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NOVEMBER, 1913. Vol. XXXVIII., No. 452. THE ANALYST. OBITUARY. JULIUS LE WKO WITSCH. CHEMISTRY has suffered a very great loss in the death of Julius Lewkowitsch, which occurred at Chamonix on September 15, after only a few days’ illness. A technolo- gist of outstanding merit, the recognised authority on vegetable and animal fats and oils, an author of marked originality and reliability, and an energetic and stimulating member of the councils of many societies associated with both pure and applied chemistry, his work will go down to posterity as a permanent tribute to a, life of exceptional and successful activity.Lewkowitsch was born at Ostrowo, in Prussian Silesia, in 1857, and received his vocational training, under Victor von Richter, at the University of Breslau, where he took the degree of Ph.D.in 1879, and that of M.A. in 1881. With the intention of devoting himself to an academic career, he accepted a position as teacher of mathematics and natural science at the Friedrich’s Real Gymnasium, Berlin, under Landolt, and subsequently became assistant to Victor Meyer at Heidelberg Universihy. A few years later, however, he turned from the promising career that appeared to be opening out to him in pure science, to what subsequently proved to be his life’s work in chemical technology.After occupying the positions of research chemist at a tar and petroleum works, and manager of a tar distillery in Germany, he came to England, when about thirty years of age, to act as chemist and technical manager to Messrs. Watson and Sons at their Leeds soap works.This last post he held for some eight years, during which he became naturalised as a, British subject. I n 1895 he commenced his work as a consultant in Manchester, and in 1898 trans- ferred his rapidly extending practice t o London. Lewkowitsch’s contributions to chemistry are associated respectively with the two separate periods of his career, as a teacher and as a technologist. During the comparatively short time that he was engaged in academic work, he published several notable papers.His first contribution was a study of the action of nitric acid on fatty acids, but in 1882 and 1883, whilst working with Landolt, he turned his attention to the experimental study of stereochemistry, a subject which was then494 OBITUARY : JULIUS LEWKOWITSCH quite in its infancy, and successfully developed Pasteur’s method for the resolution of externally compensated substances by means of living organisms.By the action of Aspergillus mwor and of Penicillium glnucum on the racemic form of aminoDium mandelate, prepared from benzaldehyde, he obtained the dextro-rotatory stereo- isomer of mandelic acid, and subsequently prepared the optically active modifications of lactic, glyceric and tartaric acid by similar means.From these investigations he was led to the study of the possible asymmetry of benzenoid compounds, from the consideration that, according to L8denburg’s prism formula for benzene, an ortho- disubstitution product, should be optically active, and attempted to isolate the optically active forms of the two methyl salicylic acids and of other compounds of similar orientation.I n the field of technology, to which Lewkowitsch devoted the greater part of his life, his work was concentrated on the subject he made so particularly his own, and on which it is not too much to say he was the greatest living authority-the technology of fats and oils. To this journal he contributed papers on the estima- tion of glycerol; on the separation of olelc acid from other fatty acids; on the differentiation of linseed oil from boiled oils ; on oxidised oils, Indian oils, Carapa oil, and on a variety of the less known fats.To the Society of Cheniical Industry he contributed the results of many important investigations bearing on analytical problems connected with the oil, fat and wax industries, in addition to papers on subjects of a wider scope, such as the ‘‘ Theory of Saponification ” and ‘‘ Problems in the Fat Industry.” These contributions, together with many others to foreign journals, are for the most part embodied in his standard book on the “Chemical Technology and Analysis of Oils, Fats and Waxes.” This work, as first published in 1895, was founded on Benedikt’s (‘ Analyse der Fette und Wachsarten,” to which Lewkowitsch made considerable additions ; the second edition, which followed in 1898, was practically an independent work, which was much expanded and brought up to date in the subsequent third and fourth editions, which were published in 1904 and 1909 respectively.A fifth edition has been issued during the present year, of which the first volume was published in July and the second volume is in the press.I n addition to the English edition of his book, Lewkowitsch also published separate editions in both French and German. His well-known ‘‘ Labora- tory Companion” to this work was published in 1901. His numerous other literary contributions include a course of Cantor Lectures before the Royal Society of Arts in 1904, on “The Uses and Application of Oils and Fats,” and the articles on oils and fats in Thorpe’s ‘‘ Dictionary of Applied Chemistry,” in Lunge’s (‘ Chemiscb-technische Untersuchungsmethoden,” and in the English edition of the same work, ‘‘ Technical Methods of Chemical Analysis,” for which he had also revised the sections on mineral oils, lubricants, and resins and balsams ; he also wrote the sections on oils and fats in the (‘ Encycloptedia Britannica,” and in Meyer’s ‘( Jahrbuch der Chemie.” The preface to Lewkowitsch’s last published work, the first volume of the fifth edition of his ‘6 Chemical Technology and Analysis of Oils, Fats, and Waxes” includes this statement : ‘‘ Whereas a decade or two ago chemical analysis pointed out the way to technical development, and purely scientific discoveries appeared to have comparatively little inff uence on the progress of our industries, the order is nowOBITUARY : JULIUS LEWKOWITSCH 495 reversed. In its influence on the advance of the oils and fats industries pure science has stepped ahead, and it is now the turn of analytical chemistry to follow in the wake of progress and to detect in the finished articles the achievements of technical work.” Lewkowitsch’s own work is a striking example of the manner in which analytical chemistry should ‘‘ follow in the wake of progress.” Few men recognised more fully the value of the services rendered by analytical chemistry to the advance of technology, and the fundamental importance of analytical accuracy in the control of the industrial applications of chemistry. The services rendered by Lewkowitsch to scientific societies were always marked by helpful and wise counsel.He served on the Council of this Society in 1902-3, on that of the Chemical Society during the same period, on that of the Institute of Chemistry from 1901 to 1904, and he was very specially associated with the work of the Society of Chemical Industry, of which he was the Foreign Secretary at the time of his death.I n 1909 he was awarded the Lavoisier Medal as Confkrencier of Ithe SociM Chimique de France. Apart from his great scientific attainments, Lewkowitsch was a man of marked individuality, with wide sympathies and knowledge, ever ready to help his fellow- workers, especially younger men, many of whom owe their success to his guidance and training.He gave his services ungrudgingly to whatever he undertook, with d l too little regard to his own leisure and recreation ; and although he was recognised a,s a strong advocate and as a powerful adversary, he has left none but the best of friends amongst a, large circle, which, owing to his exceptional linguistic abilities, .extended far beyond the confines of his adopted country. Apparently jn the full vigour of life, and with every promise of many further years of activity, Lewkowitsch passed away within sight of the Alps he knew so well, and on which he enjoyed his chief recreation. He married in 1902, and is survived by his wife and a young son and daughter. CHARLES A. KEANE.

