o nearly the bottom of the flask. Twenty C.C. of concentrated hydrochloric acid are then introduced into the flask and the contents are boiled, the liberated chlorine passing through the absorption bulbs, in which has been placed previously a solution containing 3 grms.of potassium iodide and 5 grms. of sodium acetate, together with 5 grms. of zinc oxide in suspension. A current of carbon dioxide is passed through the apparatus during the boiling, which should not be prolonged for more than a few minutes, and the liberated iodide in the bulbs is then titrated with & thio- sulphate solution.Each C.C. of the latter solution is equivalent to 0.00275 grm. of manganese. w. P. s. Colorimetric Estimation of Small Quantities of Manganese in Water. F. Haas. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 25, 392-395.)-With slight modification, the persulphate method described by Marshail (ANALYST, 1901, 26, 195) yields accurate results.The alterations recommended consist in treating the water directly with sulphuric acid and persulphate without the addition of nitric acid and silver nitrate, as this addition serves no good purpose and actually inter- feres with the test. One hundred C.C. of the water to be tested are acidified with 5 C.C.of 20 per cent. sulphuric acid, from 0-5 to 1 grm. of solid potassium persulphate is added, and the mixture is heated slowly until either a red-violet coloration develops or a brown colour, due to separated manganese peroxide, is obtained. The mixture is now cooled, a trace of sodium hydrogen sulphite is added, and the solution again heated with persulphate until the permanganate coloration reaches its full intensity.After cooling, the coloration is compared with that shown by known quantities of226 ABSTRACTS OF CHEMICAL PAPERS permanganate. The most trustworthy results are obtained with quantities of manganese varying from 0.05 to 1.0 mgrm. per litre of water. w. P. s. Estimation of Small Quantities of Manganese and Chromium in Minerals and Rocks.M. Dittrich. (Zeitsch. unorg. Chem., 1913, 80, 171-174.)-1n rocks containing traces of chromium of the same order of magnitude as the manganese, the colorimetric determination of the latter is impossible unless a separation of the two metaIs is effected. This may be easily accomplished as follows : The rock is opened up with hydrofluoric and sulphuric acids and treated with persulphate and silver nitrate in the usual manner.Excess of ammonia is next added, and the solution warmed for a short time, when all the manganese comes down with the iron, whereas the chromate is not reduced. The precipitate is filtered off, washed, dissolved by means of sulphuric acid and sulphurous acid (or hydrogen peroxide), the excess of the reducing agent removed or destroyed by boiling, and the treatment with persul- phate and silver nitrate repeated.The chromium in the filtrate may be estimated by freeing the latter from silver, concentrating to small bulk, and comparing colori- metrically with a, standard solution of potassium chromate. G. C. J. Separation of Niobium and Tantalum by Means of Potassium Chloride in Hydrofluorie Acid Solution.Meimberg and P. Winzer. (Zeitsch. angeu7. Chew., 1913, 26, 157-158.)-After describing their failure to obtain a satisfactory separation by other methods, the authors recommend the following: From 5 to 10 grms. of the mixed acid earths are dissolved in hydrofluoric acid, of which enough must be taken to allow the whole of the tantalum and niobium to form potassium double fluorides on the subsequent addition of excess of potassium chloride.Excess of a saturated solution of the latter salt is next added, and the solution allowed to cool. As the double fluoride of tantalum and potassium is not quite insoluble in a fairly concentrated solution of potassium chloride, the bulk of the solution is kept a3 small as possible, but there must bo at least 12 C.C.of liquid for every gram of potassium niobium fluoride to be separated. The tantalum double salt is filtered off, washed with a cold saturated solution of potassium chloride, and reconverted into tantalic acid by digestion with hot sulphuric acid. The acid is again dissolved in hydrofluoric acid, and separated from traces of niobium by reprecipitation as double fluoride in the manner already described.The bulk of the solution may be kept smaller this time, as only traces of niobium have to be removed. The double salt is filtered ofF, washed with potassium chloride solution, decomposed by digestion with hot sulphuric acid, and the residue boiled with water containing hydrochloric acid, and then with ammonia, the separated tantalic acid (and titanium dioxide if present in the original material) being filtered off, ignited, and weighed.Titanium, if present, is estimated colorimetricslly, and a correction applied to the weight of the mixed oxides. An alternative method is to carry the process described above as far as the first separation of the double fluoride, and to separate the last traces of niobium by solution in hydrofluoric acid and treatment with potassium chloride solution.After allowing to cool, the purified double salt is filtered off, mashed, and converted into tantalic acid in the manner already described. No test numbers areINORGANIC ANALYSIS 227 given, but the method is said to be applicable to the technical production of tantalum compounds free from all but a negligible trace of niobium. G.C. J. Estimation of MercuryasMetal by the Dry Method. A. C. Cumming and J. Macleod. ( J . Chem. SOL, 1913, 103, 513-516.)-The use of Penfield’s apparatus for water estimations obviates the experimental difficulties in the estimation of mercury by the dry method. I t consists of a tube about 15 cm. long and 5 cm. in diameter, closed at one end by a bulb A , and with a second bulb blown at B.The dried tube is weighed, a suitable quantity of the substance containing mercury introduced through a long funnel into the bulb A , and the tube and its contents again weighed. A mixture of iron filings and quicklime is next added by means of the funnel, and the whole contents of the bulb thoroughly mixed by rotating the tube, after which a mixture in about equal parts of iron filings and quicklime is introduced so as to fill about 8 cm.of the tube. This is kept in position by means of an asbestos plug at E, a shallow air passage being left at the top of the powder by tapping the tube. Finally, the open end of the tube is drawn out to a capillary as shown at F, and the whole tube enclosed in an \ LL) .:. . iron tube about 15 CM.by 1.5 cm., the bulb A being firstr wrapped in asbestos-paper. The ends of the iron tube are closed with asbestos, and an asbestos shield fixed at G to prevent the bulb B from becoming hot. This bulb is also cooled by means of wet filter-paper. The iron tube is first heated with a small flame at the end near G, and the heat