ISSN:0003-2654    

DOI:10.1039/AN9133800493

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

496 ABSTRACTS OF CHEMICAL PAPERS PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Nitrogenous Substances in Barley and Malt. 111. : Transformation of the Proteins during Mashing, Boiling of Wort, and Fermentation. H. Schjerning. (Compt. re?td. des Travaux du Lab. de Carkberg, 1913, 9, 237-396.)- The analytical methods employed are similar to those described in a former paper (ANALYST, 1910, 35, 350).The acidity of wort is now determined by a titration with sodium hydroxide “ t o the tone of colour which is produced when 2 C.C. of a, solution of phenolphthaleln (1 per cent.) and 4 C.C. of a & solution of disodium hydrogen phosphate are added to 25 C.C. of distilled water which has previously received an addition of Bismarck brown and tropeolin 0 in quantity to give the solution the same colour as the wort the acidity of which is to be determined.” Ammoniacal nitrogen is estimated by distilling the wort with a convenient excesB of magnesium oxide.The amino-acid nitrogen titratable with formaldehyde and the concentration of hydrogen ions were determined in a dilute wort by Sorensen’s method (ANALYST, 1908, 33, 19; 1909, 34, 498).Peroxidase and catalase were measured by methods previously described (Conzpt. rend. des Travaux du Lab. de Carlsberg, 1909, 8, 67 ; 1910, 8, 200, 321 ; ANALYST, 1910, 35, 350). A large amount of experimental matter is included in the paper, together with over fifty tables of figures, the summary of the (‘ principal results ” alone occupying ten pages of matter.Through all the stages of mashing, boiling, cooling, fermentation (primary and secondary), the effect of different water treatment, wort concentration, mashing temperatures, boiling-time, hop variation, aeration, etc., on the wort is followed by estimating, among other variables, the amounts of total extract, ash, acidity, total nitrogen, assimilable nitrogen, peptic cleavage products, tryptic cleavage products, ammonia, ‘‘ albumin I.and II.,” proteose, peptone, denuclein, and hydrogen ion concentration. H. F. E. H. Composition of the Seeds of Cicer Arietinum, L. (Chick-pea). A. Zlataroff and S. Stoikoff. (Zeitsch. Unterszsch. Nahr. Genussm., 1913, 26, 242- 247.)-The chick-pea is a dwarf pea cultivated in Bulgaria and Southern Europe generally, and used as a food like lentils.Resdts of analyses of twenty-four samples showed it to have the following average composition : Water, 10-47 ; proteins, 22-63 ; fat, 5.08 ; starch, 49.33 ; crude fibre, 3.09 ; ash, 2.138 per cent. The total phosphoric acid amounts to 0.88 per cent (as P,O,), of which 0.125 per cent.is present asFOOD AND DRUGS ANALYSIS 497 lecithin-phosphoric acid. The peas are frequently roasted before use, and are then known under the name of (‘ leblebiji.” A product known as (( ssimitt ” is prepared by allowing the peas to germinate and ferment. The germinated peas contain oxydase, zymase, protease, diastase, and rennin ; and the products of fermentation are hydrogen, hydrogen sulphide, carbon dioxide, butyric acid, lactic acid, succinic acid, sugar, ethyl and higher alcohols, leucine, asparagine, and aromatic substances (aldehydes and esters 1).w. P. s. Examination of Chloroform. K. Enz. (Apoth. Zeit., 1913, 28, 672-674; through Chem. ZentraZbZ., 1913, II., 1172-1173.)-The impurities of commercial chloroform include chloral alcoholate and similar chloral compounds.These may be estimated by treating the chloroform with &.alkali and titrating the excess. Pure chloroform is not affected by alkali of this strength. Aldehydic and similar com- pounds are detected by means of Nessler’s reagent, which gives with impure chloroform a red-brown deposit rapidly changing to greenish black. Pure chloroform does not give any reaction.C. A. M. Detection of Formaldehyde in Foods. F. Rachel, (Pharm. Zentralhalle, 54, 759-761 ; through Chem. ZentraZbE., 1913, II., 903.)-Friese’s method for the detection of formaldehyde in milk has been modified to make it applicable to meat, caviare, and fish preparations. The sample is treated with phosphoric acid and dis- tilled with steam in the usual way. One to two c .~ . of the distillate are thoroughly shaken with 4 C.C. of milk free from formaldehyde and 10 C.C. of hydrochloric acid (sp. gr. 1-19> containing 1 drop of 25 per cent. nitric acid in 300 C.C. If formaldehyde be present, a blue coloration is immediately produced. Since the reaction only takes place with traces of formaldehyde, it is advisable, in the case of a negative result, to repeat the test after diluting the distillate.In order to determine whether the formaldehyde is present in the free or combined condition, a separate portion may be distilled without the addition of phosphoric acid. J. F. B. Estimation of Total Formaldehyde in Fumigators and Commercial Solutions. J. J. Hinman jun. (J. hzd. and Eng. Chem., 1913, 6, 752-755.)-The author has tested comparatively, by nine different methods, a number of samples of formaldehyde preparations containing polymerides and foreign matters.The ammonia methods are not very rapid, and the end-point of the titration in presence of rosolic acid is not distinct. The litmus end-point is more satisfactory. The hydrogen peroxide methods are more rapid, and the results are easily checked.The end-point of the sulphite methods is sharper than in either of the other processes. The titrations are direct. For formaldehyde solutions they require the minimum of tims, but when polymers are to be titrated the Kleber method is the most rapid of all. For an occasional analysis the peroxide method of Haywood and Smith (ANALYST, 1905, 30,401), using litmus indicator, or the sodium sulphite method of Seyeweti and Gibello (ANALYST, 1904, 29, 288) seem to be preferable, whilst for regular analyses of large numbers of samples the bisulphite method of Kleber (ANALYST, 1904, 29, 161) would be most suitable.Legler’s ammonia method498 ABSTRACTS OF CHEMICAL PAPERS gives too low results, and Blank and Finkenbeiner's peroxide method gave the highest results.Haywood and Smith's method gave slightly lower percentages than Blank and Finkenbeiner's, closely followed by Kleber's and the other methods. J. F. B. Baobab Oil. V. Thomas and F. Boiry. (BzLZZ. SOC. Chim., 1918, 13, 827-832.) -The seeds from different varieties of baobab (Adansonia) contain considerable quantities of oil, but those of Adansonia grandidieri, a tree growing in Madagascar, appear to contain the largest amount.These seeds, in the undecorticated condition, yield 43 per cent. of a yellow-coloured oil, whilst the decorticabed seeds yield 65.4 per cent. of a white fat having the consistence of butter. The following figures were obtained on the examination of the oils, and the fatty acids separated from them : From Whole Seeds. Oil : Sp.gr. .. . ... ... Melting-point ... ... Solidifying-point . . . ... Refractive index at 40" C. . . . Saponification value . , . Iodine value (Wijs) ... ... Reichert-Meissl value ... Hehner value ... ... Melting-point ... ... Solidifying-point . . . ... Acid value ... ... ... Saponification value , . . Iodine value . . . ... ... ... Fatty Acids : ... 0.9190 (at 20° C.) 20°-210 c. 13" C.1-4585 192.4 65-66 0.77 95 *5 51'-52" C. 44.5" c. 179.0 202.5 66-67 From Decorticated Seeds. 0-9135 (at 40' C.) 39"-40' C. 33" c. 14521 196.0 36.9 - - 45'-46" C. 204.5 207.6 34-35 - The difference between the acid and saponification values in the case of the oil from the undecorticated seeds indicates the presence of lactones, and further ex- amination showed that the fatty acids contained 11.4 per cent.of lactones, the nature of which, owing to lack of material, could not be investigated. The mixed fatty acids consisted of myristic acid, 7 per cent.; palmitic acid, 32.5 per cent.; oleic acid, 36.5 per cent. ; and linoleic acid, 8.7 per cent. Stearic and arachidic acids were not present. w. P. s. Hickory Nuts and Hickory Nut Oil. G. 0. Peterson and E.H. S. Bailey. (J. Ind. and Eng. Chenz., 1913, 5, 739-740.)-Two varieties of hickory nuts have been studied-Carya ovata, or shell-bark hickory, the edible variety, and C. arnara, the swamp hickory, the nuts of which are only fed to pigs. The kernels of the edible nuts have a high food value, containing 70.2 per cent. of oil and 13.2 per cent. of protein. By cold pressing, followed by hot pressing, 65 to 66 per cent.of the totalFOOD AND DRUGS ANALYSIS 499 oil present may be extracted. The oil retains the flavour of the hickory nut, and is practically equal to olive oil as a table oil. The oils obtained from the two species of nut are practically identical, and are similar to cottonseed oil in their chemical and physical characters. The resemblance is so close that a diflerentiation from cottonseed oil would be difficult. The following constants were obtained for the two varieties of oil, and are compared with those recorded for a sample prepared at the Maine Experiment Station : CONSTANTS OF HICKORY NUT OILS.(7. Amara. - Sp. gr. at 24' C. ... ... Refractive index at 20" C. ... 1-4699 Hehner value ... ... ... 95.6 Reichert-Meissl value ...0.48 Iodine value ... ... ... 105.2 Saponification value ... ... 190.0 C. Ovata. 0.9119 1.4699 95.7 0.47 106.8 189.6 Maine Experiment Station. 0.9164 1.4696 - - 102.8 - J. F. B. Analysis of Maple Products. I. : Electrical Conductivity Test for the Purity of Naple Syrup. J. F. Snell. (J. Ind. and Eng. Chem., 1913, 5, 740-747.)-When maple syrup is adulterated with commercially pure sugar, the percentage of non-sugar constituents is reduced, and, since sugar is a non-conductor, the electrical conductivity of the syrup falls.An examination of a number of samples of genuine maple syrups showed that their conductivities varied within somewhat wide limits inversely as their densities. On dilution with water the conductivities increased until a point of maximum conductivity was reached, after which the conductivities decreased owing to the dilution of the electrolytes.The point of maximum conductivity occurs at a dilution corresponding to one volume of syrup to two volumes of water. This observation is made the basis of a rapid test for the purity of maple syrups. A suitable quantity of the syrup (15 c.c.) is measured out in a graduated cylinder and drained into a small beaker ; the cylinder is then twice washed out with equal volumes of water, and the syrup is dissolved therein.The solution is poured into the conductivity cell, the temperature is adjusted to 25' C., and the measurement is made. The constant of the cell is divided by the number of ohms, and the result inultiplied by 100,000. The values for genuine syrups lie between 110 and 200, but further experience may extend these limits a little. Syrups giving conductivity values distinctly outside these limits may be condemned without further examination ; but those giving normal values are not necessarily pure, and should be examined by the usual methods.The essential features of the apparatus are : A low voltage electrical current operating an induction coil ; a con- ductivity cell of a form suitable for liquids of low conductivity and with electrodes not easily displaced; a Wheatstone bridge with telephone; a device for exact500 AESTRACTS OF CHEMICAL PAPERS regulation of temperature.An examination of the ash of pure maple syrups indicates that the organic salts of potassium and calcium are the principal electrolytes of the syrups, and the tabulated results show close relationships on the one hand between conductivity and total ash, and on the other hand between conductivity and alkalinity of the soluble ash.Estimations of conductivity values of non-maple syrups showed that syrup from granulated sugar is practically a non-conductor, but that molasses show values many times greater than the average for pure maple syrup.Syrup made from pale brown sugar showed a value of 178, thus within the limits for pure maple, and it is evident that various mixtures of partially refined products could be made to show normal values. Consequently a normal conductivity value is in no sense evidence of purity, but the method is extremely rapid and useful for sorting out obviously adulterated samples (cf.ANALYST, 1912, 37, 538, 543). J. F. B. Detection of Added Water in Milk by Means of the Refractometer Value of the Serum. G. Schutz and L. Wein. (Zcitsch. Untersuch. Nahr. Genussnz., 1913, 26, 177-184.)-The serums obtained, respectively, by the use of calcium chloride (ANALYST, 1907, 32, 117) and by means of carbon tetrachloride and acetic acid (ibid., 1912, 37, 450) are equally suitable for refractometric purposes.The calcium chloride method of preparing the serum is simple and rapid, whilst the carbon tetrachloride method yields a serum which may be used for determining constants other than the refractometer value. I n the case of the calcium chloride serum, the increase in the refractometer value, due to the formation of acidity in the milk, may be prevented by the addition of a few drops of formaldehyde to the milk.Another source of error consists in the solubility of precipitated lime coin- pounds when the serum is allowed to remain too long a time in contact with the coagulum ; the serum should be separated within thirty minutes. w. P. s. Black Mustard Powder. H. Imbert and A.Juillet. (Bull. h'ciences Pharrnacol., 1913, 20, 385-388 ; through Chem. Zentralbl., 1913, II., 1170-1171.)- Ally1 mustard oil is estimated by the Codex method of hydrolysing the potassium myronate by means of myrosin in the presence of water. For the detection of white mustard, 5 grms. of the powder are boiled for two minutes with 100 C.C. of water containing 20 drops of alkali hydroxide solution, and the boiling mixture diluted with 200 to 300 C.C.of cold water. The deposit is separated, washed two or three times, and examined under the microscope for uncrushed particles of white mustard seed. Black mustard powder of different origin was found to contain from 0-493 to 0.899 per cent. of mustard oil, whilst a sample of white mustard powder contained 0.068 per cent.Many samples of the black powder contain turmeric and linseed- meal as impurities. C. A. M. Composition of Rums. J. Sanarens. ( A m . Falsv., 1913, 6, 488-495.)- Analyses of numerous authenticated samples of rum are recorded, and the minimum and maximum results obtained are given in the following table ; hhe results obtainedFOOD AND DRUGS ANALYSIS 501 on the examination of six samples of artificial rum are also given.The figures express grms. per 100 litres of absolute alcohol. Total acids : Minimum ... Maximum ... Minimum ... Maximum ... Minimum ... Maximum ... Higher alcohols : Minimum ... Maximum ... Furfural : Minimum ... Maximum ... Aldehydes : Esters : Msrtin- ique . 65 394 3 90 37 797 19 395 1 9 Guadc- loupe. 82 138 5 36 31 72 80 194 1 3 Rum imported from- Rdunion.128 245 4 41 56 101 73 93 1 4 Cochin- China. 20 50 6 17 12 29 153 319 trace 1 British Guiana. 80 87 10 41 24 46 139 164 1 2 Jamaica. 123 176 13 16 632 938 22 39 1 2 Artificial Ruin. 82 159 4 14 127 2,240 14 70 1 5 w. P. s. Examination of Turpentine Oil by the Methods of the German Pharma- copoeia. (Pharm. Zeit., 1913, 58, 470-471 ; through Chem.Zentmlbl., 1913, II., 1085-1086.)-For the estimation of the bromine value, 2 C.C. or 2 grms. of the sample are made up to 100 C.C. with petroleum spirit, and 4 C.C. of the solution added to a mixture of 50 C.C. each of the potassium bromate and potassium bromide solutions of the German Pharmacopoeia. Five C.C. of sulphuric acid are then added and the flask immediately stoppered, and shaken for about a minute, after which the turpentine solution is added drop by drop with continual shaking, until the petroleum spirit layer is decolorised.The bromine value is calculated from the total number of C.C. of the turpentine solution consumed. If 2 grms. of the sample were taken the value is 1,200; and if 2 C.C. were takenit is , where s represents the sp. gr.of the turpentine oil. Pure oil of turpenbine has a bromine value of 215 to 230, rarely as low as 210. Testfor Pine Oil.-Five C.C. of the sample are boiled with 5 drops of nitro- benzene, 2 C.C. of 25 per cent. hydrochloric acid then added, and the liquid again boiled for ten seconds. All pine oils give a deep brown coloration of the oily layer, whilst the acid layer becomes brown or black.In the case of turpentine oil there is either no coloration, or the oily layer shows a greenish tint, whilst the acid layer is coloured light brown. By means of this test an addition of 5 per cent. of pine oil to oil of turpentine may be detected. H. Wolff. 1200 X XS C. A. M.502 ABSTRACTS OF CHEiMICAL PAPERS Estimation of Chlorides in Wine. C. von der Heide and M.Kartschmar. (Zeitsch. anal. Chem., 1913, 52, 645-651.) -In wines containing less chloride than corresponds to 5 mgrms. chlorine per 100 c.c., it is unnecessary to add alkali before igniting the residue ; but with wines containing 10 mgrms. or more chlorine per 100 C.C. there is considerable loss if the addition of alkali be omitted. Incinerating wine residues to which alkali has been added is troublesome, often attended with loss, and the authors have tried several alternative methods for the estimation of chlorine in wine, and recommend the following, which gives exact results with natural wines : A measured and more than sufficient amount of TG silver nitrate solution is added to 100 C.C.of wine, together with 2 to 3 grms. of animal charcoal in the case of white wines, or 5 to 8 grms.in the case of red wines. The mixture is boiled for fifteen minutes, 20 C.C. of dilute nitric acid is then added, boiling continued for a further ten minutes, and the solution filtered. The charcoal and filter are washed with 200 to 300 C.C. of hot very dilute nitric acid, and the filtrate and washings are allowed to cool. Carbamide is added if necessary to destroy nitric oxide, and the excess of silver titrated with thiocyanate. Direct volumetric determination of chlorine in the original wine is impossible on account of the colour, and the results of gravimetric determinations on the original wine are always too high, Musts and very sweet wines are best treated as follows : The sugar is fermented away as far as possible, and the fermented liquid is evaporated to a syrup, mixed with 10 grms.of slaked lime, dried, and burnt. The ash is extracted with water, and the aqueom extracts are filtered into a vessel containing 25 or 50 C.C. & silver nitrate solution. Finally the lime is dissolved in dilute nitric acid, and this solution also filtered (from particles of carbon, etc.) into the vessel containing the silver nitrate.The excess of silver is then determined by titration with thiocyanate. G. C. J. Estimation of Tartaric, Succinic, and Malic Acids in Wine. P. Dutoit and M. Duboux. (BUZZ. SOC. Chim., 1913, 13, 832-862.)-A detailed description is given of the combined volumetric and conductivity method (cf. ANALYST, 1909, 34, 56 ; 1912, 37, 600) for the estimation of organic acids in wine.The procedure is as follows : The total acidity and sulphates are first estimated, and let a denote the number of C.C. of f alkali solution required to neutralise 1 litre of the wine. One hundred C.C. of the wine are then heated in a flask to boiling, and a quantity of barium chloride solution just sufficient to precipitate the sulphates is added, followed by the addition of 2 C.C.of a 25.2 per cent. uranium nitrate solution. The mixture is shaken for a few minutes, neutralised with sodium hydroxide, 0-18 C.C. x a of f silver nitrate solution and 250 C.C. of 95 per cent. alcohol are added, and the mixture is filtered. The filter and precipitate are transferred to the flask, and mixed thoroughly with 0.12 C.C. x a of sodium bromide solution (prepared with 50 per cent.alcohol) and 100 c.0. of 47.5 per cent. alcohol. After the lapse of about ten minutes the mixture is diluted to 202 C.C. with 47.5 per cent. alcohol, and filtered. The filtrate now contains the organic acids, and is used for the estimation. Estimation of Tartaric, Malic, and Succiizic Acids.-A definite volume of the solu tion of the acids (according to the acidity of the wine; see below) is placed in theFOOD AND DRUGS ANALYSIS 503 conductivity vessel, an equal volume of 47.5 per cent.alcohol is added, then 0.5 C.C. of Tc acetic acid, and the conductivity of the solution is determined while the latter is titrated with lanthanum nitrate solution which has been standardised in a similar way against f sodium tartrate solution..Acidity of the Wine in C.C. per Litre. Below 90 90-115 115-140 Above 140 Volume of the Acid Solution to bc taken. Volume of 47.5 per Cent. Alcohol to be added. Estimation of Tartaric, and Malic Acids.-Another quantity of the solution (see below) is treated with 1 C.C. of glacial acetic acid and alcohol, and titrated with lanthanum nitrate solution while the conductivity is determined.In this and in the previous titration the lanthanum nitrate solution is added in quantities of about 0.1 C.C. at a time : Acidity of the Wine in C.C. 2 per Litre. Volume of the Acid Solution to be taken. Below 90 90-115 115-140 Above 140 15 ,, 10 9 , Volume of 4 i - 5 per Cent. Alcohol to be added. Volume of 76 per Cent. Alcohol to be added. Estimation of the Tartaric Acid.-Two titrations may be necessary, according to the amount of mslic acid also present.A portion of the solution containing the acids is mixed with 5 C.O. of glacial acetic acid and 75 C.C. of 95 per cent. alcohol, and the conductivity is determined while the mixture is titrated with barium acetate solution, the barium equivalent of which has been ascertained by the conductivity method.If from the results obtained the ratio of malic acid to tartaric acid is less than 1 : 3.7, a second titration must be made, as the presence of much malic acid renders the first titration untrustworthy. Another portion of the solution is treated with C.C. per C.C. of the acid 1,000 eolution taken, rn expressing the amount of malic acid per litre in C.C. of solution, and t the amount of tartaric acid in C.C.of Five C.C. of glacial acetic acid and 75 C.C. of 95 per cent. alcohol are then added, and the mixture is titrated with the barium acetate solution. 3.7 m - t sodium tartrate solution, the quantity added being solution.504 ABSTRACTS OF CHEMICAL PAPERS Sum of Tartaric + Malic + Succinid Acids in C.C. per Litre. Below 70 70-90 90-110 110-130 First Titration.Volume of Acid Solution to be taken. Volume of 4 7 5 per Cent. Alcohol t o be added. Second Titration. Volume of Acid Sohition to Le taken. Volume of 4 7 5 per Cent. Alcohol to be added. When excessively large quantities of malic acid are present in wines, it is advisable to estimate the tartaric acid separately by the ordinary potassium hydrogen tartrate method.This also applies to wines containing citric acid, as this acid is estimated~ together with the tartaric acid in the conductivity-titration method. W. P. S. Estimation of Tartaric, Citric, Lactic, and Malic Acids in Musts, Wines, etc. L. Mathieu and L. Ferre. (BulZ. Assoc. Chim. Sucr. et Dist., 1913, 30, 842- 844; through Chem. Zentralbl., 1913, II., 709.)-In the case of wines the acids are first separated by Mestrezat’s method (ANALYST, 1907, 32, 266, 388), and the lactic acid in the filtrate estimated by Moslinger’s method. The tartaric acid is estimated in a portion of the precipitate, dissolved in sulphuric acid, by the method of Kling (,~NALYST, 1912, 37, 516), whilst another portion of the precipitate is oxidised by Mestrezat’s method in acid and in alkaline solution. One grm. of tartaric acid is oxidised by 1.447 grms. of potassium permanganate in acid solution, and by 0.620 grm. in alkaline solution ; 1 grm. of malic acid by 2.078 grms. in acid solution, and 0.615 grm. in alkaline solution; and 1 grm. of citric acid by 1.820 grms. in acid solution and 0.480 grm. in alkaline solution. If x grms. of tartaric acid, y grms. of malic acid, and z grms. of citric acid are present, the proportion of y and x may be calculated by means of the following equation, in which Vrepresents the volume of’ acid permanganate solution, and 71 the volume of alkaline permanganate solution,” and a the strength of the solution, The value of x has been found by direct- estimation : y x 2.078 + x 1.820 = Va - x 1.447 y x 0.615 + x 0.480 = Vla - x 0-620 The method is applicable even in the presence of succinic acid, since the latter, althou,gh precipitated by Mestrexat’s method, is not attacked by the permanganate solution, and may be separated by the usual methods (cf. ANALYST, 1913, 381). C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800496