gradually increased and extended until the whole of the tube is of a dull red heat.After the whole of the mercury has distilled and has been collected in B (about an hour), the glass tube is withdrawn from the iron tube and heated at a point about midway between E and B, so that it can be drawn out into a tube as shown at H. Any moisture is removed by drawing a current of dry air through this tube until the weight becomes constant, after which the mercury is expelled by shaking the tube, and if necessary heating it and blowing air through it.Finally, it is cooled and again weighed. The method is shown to give accurate results, but in the case of mercuric iodide and mercuric sulphide, it was necessary to add lead chromate to the mixture in the proportion of 1 part to 2 of iron filings and 1 of quick- lime.For the estimation of mercury in minerals of unknown composition from 0.5 to 1 grm. of the sample should be heated, as described, with 2.5 to 3 grms. of the mixture containing the lead chromate. C. A. M. Application of Selenic Acid to the Estimation of Bromide in Presence of Chloride. F. A. Gooch and P. L. Blumenthal. (Zeitsch. anorg. Chenz., 1.913, 80, 161-170.)-Selenic acid is capable of reacting with bromides and chlorides, with228 ABSTRACTS OF CHEMICAL PAPERS liberation of the halogen and formation of selenious acid, but the reaction in either case is a reversible one.The present paper describes researches directed to the determination of the conditions under which the reaction with bromide is approxi- mately quantitative, and that with chloride almost wholly inhibited.I n mixtures of 0.1 grm. potassium bromide with 0.1 grm. sodium chloride, the bromine may be estimated as follows, with an error of - 0-6 k 0-5 mgrm. : The solution (30 C.C. 01' more) is contained in a flask fitted with a tap funnel and a gas exit tube. The tap funnel is charged with 5 C.C. of 40 per cent, selenic acid, or with 2 grms. of sodium selenate dissolved in 3 C.C.of dilute (1 : 1) sulphuric acid, and its constricted top is connected to a carbon dioxide generator. The gas exit tube is bent, and dips into 10 to 15 C.C. of water containing 2-5 C.C. of selenic acid (or 0.3 grm. selenate and 1 to 2 C.C. of dilute sulphuric acid), and contained in a flask which is maintained at 115" to 120" C . in an oil-bath. This apparatus serves to oxidise any hydrogen bromide which may escape oxidation in the reaction flask proper.The oil-bath being hot, the selenic acid is allowed to flow into the reaction flask, and a current of carbon dioxide is passed through the apparatus, whilst the contents of the reaction flask are heated to boiling and concentrated to about 10 to 15 C.C. The gases passing away from the second flask are conducted below the surface of 200 C.C.of water containing in solution 3 or 4 grms. of potassium iodide, and the usual precautions are taken to guard against loss of iodine. The liberated iodine is titrated, and its bromine equivalent calculated in the usual manner. If the concentration is not pushed below 10 c.c., no chloride is decomposed. The oxidation of the bromide is never quite complete, but 'the results are fairly concordant, being, as stated above, from 0.1 to 1.1 mgrms.low. G. C. J. Gay-Lussac Method of Silver Determination. F. P. Dewey. (J. Ind. and Erzg. Chem., 1913, 5, 209-214.)-The exact modification of the method employed in the United States mint service is described, and the results of some thousands of assays are tabulated to show that two operators, working on identical samples of standard silver and making four determinations each, may differ as much as 1 fine in their reports.Nevertheless, the method is preferred to fire assay for mint work. I t is useless for a person who uses it only occasionally to expect to attain high accuracy with it, without spending more time upon a determination than is warranted in a busy commercial laboratory.G. C. J. Volumetric Method for the Estimation of Sulphur in Illuminating Gas. F. Schulz. (Petroleum, 1913,8,585-586 ; through Chem. Zentralb7., 1913, I., 1063.) -As a technical method, only the lamp method of Heusler and Engler is generally available, that of Hempel and Graefe being not quite satisfactory with volatile oils. The lamp method may be still further simplified by passing the gaseous products of combustion through a solution of hydrogen peroxide, and estimating the sulphuric acid produced.The absorption flask is charged with 30 C.C. of a 3 per cent. solution of hydrogen peroxide, diluted with 30 C.C. of water, and neutralised to methyl orange with & sodium hydroxide. In the case of petroleum, 5 to 6 grms.a m burnt (at the rate of 1.3 to 1-6 grms. per hour). A strong current of air is drawn through theINORGANIC ANALYSIS 229 apparatus to insure freedom from smoke, otherwise the absorption would be incom- plete. The estimation of sulphur dioxide in the air used for combustion is carried out in a blank experiment. After weighing back the lamp, the acidity produced in the absorption liquid is titrated with TG alkali. If the influence of oxides of nitrogen is to be eliminated, hydrogen peroxide free from sulphuric acid should be used for the absorption.According to the author’s determinations, samples of European petroleum contained from 0*056 to 0.077 per cent. of sulphur. J. F. B. Volumetric Method for the Estimation of Tin by Means of Potassium Bromate.F. Fichter and E. Muller. (Chem. Zeit., 1913, 37, 309.)-The follow- ing method, due to Zschokke, but hitherto unpublished, has proved of special value in silk works, and in the author’s hands gives more accurate results than they are able to get by the iodimetric method. The tin solution (20 c.c.), which should be approxi- mately +$ and not too strongly acid, is treated in the cold with about 0.15 grm.of aluminium in the form of wire. The separated tin is next dissolved by adding to the contents of the flask 30 C.C. of hydrochloric acid and 20 C.C. of water, and boiling, oxidation of the stannous chloride being prevented by the use of a Bunsen valve. The cooled solution is then fitrated with & potassium bromate until the appearance of the yellow colour due to the bromine, which results from the interaction of hydrogen bromide with the first drop in excess of the reagent.The bromate solution is standardised iodimetrically. For use in silkworks, the method has the advantage that it is available in presence of phosphates. G. C. J. Estimation of Titanium in Presence of Iron. W. M. Thornton jun. (Chem. News, 1913, 107, 121-l22.)-Gooch’s method for the gravimetric estimation of titanium in presence of iron, aluminium, and phosphoric acid, leaves nothing to be desired in point of accuracy, but is unnecessarily tedious for the analysis of minerals and rocks which contain little or no aluminium, but much titanium.In theanalysis of such materials the author proceeds as follows: Tartaric acid is added to the solution in amount equal to at least three times the weight of the oxides of titanium and iron, and the iron is next reduced to the ferrous state by means of hydrogen sulphide.The solution is then rendered faintly alkaline with ammonia, and hydrogen sulphide is again passed in until precipitation of the iron is complete. The ferrous sulphide is filtered off and washed with very dilute, colourless ammonium sulphide, and the titanium in the iron-free filtrate is determined as follows : The filtrate is evaporated with 10 to 15 C.C.of sulphuric acid until the tartaric acid begins to char. After cooling a little, 5 C.C. of fuming nitric acid are added cautiously, and the decom- position of the tartaric acid completed by the cautious application of heat until fumes of sulphuric acid finally appear.The liquid is diluted by pouring it into 100 C.C. of water, and ammonia is added until the appearance of a precipitate which disappears with difficulty. About 1 C.C. of a strong solution of ammonium bisulphite is added to hold up any trace of iron which may remain in the solution, and this is followed by 5 C.C. of acetic acid and 15 grms.of ammonium acetate. The solution is then diluted to about 350 c.c., heated to boiling, and maintained in ebullition for two minutes. The titanium hydroxide, which comes down in an easily filterable condition, is230 ABSTRACTS OF CHEMICAL PAPERS filtered off, washed successively with very dilute acetic acid and water, and finally ignited for twenty minutes over a Meker burner.Titanium dioxide (0.13 grm.) can be separated from an equal weight of ferric oxide with an error not exceeding +0*6 mgrm., and the titanium is never under-estimated. G. C. J. New Method for Volumetric Estimation of Uranium. V. Auger. (Bull. Soc. Chim., 1913, 13, 109-117.)-1n presence of iron, but absence of titanium, uranium may be estimated by reduction of the acid solution by means of amal- gamated zinc, and titration of the quadrivalent uranium by means of a, standard ferric solution, which oxidises it to the hexavalent condition, thiocyanate serving as indicator. As the concentration of acid is increased, a higher temperature is necessary to bring about the reaction with the ferric salt, and at higher temperatures the error due to oxidation by the air ceases to be negligible.For this reason, and because high saline concentrations exercise a prejudicial influence, though large quantities of salts are without effect unless their concentration is very high, the reduced solution is diluted considerably before titration. Hydrochloric acid should not be used for acidifying the solution to be reduced, since aerial oxidation at a later stage is more to be feared in presence of much hydrochloric acid; but chlorides in considerable quantity are without effect. The ferric solution, which may con- veniently be Tc or &, is preferably a solution of iron alum containing free sulphuric acid.It is standardised by means of a solution of uranium of known strength. The solution to be analysed, or 25 C.C. of the standard uranium solution, is rendered strongly acid by addition of 25 to 50 C.C.of dilute sulphuric acid (1 : lo), a d the mixture is poured into a flask nearly filled with amalgamated zinc. At the tempera- ture of the water-bath reduction is complete in ten minutes. The cooled solution is filtered through a plug of glass-wool, the zinc is washed with acidulated water, and the filtrate and washings are aerated by shaking or the use of a current of air to oxidise any trivalent uranium which may possibly be present.Ammonium thio- cyanatc solution, equivalent to 2 grms. of the salt, is added, and the mixture diluted to 200 C.C. or more with hot water. The titration with ferric solution is then carried out at a temperature of 40" to 50" C. I n presence of titanium and iron, the following method is recommended.I t depends on the reduction of the uranium and iron in alkaline tartrate solution by means of titanous sulphate, using azo-induline to determine the presence of the least possible excess of the reagent, followed by titration of the uranium with ferric sulphate in acid solution in the manner already described. The titanous solution is made by dis- solving 100 grms.of hydrated titanium dioxide in 300 grms. of hot, slightly diluted sulphuric acid, diluting to 1,000 c.c., and reducing in the cold with amalgamated zinc. A weaker titanous solution is also required, and is made by diluting some of the stronger solution to one-tenth strength. The tartrate solution is made by saturating 150 grms. of tartaric acid with sodium carbonate and diluting to 500 C.C.The reduction is effected in a flask with a wide neck, fitted with a double-bored stopper, one hole of which serves for the introduction of a current of carbon dioxide, whilst the other carries a straight tube 5 cm. long and as wide as a test-tube, The above method is not available in presence of titanium.INORGANIC ANBLYSIS 231 Enough tartrate solution to saturate any free mineral acid and a few drops of a 1 per cent. solution of azo-induline are added, and titanous chloride is then run in until the violet colour gives place to orange, using the stronger titanous solution until approaching the end-point if the sample contains large quantities of iron and only little uranium. If the end-point be overstepped, ferric solution is added until the colour changes, and then again dilute titanous solution, drop by drop. Enough hydrochloric acid is now added to insure the presence of free mineral acid (2 C.C. of acid to each 5 C.C. of tartrate solution taken), and the uranium is finally titrated with ferric solution, as already described. G. C. J. Radio-Activity of Solutions of Uranium Salts : Method for the Estimation of Uranium. L. Michiels. (BUZZ. SOC. Chim. BeZg., 1913, 27, 69.)- Solutions of uranium salts were found to give a-ray standards of greater accuracy than can be obtained by the use of the powdered solid substance. The ionisation produced is, moreover, a measure of the amount of uranium present. A series of solutions of potassium uranyl sulphate and of uranyl nitrate mere examined by means of a special electroscope, the amber insulation of which was unaffected by an atmosphere saturated with moisture. With constant volume, area, temperature, and depth of solution, the a-radiation was proportional to the quantity of uranium in the solution. With concentrated solutions, however, the ionisation did not keep pace with the increase in concentration, but if, however, a series of solutions of the uranium salt of different concentrations are brought to the same sp. gr. by means of ferric chloride, the proportion- ality between ionisation and concentration is re- stored. It is thus possible, in the absence of other radio-active substances, to estimate uranium without preliminary separation from other metals. 0. E. &!I.