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

504 ABSTRACTS OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Methods of Estimation of Carbohydrates, especially in Plant Extracts. W. A. Davis and A. J. Daish. (J. Agric. Sci., 1913,5,437-468.)-The alcoholic extract is evaporated 4% vacuo to a small definite volume, usually 500 C.C. Two portions of 20 C.C. each are dried down in vacao for eighteen hours at 100' C.; this gives theBACTERIOLOGICAL, PHYSIOLOGICAL, ETC.505 Zlotal dry matter in the extract. Another 440 C.C. are treated with basic lead acetate, filtered under pressure on a Biichner funnel and washed to a known volume (2,000 c.c.). This is solution A ; 300 C.C. of A are freed from lead by solid sodium carbonate and made up to 500 C.C. This is solution B. (1) 25 C.C. of B are used for direct reduction with Fehling's solution, and is also polarised.The reduction is due to maltose, dextrose, Ievulose, and pentoses. (2) For cane sugar, 50 C.C. of B are inverted (a) by invertase, after making faintly acid to methyl orange with sulphuric acid. One or 2 C.C. of autolysed yeast and a few drops of toluene are added, and the whole left for twenty-four hours at 38-40' C., after which 5 or 10 C.C.of alumina are added and the solution filtered, washed, and made up to 100 C.C. The reducing power of 50 C.C. ( = a 5 C.C. B) is taken, and the solution again polarised. ( b ) By citric acid. The solution is made just acid as before, and a weighed quantity of citric acid is added so as to have 10 per cent. of the crystalline acid present. After boiling ten minutes, cooling, neutralising with caustic soda, the solution is made up to 100 C.C.and treated as before. The cane sugar is calculated from the increase of reducing power and change of rotation, and the values obtained by each of the two methods, (a) and ( b ) should agree closely. Another 300 C.C. of solution A are freed from lead by means of sulphuretted hydrogen and filtered, the precipitate being washed until the total volume of filtrate and washings is about 450 C.C.Air is aspirated through this for about one and a half hours to expel hydrogen sulphide. A little ferric hydroxide is added to remove the last trace of the latter, and the solution is made up to 500 C.C. After filtration, 50 C.C. portions are fermented with (a) S. marxianzu; ( b ) S. anomalus; (c) S.exiguus; ( d ) and (e) baker's yeast. Pure culture inoculations from agar yeast-water are employed, and 5 C.C. of sterile yeast- water are added to each flask, the fermentation of the sterile sugar solution being carried on for three to four weeks at 25" C. I t is often necessary in order to insure good growth of the yeast first to reduce the acidity by adding 2 to 5 C.C.of sodium carbonate to the 50 C.C. before fermentation. At the end of the fermentation, 5 C.C. of alumina cream are added, the solution made up to 100 c.c., filtered, and 50 C.C. used for reduction. The difference between the average reduction with (a) ( b ) (c), and the average of ( d ) and ( e ) is the reduction due to maltose. (4) Pentosos. These are approximately determined in 50 C.C.oE A by distilling with hydrochloric acid according to the A. 0. A. C. method, and weighing as phloroglncide. (5) When the reduction in (1) due to pentose and maltose has been allowed for, the remaining direct reduction is due to dextrose and Ievulose, the actual proportions of these being calculated from the reducing power and specific rotation. The cupric reduction methods employed throughout are those of Brown, Morris, and Millar (Trans.Roy. SOC., 1897, 71, 72-123), whose tables are employed. Special attention is drawn to the necessity of boiling the asbestos employed with 20 per cent. caustic soda hefore use ; otherwise with some specimens large errors may be introduced due to the solu- bility of some of the silicate in the hot Fehling's solution.The copper should never be weighed as Cu,O, but always as CuO. The volumetric methods of Ling, Rendle, and Jones (ANALYST, 1905,30,182, ibzd., 1908,32,160) and Bertrand (BUZZ. SOC. China., 1906, 35,1285) have been studied and compared, the former being in all respects preferable to the latter, which can only be regarded as roughly approximate. In (3) Maltose.506 ABSTRACTS OF CHEMICAL PAPERS fact, the authors find that the volumetric method of Ling is capable of an accuracy of 0.3 per cent.against the 0.3 to 0.5 per cent. found with the gravimetric method. I n dealing with plant extracts which have been cleared with basic lead acetate, inversion by citric acid of less than 10 per cent. concentration is incomplete owing to the accumulation of sodium acetate in the solutions analysed.Inversion by invertase is not interfered with by this salt, and both methods should be employed as a check. No loss of sugar occurs owing to the employment of basic lead acetate. I t is shown by a detailed study of the action of dilute hydrochloric acid on different sugars that it is impossible completely to hydrolyse maltose at either 70" or 100' C.without destroying simultaneously large amounts of any Imwlose or dextrose present, Novelty is claimed for the estimation of maltose in presence of other sugars by means of maltase-free yeasts as above described (cf. Baker and Dick, ANALYST, 1905,30,79)- Note by Abstractor.-Three and a half pages of this paper are devoted to the discussion of the fact (well known to sugar chemists) that certain kinds of asbestos used for filtration purposes are to some extent soluble in Fehling's solution unless previously boiled with cauetic soda (see Allen, 4th ed.,vol.i., p. 335 ; and LSach, Food Inspection and Analysis, 1909, pp. 594, 598). Any loss of this kind would of course become apparent immediately the copper oxide is dissolved and the Soxhlet tube or Gooch crucible weighed again for another determination.H. J?. E. H. Method of Sensitising Mylius's Reaction for the Detection of Cholalic Acid and Other Biliary Acids. J. Ville. (BzdZ. Xoc. Chinz., 1913, 13, 866-868).- Mylius's reaction depends on the formation of blue, needle-like crystals of the potas- sium salt of iodocholalic acid when an alcoholic solution of the acid is treated with iodine dissolved in potassium iodide.The reaction i8 not very sensitive, m d the crystals are not obtained when the iodine solution employed is freshly prepared. The author finds, however, that the addition of sodium chloride makes the test an extremely sensitive one, and he recommends the following procedure : The iodine reagent used is prepared by diluting 0.5 C.C.of iodine solution with 200 C.C. of a 33 per cent. sodium chloride solution ; if 1 C.C. of this reagent be added to 0-1 C.C. of a 0.2 per cent. alcoholic cholalic acid solution (i.e., 0.0002 grm. of the acid), a blue: crystalline precipitate is formed immediately. w. P. s. Enzymes of the Tobaeco Plant. J. du P. Oosthuizen and 0. M. Shedd.. (J. Amer. Chem. SOC., 1913, 35, 1289-1309.)-Loew (Reports Nos.59 and 65, Div. of Veg. PhysioZogy and Pathology, U.S. Dept. of Agric.) has shown that the fermentation, curing and aroma of tobacco are not due to bacteria (the fermenting leaves being destructive to bacterial life), but are caused by the action of the plant's own enzymes. The following enzymes were tested for in various portions of the plant at different ages : - Invertase : Fehling's solution was employed qualitatively to test if invert sugar were formed by the action of the decanted plant extract on cane sugar.Diastase : One per cent. starch paste solution was employed, and tested both by iodine and Fehling's solution as above, after standing for sixteen hours at 37" C. in presence of toluene. Lipuse: Ethyl butyrate and olive oil were employed as substrates,BACTERIOLOGICAL, PHYSIOLOGICAL, ETC.507 digestions being carried out for various periods of time at 37' C., the solutions being then titrated with & caustic potash, using phenolphthalein as indicator. Oxidnses : Two reagents were employed in this test, guaiacum (fresh 20 per cent. tincture previously digested for several days in alcohol) and phenolphthalein, both of which were first shown to be reliable in presence of amounts of nitrites in excess of anything that would be found in plants.Emulsiiz: Amygdalin was employed in the tests for this enzyme, after which reducing sugar was tested for with Fehling's solution, the smell of benzaldehyde noted, and hydrocyanic acid tested for. IizuZase : Inulin solution was employed, and reducing sugar tested for as before.Proteolytic enzymes were looked for by the method of Meunier as described in Euler's ( ( General Chemistry of the Enzymes " (English translation, 1912, p. 298). This is based on the fact that, since hydrochloric acid combines with protein during digestion, the diminution of free acid expresses the extent of the action ; the method did not prove very satisfactory in practice, trouble being experienced with the end-colours of the titrations.Reductuses : Methylene blue was used. Conclusions : Invertase, diastase, emulsin, and reductases, are present in appreciable amounts in the seed and leaf in all stages of growth and after curing. Lipase, inulase, and a proteolytic enzyme, were possibly present in small amounts. All tests for enzymes in the soil were negative, with one or two exceptions. Oxidases were always present in the green leaf, gradually disappearing as maturity approached, and being absent in the cured leaf.Practically all the starch disappears during tnhe early part of the curing process, and sugar is formed; and this soon disappears, probably by oxidation. There is considerable reduction of the protein content of the leaf during ripening, curing, and fermentation, due to the proteases.A small amount of a glucoside was shown to be present, the breaking down of which by the ferment present may be partly responsible for the aroma. The presence of much fat or protein in4 the leaf during combustion would impair the flavour, and their removal is effected by the lipase and the proteases present.H. F. E. H. Distinctions between Pepsin and Peptase. R. Wahl. (J. Iizd. and Eng. Chem., 1913, 5, 752.)-The animal proteolytic enzyme, pepsin, may readily be prepared and preserved in the dry state, but the vegetable peptase of malt loses most of its activity when it is attempted to reduce malt extracts of high proteolytic strength to a dry form.Pepsin exerts its maximum effect in the presence of a mineral acid, preferably hydrochloric acid, the secretion of which in the animal organism insures the best conditions for the activity of the digestive enzyme. In an analogous manner, the digestive power of malt peptase is greatly enhanced by the presence of lactic acid of bacterial origin. The presence of this acid is likewise insured under natural conditions by the introduction of lactic bacteria to the steep-water on the surface of the raw barley.The optimum temperatures for the two varieties of enzyme differ materially: pepsin acts most rapidly at a temperature about 50" C. ; peptase shows a maximum activity at 35" to 40" C. Barley peptase is capable of exerting an action at a temperature as low as 2 O C.; pepsin is inactive at so low a temperature.The usual methods for measuring the proteolytic activity of Peptase is rapidly destroyed at 60" C. ; pepsin is not.508 ABSTRACTS OF CHEMICAL PAPERS pepsin are not applicable to peptase. The best test for the proteolytic activity of malt extract is the liquefaction of gelatin. Another, almost equally reliable, is the auto-digestion test by estimating the amount of coagulable protein in the malt extract before and after digestion.Malt extracts rich in active peptase are employed for converting the coagulable colloidal proteins of unstable beers into permanently soluble peptonised forms. J. F. B. Fish Roe as Human Food. J. Konig and J. Groszfeld. (Biochem. Zeitsch., 1913, 54, 351-395.)-Fish roe contains fleeh bases (xanthine, hypoxanthine, and oreatinin), amino acids (taurine, I-tyrosine, glycocoll, and thymine), proteins soluble and insoluble in water, and fat.The proteins are rich in sulphur and phosphorus, and do not yield protamines. The fat is characterised by a high lecithin content (up to 59 per cent.), and also contains cholesterin (3.91 to 14.0 per cent.).Caviare and roe contain free acid which increases in quantity until putrefaction sets in. The ash contains a considerable quantity of free acid, which is due to the sulphur and phosphorus being present mainly in organic combination. E. W. Occurrence of Succinic Acid in Meat Extract and Fresh Meat. H. Einbeck. (Zeitsch. Physiol. Chem., 1913, 87, 145-158.)-Succinic acid wag found in Liebig’s meat extract (about 0.3 per cent.), fresh beef (0.133 grm.in 1.8 kgrm.), and in fresh dog’s flesh (0-24 grm. in 1.5 kgrm.). There is no evidence that the quantity increases on storing. E. W. Occurrence of Carnosine, Methylguanidine, and Carnitin, in Horseflesh. J. Smorodinzew. (Zeitsch. Physiol. Chem., 1913’87, 12-20.)-Fresh horseflesh was found to contain 1.82 per cent. carnosine, 0.11 to 0.83 per cent. methylguanidine, and 0.17 to 0.2 per cent. carnitin. E. W. New Indican Reaction. A. Jolles. (Zeitsch. Physiol. Chem., 1913, 87, 310- 312.)-Urine (10 c.c.) is treated with 2 C.C. of 20 per cent. lead acetate solution, filtered, and to the filtrate 0.5 C.C. of 10 per cent. alcoholic thymol solution, 10 C.C. hydrochloric acid containing ferric chloride (Obermayer’s reagent), and 4 C.C. chloro- form, are added, On shaking, the presence of even minute traces of indican is indicated by a beautiful violet coloration of the chloroform. This reaction is much more sensitive than any indican test hitherto proposed. p-xylenol (CH, : CH, : OH = 1 : 4 : 5) and o-xylenol give similar colorations, that formed by the latter compound being stable towards water and alkalis. The residue which remains after evaporating the chloroform solution dissolves in amyl alcohol to a red solution, and in glacial acetic acid to a violet solution. E. W.

ISSN:0003-2654    

DOI:10.1039/AN9133800504

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

508 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Notes on Alcoholometry. A. F. Joseph and W. N. Rae. ( J . SOC. Chenz. Ind., 1913, 32, 856-857.)-The paper deals with the estimation of alcohol in countries where condenser water and air temperatures are abnormally high. The usual tables accompanying the Sikes hydrometer are inaccurate to several per cent. when usedORGANIC ANALYSIS 509 at high (80' to 100' F.) atmospheric temperatures.It is seldom recognised that, to obtain a sp. gr. result correct to the fifth place of decimals as given in many tables, the temperature must be adjusted to 0.01" C. Experimental distillations were made in which the temperature of the condenser liquid was varied from 60" to 120" F., the percentage of alcohol being calculated from the tables of Osborne, McICelvy, and Pearce (Bull.Bureau of Stanclads 9, Sci. Paper 197 ; J. SOC. Chem. Ind., 1913, 304). Condensation was found to be equally eficient at various points between these extremes, estimations being made by means of a brass hydrometer, and also with quartz sp. gr. bottles. There was found to be a large error in using the Sikes hydrometer with the ordinary tables as compared with density determina- tions, but a great improvement is made if the tables compiled by C.H. Bedford are employed in conjunction with Oertling's glass Sikes hydrometer, Bedford's tables always showing the higher alcohol value. H. F. E. H. Detection and Estimation of Methyl Alcohol. R. Schmiedel. (Pharm. Zentralhalle, 1913, 54, 709-716 ; through Chem.Zeiztralbl., 1913, II., 717.)-The mebhod is based upon the oxidation of the methyl alcohol to formic acid, and estimation of the latter. The sample is cooled to 5' C., rendered alkaline with sodium hydroxide, and treated with successive portions of 3 to 5 C.C. of 1 per cent. hydrogen peroxide solution, first at intervals of thirty minutes and subsequently of forty-five minutes to an hour, until no more gas is evolved.The liquid is then allowed to stand for eight hours, and, after destruction of the excess of hydrogen peroxide by means of thiosulphate, it is acidified and distilled in a current of steam, the distillate being collected in a receiver containing boiling water with calcium carbonate in suspension. About 700 C.C. of the distillate are filtered hot, the filtrate evaporated to dryness, and the residue heated for an hour at 125O to 130' C.I t is then dissolved in 100 C.C. of water, and the solution twice extracted with 25 C.C. of ether. The aqueous layer is mixed with 2 grms. of crystalline sodium acetate slightly acidified with hydrochloric acid, and heated with 100 C.C. of 5 per cent. mercuric chloride solution for two hours in a boiling water-bath.The precipitated mercurous chloride is washed by decantation with hot water, and then in a Gooch crucible with hot water, alcohol, and ether, and dried until constant in weight. One grm. of mercurous chloride corresponds to 0.0875 grm. of formic acid and 0.0678 grm. of methyl alcohol. C. A. M. Estimation of Cellulose by Means of Nitric Acid. V. Rao and B.Tollens. ( J . fiir Landw,, 1913, 61, 237-244 ; through Chenz. Zentralbl., 1913, II., 903.)-The authors have simplified the method of Dmochowski and Tollens (ANALYST, 1910, 35, 408) in the following manner: The heating of the material with the respective reagents is performed always in the same Waltenberg's dish of 200 C.C. capacity. The liquids are drawn off by suction by means of an immersed inverted funnel covered with linen cloth or hardened filter-paper, the mouth of the funnel being covered with a finely perforated plate fused on to the body.Finally the treated cellulose is collected in a Gooch crucible, dried, weighed, incinerated, and weighed again. The method has been tested comparatively with those of Cross and Bevan5’10 ABSTRACTS OF CHEMICAL PAPERS and of Konig.The factors for comparing this method with Cross and Bevan’s vary with different materials, and must be determined by future investigations, Cross and Bevan’s method gave higher results. J. F. B. Detection of Free Sulphuric Acid in Cotton. W. Zanker and K. Schnabel. (Fiirber-Zed., 1913, 24, 260-263 ; through Chem. Zentralbl., 1913, II., 907-908.)-Cotton absorbs sulphuric acid from dilute solutions, and retains traces of it so persistently that it is practically impossible to obtain 8 neutral product by simple washing with distilled water.Thus, in testing for minute traces of sulphuric acid in cotton, it is not sufficient to digest the fibre with water and test the extract. Such residual traces of acid are sufficient to bring about a marked weakening of the fibre when the latter is exposed to dry heat for any length of time.For the detection of small traces of acid the authors thoroughly moisten 2 to 3 grms. of the sample in a platinum dish, and then evaporate the water on the water-bath until the cotton retains about half its weight of moisture. A strip of violet litmus-paper is then wrapped up in the sample, and the whole is placed under pressure in a press.The quantity of moisture in the fibre should be sufficient just to damp the litmus-paper when the sample is left for some time under heavy pressure. In this way 0.25 ingrm. of sulphuric acid in 2.5 grms, of cotton, or 0.01 per cent., can be detected, whereas the aqueous extract from such cotton has no effect even on highly sensitive litmus- silk.M7ith coloured samples the fibre should be moistened with alcohol and ether, and in this case the evaporation should be carried somewhat further than when water is employed ; control tests must be carried out with pure cotton, in order to ascertain that the reagents themselves are free from acid. The destructive action of small traces of sulphuric acid on the cotton fibre only becomes evident after pro- longed heating ; under ordinary circumstances the strength of the material is even increased.If a sufficient quantity of the sample be available, 10 to 20 grms. may be digested with water in a platinum dish on the water-bath, and the liquid pressed out by means of a pestle. If this operation be performed repeatedly, the greater portion of the acid may be extracted even when the sample contains only 0.01 per cent.According to the authors, the quantity of free acid may be estimated by treating the sample with & sodium hydroxide solution and titrating back the excess. In this manner 0.08 per cent. of sulphuric acid has been found in surgical cotton-wool, and as much as 0.17 per cent. in certain parchment-papers.J. F. 13. Estimation of Small Quantities of Wool in Cotton Goods. P. Heermann. (Mitt. Kaiserl. Materia@rufungs-Arnt Gross-Lichterfelde West, 1913, 31, 176, Abt. 3 ; through Chem. Zentralbl., 1913, II., 999.)-The method depends upon the compara- tive insolubility of wool in sulphuric acid of strength suitable to dissolve the cotton. Five to ten grms. of the sample are boiled first with ether, and then with 96 per cent.alcohol, pressed, immediately immersed in from 20 to 100 times its weight (according to the quantity of sample taken) of cold sulphuric acid of 80 per cent, by weight, and well shaken, especially for the first hour. The cellulose ie dissolved in three or four hours. The mixture is poured into an excess of water, and the insoluble portion collected on a fine copper sieve, and washed with water alone and with waterORGANIC ANALYSIS 511 containing ammonia. The air-dried wool is weighed, or it may be dried at 105" to 110' C., when 17 per cent., representing the normal moisture content, is added to its weight. 0.E. M. Estimation of Caoutchouc in Crude Rubber. R. Marquis and F. Heim. (BzcZZ. Soc. Chim., 1913, 13, 862-866.)-The method depends on the action of sulphuric acid on caoutchouc in chloroform solution.One grm. of the rubber, freed from resins by previous treatment with acetone, is dissolved in 100 C.C. of chloroform, 8 grms. of pure sulphuric acid are added, the mixture is shaken for five minutes, and then poured into 200 C.C. of alcohol. The white flocculent precipitate which forms is collected on a filter, washed with alcohol until free from acid, dried at looo C., and weighed.I t s weight will be within 0-7 per cent. of that of the caoutchouc actually present. In a few cases the authors have applied the method to rubbers from whicli the resins have not been removed, the results obtained being satisfactory ; but until this has been done with all the different varieties of crude rubber, it is advisable to remove the resins before the caoutchouc is estimated in any given sample.w. P. s. Volatile Constituents of Coal. Part 111. A. H. Clark and R. V. Wheeler (J. Chern. SOC., 1913,103, 1704-1713), and with C. B. Platt (ibid., 1713-1715).-The authors have before expressed the view that coal contains two types of compounds of different degrees of ease of decomposition.The more easily decomposed type was designated " paraffin yielding," the less easily decomposed type " hydrogen yielding," as indicating the main gaseous products of their thermal decomposition. In the present paper experiments are described in which finely divided coal was fractionated by means of volatile solvents, and the separate fractions submitted to destructive distillation.The coal was first treated with pyridine in a Soxhlet extractor, and both the residue (80 per cent. of the whole) and the extract freed from pyridine were distilled at various temperatures. A portion of the pyridine extract was further fractionated by treatment with chloroform, which dissolved about a third of it, and the two fractions were freed from chloroform and distilled.The portion soluble in pyridine, but insoluble in chloroform, was intermediate in character between tho portion insoluble in pyridine and the portion soluble in chloroform, but resembled the former much more closely in ultimate composition, proportion of volatile matter, and composition of gaseous products of destructive distillation. The portion soluble in chloroform is regarded as mainly derived from the resins and gums of the coal plants, the portion insoluble in pyridine as probably consisting of the degradation products of cellulose and the like.In addition to the distillation experiments with the coal fractions, similar ones were made with '' dehydrated cellulose " prepared from filter-paper in the manner described by Cross and Bevan (Phil.Mag., 1882, [v], 13, 325). Distillation experiments were conducted in a platinum retort at 600", 700°, SOOO, 900", and 1000" C. The following table gives the results at the extreme temperatures. The analyses of the materials subjected to distillation are calculated on the ash-free dry substmce, as are the percentages of volatile and tarry matter and the volumes of gas obtained on distillation.5'12 ABSTRACTS OF CHEMICAL PAPERS The portion of coal soluble in chloroform resembles ordinary colophony in that it powerfully affects a photographic plate (cf.Russell, P. Roy. SOC., 1908, B, 80, 376). When the powder was spread over an area as large as a, threepenny piece an a photographic plate (film-side up) in the dark for sixteen hours, and the plate subse- quently developed, not only did the small area come out black, but it was surrounded by a corona as large as a shilling.The unfractionated pyridine extract gave a sharp negative, but no corona, and the portion insoluble in pyridine had no visible effect on a photographic plate. Plane (not necessarily polished) surfaces of coal give negatives showing streaks and patches of difierent intensity. Apart from certain yellow markinga, which are due to pyrites, these streaks and patches are attributed by the authors to those constituents of the coal which are resins or partly changed resins.Proximate analysis : Ultimate analysis : Volatile matter . . . ... Fixed carbon ... ... Carbon ... ... ... Hydrogen ... ... ... Oxygen ... ...... Nitrogen ... ... ... Sulphur . . . ... ... Distillation temperature "C. . . . Total volatile matter . . . ... Tarry matter . . . ... ... C.C. gas (at N.T.P.) per gram ... Gas analysis : Carbon dioxide . . . ... Ethylene ... ... ... Carbon monoxide.. . ... Hydrogen ... ... ... Methane ... ... ... Ethane ... ... ... Nitrogen ... ... ... Volatile Constituents of Portion of Coal Insolublc in Pyridine.35.0 65.0 80.8 5.2 10.4 2.2 1.4 600 1000 24.0 37.7 7.0 3.8 93.3 417.1 7-- 9.8 5-3 1.5 0.8 14.3 30.8 22.2 44.9 44.7 11.7 5.5 2.3 2.0 4.2 Portion of Coal Soluble in Chloroform. 77.3 22.7 85.3 7.1 4-6 1.7 1.3 6 C ' l d O O 64.0 78.2 56-0 42.9 55.0 221-6 1.8 4-7 6.7 8.6 4.7 10.6 26-6 39-5 35.5 31.9 18.6 3.5 6.1 1.2 Dehydrated Cellulose. 61.3 3.7 35.0 6 0 ~ ~ 0 0 46.0 55.0 2.0 2.0 216.2 462.0 46.0 24.8 0.3 0.4 30.2 41.3 9.6 24.7 10.4 6.1 1.2 0.6 2.3 2.1 G.C. J. Coal. Part IV. Relative Inflammabilities of Coal Dusts. R. V. Wheeler. (J. Chem. SOC., 1913, 103, 1'715-1722.)-1t has been shown before that, of two coals, that which yields the higher percentage of '' volatile matter '' is not necessarily the more inflammable in the form of dust.If coal be regarded as a conglomerate of two main types of compounds, one yielding readily inflammable gases and vapours on heating to a, comparatively low tempera- ture, the other requiring td higher temperature of more prolonged duration to decom-ORGAXIC ANALYSIS 513 pose it freely (see preceding abstract), the absence of any necessary connection between inflammability and total content of volatile matter might be expected.The direct determination of relative inflammability involves the use of elaborate apparatus of which a convenient type is described and illustrated in this paper. The author has previously suggested an indirect method based on the volume of paraffin hydrocarbons evolved by 1 gram of the ash-free dry coal when heated in vaczLo at 650OC. It is now found that the percentage extractable by pyridine affords a very dose measure of the inflammability of a coal.The coal is ground to pass a sieve of 94 meshes per lineal centimetre, and, after drying, from 3 to 10 grms. are extracted with pyridino for a week in a8oxhlet extractor, I n the samples tried, all of which were bituminous coals with from 25 to 36 per cent.volatile matter, the pyridine extract ranged from 18 to 38 per cent., and a series of thirty experiments show a very close connection between pyridine extract and temperature of inflamma- tion under standard conditions, a higher pyridine extract corresponding to a relatively highly inflammable coal. G . C. J. Formic Acid as a Solvent. 0. Aschan. (Chenz. Zeit., 1913, 37, 1117-1118.) -Formic acid may be used as a solvent for many inorganic salts and organic com- pounds.For example, 100 grms. of the 95 per cent. acid will dissolve 16.5 grms. of sodium sulphate, 7.3 grms. of barium chloride, 75 grms. of barium iodide, and 43.1 grms. of calcium chloride at about 20" C . Certain aromatic hydrocarbon deriva- tives such as terephthalic acid, indigo, uric acid, and alizarine, are fairly soluble in cold formic acid, and are still more solubIe in the boiling acid, so that these bodies may be crystallised from 95 per cent.formic acid. Uric acid, for example, forms microscopic rhombohedra, whilst alizarine forms large yellow needles. I n the case of some compounds, such as suberic acid, citric acid, a-brom-camphor, a-nitronaphtha- lene, m-dinitrobenzene, etc., very large crystals are obtained.C. A. M. Quantitative Separation of Nitrosubstitution Compounds from Nitro- glycerine. A. L. Hyde. (J. Amer. Chem. Soc., 1913,35, 1173.)-The method is a development of that already given (ANALYST, 1912, 37, 572). When a mixture containing nitroglycerine and a nitro-compound ig shaken with carbon disulphide and an acetic acid and water mixture, a partial separation is effected, the carbon disulphide layer containing a higher proportion of the nitro-compound than the original mixture, and the acetic acid layer a higher proportion of the nitroglycerine.The author's apparatus is designed to give a continuous fractional separation on this principle. It consists of thirteen upright tubes to hold the solvents, closed with double-bored rubber stoppers, and connected by tubes rising from the bottom of one tube and terminating in a fine jet below the stopper of the next.To the first tube and above it is attached a condenser and siphon measuring device ; to the last, a, siphon leading through a stopcock to a flask at a lower level, in which the solvent (the carbon disulphide) is evaporated, and rises in the form of vapour through a second tube to the condenser.The first upright tube contains the sample dissolved in acetic acid and water ; the next ten contain a layer of carbon disulphide and a layer of acetie acid and water; the last two contain The whole system is airtight.514 ABSTRACTS OF CHEMICAL PAPERS water, to arrest any acetic acid carried over by the carbon disulphide.In operation a regulated stream of carbon disulphide from the condenser passes in fine drops through each tube in succession, carrying the nitro-compound, which collects in the evaporating flask with it. It also carries over some of the nitroglycerine, which is arrested by the acetic acid in succeeding tubes. Results of experiments show that separation of nitroglycerine from the nitrotoluenes, except crystallised trinitro- toluene, and from the nitrobenzenes and nitronaphthalenes, could be carried out satisfactorily.For trinitrotoluene a longer time, and refractionation of the mixture obtained, would be necessary. The method was also applied to the separation of nitrotoluenes from each other, and it is pointed out that it is applicable in general to other mixtures, provided that a pair of solvents of 'suitable properties can be found.0. E. M. Analysis of Black Powder and Dynamite. W. 0. Snelling and C. G. Storm. (Bzdletin 51, Bzireau of Hines, U. S.A., 1913.)-This bulletin describes the methods of analysis applied by the Bureau of Mines to cc ordinary" dynamite, the ammonia, gelatine, low-freezing, and granular dynamites, and the common grades of black gunpowder and blasting powder.cc Permissible " explosives will be dealt with in a later bulletin. Physical examination, determination of gravimetric density (by displacement of sand in a stricken measure), tests for exudation and stability, sampling, with special reference to segregation of the nitroglycerine, chemical examination, and the determination of moisture and other constituents, are considered in detail for dynamite; the chemical analysis of the others, and the granulation and specific gravity of black powders, are briefly dealt with.0. E. M. Composition of Arachis Oil. H. Meyer and R. Beer. (Monatsh, fiir Chem., 1913, 34, 1195-1208.)-Hehner and Mitchell (ANALYST, 1896, 21, 328) isolated from arachis oil about 7 per cent.of a fatty acid which they considered from its melting- point to be stearic acid. The authors have repeated the estimation by means of 8 saturated solution of stearic acid, and have also obtained a fatty acid melting at 68" C. When, however, this was mixed with pure stearic acid of m.-pt. 69" C , the mixture melted at 62' to 63' C. By fractional crystallisation it was proved that the deposit from the saturated alcohol contained arachidic and lignoceric acids, but that no stearic acid was present.With regard to the unsaturated acids, no hypogsic acid could be detected in arachis oil, the only oxidation product yielded by the liquid fatty acids being a-sativic acid, derived from the oleic acid. C. A. M. Candelilla Wax. H. Meyer and W.Soyka. (Moizatsh. fiir Chem., 1913, 34, 1159-1172.)-The resinous constituent giving the Liebermann-Storch reaction was separated by extracting the wax with boiling 96 per cent. alcohol. On evaporating the alcoholic extract a yellow resinous mass was left, which, when distilled with zinc dust in a current of hydrogen, yielded a colourless sesquiterpene. The wax from which the resin had been removed consisted in the main of dotriacontane, C,,HG6 (m.-pt.71" C.), and an oxylactone, C,,H,,O, (m.-pt. 88" C.), which closely resembled in its properties the oxylactone of lanoceric acid, isolated by Darmstaedter andORGANIC ANALYSIS 515 Lifschutz from wool fat. The sample of candelilla wax examined contained from 18 to 20 per cent. of resin (probably formed in the preparation of the wax), 74 to 76 per cent.of dotriacontane, and 5 to 6 per cent. of the oxylactone. C. A. M. Estimation of Sniall Quantities of Mercury in Organic Substances. s. Lomholt and J. A. Christiansen. (Comptes-rendus Trau. Lab., Carlsberg, 1913, 10,259-266.)-A method is described for the estimation of minute quantities (2 mgrms. or less) of mercury in such substances as urine, faeces, organs, etc., and consists in decomposing the organic matter, precipitating the mercury as sulphide a€ter the addition of copper sulphate, dissolving the mixed sulphides, and depositing the mercury electrolytically on gold-foil.Solid substances are decomposed by heating with nitric acid; in case much fat is present, it is convenient to interrupt the oxidation, separate the layer of fat, and continue the oxidation of the liquid portion by the addition of permanganate.Urine is decomposed directly by heating it with the addition of permanganate. In either case the excess of -permaqganate intrc- duced is destroyed by means of oxalic acid. About 0.05 grm. of crystallised copper sulphate is added to the clear solution, which is then partially neutralised with ammonia, and saturated with hydrogen sulphide. The mixed sulphides are collected on an asbestos filter, washed, and redissolved in a mixture of 5 C.C.of nitric acid and 1.5 C.C. of hydrochloric acid. The filter is washed, and the solution, which should measure about 40 c.c., is submitted to electrolysis. A platinuiii wire is used as the anode, whilst a piece of gold foil (1 x 2 cm.) soldered to a platinum wire serves as the cathode; a current of 1.5 volts and 1 milliamphe is employed, and the electrolysis is continued for eighteen hours.The liquid is then drawn off, and the electrodes are rinsed by the addition of water while the current is still passing. After the gold cathode has been dried in a desiccator, it is weighed, then heated to redness in a tube through which a current of hydrogen is passed, and again weighed.The difference between the two weights gives the quantity of mercury present. The gold cathode must not be drisd by washing it with alcohol and ether, as this treatment detaches an appre- ciable quantity of mercury, particularly when relatively large amounts are deposited Traces of copper are also deposited with the mercury, and the volatilisation of this metal must be carried out in an atmosphere of hydrogen in order to prevent oxidation of the copper. w.P. s. Estimation of Sulphur in Organie Substances. H. Apitsch. (Zeitsch. angezo. Chem., 1913, 26, 503-504.)-The method consists essentially in burning the substances in a current of oxygen, absorbing the products of combustion in bromine, and estimating the resulting sulphuric acid.A weighed portion of the substance, contained in a platinum boat, is placed in a combustion tube, one end of which is connected with a supply of oxygen, whilst the other end is drawn out to form a, narrow tube which passes through a, rubber stopper into the absorption vessel. The latter consists of a Fresenius receiver containing sodium hydroxide solution to which has been added an excess of bromine ; should this solution become colourless during the operation, more bromine must be added. Spirals of platinum gauze are placed in the combustion tube at a short distance on either side of the boat, and these516 ABSTRACTS OF CHEMICAL PAPERS spirals are maintained at a dull red heat during the combustion.The combustion tube must be free from any oily drops at the end of the combustion, but droplets of sulphuric acid may be igrqred at this stage of the operation. After cooling, the tube, together with the boat and spirals, is washed out with water, the solution is added to the contents of the receiver, and the sulphuric acid is then estimated in the solution in the usual way.With suitable modification the method may be used for the estimation of sulphur in very volatile organic substances. w. P. s. Quantitative Determination of Rosin in Paper. C. F. Sammet. (J. I d . and Bag. Chem., 1913,5, 732-735.)-0f the various methods investigated, the following gave the most reliable results.: Five grms. of paper, cut into strips about + inch wide and folded into numerous tranverse folds, are placed in a Soxhlet extractor and covered with acidulated 83 per cent.alcohol, prepared by adding to 100 C.C. of 95 per cent. alcohol 15 C.C. of 5 per cent. aqueous acetic acid. The extraction flask is placed direchly in the boiling water of a water-bath, and the rosin is extracted by distilling up the solvent from six to twelve times, according to the nature of the paper.The alcoholic extract, which may contain other bodies besides rosin. is transferred to 8 beaker, and evaporated on the water-bath to & bulk of a few C.C. The residue is cooled and taken up with about 25 C.C. of ether; the solution is transferred to a 300 C.C. separating funnel with about 150 C.C. of water containing a little sodium chloride to prevent emulsion; the liquid is shaken thoroughly and allowed to separate.The water is drawn off into a second funnel, and washed with another 25 C.C. of ether ; the ethereal extracts are combined, and washed twice with 100 C.C. of water, or until the separation is sharp and the ether clear. If glue is present, it may be necessary to shake the ethereal extract with salt solution before washing with water.The washed ethereal extract is evporated in a-platinum dish. and dried at 9 8 O to looo C. for exactly one hour ; prolonged heating causes a con- tinual loss of rosin. It is found that, if acidulated 95 per cent. alcohol be used, the decomposition of the resinates is incomplete; an alcoholic strength of 83 to 86 per cent. gives the best results. Control tests have shown that the further quantity of rosin extracted by a second treatment is negligible for practical purposes, and the error involved by the process described above is within the limit of 0-20 per cent. Direct extraction of the paper with acidified ether tends generally to give low results, due to the slowness of extraction; but in certain cases the results m e too high, owing to the separation of insoluble substances from the paper. J. F. B. Use of Amalgamated Aluminium in the Estimation of Tannin. E. Kohn-Abrest. (Ann. Chim. anal., 1913, 18, 349-351.)-0ne hundred C.C. of the tannin solution are placed in contact with a piece of amalgamated aluminium-foil (cf. ANALYST, 1911, 36, 516) about 1 mm. in thickness and weighing 3 grms. Contact is maintained for about five hours, or until all the tannin has been precipitated and the solution no longer gives a, coloration with ferric chloride. If the solution is shaken continuously, the time required for the precipitation is only about one hour. The liquid is then filtered, the precipitate is washed, the filtrate diluted to a definite volume, and an aliquot portion is evaporated. The difference between the weight ofINORGANIC ANALYSIS 517 this residue and that of the residue obtained on evaporating a oorresponding volume of the original solution is equivalent to the amount of tannin precipitated. As a trace of aluminium is dissolved, a correction may be made for its amount by estimating the quantity of ash in the two residues. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800508