ISSN:0003-2654    

DOI:10.1039/AN9133800220

出版商:RSC    

年代:1913

数据来源: RSC

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INORGANIC ANBLYSIS 231 APPARATUS, ETC. Improved Apparatus for Testing the Jelly-Strength of Glues. E. C. Hulbert. ( J . Ind. and Eng. Cheqn., 1913, 5, 235.)-The apparatus consists of a thistle-tube, the stem of which is twice bent as shown. The two larger bulbs are 2 cm. in diameter, and serve as safety- traps ; the smallest is graduated to contain exactly 1 C.C. Over the mouth of the thistle-tube is stretched a diaphragm oE thin rubber.The far end of this tube connects through a 4way stop- cock with a mercury-filled U-tube, having its further arm extended upwards and of smaller bore, containing water or other liquid above the mercury to serve as a gauge. .the fourth arm being left open to the air. A rubber bulb is attached to one arm of the stopcock, The sample of glue-jelly is raiaed by means232 ABSTRACTS OF CHEMICAL PAPERS of the adjustable stand until the liquid in the bulb-tube reaches the upper graduation ; the stand is then secured, and the stopcock set to connect the arms A , B, and C.The cock is next turned to connect the arms A , B, and D, and enough air is forced into the system by the rubber bulb to force the liquid in the bulb-tube down to the lower graduation, the cock being then turned to an intermediate position and the reading taken.The reading may be repeated several times on the same sample, and is uninfluenced by the condition of the surfaceof the sample, such as skin formation. The error due to supporting column of water resting on the glue surface, as in some similar apparatuses, is avoided ; this is important in cases of low-grade glues.H. F. E. H. New Apparatus for Quantitative Dialysis. A. Golodetz. (Chem. Zeit., 1913, 37, 259-260.)-The principle of dialysis has hitherto been but rarely adopted in quantitative analysis because the volume of water required to remove the dialysate is so large that the recovery of the latter in a quantitative manner has been practically impossible.Nevertheless, in the examination of physiological substances, such as blood, milk, animal organs, and secreta, as well as food-stuffs and the like, dialysis may play an important part in the separation of mineral salts, sugars, crystallisable bases, etc., from the colloidal matter in which they may be contained. In designing an apparatus for this purpose (see Fig.), the author has adopted the principle of the well-known Soxhlet extraction apparatus.The water is placed in a boiling-flask, and is continuously distilled up into the top of the condenser, from which it passes down through the dialysing chamber, carrying the dialysed substance into the flask, in which it accumulates. Sufficient water is charged into the apparatus to keep the dialysing cylinder full and the boiling-flask about half-full.In order to have as large a dialysing surface as possible, the dialysing bag is made in the form of an annular cylinder, so that water may pass down one side and up the other on its way to the overflow leading to the flask. In physiological and forensic analyses, using parchment-paper bags, the author was able to recover 98 to 99 per cent.of the dialysable matters in five to seven hours. The heat from the boiling-flask is sufficient to keep the water in the dialysing cylinder warm, thus accelerating the dialysis. For many purposes it is not desirable for such prolonged periods, with a water vacuum pump, to subject the dialysed matter to a temperature of looo 6. and in such cases it is advisable to connect the apparatus by which means distillation is carried on at a temperature of 40° to 45" C.In order to prevent bumping, a slight current of air, regulated by a clip, is admitted through a capillary tube extending to the bottom of the distillation flask.APPARATUS, ETC. 233 The apparatus may be obtained from the Vereinigte Fabriken fur Labora- toriumsbedarf, Berlin.J. F. B. Extraction with Liquefied Gases. F. Friedrichs. (J. Amer. Chem, Soc., 1913, 35, 244-247.)