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

INORGANIC ANALYSIS 517 INORGANIC ANALYSIS. Precipitation of Aluminium Hydroxide and Separation of Aluminium and Chromium. W. Jakob. (Zeitsch. anal. Chem. 1913 52 651-657.)-The precipitation of alumina from solutions of alkali aluminate by addition of bromine is complete only when the temperature is above 60" C. and the higher the temperature of precipitation the more compact is the precipitate. If caustic alkali be added to a solution of aluminium nitrate until the precipitate at first formed redissolves the Eiolution heated to boiling and excess of bromine-water added slowly so as not to reduce the temperature the precipitate will not be gelatinous. If the mixture be boiled to expel bromine filtered and the precipitate well washed the whole of the alumina free from any trace of alkali will be recovered.The best way to transfer to a filter particles of alumina which attach themselves to a beaker is to treat the contents of the beaker with a little dilute nitric acid which effects no visible change, but loosens the alumina from the glass. Ammonia is then added in excess and the particles of alumina are washed on to the filter. For the separation of aluminium from chromium caustic alkali is added to the solution of the metals until the precipitate at first formed redissolves. Bromine-water is cautiously added to the cold solution until its green colour gives place to the yellow of a chromate solution. Chromium hydroxide may separate at first but rapidly oxidises and redissolves. Finally the solution is heated to boiling and more bromine-water added drop by drop to secure the precipitation of the alumina in a compact form.It always carries down some chromium hydroxide from which, however it can be completely freed as follows The supernatant liquid is decanted through a filter and the precipitate is boiled with water containing ammonia and ammonium nitrate transferred to the filter and washed there with water containing ammonia and ammonium nitrate. Test numbers obtained with pure solutions of aluminium nitrate and chromium chloride and others obtained in presence of 1 or 2 per cent. of zinc and magnesium are exact ; but zinc and magnesium may come down with the alumina and the method is not recommended in presence of these metals. Nor is it available in presence of sulphates or borates.G. C. J. Differentiation of Natural and Artifieial Barium Sulphate. J. Jambor. (Chem. Zeit. 1913 37 1077.)-A method of distinguishing between natural and artificial barium sulphate is based upon the greater covering power of the latter. If equal quantities of the finely powdered sulphates are mixed with equal quantities of zt dyestuff into a paste the colour of the mixture prepared from the natural product will be of a lighter colour. The test may be made approximately quantitative by comparing the colour with those of standard mixtures containing up to 10 per cent, of the respective barium sulphates the different pastes being pressed between glas 518 ABSTRACTS OF CHEMICAL PAPERS plates with paraffin wax at the edges. Since differences of 2 per cent. and more may be observed with barium sulphates of different origin the accuracy of the estimation is not greater than 5 per cent.It is noteworthy that a dyestuff mixture containing 1 per cent. of Water Blue and 0.5 per cent. of Auramine colours artificial barium sulphate violet but the natural product green and by varying the relative proportions of the two sulphates all shades between these colours may be obtained. In this way it is possible to distinguish variations of 1 per cent. C. A. M. Characteristic Reaction of Bromine. I. Guareschi. (Zeitsch. anal. Chem., 1913 52 607-616.)-The author refers to his earlier papers ( A t t i R. Accad. Sci. Torho 1912 47 696 988) and claims priority for the discovery that Schifs aldehyde reagent affords a means of detecting minute quantities of bromine in presence of much chlorine and iodine (cf.Denigds ANALYST 1912,37 581). The use of hydrogen peroxide as suggested by Denigds is unnecessary. The reagent is most conveniently employed distributed on starch-free paper ; and if this is dried between other pieces of filter-paper no free sulphur dioxide will remain and less than 0.01 mgrm. of bromine is easily detected. For detecting traces of bromide in com-mercial chlorides and iodides a considerable quantity of the substance is warmed with 8 25 per cent. solution of chromic acid and the vapours tested with filter-paper prepared 8 s described. For detecting bromine in an organic compound of which it is a constituent and not merely an accidental impurity a fraction of a milligram suffices. The reagent may be made not only from fuchsin but from fnchsin S, rosaniline acetate p-rosaniline hydrochloride or Hofmann’s violet decolorised as described by Schiff or preferably as described later by Gayon (see Denigds Zoc.tit.). Hofmann’s violet affords the most sensitive reagent but the colour used must be the original colour of Hofmann-namely trimethyl- or triethyl-pararosaniline chloride-and not methyl violet B extra which is also sold as Eofmann’s violet. The reaction depends on the formation of tetrabromo-derivatives of the dyestuff, and is readily distinguished from the reaction given by aldehydes. The latter reaction is given only in solution and the reddish-violet colour is not removed from the solution by ether. When a liquid containing the tetrabromo-dyestuffs is shaken with ether the violet-blue colour collects between the ethereal and aqueous layers.G. C. J. Volumetric Estimation of Calcium. T Doring. (Zoitsch. angew. Chem., 1913 26 478-480.)-DuprB and Muller have thrown doubt on the accuracy of the method which depends on precipitation of the calcium as oxalate and titration of the washed precipitate with permanganate (Zeitsch. angew. Chem. 1902,15 1244). According to them the results may be 2 per cent. low The author shows that quantities of calcium up to 0-1 grm. (the equivalent of 50 C.C. of permanganate) can be determined with an error not exceeding 20.1 mgrm. Larger quantities should not be taken for analysis as large precipitates are more difficult to wash and calcium oxalate is soluble to the extent of 0-5 mgrm.in 100 C.C. of water and water containing ammonium oxalate cannot be used for washing when the calcium is to be determined volumetrically. Large quantities may thus be under-estimated b INORGANIC ANALYSIS 519 0.5 per cent. Indirect estimation as usually practised leads to results which are always high usually more than 1 per cent. too high. This is due to the co-precipita-tion of ammonium oxralate with calcium oxalate. The indirect method gives fairly accurate results if the precipitate be thoroughly washed but the necessity for such washing removes the sole advantage of the indirect method-namely its greater rapidity. As it possesses the added disadvantage that two standard solutions are required it cannot be recommended for exact work. G. C. J. Cerium Dioxide as Contact Substance in Analysis by Combustion.J Bekk. (Ber. 1913 46,2574-2579.)-Cerium dioxide distributed on asbestos is an effective substitute for the platinised asbestos of Desnstedt. Asbestos is steeped in ra saturated solution of cerium nitrate dried and ignited. A 30-cm. length in the combus-tion-tube makes it possible to complete a combustion of 0.2 grm. of avolatile substance in generally less than twenty minutes from the time of beginning to heat the substance to the turning out of the flame. The catalyst does not retain halogens which may be estimated simultrtneously by placing in the forward part of the combustion-tube two tared boats containing reduced silver (Dennstedt) or better by means of rt spiral of silver gauze wrapped round with platinum wire to guard against mechanical loss of silver halide during withdrawal.Nitrogen and sulphur are retained by lead peroxide placed in the forward part of the tube as in Dennstedt’s method ; but sulphur cannot be determined simultaneously as the catalyst retains an amount which varies with the temperature of combustion. The sulphur dioxide thus retained by the catalyst does not appreciably impair its efficiency and can be expelled by prolonged and intense heating in a current of air. The catalyst is not poisoned by arsenic or by lead peroxide. After about fifty hours’ effective use the asbestos becomes reduced to a powdery codition. It is still usable but the cost of its replacement is negligible. G. C. J. Estimation of Copper by Means of Sodium Hypophosphite.J. H a d . (Zeitsch. anal. Chem. 1913 52 616-618.) - Dallimore (ANALYST 1909 34 452) described a modification of the Muthman-Mawrow method (Zeitsch. anorg. Chem., 1896 11 268) for the estimation of copper and Windisch (ANALYST 1913 75) has recommended this modified method as exact. The author shows that it is open to the same criticism as the original Muthman-Mawrow msthod which he and Soukup found (ANALYST 1911 36 302) to be dependent on approximate compensation of errors which are individually large and which may be very far from being mutually compensating. That Windisch did not find copper in all his filtrates-he found it in some-is probably due to his testing the first filtrate and not the subsequent wash-waters which alwayg contain much more copper than the first filtrate.Better results are obtained by neutralising exactly with $ sodium hydroxide using phenol-phthalein as indicator as soon as precipitation is complete followed by rapid filtration and washing. Even then the method is useless for the exact determination of copper in presence of cadmium and zinc. As a technical method for the valuation of commercial copper sulphate using large quantities as recommended by Dallimore, it may have some value. G. C. J 520 ABSTRACTS OF CHEMICAL PAPERS Estimation of Copper by Means of Sodium Hypophosphite. R. Windisch. (Zeitsch. anal. Chem. 1913 52 619-628.)-The author seeks to show that the method described by Dallimore and recommended by him is free from the objections raised by Hanus and Soukup to the original Muthman-Mawrow method (cf.preceding abstract). Pure solutions of copper sulphate were precipitated in the manner previously described and the ignited precipitates proved to be substantially pure copper oxide. The filtrates were proved to contain so little copper that the error due to incomplete precipitation is estimated as less than 0-2 per cent. but the wash-waters do not appear to have been examined (cj. preceding abstract). A sample of Merck's copper sulphate was found to contain 99-16 per cent. of CuSO;5H20 as the mean of sixty-four experiments but the individual results range from 98.76 to 99.55. G. C . J. Determination of Oxygen in Copper and Brass. T. West. ( J . Inst. Metals advance proof issued August 1913.)-Turner has shown (J. Inst. Metals 1912, 8 248) that any oxygen in brass probably exists as zinc oxide and therefore cannot be determined by the methods adopted for determining oxygen in copper ; for though the zinc oxide is reduced by hydrogen at a high temperature in the cooler portion of the combustion-tube the reverse reaction occurs.The author has had resort to reduction in a current of carbon monoxide. The method was first applied to copper, and after results had been obtained which agreed closely with those obtained by reduction in hydrogen further experiments were made with zinc oxide. When the conditions for the accurate estimation of oxygen in zinc oxide had been determined, some brasses were examined with the result that it is shown that brass of good quality contains on an average 0.002 to 0.003 per cent.of oxygen. The combustion-tube used was of clear silica and rested in the porcelain tube of an electric furnace. The carbon monoxide was generated from sodium formate and sulphuric acid and stored in a gas-holder between which and the combustion-tube were (1) a caustic potash wash-bottle (2) a tube containing solid potash (3) a heated Jena glass tube containing copper gauze (4) another potash wash-bottle (5) a sulphuric acid wash-bottle (6) another heated glass tube containing copper (7) another tube containing solid potash and (8) another sulphuric acid wash-bottle. The carbon dioxide resulting from the combustion was absorbed by potash contained in Geissler bulbs provided with a small calcium chloride tube and the train of apparatus was terminated by a guard-tube containing sulphuric acid.The temperature was con-trolled by a rheostat and measured by a thermocouple the wires of which passed between the porcelain and silica tubes. In use the boat containing the drilling is introduced into the combustion-tube and a current of carbon monoxide is passed through the apparatus until the Geissler bulbs show no change in weight in one hour. The temperature is then raised to 1,050' C. and maintained there for one and a half hours after which the electric circuit is broken the apparatus allowed to cool for thirty minutes without checking the stream of gas and the Geissler bulbs are weighed full of carbon monoxide. Experiments with zinc oxide showed that the use of too slow a gas curren INORGANIC ANALYSIB 521 might lead to results much below the truth but with three bubbles per second exact results were obtained.The method is not available for copper-zinc alloys containing tin or nickel as such alloys decompose carbon monoxide although tin alone does not do so. G. C. J. Volumetric Estimation of Fluorine. A. Greef. (Ber. 1913,46 2511-2513.) -The method depends on the fact that when sufficient ferric chloride is added to a neutral solution of an alkali fluoride the whole of the fluorine separates as a white insoluble fluoride of the type Na3FeF,. The end-point of 4 simple titration with thiocyanate as indicator is not easily seen as no intense red but only a particular shade of yellow marks it. The use of ether and alcohol gives the characteristic red colour in the ethereal layer but the end-point is only sharp when the slight solubility of the precipitate is still further repressed by large addition of sodium chloride.To 25 C.C. of a neutral solution of an alkali fluoride 20 grms. of sodium chloride and 5 C.C. of a 20 per cent. solution of potassium thiocyanate are added. The mixture is then titrated with ferric chloride solution (1 C.C. =- 0.01 grm. NaF) until a faint yellow colour appears. Alcohol (10 c.o.) and ether (10 c.c.) are then added, and the titration continued with vigorous agitation after each addition until the ethereal lager acquires a persistent red colour. Commercial sodium fluoride usually has an acid reaction and contains sodium hydrogen fluoride and sodium silicofluoride. On titration with sodium hydroxide, using phenolphthalein as indicator these compounds react as follows : NaF-HF + NaOH = 2NaF + H,O and Nrt,SiF +4NaOH = 6NaF + SiO + 2H,O.As the neutralised solution contains the whole of the fluorine as sodium fluoride, total fluorine may be estimated in the manner above described. The sodium hydrogen fluoride is determined in a separate portion of the sample as follows The substance (0.5 grm.) is dissolved together with an equal weight of potassium chloride in 25 C.C. hot water the solution cooled 20 C.C. alcohol added to render potassium silicofluoride insoluble and the sodium hydrogen fluoride titrated with & sodium hydroxide using phenolphthalein as indicator. The percentage of sodium hydrogen fluoride being known the percentage of sodium silioofluoride can be calculated from the amount of alkali required to neutralise the solution taken for the estimation of total fluorine.The following are typical results Present 0.6 grm. NaF 0.2 grm. NaF-HF, 0-2 grm. Na,SiF ; found 0.598 grm. NaF 0.201 grm. NrtF*HF 0.201 grm. Na,SiF,. G. C. J. Method of Analysing Hypochlorites. F. Ducelliez. (Ann. Chim. anal., 1913 18 345-349.)-When 'cobalt chloride is brought into contact with calcium hypo-chlorite oxygen is evolved and cobalt peroxide is precipitated ; under the conditions given below this reaction may be applied to the estimation of hypochlorites. Two grms. of the calcium hypochlorite under examination are placed in a test-tube together with 50 C.C. of boiled water ; the test-tube is closed with a rubber stoppe 522 ABSTRACTS OF CHEMICAL PAPERS carrying a delivery-tube which is connected by a length of rubber tubing with a measuring burette supported in a vessel of water.The test-tube is first held in an inclined position while a quantity of 0.05 grm. of crysta.1lised cobalt chloride is placed in it just below its mouth ; the stopper is then inserted the cobalt chloride is caused to fall into the solution and the test-tube is immersed in a boiling water-bath the evolved oxygen being collected in the burette. At the end of about thirty minutes the test-tube is cooled placed in the water in the vessel containing the burette and the volume of oxygen is read off. The volume of gas found is multiplied by 0.93 to correct for vapour pressure of water and temperature provided that the temperature of the water is 1 5 O C and to the result is added 1.2 c.c.this being the volume of oxygen absorbed by the cobalt oxide to produce cobalt peroxide The method may be spplied to alkali hypochlorites and the. results obtained agree with those found by the iodometric process. w. P. s. New Method fop the Determination of the Concentration of Hydroxyl Ions. F. Francis and F. H. Geake. (J. Chm. SOC. 1913 103 1722-1734.)-The rate of decomposition of nitrosotriacetonamine into nitrogen and phorone under the action of alkalis affords a measure of the concentration of hydroxyl ions. The velocity constants have been established in presence of aqueous solutions of sodium, potassium and barium hydroxides and found to be proportional not to the concen-trations of the bases themselves but to the concentration of hydroxyl ions.In any individual experiment the values of the velocity constant agree to within 1 to 2 per cent. and the results are reproducible to within 2 to 3 per cent. The method is available with this degree of accuracy for the estimation of the concentration of hydroxyl ions up to 0.05 N and the general formula may be expressed aa follows : Concentration of OH’ = K:t./R where R = 1.96 x 2.20 10 Kt- is tho observed con-stant at the temperature to. Between concentrations of 0.05 Nand 0.3 N hydroxyl ion the unimolecular oonstanta ‘‘ drift,” and the method is inapplicable within these limite. The drift ceases a t the latter concentration ; from that point up to a concen-tration of 1.4 N the accuracy is diminished and beyond that considerably dimin-ished since the velocity constants change only slightly with large increases in the concentration of the hydroxyl ions near the higher limits.The effeot of the presence of neutral salts in moderate quantities is unimportant. to-30, J. F. B. Valuation of Hydrated Oxide of Iron by Means of the *‘Sulphuretted Hydrogen Burette.” E. Linder. (Forty-ninth Annual Report on Alkali etc., Works Proceedings during 1912 pub. 1913 20-26.)-The method consists in treat-ing a small weighed quantity of air-dried and moistened oxide (0.6 to 1 grm. oxide containing 15 to 20 per cent. moisture) with excess of eulphuretted hydrogen. The oxide is contained in a small glass cup floating on the surface of mercury in a ( 6 laboratory vessel ” (the bell-shaped piece of apparatus so called by designers of apparatus for exact gas analysis).The eulphuretted hydrogen is measured in a burette over mercury. To eliminate air from the upper part of the laboratory vessel the cup is made as small as possible and its neck constricted to follow th INORGANIC ANALYSIS 523 ourvature of the upper part of the laboratory,vessel into which it can in consequence rise. The body of air is further reduced by causing the mercury to rise in the annulus between the cup and the walls of the laboratory vessel as far as a mark on the neck of the Iabter. By this means the working space is reduced to about 15 c.c., and the air in this space ie displaced by hydrogen before the sulphuretted hydrogen is admitted. By thus working with a constant volume of an inert gas in the laboratory vessel the contraction that ensues during the sulphiding of the oxide is made an exact measure of the weight of sulphur absorbed as temperature and pressure corrections for 16 C.C.of gas are insignificant in comparison with the large volume (150 to 200 c.c.) of sulphuretted hydrogen absorbed by the oxide and can easily be caloulated and allowed for if desired, The sulphuretted hydrogen burette is water-jacketed and is partly of wide, partly of narrow bore so that any quantity of gas from 140 to 250 C.C. can be measured accurately to within 0.1 C.C. The rest of the apparatus includes levelling slide rising table and generators for hydrogen and hydrogen sulphide and is fully illustrated in the original which also describes the method of operation including the determination of the gas space above the mercury in the laboratory vessel, determination of a correction factor for the solubility of hydrogen sulphide in the water originally present and that produced during the sulphiding operation and analysis of the residual gas when this is necessary as with oxides containing carbonates.The merits of this method are best considered by reference to a standard method, such as that described in Lunge and Keane’s “Technical Methods of Chemical Analysis,” vol. ii. part ii. p. 772. The advantage of the method there described lies in the fact that a large weight of material can be operated on. But air is not effectually excluded and no account is taken of carbon dioxide which is freely liberated from some oxides and lost in the residual gases.Moreover that method is not well suited for determining the maximum efficiency of oxides which absorb sulphuretted hydrogen over a period of six or seven days. I n purifiers which remain undisturbed for many days the bottom layers of oxide are in contact with gas for prolonged periods and a measure of the maximum efficiency attained on exhaustive exposure in a desideratum. A gravimetric method with apparatus involving many parts and neceesitating disconnection for weighing from time to time is less con-venient than the volumetric method now desoribed and finally the use of dry air at the end of an experiment to displace residual gases is inadmissible in exact analysis. G. a. J. Detection of Molybdenum. E Kedesdy.(Mitt Eaisert. Materiatprafungs-Amt Gross-Lichterfelde West 1913 31 173 ; through Chem. Zentralbl. 1913 II., 996.)-The detection of molybdenum by means of potassium t hiocyanate is recom-mended by Treadwell (Kurzes Lehrbuch der analyt. Chem.) who states that there is no reaction with acid molybdate solutions but on addition of zinc or stannous chloride a blood-red coloration of molybdenum thiocyanate is produced even if phosphoric acid is present which distinguishes molybdenum from iron. The molybdenum thiocymate is taken up by ether on shaking. As hexavalen 524 ABSTRACTS OF CHEMICAL PAPERS molybdenum does not give the reaction it is better to effect reduction before carrying out the reaction and also when the valency of the molybdenum is un-known. The reduction is also necessary in order to convert any ferric compounds to ferrous since phosphoric acid or pbosphate not only checks the reaction of thiocyanate with iron but also with molybdenum.If the reduction is carried too far the reaction may fail altogether or be much weakened. Commercial ether usually contains peroxide which would cause the reoxidation of small quantities of ferrous to ferric iron. In carrying out the reaction iron should be as far as possible excluded over-reduction of the molybdenum avoided and ether freshly distilled from stannous chloride alone used. 0. E. M. Action of an Excess of a Soluble Ferrocyanide on Solutions of Zinc, Copper and Nickel and a Volumetric Method for the Estimation of Nickel. R. Meurice. (Ann. Chirn. anal. 1913 18 342-345.)-Zinc salts when treated with an excess of potassium ferrocyanide yield a definite compound having the com-position Zn,K,[Fe(CN),I, and the reaction may be employed for the volumetric estimation of this metal.The zinc solution is treated with an excess of potassium ferrocyanide solution diluted to a definite volume the precipitate is allowed to settle and an aliquot portion of the clear supernatant liquid is titrated with potassium permanganate solution after the addition of sulphuric acid. The ferrocyanide solution is standardised against the permanganate solution and this in turn against pure iron. I n the case of copper the ferrocyanide precipitate varies in composition with the concentration of the solutions and is moreover slightly soluble 80 the above method cannot be applied to the estimation of copper.Nickel however, yields a precipitate having the composition NiK(,Fe( CN), but only under certain conditions-namely in the presence of an excess of ferrocyanide and of ammonium sulphate. For the estimation of nickel the solution containing about 0.1 grm. of the metal is treated with 100 C.C. of a 3.5 per cent. potassium ferrocyanide solution, 5 grms. of ammonium sulphate are added the mixture is diluted to 200 c.c. filtered, and an aliquot portion of the filtrate is diluted with seven times its volume of water, acidified with sulphuric acid and titrated with permanganate solution One atom of iron is equivalent to 1 atom of nickel. w. P. s. Separation of Palladium from Gold Platinum Rhodium and Iridium. M. Wunder and V.Thuringer. (Zeitsch. anal. Chern. 1913 52 660-664.)-Palladium and gold can be separated from the other metals o€ the platinum group, except platinum itself by precipitation from weak (1 per cent.) hydrochloric acid solution by means of dimethylglyoxime. The reagent is dissolved in boiling water and added to the boiling solution which is maintained in ebullition for Home time, and then allowed to cool. The precipitate is collected on a hardened filter and washed with 1 per cent. hydrochloric acid. The filter and its contents are then cautiously incinerated (cf. ANALYST 1913 79) and the residue finally heated strongly with a blowpipe flame. The metal sponge is dissolved in a few drops of aqua regia and the solution repeatedly evaporated to dryness with hydrochloric acid.The residue is dissolved in water 1 to 2 grms. ammonium oxalate are added and the mixtur INORGANIC ANALYSIS 525 digested at 60' C. for some hours. Dilute sulphuric acid (10 to 15 c.c.) is added to assist filtration and the gold is filtered off on a hardened filter washed first with water containing sulphuric acid then with 1 per cent. hydrochloric acid dried and ignited. The filtrate is nearly neutralised with ammonia and the palladium re-precipitated by means of dimethylglyoxime. After cautious incineration of the filter-Paper the palladium is reduced in hydrogen and allowed to cool in a current of carbon dioxide. Platinum must be separated as ammonium platinic-chloride before palladium is precipitated by means of dimethylglyoxime. The neutral solution is concentrated t o small bulk saturated with ammonium chloride and left for two days.The precipitate is washed with a saturated solution of ammonium chloride dried the filter cautiously incinerated the residue strongly ignited at first with access of air, then in a current of hydrogen and finally cooled in a current of carbon dioxide. The palladium is determined in the filtrate in the manner already described. Palladium is separated from rhodium by precipitation with dimethylglyoxime. The rhodium in the filtrate is determined as follows The filtrate is concentrated to small bulk hydrochloric acid and a pinch of sodium chlorate are added and the mixture heated until chlorine is expelled. This destroys the dimethylglyoxime which might interfere with the subsequent reduction of the rhodium.The solution is diluted and the rhodium reduced by repeated addition of small pieces of magnesium. When the solution is colourless and all magnesium apparently dissolved the rhodium is filtered off washed with 5 per cent. sulphuric acid to remove traces of magnesium ignited, reduced in hydrogen and cooled in a current of carbon dioxide. The separation of palladium from iridium and subsequent determination of the iridium is carried out in an exactly similar manner the destruction of the dimethylglyoxime in this case being absolutely necessary G. C. J. Quantitative Volatilisation and Separation of Phosphoric Acid from the Metals of the Copper Group and from Aluminium Tin and the Alkali Metals. P. Jannasch and R. Leiste. ( J .f. prakt. Chem. 1913 88 129 ; through Chem. Zentralbl. 