-The apparatus here shown has been devised for extracting substances with liquefied gases. It consists of an extraction vessei, D, in which is suspended from three glass projections a container, C, and of a condenser, B, which is ground to fit into D. This condenser is of the screw type, with a hollow, into which the refrigerating material is introduced. Both condenser and extrac- tion vessel are insulated by means of a vacuum jacket, and between this jacket and the inner vessel a small quantity of the refrigerant may be placed.The upper part of the condenser is connected with a gas-cylinder or generator, and with 6 mercury manometer to indicate the pressure and to act as a safety-valve.For the extraction of substances with liquid ammonia, sulphur dioxide, hydrogen sulphide, methylamine, and similar liquefied gases, solid carbon dioxide and ether may be used as the refrigerant ; whilst for gases of lower boiling-point, such as oxygen or methane, liquid air is a suitable refrigerant. In such cases it is advisable to introduce a little ether before the liquid air to prevent risk of breakage.Still lower temperatures may be obtained by connecting the condenser with an air-pump and evaporating the refrigerant under reduced pressure. By the use of this apparatus it was proved that hydrazine sulphate is quantitatively decomposed by liquid ammonia into free hydrazine and ammonium sulpbate. A weighed quantity of the pure salt wag placed, together with a little glass wool, in a Schleicher and Schull extraction thimble in the vessel C, the thimble being supported on a perforated porcelain plate, and prevented from touching the walls of C by means of short pieces of glass tubing.Air was expelled from the apparatus by a current of ammonia, end the refrigerant then introduced into the condenser screw and the space between the vacuum jacket and the apparatus.The tube between the stopcock G and the bulb F h a d previously been filled with mercury, and this conveyed sufficient heat to evaporate the liquid ammonia in the bulb F. As soon as this bulb had become filled to about three-fourths of its capacity with liquid, the valve of the ammonia cylinder was closed and the extraction then continued automatically.All that was required was to replenish the refrigerant in the condenser screw from time to time. When the extraction was complete the apparatus was allowed to become warm and the gas to escape through the u - 3 -0 safety outlet. The extract was then drawn off through the stopcock G. I t is suggested that with an apparatus made of iron instead of glass a large amount of anhydrous hydrazine might be prepared by this method.C. A. M.234 ABSTRACTS OF CHEMlCAL PAPERS Absorption Apparatus for Use in Nitrogen Estimations by Dumas’ Method. F. Friedrichs. (Zeitsch. artgew. Chcm., 1913, B 26, 143.)-The mixture of carbon dioxide and nitrogen obtained in Dumas’ method for the estimation of nitrogen in organic substances is collected in the lower part, A , of the apparatus shown in the illustration.This part of the apparatus is filled with concentrated potassium hydroxide solution, and is connected with a reservoir ; a quantity of mercury, just sufficient to cover the gas inlet, is placed in the apparatus. When the combustion iscompleted, the tap C is turned, so that the nitrogen which has collected in the bulb of the absorption part of the apparatus may be driven upwards into the burette B.This is surrounded by a water-jacket, and is filled with water, and the volume of the gas is read off in the usual way. The advantage gained in using the apparatus lies in the fact that the gas is saturated with water-vapour and is measured over water; in the ordinary apparatus the gas is measured over an alkali solution whose vapour pressure varies with its concen- tration.w. P. s. New Separating Funnel. C. E. Parker. (J. Amer. Chem. S‘oc., 1913, 35, 295-297.)-1n order to avoid the formation of emulsions in shaking liquids with im- miscible solvents, a form of funnel has been devised in which the surfaces of the liquid in contact are eight to ten times as large a8 in the funnels of the usual form. With this end in view, the funnel has been made in the form of a shallow plano-convex lens of wide superficial diameter (up to 17-5 cm.). During the extraction the funnel is placed on its flat side upon a disc, which i B made to revolve in a nearly horizontal position at the rate of about twenty revolutions per minute, by means of an electromotor. Tke inclination of the apparatus may be adjusted by means of a screw at a suitable angle to promote a gentle movement of the liquids upon each other. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800231