1913 II. 994.)-.In continuation of previous work (ANALYST 1909, 34 507) it was found that the volatilisation of the phosphoric acid may be repre-sented thus : 1. P,O + 2cc1 = 2POC1 + COCI + co,. 2. 2P,O + 3CC1 = 4POCJ3 + 3c0,. 3. MuPO + 2CCl,= MeCI + POCJ + COCI + CO,. While the secondary splitting up of the carbon tetrachloride takes place thus : and 4. 2CC1 = C,CI + 2C12, 5. 2CCl = C2C1 + C1,. I n all reactions at a high temperature free chlorine and hexachloroethane were formed but not at temperatures below a red heat. The quantitative decomposition of a phosphate thus due to carbon tetrachloride alone is hindered by the presence of chlorine t o remove which a new method involving the use of intermittent currents -was employed; this also prevents the regeneration of phosphoric acid in th 526 ABSTRACTS OF CHEMICAL PAPERS distillation-tube.The following conditions were found necessary for the complete separation of phosphoric acid from the bases (1) The use of an asbestos plug to hold back the metallic chloride; (2) the use of a diluting agent such as quartz powder to prevent the substance from fusing together; (3) complete absence of moisture. The methods and apparatus used for the separation of phosphoric acid from copper silver lead cadmium mercury bismuth aluminium tin and the alkali metals by means of the stream of carbon tetrachloride are described in detail. The addition of quartz powder renders the method applicable to phosphates of the alkaline earth and alkali metals and the ammonium sulphide and hydrogen sulphide groups.Aluminium and tin however require the addition of potassium chloride also. 0. E. M. Estimation of Phosphoric Acid SolubIe in Citric Acid in Thomas Slag. M. Popp. (Chem. Zeit. 1913 37 1085-10S7.)-It has been proposed previously (cf. ANALYST 1913 171) in the estimPtion of phosphoric acid in Thomas slag to prevent the interfering action of dissolved silica by the addition of ferric chloride, hydrogen peroxide being also added in order to oxidise any hydrogen sulphide which may be present and the aulhor now gives details of a method embodying these principles. Fifty C.C. of the citric acid extract of the slag are treated with 25 C.C. of iron-ammonium citrate solution and 1 C.C. of 3 per cent.hydrogen peroxide ; more o€ the latter must be added if the mixture is still dark in colour owing to the presence of unoxidised ferrous sulphide. Twenty-five C.C. o€ magnesia mixture are then added and the estimation is continued in the usual way. The iron-ammonium citrate solution is prepared by mixing 1 kilo of citric acid with 30 grms. of ferric chloride dissolved in 50 C.C. of water adding 4 litres of 20 per cent. ammonia and, when solution is effected diluting the whole with water to 5 litres. The results are usually within 0.3 per cent. of those found when the silica has been removed by w. P. s. means of hydrochloric acid. Volumetrie Estimation of Phosphorus in Steel by Maeagno’s Method. H. Wdowiszewski. (Chem. Zeit. 1913 37 1069-1071.)-Macagno (Gazzetta 1874, 4 467) proposed to estimate phosphorus by reducing the phosphomolybdate pre-cipitate by means of zinc in sulphuric acid solution and titrating the resulting molybdenum sesquioxide with permauganate.As modified by Emmerton (Zeitsch. anal. Chem. 1892 31 71) who concluded that the final product of reduction by zinc was M O ~ ~ O ~ ~ and not Mo,O, the method is given in many textbooks-for example, in Blair’s ‘‘ Chemical Analysis of Iron.” The method as described by Blair gives rise to results which may be 100 per cent. too high but are more commonly from 10 to 30 per cent. too low. The author finds that it is essential to success to wash the phosphomolybdate precipitate with water after washing it with dilute nitric acid, as otherwise ammonium nitrate will pass into solution when the precipitate is dissolved in ammonia and this nitrate will be reduced by the zinc to nitrite which may double the consumption of permanganate in the final titretion.The time allowed by Blair (ten minutes) and others for reduction is much too short but molybdic acid can be reduced to Mo,O by zinc. On the other hand the reduce INORGANIC ANALYSIS 527 eolution is so rapidly oxidised beyond the stage of the hypothetical Mo,,019 that accurate results cannot be obtained by any method involving filtration from un-dissolved zinc or direct titration with permanganate. By decanting from the zinc into a measured and more than sufficient volume of standard permanganate and titrating back with oxalic acid excellent results can be obtained. The phosphomolybdate precipitate obtained in any manner which ensures its having a P20, MOO ratio closely approximating 1 24 is freed from iron by washing with 1 per cent.nitric acid and from nitric acid by washing with water. The filter is set in the neck of the 300 C.C. conical flask used for precipitation, the precipitate dissolved in a little 4 per cent,. ammonia and the filter washed with hot water until the contents of the flask amount to about 30 C.C. From 80 to 100 C.C. dilute (1 4) sulphuric acid and 10 grms. zinc are added and the mixture is maintained just short of ebullition for forty-five to fifty minutes which is only about fifteen minutes longer than is absolutely necessary. I t is then removed from the hot-plate and the clear liquid immediately decanted into another flask containing a measured volume of standard permanganate.The flask and zinc are rinsed with hot 10 per cent. sulphuric acid which is also decanted into the flask containing the permanganate and the excess of permanganate is titrated with an oxalic solution of equivalent strength. The test numbers agree well with those obtained on large quantities of steel by the use with every precaution of the gravimetric (magnesia) method and still more closely with results obtained on the same steels by the alkalimetric method. A single determination cannot be completed in much less than two hours from weighing the drillings but several can be conducted simultaneously. G. C. J. Estimation of Cobalt and Uranium in Steel. H. Konig. (Chew. Zeit., 1913 37 1106-1107.)-The method for the determination of cobalt depends on the electrode position of cobalt nickel and iron from an ammonium oxalate electrolyte, the separate estimation of iron and nickel and calculation of cobalt by difference.The metallic deposit after being weighed is used for the determination of iron as follows I t is dissolved in hot dilute sulphuric acid and nickel sulphate solution is added cautiously until its green colour just predominates over the pink due to cobalt. The iron can then be titrated with permanganate as usual. Contrary to the state-ments of Brunck (Stahl. u. Eisen 1908 331) and others nickel cannot be separated from cobalt by means of dimethylglyoxime. In steels containing nickel and cobalt, the former can be determined as follows Tungstic acid is separated as usual by means of a p a regia most of the iron removed from the solution by shaking with ether dissolved ether is boiled away the solution reduced by means of sulphurous acid the excess of the latter boiled away and the solution neutralised with potassium hydroxide.When cool potassium cyanide solution is added whereby nickel cobalt, and iron go into solution but chromium is precipitated. The mixture is made up to 200 c.c. mixed filtered and 100 C.C. taken for the estimation of nickel. This 100 C.C. is boiled whereby the potassium cobaltocyanide is transformed for the most part into cobalticyanide which is not precipitated by potassium hydroxide and bromine water. Addition of bromine water to the cooled solution completes this transforma 528 ABSTRACTS OF CHEMICAL PAPERS tion and precipitates the nickel as hydroxide.The nickel hydroxide is filtered off, washed dissolved in dilute hydrochloric acid chlorine expelled by boiling and the nickel precipitated by means of dimethylglyoxime. For the concentration of small quantities of uranium from solutions containing much iron advantage is taken of the fact that uranium is not deposited from an ammonium oxalate electrolyte. The steel is treated with aqua regia to separate tungsten chlorides are decomposed by evaporation with sulphuric acid and the iron is deposited electrolytically after neutralisation of excess of acid by ammonia and addition of ammonium oxslate. After the iron has been deposited the electrolysis is continued to destroy ammonium oxalate.The solution usually acquires a yellow colour due to formation of chromate and a precipitate containing uranium as well as chromium manganese and vanadium and a trace of iron may separate. The solution is boiled down to one-third of its bulk to destroy ammonium carbonate, which results from the decomposition of the oxalate and the precipitate containing all the uranium together with more or less chromium aluminium manganese iron, and vanadium is filtered off and washed with a dilute solution of ammonium chloride. It is then dissolved in dilute hydrochloric acid any chromic acid present is reduced by addition of a few drops of alcohol and the solution boiled with a little nitric acid and transferred to a small flask in which it is cooled. To the cold liquid, excess of ammonium carbonate and ammonium sulphide are added and the flask is corked and set aside for twelve hours.Iron chromium manganese and aluminium are thus precipitated and in the filtrate uranium is separated from vanadium by acidifying with acetic acid and heating to boiling when vanadium comes down a8 sulphide. The filtrate from the vanadium is reoxidised by boiling with nitric acid, uranium is precipitated by means of ammonia the precipitate washed with dilute ammonium chloride and the uranium finally weighed as U,O, or as UO,. The author prefers to ignite the precipitate in a Rose crucible in a current of hydrogen and weigh as UO,. G. C. J. Preparing Sections of Fractures of Steel for Microscopic Examination. A. Campion and J. M. Ferguson. (J. Iron and Steel Inst.1913 Advance Proof.) -In investigations relating to the breakdown of metals an examination of the fracture or of a section through the fracture is often of importance. The preparation of sections of fractures for microscopical examination especially of soft and ductile materials presents considerable difficulty as during the polishing operations the edges of the fracture become rounded or worn away. I n order to overcome this difficulty Roeenhain embedded the fracture in copper by electro-deposition and then cut through the copper and steel in the desired direction. The method is excellent, but requires much attention and considerable time for the deposition of Q inch of .copper. The authors find that satisfactory results may be obtained by embedding the fractured end of a test bar in a suitable fusible alloy cutting a section and polishing.Of several alloys tried the following was found the best for general work: Bismuth 50 lead 30 tin 25 zinc 3 ; m.-pt. below 100" C. This alloy readily penetrates the minute fissures in the fracture is hard enough to support the edges of the fracture during polishing and adheres strongly to the specimen. The fracture INORGANIC AhT-tQLYSIS 529 test-piece is dipped momentarily into dilute (1 1) hydrochloric acid then into similar acid which has been ‘‘ killed ” by zinc and finally into the alloy a little above its melting-point. If the alloy freezes the test-piece is held in position until it melts again. It is then allowed to cool still holding the test-piece until solidification takes place.When cold sections are cut by means of a fine saw and the specimen polished in the usual manner. A section can be prepared and a photograph obtained within half an hour of the breaking test. G. C. J. Rapid Estimation of Sulphur in Burned Pyrites. L. Sznajder. (C7zenz. Zeit. 1913 37 1107.)-2-5 grms. of the finely divided material is mixed with about 1 grm. sodium carbonate and 4 grrns. zinc oxide in a spun iron crucible and kept a t The cooled contents of the crucible are transferred to a 250 C.C. flask with hot water the flask is filled to the mark and its contents are shaken and filtered. Two hundred C.C. of the filtrate is heated to boiling and exactly neutralised to phenolphthalein by addition of dilute hydrochloric acid to the boiling solution.Thirty C.C. of barium chloride solution are added whilst main-taining violent agitation of the liquid and the excess of barium chloride is then titrated with I n spite of the presence of the precipitate the first appearance of a pink tinge is readily recognised after a little practice. The method gives results about 1 per cent. higher than those obtained gravimetrically, but on material with only 2 to 3 per cent. of sulphur this is negligible. red heat €or thirty minutes. sodium carbonate. G. C. J. Quantitative Precipitation of Tungstic Acid by Means of Aromatic Amines. E. Kafka. (Zeitsch. anal. Chenz. 1913 52 601-606.)-1t is known that tungstic acid can be precipitated by means of benzidine and a-naphthylamine (v. Knorre Ber. 1905 38 783; Tschilikin Ber.1909 42 1302). The author now shows that cumidine tetramethylparadiaminodiphenylmethane and tetramethyl-diaminobenzophenone can be used for the purpose. The reagents are prepared as follows Cumidine (5 grms.) is mixed with 10 C.C. water and dissolved by addition of 5 C.C. concentrated hydrochloric acid or 6 grms. tetramethyldiaminodiphenylmethane is dissolved in 4 C.C. hydrochloric acid or 7-5 grms. recrystallised tetramethyldiamino-benzophenone is dissolved in 10 C.C. hydrochloric acid and the solutions are diluted to 100 C.C. As the precipitates are somewhat soluble in water but much less so in dilute solutions of the reagents they are washed with a solution made by diluting 5 C.C. of the reagent to 100 C.C. To 50 C.C. of a solution containing about 0.2 grm.tttngstic acid as sodium tungstate 10 to 15 C.C. of the reagent is added with constant stirring. The mixture is stirred from time to time during an hour at the end of which time the precipitate is filtered off washed ignited in a platinum crucible without previous drying and weighed as WO,. Test numbers obtained with solutions of pure sodium tungstate are accurate within *O-8 per cent. The precipitates cannot be dried without partial decomposition but analysis of such dried precipitates leaves no doubt that the original precipitate in the case of tetramethyldiaminodiphenyl-methane has the composition WO,.CI7H2?N2 and in the case of tetramethyldiamino-benzophenone 2W0,.3C,7H,oN,0. G. C. J 530 ABSTRACTS OF CHEMICAL PAPERS Action of Various Waters on Lead. H. Heap.(J. SOC. Chem. Ind. 1913, 32 771-775 811-815 847-856.)-Experiments were made by a modification of Frank-land's lead-pipe method and by a method,depending on the use of pure lead foil. At an early stage in the research it was found that lead pipes could not be used continuously for a series of comparable experiments with different waters. Once they had acquired a protective coating from one water they resisted the action of other water which would have attacked clean lead the protective coating gradually dissolves in a corrosive water with the result that corrosion is slow at first and then accelerates. The disadvantages of using new lead pipe for each experiment are obvious and fortunately it was found that such experiments gave results in close agreement with those made by the foil method which was consequently adopted in all the later work.The foil (0.012 cm. thick) waR polished brightly with wash-leather and cut into strips 6.35 by 2-54 cms. In each experiment one of these strips was placed in a specially constructed glass vessel entirely filled with the water to be tested. The vessels were cylindrical in shape held about 120 c.c. and were fitted with broad conical stoppers so that by filling the vessel with water and inserting the stopper, water was displaced until the stopper fitted tightly. I n experiments made at temperatures far removed from room-temperature the water in the bottle was allowed to reach the temperature of the thermostat and the foil and stopper then inserted. In some experiments the water was placed under anaerobic conditions.The gases were pumped off by making use of Adeney's gas analysis apparatus which offers the further advantage that various gases can be introduced at definite pressures to the gas-free water. The most important conclusion reached is that oxygen is the most potent factor in the solution of lead. Whereas distilled water free from gases only dissolved 0.01 part per 100,000 in twenty-four hours at 24" C. and water under 1 atm. pressure of carbon dioxide 1-6 part water under 1 atm. pressure of oxygen dissolved 12 parts. Of all the salts tried only ammonium nitrate had a solvent action of the same order as oxygen and ammonium nitrate has to be present in a concentration approximating 25 parts per 100,000 before it is as corrosive as distilled water saturated with oxygen.The function of carbon dioxide is a secondary but important one. In absence of carbon dioxide the action of oxygen ceases when the water is saturated with lead hydroxide but in the simultaneous presence of carbon dioxide the lead is precipitated as carbonate or basic carbonate and the action is continuous so long as any oxygen remains in solution. This is the mechanism of the familiar phenomenon known as the '' erosion " of lead. Waters containing the carbonates or bicarbonates of the alkali or alkaline earth metals give rise to a protective coating of lead carbonate after the formation of which no more lead dissolves. If a phosphate is present so little lead dissolves before the formation of a protective coating that it can only be detected by refined methods On the other hand calcium sulphate affords no protection and water containing calcium sulphate but no bicarbonate attacks lead vigorously.G. C. J INORGANIC ANALYSIS 531 Estimation of Lithium in Mineral Waters. L. W. Winkler. (Zeitsch. anal. Chenz. 1913 52 628-640.)-Isobutyl alcohol affords an excellent means of separating lithium chloride from the chlorides of sodium and potassium and is much less objectionable to work with than amyl alcohol which was recommended by Gooch. At room temperature 10 C.C. isobutyl alcohol dissolve only 0.5 mgrm. of potassium and sodium chloride whereas amyl alcohol dissolves twice as much. From quantities of alkali chloride not exceeding 1 grm. the lithium may be separated as follows The mixed chlorides are dried at 130' C.and when cold are extracted with successive small quantities of isobutyl alcohol (about 2 C.C. each time) delivered from a measuring cylinder and the extracts decanted through a 4 cm. filter into a platinum crucible. About 10 C.C. of the alcohol should be used in all and the amount measured. The filtrate is evaporated to dryness the residue dissolved in a few drops of water about five times its weight of ammonium sulphate added the mixture dried on the water-bath and then in an oven the temperature of which is gradually raised until at about 180" C. the contents of the crucible begin to emit fumes. The covered crucible is then heated over a small flame which is subse-quently raised until an incipient red heat is attained. The cover is removed once or twice until no further fumes are seen and the crucible and lithium sulphate are then allowed to cool in the air and weighed.From the increase in weight of the crucible 0.5 mgrm. is deducted to correct for the solubility of the chlorides of sodium and potassium. I n this way approximately 90 per cent. of the lithium is recovered. The residue from the treatment with isobutyl alcohol is dissolved in water the solution acidified with hydrochloric acid evaporated to dryness dried at 120" C., re-extracted with isobutyl alcohol as before the residue is dissolved as before and the whole series of operations repeated a third time. The quantity of lithium sulphate obtained from the third extraction after correcting for the solubility of sodium and potassium chloride is usually of the order of 0.1 mgrm.The chlorides of calcium magnesium and aluminium are soluble in isobutyl alcohol and must be absent from any saline residue submitted to the process. The process as described can be applied to the mixture of alkali chlorides obtained in the ordinary course of a water analysis but lithium will usually be under-estimated if lime salts have been eliminated in the usual manner. In a water with 100 degrees of hardness approximately 10 per cent. of the lithium will be co-precipitated with the calcium as carbonate and in a water of 10 degrees of hard-ness about 1 per cent. of the lithium will be lost. I t is better to determine lithium in a separate portion of the sample. If the water has more than 100 degrees of hardness it is first diluted.Waters less hard are not concentrated but treated with excess of alkali hydroxide and carbonate to precipitate magnesium and calcium. A litre of the water is treated with these reagents heated on the water-bath for an hour allowed to cool filtered and the residue washed with water containing a little alkali carbonate and hydroxide. If the lime-hardness exceeds 10 degrees the pre-cipitate is dissolved in hydrochloric acid the solution evaporated to dryness the residue redissolved in a Iitre of water and calcium and magnesium reprecipitated as before The united filtrates are acidified with hydrochloric acid treated with excess of barium chloride and a little nitric acid (to destroy organic matter) and evaporate 532 ABSTRACTS OF CHEMICAL PAPERS to a pasty consistency.The lithium is next separated from the greater part of the other alkali chlorides present by treating the pasty mass with five times its own weight of absolute alcohol which is decanted off through a filter. The residue is redissolved in water the solution acidified with hydrochloric acid evaporated to a paste and the paste extracted with alcohol as before. The residue is again dissolved and the series of operations repeated. The alcoholic filtrates are united, diluted with an equal bulk of water and evaporated to dryness. The residue is dis-solved in water acidulated with hydrochloric acid and the solution usually cloudy, is filtered and evaporated to dryness. The saline residue is freed from the last traces of calcium and magnesium by solution in 10 to 20 C.C.water treatment with a few drops of a solution of alkali hydroxide and carbonate and filtration washing with a dilute solution of the precipitant. The filtrate is acidified with hydrochloric acid evaporated to dryness and the residue redissolved in 10 to 20 C.C. water. The last trace of aluminium is eliminated by addition of a few drops of ammonia heating to boiling allowing to stand an hour and filtration washing with water contailaing a few drops of ammonia. A few drops of alkali hydroxide solution are added to the filtrate which is next evaporated to half bulk to expel ammonia as ammonium chloride increases the solubility of potassium and sodium chlorides in isobutyl alcohol. Finally the solution is acidified with hydrochloric acid evaporated to dryness and the saline residue dried at 120" C.Usually it will weigh less than 1 grm. and the lithium is then separated as described in the opening paragraph; but if much more than 1 grm. the lithium should first be concentrated by treatment with alcohoI. A single extraction with ten times its weight of alcohol and filtration through a plug of cotton-wool suffices at this stage. G. C. J. Hydrolytic Action a Source of Error in the Estimation of Iodine and Bromine in Mineral Waters etc. P. Kaschinsky. (Zeitsch. angew. Chem. 1913, 26 492-494.)-Owing to the dissociation of magnesium halides according to the equation MgX + 2H,O = Mg(OH) + 2HX the whole of the iodine and almost all the bromine present as iodides and bromides in a mineral water may be lost when the water is evaporated and the residue ignited.I t is essential that the magnesium salts be removed by precipitation with alkali hydroxide and subsequent filtration before the iodine and bromine are estimated. Potassium hydroxide is to be preferred to calcium hydroxide for the precipitation of the magnesium saltp as potassium chloride is less soluble than calcium chloride in the alcohol which is used in the process. w. P. s. Estimation of Small Quantities of Hydrogen Sulphide in Natural Waters. L. W. Winkler. (Zeitsch. anaZ. Chem. 1913 52 641-645.)-The reagent employed for producing the coloration the intensiiy of which is made the measure of the hydrogen sulphide present is a solution of 10 grms. Rochelle salt 10 grms. ammonium chloride and 0.1 grm. lead acetate in 100 C.C.of 5 per cent. ammonia. The Rochelle salt and ammonium chloride prevent the precipitation of calcium carbonate and the hydroxides of magnesium and iron and Rochelle salt also prevents the development of any interfering colour due to iron sulphide. The standard solution used for makin INORGANIC ANALYSIS 533 the colour comparison is an approximately 0.1 per cent. solution of sodium sulphide, Ne2S.9H,0 a salt which can now be obtained (from Kahlbaurn) substantially pure. Whereas a dilute solution of sodium sulphide in distilled water suffers a loss of titer of 35 per cent or more in twenty-four hours a solution made up with a 50 per cent. solution of sodium nitrate instead of water loses its titer at less than one-third of this rate. Such a solution has been found useful but it should be used as soon after preparation as possible.A completely satisfactory deiiermination of hydrogen sulphide in water can only be made at the source. The sodium sulphide is best conveyed to the point of collection of the sample as follows About 0.1 grm. is accurately weighed into a weighing-bottle of not more than 1 C.C. capacity. The stopper is then greased bhe bottle taken to the place of collection and its contents dissolved in 100 C.C. of sodium nitrate solution rendered feebly alkaline with ammonia. The water to be examined is collected in a bottle of known volume (about 100 c.c.) 5 C.C. of the lead reagent is added the stopper inserted and the contents shaken and then transferred to a 200 C.C. beaker. In a second beaker 100 C.C. of distilled water and 5 C.C. of the lead reagent are mixed and standard sodium sulphide solution is run in from a burette until the tint matches that of the sample under examination. If the water to be examined is naturally coloured the influence of this colour may be corrected for as follows Some of the water is treated with the lead reagent placed in a stoppered bottle which it should only half fill and shaken at intervals for an hour or two. The lead sulphide at first formed is thus oxidised and the resulting solution identical with the original water in colour and free from hydrogen sulphide, is then used instead of distilled water for the preparation of the standard of com-parison. G. C. J