出版商:RSC    

年代:1913

数据来源: RSC

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R EVIE W-S 235 REVIEWS. A HANDBOOK OF SUGAR ANALYSIS: ,4 PRACTICAL AND DESCRIPTIVE TREATISE FOR USE IN RESEARCH, TECHNICAL, AND CONTROL LABORATORIES, By C . A. BROWNE, Ph.D. London : Chapman and Hall. 1912. Price 25s. 6d. net. I t is not infrequently alleged that methods which are in use for the estimation of sugars and their allied compounds are largely empirical ; and whilst this cannot he denied, it must be admitted that these methods have now been brought to such a high state of perfection that the accuracy and precision of which they are capable fall little short of what can be attained with methods applied to inorganic substances which are based entirely on chemical principles.Nor can the reliability of sugar estimations be doubted, seeing that practically identical values can be obtained by means of methods differing so widely in principle as those based on the rotation of the plane of polarised light and on the reduction of cupric salts respectively.The statement, however, needs some qualification in the case of the analysis of the residual products of the sugar factory, where tho results are affected by the presence of the impurities derived from the raw juice, as well as by certain of t.he substances used in the defecation of the latter (both cane and beet products are here referred to), and also because they have been intermittently boiled with these, giving rise to certain products of change.The precise nature of most of these secondary matters is at present unknown to science; consequently the analysis of such residuals can only be interpreted in terms of known sugars, and the results as returned are not so reliable as those obtained with purer producte.Modern developments of sugar analysis are for the most part known only to specialists, and the bulk of those that are published are inaccessible to chemists outside the sugar and fermentation industries. Yet methods of sugar analysis play an increasing rale in the work of the general analyst, and on this account the want has long been felt for a practical handbook describing the most approved methods in this branch of technology.The author of the present volume is eminently qualified to write such a treatise. Originally a student of Professor Bernard Tollens of Gottingen (who has added so much to our knowledge of the chemistry of the sugars and allied compounds), Dr.Browne has acted successively as chief of the sugar laboratory of the U.S. Bureau of Chemistry, Washington, and as research chemist of the Louisiana Experiment Station, New Orleans, whilst at the present time he occupies the position of chemist to the New York Trade Laboratory. The work is indeed to be regarded as a valuable addition to the literature. Covering 787 pages, together with 100 pages of tabular matter, it cannot be denied that the text is written for the most part clearly and concisely.It is to be regretted, however, that some branches of the subject reoeive either no notice at all or are dealt with in a veryper- functory manner, whilst some 260 pages (forming the second part of the vdume) are devoted to matters of pure chemistry which are altogether outside the scope covered by the title.With this part of the work it is not proposed to deal in detail. Some excellent directions are given for sampling sugars and sugar products, and attention is called to the changes in composition which occur owing to the loss or New York: John Wiley and Sons.236 REVIEWS gain of water, as well as to the action of enzymes and micro-organisms, considera- tions the importance of which will be conceded when it is remembered to what extent the so-called (( polarisation value ” of raw cane sugars (on which the duty is based in this country) is affected during their transit.The description of physical methods forms, perhaps, one of the most important features of the work, and special mention in this connection must be made of the chapters on the principle and use of the refractometer and of the polarimeter.To sdme it might appear that a description of the measurement of osmotic pressure by plasmolysis was extraneous, as it has no direct bearing on sugar technology ; how- ever, many will no doubt find its inclusion acceptable.The use of the refractometer in determining the percentage of solid matter in sugar products has, when expedition is essential, advantages over the ordinary methods. Refractometric methods are also superior to densimetric methods, as their accuracy is affected to a lesser extent and by a smaller number of the extraneous substances present in commercial sugar products. As the author very truly remarks, H.Main was the first to demonstrate the practical utility of the Abbe refractometer in sugar-house work as an accurate measure of the moisture and total solids in all products except the very lowest. I t may here be pointed out, moreover, that the more recent determinations of Schonrock (‘( Physikalisch-Technische Reichanstalt,” Berlin) accord remarkably with those of Main.It is to be regretted that the author occasionally refers to quartz-com- pensating aaccharimeters as ‘‘ polariscopes,” since they have an equal right to the more accurate term (‘ polarimeter,” as those instruments in which measurements are made by the direct rotation of the analyser. It is well known that in polari- metric methods of estimating sucrose in raw sugars depending on both single and double observations, the use of clarifying agents introduces numerous errors, and much work has been conducted during recent years towards the elimination of these errors.Dr. Browne must be congratulated on the full and accurate account which he has given to this part of the subject. Under physical methods some mention should, in the writer’s opinion, have been made of the method of estimating ash in sugar products by determining their electrical conductivity, which was first elaborated by Main, and more recently improved by Lange.The analysis of sugar beets is quite adequately dealt with, and most of the Continental methods are described. With regard, however, to the pulping of the roots for analysis, Keil’s boring rasp only is illustrated, whilst no mention is made of Kiehle’s rasping machine, which is designed to take out a longitudinal section right through the middle of the root; and in the writer’s opinion this is the most satisfactory of any machine on the market, it being used exclusively in his laboratories.Of cupric reduction methods for the estimation of the sugars, all the leading gravimetric methods are given, whilst volumetric methods are dealt with very sparsely.Seeing that so much of the so-called (‘ dextrin-maltose ” or 1‘ glucose syrup ” is manufactured in America, it is not a little surprising to find no mention of this product in the book, especially in view of its wide use in confectionery. The writer has frequently to estimate the quantity of glucose syrup present in admixture with other sugars, and he has always found fermentation to give satisfactory results.REVIEWS 237 Dr.Browne, however, in mentioning fermentation as a means of eliminating sugars from fruit products containing dextrin, gives as an objection to the method that most yeasts ferment or modify dextrin to a greater or less degree. For the analysis of starch conversion products, a method originally described in a former edition of Allen’s ‘‘ Commercial Organic Analysis ” is reproduced.Dr. Browne, it is true, throws some doubt on the accuracy of this method, but as an expert on the subject he ought to know that, it could not give results with any approach to accuracy. The method recommended for the estimation of so-called (( dextrin ” in honey is one of precipita- tion with alcohol.Honey dextrin is said to have a specific rotatory power of [Q]D + 115°-1600. Methods have been devised for the detection of cane-sugar in maple products depending on the measurement of the basic lead acetate precipitate, and the author, after devoting more than two pages to their description, quotes an experiment of Doolittle and Seeker exposing their fallacy.The writer cannot agree with Dr. Browne’s statement that one of the most valuable means of ascertaining the source of a sugar is to determine the composition of its ash. This is a long-since exploded notion. I t is, however, quite true that beet products are more apt than cane to contain nitrates. Many parts of this book leave nothing to be desired, and it is to be hoped that Dr.Browne at no distant date will remodel the whole, leaving out many portions of the text on which information can be found in other treatises, and filling in certain lacunae. This will render his book even more valuable than it is a t present. ARTHUR R. LING. DIGITALIS ASSAY. By W. H. MARTINDALE, Ph.D. H. K. Lewis. London. 1913. I n this communication to the Pharmaceutical Society, now published in book form, a comparison is made between the physiological and chemical methods for the assay of digitalis, and a new and simple method is put forward for the approximate chemical assay.The first eleven pages are devoted to a brief review of the present knowledge of the digitalis glucosides and of the methods suggested for their isolation or determina- tion, and subsequently some seven pages are occupied with the chief methods of physiological standardisation which have been suggested or are in actual use.When it is realised that the therapeutic effects of digitalis are due to at least four glucosides, about which not very much is known; that these are not uniformly distributed throughout the plant, and differ as regards both the nature and the power of their action ; and, further, that the proportion in which they occur, and consequently the activity of the preparations, varies with the age of the plant, the soil and climatic conditions under which it is grown, and the time at which it is gathered, it will be readily admitted that a satisfactory process for their assay is as greatly needed as it is difficult to devise.The chemical processes hitherto employed for the standardisation of the preparations have really been nothing more than rough colorimetric determinations. of the digitoxin. The Pharmacopoeias of Great Britain, the United States, Belgium,. Pp. 47. Price 2s. net.238 REVIEWS and Denmark contain no directions for the assay of the drug or its preparations, and the suggestions put forward in the other Pharmacopceias have reference mainly to the Keller-Kiliani test, which is a colour test for digitoxin, and takes little or no account of the water-soluble glucosides, on which so much of the activity of digitalis depends.The physiological tests which are at present mainly used for standardising the tincture cannot be regarded as much more satisfactory, inasmuch as they really afford a standard of toxicity rather than of therapeutic value.The fact that the results of physiological trials by no means always correspond with those of chemical examination, though not necessarily an objection, is certainly not a reassuring factor. Apart from the uncertainty of any method based on experiments on animals so low in the scale as frogs, it is obviously desirable that some simpler plan, not requiring the aid of an expert physiologist, should be available.A method which really only gives the information that a certain volume of the tincture under examination will kill 100 grms. of ‘‘ frog ” in, say, twelve hours does not inspire too much confidence when it is realiaed that the result varies with the species of frog, its age, its size, its sex, and its condition.Nevertheless, it has proved of great value in the past, and is the best at our disposal at the present time. The author’s new test aims at making the pharmacist independent of the physiologiat, and is a great advance on the Keller-Kiliani process, as it takes into account the curative constituents on which the action of the drug mainly depends- i.e., the water-soluble glucosides.After a preliminary treatment to remove various interfering substances, 0-1 C.C. of the product is mixed with Frohde’s reagent, and should then produce a pink colour varying in intensity with the proportion of soluble glucosides present. By com- parison with a colour scale, reproduced in the text, the strength in terms of the physiological test is ascertained.A further 0.1 C.C. of the extract is mixed with glacial acetic acid and poured on the surface of the Frohde’s reagent, when a blue ring, indicative of digitoxin, should be obtained. As the result of numerous experiments the author states that ‘‘ it was possible to obtain depths of colour comparing most favourably with the physiological data, and it is claimed that the method can be made to yield results which may obviate physiological assay of digitalis tincture by means of frogs.” From the point of view of the analyst the method is obviously open to miticism. There is always an element of uncertainty about colorimetric processes, and when comparison has to be made between a liquid in a test-tube viewed partially at least by transmitted light, and a patch of colour on paper viewed entirely by reflected light, this uncertainty is not decreased.The fact, moreover, that so much depends on the accurate measurement of such a small volume of liquid as 0.1 C.C. is a further drawback. Nevertheless, the work is a step in the right direction in so far as it attempts to measure the really curative constituents of the drug, and