ISSN:0003-2654    

DOI:10.1039/AN9133800517

出版商:RSC    

年代:1913

数据来源: RSC

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INORGANIC ANALYSIS 533 APPARATUS, ETC. Use of Bomb Calorimeter for Elementary Analysis and Heat of Com- bustion. M. Diakow. (Biochem. Zeitsch., 1913, 55, 116-124.)-1n the application of the bomb calorimeter to the study of metabolism, the oxidation of nitrogen to nitric or nitrous acid is a serious source of error. I t is usual to correct for this by estimating the acid formed and assuming it to consiot entirely of nitric acid.This assumption is only correct for ash-free substances ; in other cases a direct estimation of nitric acid is necessary. Carbon, oxygen consumed, and nitrogen liberated, are estimated by the following method: The bomb is weighed before and after the introduction of oxygen, and after combustion a part of the gas is passed through a carbon dioxide absorption apparatus, and a part is collected and analysed, the carbon dioxide, nitrogen, and oxygen being estimated.From the total carbon dioxide and the percentage of carbon dioxide in the gaseous product, the total gaseous product, and hence also consumed oxygen and liberated nitrogen, can be calculated. In correcting for the " apparent nitrogen " in the compressed oxygen, it is necessary to bear in mind that this gas consists largely (76 per cent.) of argon. E.W.534 ABSTRACTS OF CHEMICAL PAPERS New Method and Apparatus for the Estimation of extremely small Quantities of Carbon Dioxide. Shiro Tashiro. (Amer. J. PhysioZ., 1913, 32, 137 ; through Chem. Zentralbl., 1913, II., 978.)--The smallest quantity of pure carbon dioxide able to cause turbidity in a drop of known barium hydroxide content is first determined; the smallest quantity of the gas under investigation able to produce the same turbidity in a similar drop is then found.The apparatus consists of two chambers of known volume joined by a capillary tube provided with a stop- cock ; into the first a drop of the barium hydroxide solution is introduced through a capillary, and the gas sample, contained in the second chamber, is then forced through the stopcock until turbidity is produced.Details are to be found in the original paper. 0. E. M. Automatic Pipette. P. Medinger. ( C h m Zed., 1913, 37, 1107.) -- The pipette illustrated differs from other pieces of apparatus designed to serve the same purpose in having a single cock, which by turning-always in the same direction -provides for filling the pipette, equalising the pressure within and without the apparatus, discharging the pipette, and, after recharging it, discharging the liquid which would otherwise be retained by capillarity in the discharging jet.With the cock in the position shown, the pipette is filled by means of a pressure ball attached to G.I t is then given a quarter turn, whereby the bottle is put in connection with the atmosphere by means of a channel grooved in the body of the plug, which channel in this position of the plug connects B with D. Another quarter turn leads to the discharge of the contents of the pipette through D, and to the flow back of liquid from K to the bottle. Another half turn brings the cock once more to the filling position. The pipette is filled, and the next quarter turn of the cock not only equalises the pressure within and without the apparatus, but leads to the discharge of liquid in D by the escaping air. The receiver below D is then changed, and the cycle of operations repeated. When not in use, the plug is so turned that the horizontal channel is at the top connecting the pipette with G. The makers, Warmbrunn, Quilitz and Co., Berlin, deliver the apparatus with the plug of the cock constructed of glass, silver, or phosphorbronze. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9133800533