in expert hands the process may prove on further experience to be all that the author anticipates. The monograph in any case embodies the results of much labour ; it deals withREVIEWS 239 many points of interest in connection with digitalis, apart from the question of standardisation, and is a valuable contribution to the literature of a very complicated subject.C. H. CRIBB. CHEMISTRY FOR DENTAL STUDENTS. By H. CARLTON SMITH. New York: John Wiley and Sons. London : Chapman and Hall, Ltd. 1912. Second edition. Price 10s. 6d. net. This book is divided into eight parts, dealing with qualitative analysis, dental metdlurgy, volumetric analysis, microchemical analysis, organic chemistry, physio- logical chemistry, digestion, and urine, and ‘( follows closely the lecture course in dental chemistry at the Harvard Dental School.” (‘ Its aim has been to give the student, as concisely as possible, such portions of the various branches of chemistry as are most likely to be of value in practical work.” We doubt very much if this aim has been achieved; it would rather appear that, in attempting to cover so much ground and to be concise, the author has only succeeded in producing a book which, though possibly of use to a student in preparing for certain set examinations, would be certain to produce a bad form of chemical indigestion. As an example of the sacrifices made on behalf of conciseness, we may mention that malonic acid is dis- missed in two lines, with the observations that it ‘‘ is an oxidation product of malic acid (from apples), and is comparatively unimportant.” The student using the book is supposed to have had a laboratory training in general chemistry, and to be conversant with the principles of theorefical and physical chemistry, yet it is considered necessary in an introductory chapter to revise some definitions, such as element, compound, atom, molecule, etc., and here we find that: in the symbol ‘( H-0-H the dash (bond) shows that oxygen has two combining points relative to the hydrogen, which is considered to have one”; and in the section devoted to qualitative analysis the following are among many similar instructions : Break point of filter-paper with glass rod and wash Group 2 into beaker with warm (NH,),S.” 6‘ Filter and wash. Throw away wash-water.Pierce filter and wash sulphide into large test-tube or small beaker.” Is such information really necessary for students who have had a laboratory training in general chemistry ? The book does not appeal to the reviewer, and he cannot recommend it to students desirous of obtaining an adequate training in the principles of chemistry as applied to dental science. EAUX-DE-VIE : EAUX-DE-VIE NATURELLES ET INDUSTRIELLES.By x. ROCQUES. Pp. 316 +Table of Contents. Paris : Ch. BQranger. 1912. Price 6 francs. This little volume is one of a series of ‘ l Manuels Pratiques d’dnalyses Chimiques,” edited by MM. Bordas and Roux. Chapter i. deals with the nature of various spirits, chapter ii. with their analysis, and chapter iii.consists of a series of tables of analytical results interlarded with critical notes. The work concludes with a number of appendices, dealing (1) with spirit legislatiou in various countries, and (2) with official methods of analysis. Chapter i. contains, in tabular form, an inter- esting series of suggestions regarding the denomination of various types of blended ARTHUR W.CROSSLEY.240 REVIEWS spirits, but it does not appear that this classification is official. The section dealing with analytical methods is brief, covering some thirty-six pages, but is no doubt suited to the requirements of French official practice. The collection of tables in chapter iii. should be useful to those interested in the constitution and analysis of French spirits, but the information regarding other spirits is meagre.The appen- dices give the reader a very fair idea of legislation in a number of countries, but it is not quite clear why the resume of official methods of analysis should have been restricted to data concerning Belgium and Italy. P. SCHIDROWITZ. INTRODUCTION TO THE RARER ELEMENTS. By P. E. BROWNING. Third edition.London : Chapman and The third edition of this useful little book is an improvement in several respects on the earlier editions. The chapter on qualitative separation has been considerably enlarged, and may be commended as an admirable summary of work which in the original memoirs is too voluminous to be directly useful, and much of which is of very recent date. The chapter on the technical application of the rarer elements has also been expanded, and a table of spectroscopic lines, and plates showing typical spectra, have been added.The index is deserving of imitation. Arranged in tabular form, it occupies only two pages, but contains as much information as an ordinary index of seven times that length, and contains it in a more readily accessible form. The analyst must not expect to find in this small volume detailed directions for the quantitative separation and estimation of the rarer elements.For example, he would look in vain for a method for the estimation of vanadium in presence of chromium, a commonly occurring problem, formerly very difficult of accomplishment, but to-day comparatively easy. Similar instances might be multiplied, but this would not be fair to the author, who described his book, in the preface to the first edition, as a “handbook in the introductory study of the rarer elements.” The book is addressed to senior students, not to analysts, but as a first reference, where one of the really rare elements ia concerned.it may well prove useful to the analyst. Its utility would be enhanced by more frequent reference to original memoirs in which difficult quantitative separations are dealt with in detail, and the existing references would be more handy if the dates as well 8s the volume numbers of periodicals were given. Pp. xii+232. New York : John Wiley and Sons. Hall. 1912. Price $1.50. G. C. JONES. 9 % @ % ? @ INSTITUTE OF CHEMISTRY. PASS LIST : MARCH-APRIL (1913) EXAMINATIONS. OF twenty-five candidates who presented themselves for the final examination fourteen passed. In the Branch of Mineral Chemistry : S. C. Bate, B.Sc. (Lond.), F. G. Crosse, and S. G. Greene; in the Branch of Metallurgical Chemistry: E. Marsden ; in the Branch of Organic Chemistry : W. F. Hollely, T. S. Jones, B.Sc. (Lond.), H. Lambourne, B.Sc. (Lond,), D. H. Peacock, B.Sc. (Lond.), B.A. (Cantab.), and F. Sproxton, B.Sc. (Lond.); in the Branch of the Chemistry of Food and Drugs, and of Water: A. L. Davidson, R. E. Griffiths, B.Sc. (Lond.), F. W. Hoyland, W. G. Saunders, and W. A. Storey.

ISSN:0003-2654    

DOI:10.1039/AN9133800235

出版商:RSC    

年代:1913

数据来源: RSC