出版商:RSC    

年代:1913

数据来源: RSC

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REPORTS 535 REPORTS. Report to the Local Government Board on Bacterial Food-Poisoning and Food Infections. (Food Reports, No. 18, 1913.)-This Report presents a summary of our present knowledge on the subject of bacterial food infections, and is a continuation of Dr. Ballard’s review in the Annual Report of the Nedical Officer of the Board for 1890. A memorandum issued by the Board, September, 1911, is again printed as Addendum B., p.68, and Dr. Newsholme concludes that ‘‘ Recent additions to our knowledge concerning the procedure to be followed in dealing with outbreaks of illness suspected of being due to the consumption of certain foods, tend to empbasise rather than to lessen the importance of inspection of meat at slaughter-houses, of the exercise of adequate control in regard to the suitability of places where food is prepared and stored, and of measures to secure cleanliness in all stages of food preparation.” Cases of so-called ‘( ptomaine-poisoning ” are now generally reeognised to result from the presence in the food materials consumed of certain pathogenic organisms (generally members of the Gaertner group), which are either living, capable of active multiplication, or which, although killed in the cooking, are nevertheless poisonous by means of the toxins contained in them.A large number of cases of food-poisoning are summarised, and it is concluded that for none of them was it definitely established that B. protezis was etiologically con- cerned, nor is the available evidence sufficient to establish that this organism is ever a cause of extensive outbreaks of food-poisoning.I t still remains a matter of con- troversy as to how far the occurrence of putrefaction in meat may be a cause of even isolated cases of human diseaee, while for extensive widesprcad outbreaks it can certainly be excluded. Section 5 deals fully with the Gaertner group in relation to food-poieoning, and the ease with which the toxins of this group may escape destruction when subjected to ordinary cooking temperatures is especially emphasised ; nor are the ordinary methods of food preservation, such as smoking and pickling in brine, very efficacious for their destruction. The study of recorded outbreaks in this country shows in a con- siderable number of them that infection of the foodstuff may with great probability be accepted as taking place during or after the preparation of the animal for sale, although it is certainly probable that in other cases the food was contaminated because it was derived from an animal suffering from a general or local disease caused by one or other member of the true Gaertner group, animals used for food being not uncommonly affected by such organisms.The following three hypotheses are con- sidered at some length : (a) That the Gaertner group bacilli which are the cause of the food-poisoning outbreak are of human origin, the meat being infected with patho- genic Gaertner bacilli from a human source-Le., a case of disease (paratyphoid fever) or a carrier case. (b) That the Gaertner group bacilli which set up the food- poisoning outbreaks are derived from ordinary fmal infection of the food.(c) That food-poisoning outbreaks are due to infection of the food with virulent Gaertner group organisms (or other special bacilli) derived from animals which are either at the time suffering from disease due to Gaertner group bacilli or acting as carriers of these W. G. Savage.536 REPORTS bacilli.I n Dr. Savage’s opinion this last view is the one which best explains all or most of the phenomena of food-poisoning. From the review of existing knowledge as given in the Report it is clear, the author says, that from the preventive standpoint food-poisoning cases must be looked upon as forming two groups : (a) those due to the consumption of meat derived from diseased animals ; and ( b ) those due to the contamination of meat or other food with food-poisoning bacilli derived from sources other than the food itself.I t is probable that this second group is considerably larger than the first. A discussion of various preventive measures suggested con- cludes the Report. A useful addendum consists of a tabulated list of seventy-nine British and forty-four Continental outbreak8 dating from 1878 to 1911, in which tho number of cases, deaths, kind of food eaten, bacteria isolated, etc., are recorded.A bibliography consisting of 155 .British and foreign references to the literature is also included. H. F. E. H. Report of the Government Chemist upon the Work of the Government Laboratory for the Year ended March 31, 1913, with Appendices.(Issued as a Parliamentary Paper [Cd. 70011, pp. 1-25.)-The total number of samples analysed and examined in the Government Laboratory during the year was 209,502 ; in addition to these, 145,257 samples were examined at Ehe chemical stations in the provinces. With a view of preventing or detecting the use of prohibited substances, 91 samples of finished beer from brewers’ premises were specially examined as to the presence of saccharin, saponin, etc., but no deleterious or illegal substance was detected in any of the samples. As regards dilution of beer by retailers, out of 9,453 samples analysed, 581 wera found to have been diluted.The dilution did not usually exceed 3 gallons of water to the barrel of 36 gallons, but occasionally was as high as 12 gallons to the barrel.The amount of alcohol was estimated in 356 samples of herb beers, beer substitutes, and temperance beverages. I n 268 cases the quantity of alcohol was below 2 per cent, of proof spirit; 63 samples contained between 2 and 3 per cent., 15 between 3 and 5 per cent., whilst 10 samples described as ginger beer or herb beer contained from 5.7 to 11.5 per cent.of proof spirit. The number of samples of beer and brewing materials examined for the presence af arsenic was 815. Of these only 16 were found t o contain arsenic in excess of the limits laid down by the Royal Commission on Arsenical Poisoning. Out of a total of 434 samples of malt and sugar, 2 samples contained excess of arsenic, the amount being & gr. per pound in one case, and & gr.in the other. The limit was exceeded in 5 out of 242 samples of beer and wort, but in none of the samples did the amount exceed Nine of the miscellaneous samples examined contained an excess of arsenic, but, with one exception, it was of a trifling character. During the year 6 samples purchased as cider were found t o b3 artificially prepared liquids; of 262 samples of imported cider 2 wera found to be factitious.Many non-alcoholic ciders, so-called, are entirely free from fermented apple-juice, and consist of solutions of sugar which have been aerated, flavoured, and coloured. The use of any name for such beverages, which suggests that they consist of fermented apple-juice or cider, is gr. per gallon.REPORTS 537- an infringement of the Merchandise Marks Act.Twenty-three samples of liqueur chocolates were examined for the presence of alcohol ; 6 contained from 5 to 8 per cent. of proof spirit, and in 2 cases the amounts were 23 and 27.4 per cent. The average percentage of proo€ spirit found in 269 samples of imported liqueur chocolates was 5.4, the highest amount being 21.9 per cent. The number of samples examined for the Board of Agriculture and Fisheries, the Board of Agriculture for Scotland, and the Department of Agriculture and Technical Instruction for Ireland, was 2,944.Imported Milk and Cream.-Of the 73 samples of condensed sweetened and un- sweetened milk, 65 were condensed whole milk, and 8 condensed skim milk ; all the cases were properly marked. Ths percentage of fat in the samples of whole milk ranged from 8.0 to 11.3, and in no case was there evidence that the original milk contained less than 3 per cent.of fat. Of the 64 samples of dried milk analysed, 15 were whole milk powders, 5 had been prepared from impoverished milk, and 41 from skimmed milk. Two of the samples consisted of milk proteins and 1 of lactose only. The range of fat in the cream imported from France was 40.4 to 65.8 per cent., and i n that from Norway 18.3 to 32-1 per cent.Imported Butter.-Out of 1,309 samples, 13 contained between 16 and 17 per cent. of water, and 6 samples more than 17 per cent. A11 the samples were free from foreign fats. Imported Margarim-None ol the 598 samples examined contained more than 10 per cent. of butter fat, but water in excess of the legal limit was found in 5 cases.The samples were all free from paraffin wax. Imported Cheese.-The 65 samples analysed were free from fat other than milk fat, but in several cases the amount of fat was very small, indicating that the cheeses had been prepared from skimmed or separated milk. Eighty-three samples of sheep-dips were received for examination ; 12 were found to be deficient in active ingredients, and in 42 cases the formula? required alteration to insure an efficient dip.Samples of potatoes grown on experimental plots which had been treated with different copper fungicides were examined with the view of ascertaining whether the tubers had absorbed copper. I n view of the statements to the effect that imported butter frequently contains considerable quantities of non-fatty milk solids, the curdy matter was estimated in 366 samples, representing practically every class of imported butter.The results obtained showed that the amount of curd in foreign butter is not excessive, and is quite comparable with the quantity which occurs in well-made butter in this country. All the samples of milk, cream, and butter were tested for th8 presence of preservatives.The samples of whole milk imported in churns, and of sterilised milk, sterilised cream, and condensed milk, were free from preservatives. One sample of milk powder contained boric acid. The creams, when preserved, contained boric acid only, the amount of this varying from 0.12 to 0.46 per cent. All the samples of cream imported since October 1, 1912, complied with the new regulations which then came into operation. Boric acid was also the only preservative found in imported butters.The butters imported from Denmark, Russia, Norway, and Sweden were No evidence of absorption was obtained.538 REPORTS free from boric acid, whilst over 70 per cent. of those from France, Argentina, Australia, and New Zealand contained this preservative.Fifty-eight glazes from various works where lead-poisoning had occurred were analysed to determine both the total amount of lead and the amount of soluble lead present. I n most of these cases almost the whole of the lead, frequently amounting t o 30 per cent. of lead monoxide, was found to be readily soluble in hydrochloric acid of a strength equal to that usually present in the gastric3 juices.6 6 Leadless ” glazed pieces of pottery were also examined, and in only a few cases was the amount of lead found in the glaze of the finished ware so great as to leave no doubt that ordinary lead glaze had been used in their manufacture. The permissible quantity of lead monoxide in a leadless glaze has been fixed at 1 per cent.to allow a margin for the small quantities of lead which may be picked up from the grinding vessels and dipping-tubs. Ninety-two samples were referred to the Laboratory by magistrates under the Sale of Food and Drugs Acts; these included 74 samples of milk, 8 of butter, 2 each of ginger beer and vinegar, and 1 each of brandy, cream, cream of tartar, flour, rice, and whisky. In the case of 1 sample of milk in which decomposition had proceeded to an unusual degree, no certificate was issued.The results of the analyses differ from those of the public analyst in 5 cases. The following are the particulars of the more important cases : Butter.-The results of the examination ware in agreement with those of the public analyst in the cases of 2 samples of butter alleged to contain a n excess of water, and in the case of a sample of butter containing an excess of boric acid.I n 3 out of 5 cases in which foreign fat was alleged to be present the results of the public analyst were confirmed, but in the remaining 2 cases, although the butter was of abnormal character, no evidence of the presence of foreign fat was discovered. Ginger Beer.-Lead to the extent of 8.3 and 6.5 grains per gallon was found in 2 samples in which it was stated to be present by the public anztlyst. Vinegar.-One sample was found to contain 0.78 grain of copper per pint, and the other to be deficient in acetic acid, as alleged.Brandy.-The public analyst reported that the sample contained spirit other than that derived from the grape, and this was confirmed, the sample being deficient in the characteristic constituents of brandy to such an extent as to indicate the presence of a large proportion of neutral spirit.Cream of Tartar.-The allegation that the sample contained a considerable quantity of lead could not be confirmed. Flour.-The sample contained nitrites, as alleged. In regard to the samples of whisky alleged to be deficient in strength, of rice alleged to be faced with talc, and of cream alleged to be preserved with boric acid, the results agreed with those of the public analyst.Milk.-In the 73 cases in which certificates were issued, the charges were as follows : I n 33, added water ; 26, abstraction of fat ; 3, added water and abstraction of fat; 2, added water and colouring matter; 1, added water and boric acid; 5, boric acid ; 2, other preservatives ; and in 1 an excessive quantity of dirt.In connection with experiments and investigations arising out of the examination of the samplesREPORTS 539 referred to under the Food and Drugs Act, 192 samples were analysed in order to obtain data for the purpose of comparison. The number of saniples submitted by the Board of Agriculture and Fisheries under the Fertilisers and Feeding Stuffs Act was 25, consisting of 15 fertilisers and 10 feeding stnffs.The fertilisers comprised samples of basic slag, various potato and root manures, wool waste, hoof and horn meal, grass manure, guano, fish manure, and sulphate of potash. A sample described as ' I dissolved bone " consisted mainly of mineral phosphates mixed with nitrates.The feeding stuffs examined consisted of samples of bran, barley meal, poultry food, and various feeding and cake meals. An article sold as barley meal contained a considerable proportion of ground weed seeds and seed husks; another sample of barley meal contained over 3 per cent. OE sand. Several of the feeding meals and cakes were deficient in oil, and others contained sand and earthy matter in excess.Details as to the numbers of various substances examined in the Laboratory and in the provincial stations during the year are given in the Appendices to the Report. w. P. s. Royal Commission on Sewage Disposal : Appendix t o Eighth Report, March, 1913. G. McGowan, C. C. Frye, and G. B. Kershaw.-This Report cmtains the results of analysis and of physical observation of streams receiving sewages and effluents during the years 1909-12, together with notes on the tests in use and a description of the standard tests selected by the Commission for judging the quality of an effluent in relation to the stream into which it is discharged.These standard tests are two-namely, the dissolved oxygen absorption and the determina- tion of suspended solids.The description of the standard conditions for carrying out these two tests form the items of greatest analytical interest in the Report. Five Days.-The principle followed is that of Winkler, with Rideal and Stewart's modifications (see ANALYST, 1901, 26, 141). The sample of effluent in its bottle is well shaken for a half minute in order to mix any deposited solids and to effect fairly complete aeration.About 300 C.C. will be required, and this volume is accurately diluted with four times its volume of well aerated tap-water at 65" F. The dilution is gently mixed and poured quietly into four bottles, also at 65" F., the capacity of each being about 350 c.c., and being accurately known. The bottles are allowed to stand full to the mouth for five minutes and then stoppered.Two bottles are placed in an incubator at 65' F. for five days, and in the other two the amount of dissolved oxygen is determined at once, as follows : 0-9 C.C. of sulphuric acid is added and 1 to 2 C.C. of permanganate, and the contents mixed and allowed to stand for twenty minutes. The authors found that this length of time was necessary in order to oxidise any nitrites. Then the excess of permanganate is destroyed by the addition of about 1 C.C. of 2 per cent.potassium oxalate, and when the liquid has become colourless 1 C.C. of 33 per cent. manganous chloride is run into the bottom, and immediately afterwards 4 C.C. of alkaline iodide solution (70 per cent. potash and 10 per cent. potassium iodide) are added.The bottle is then inv'erted once or twice, allowed to stand for a, few minutes, inverted Dissolved Oxygen Absorption540 REPORTS again, and then allowed to settle. F'v C.C. of hydrochloric acid are added, and the bottle allowed to stand in the dark for five to ten minutes with occasional rotation. Twenty C.C. of the liquid are pipetted out and thrown away, and the remainder titrated with % thiosulphate, using clear starch solution as an indicator.The result is calculated into parts of dissolved oxygen per 100,000 parts of the mixture. The second bottle is treated in the same way, and the mean of the two results is taken. At the end of five days the dissolved oxygen in the bottles in the incubator is determined, and the mean of the results subtracted from the first mean gives the amount of dissolved oxygen absorbed by the mixture during the five days.This result multiplied by 5 gives the amount of dissolved oxygen absorbed by 100,000 parts of the effluent. The Commission has fixed a standard of 2 parts per 100,000 for the dissolved oxygen absorption. For tank effluents the dilution should be 1 of effluent to 49 of tap-water, and for sewages, 1 volume to 99 volumes, the object being to have about half the dissolved oxygen in the mixture left unabsorbed at the end of the test.As samples have usually to be sent from the outfall to a laboratory, and as it is desirable that results from different places should be comparable, it is recommended that all samples should be allowed to stand at 65" F.for a uniform time of forty- eight hours after sampling before carrying out the test. If it is not possible to com- monce the test at the end of that time, the sample should be kept on ice for any further period. Solids iiz Sz6spension.-These are determined by filtering a known volume of the effluent through asbestos in a Gooch crucible. The crucible used should be about 14 inches high and 19 inches in diameter at the top, and its weight should not exceed 20 grms.Asbestos floss is used, consisting of silky fibres about 2 cms. long, and is treated with acid to free it from iron before use. Some of the asbestos is placed in the crucible supported in a pressure filter-flask, and is pressed down with a flattened glass rod to form a layer about 0.2 cm.thick, a stream of water being kept running through the crucible. When all loose particles of asbestos have been washed away, the crucible is washed with distilled water, dried at 105' C., and ignited and weighed until constant. In the case of average eauents, 200 C.C. of the shaken sample are poured into a measuring-flask for the estimation. The asbestos is moistened with a small quantity, then the pump is turned on so as to produce a reduced pressure of not more than 100 mm., and the remainder of the quantity run through gradually.If the filtrate should contain any deposited solids, a new estimation must be begun. Then the crucible is washed with distilled water, dried at 105' C., and weighed once every twenty-four hours until constant to within 0.3 mgrm.The increase in weight gives the solids in suspension. For this result, the Committee has fixed a standard of 3 parts per 100,000. I n the case of sewages and tank effluents, 25 C.C. of an average sewage and 50 C.C. of an average tank effluent should be taken. The authors express the opinion that the Gooch filtrates from these samples appear to contain about 3 or 4 parts of colloids.The same directions as to the time interval between the making of the test andREPORTS 541. the taking of the sample are given as for the dissolved oxygen absorption test ; in fact, both tests are made on the same bottle of sample. River Waters.-A large number of physical observations were made upon the condition of the water in many rivers, and a full chemical analysis of samples repre- senting the various conditions was undertaken.It was found that the results of the dissolved oxygen absorption test agreed best with the conditions observed. The figures obtained with this test corresponding to the various states of the river were as follow : Condition of Average Dissolved Reach of River. Oxygen Absorption. Very clean ... ... ... ... ...0.10 Clean ... ... ... ... ... ... 0.20 Fairly clean ... ... ... ... ... 0.271 0 30 Moderately clean.. . ... ... ... ... 0.311 Doubtful ... ... ... ... ... ... 0.48 Bad ... ... ... ... ... ... 0.97 From these results the authors have adopted the figure of 0.40 part per 100,000 as the ‘( limiting figure” for the dissolved oxygen absorption of a river water, if it is to be considered as in a satisfactory condition and as not exhibiting signs of pollution.The Report also gives tables showing the chemical composition of the mud, and of various algE and fresh-water plants found in rivers, for the analysis of which the ordinary methods were found suitable. J. H. J. Report of the Connecticut Agricultural Experiment Station for the Year 1912. (Public Document No.24, pp. 1-531.)-The work of the chemical, botanical, entomological, forestry, plant-breeding, and protein research departments of the Experiment Station during the year 1912 is recorded in the present report. Seven hundred and eighty samples of fertilisers and manures and 273 samples of feeding-stuffs were analysed, the results obtained being given in tabular form. The question of valuation is also considered in the case of the fertilisers, etc., and figures are given in most cases. The valuation of a fertiliser is the result obtained by calculating the retail cash cost at freight centres of an amount of nitrogen, phos- phoric acid, and potash in high-grade materials equal to the amount contained in one ton of the fertiliser. The variations in the net weight of certain classes of foods sold in package form were also investigated, about 2,000 packages, representing 150 brands of about 75 kinds of foods, being weighed. A definite weight was claimed on 594 of the packages examined, and in 77 cases the weight was found to be deficient. The work of the botanical department included experiments on the effect of fertilisers on growth, yield, etc., of trees; the effect of various sprays ; the study of the nature and spread of the chestnut blight ; seed testing, etc. The entomological department has determined the life-histories of three little-known and destructive insects and the means for combating these and other pests. The protein research department is occupied in determining the nutritive effect of the separate proteins of foods. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800535

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

542 REVIEWS REVIEWS. THE NATIONAL PHYSICAL LABOHATORY. COLLECTED RESEARCHES. Vol. x. 1913. This volume of 253 pages, quarto, contains eleven papers on a variety of subjects, reprinted from various journals, reports, etc. The first paper is the “Tenth Report to the Alloys Research Committee of the Institution of Mechanical Engineers,” reprinted from the Proc. Inst. Mech. Eng., April and May, 1912, and is an exhaustive study of the constitution, mechanical properties, and micro-structure of the alloys of aluminium and zinc, by Dr.W. Rosenhain and Mr. S. L. Archbutt. The authors conclude that the alloy con- taining 20 per cent. of zinc is the most generally useful of the simple binary alloys of these metals, and that those containing from 15 to 25 per cent. of zinc are better deserving of notice than the, at present, more widely used alloys containing less than 15 per cent.of zinc. When prepared from the pure metals, these alloys do not show the tendency to crack on cooling, or the brittleness or liability to rapid corrosion, which many of the commercially made alloys of this class have shown, and which the authors attribute to the presence in the latter of impurities.They can be rolled into bars and drawn into wire of considerable teosile strength, increased by the addition of a small percentage of copper, but the strength rapidly falls off with rise of temperature. The industrial alloys of this class containing less than 40 per cent. of zinc are shown to be homogeneous solid solutions. This Report will take its place among the classical researches on binary alloys, and will be found of value by all metallurgical analysts.The first of them, reprinted from the Journal of the Institute of Metals, No. 2, vol. viii., 1912, contains an experimental research by Dr. Rosenhain and Mr. D. Ewen on (‘ Inter- crystalline Cohesion in Metals,” which they believe to be due to the existence between the crystals of a cementing film of metal in the amorphous form discovered by Beilby.I n this paper a new method of developing the micro-structure of metals by ‘‘ vacuum etching ” is described, and illustrated by some highly interesting and beautiful photographs. I n the third paper, reprinted from the ‘( Carnegie Scholarship Memoirs of the Iron and Steel Institute,” vol. iv., 1912, Mr.J. C. W. Humphreys shows that intercrystalline brittleness may be caused in iron by annealing in a, slightly oxidising atmosphere, and he describes experiments in support of his theory that this is due to the existence of an oxide of iron which is soluble in y iron, but not in a iron, and is therefore rejected to the boundaries of the crystals on cooling. I n an appendix to this paper some electric-resistance furnaces are described, of simple construction, for annealing and melting metals in vacuo in the laboratory.Papers on ‘‘ The Measurements and Notes on the Visibility of Point Sources of The second and third papers are mainly of theoretical interest.REVIEWS 543 Light,” by Messrs. Paterson and Dudding; on ‘( Tests of Tungsten Filament Glow Lamps, made for the Engineering Standards Committee,” by Dr.Glazebrook and Mr. Paterson ; on The Transmission of Visible Light by Photographic Lenses,” by Mr. R. W. Cheshire ; on ‘‘ The Shape of Scales required for Reflecting Instruments with Concave Mirrors,” by Mr. E. H. Rayner ; on ‘( The Ideal Photographic Lens,” by Mr. T. Smith ; and on “The Results of Some Tests of Photographic Shutters,” by the same author, are not of special interest to the readers of this journal.I n the paper on “The Testing of Ebonite for Electrical Purposes,” by Messrs. Paterson, Rayner, and Kinnes, reprinted from the J. Inst. EZect. Ey., Part 217, uol. I., 1913, there are several points of interest to analysts. I t is shown that ebonite made from Para rubber and sulphur only has a far higher electric strength than that made from any other kind of rubber, and that all mineral admixtures and other adulterants reduce the strength ; also, that whilst the electric strength can only be ascertained by an electric test which is costly to carry out, information of value can be obtained by a determination of the specific gravity and by a yield test which the authors describe, and which depends upon the bending of a weighted cantilever of the material at 7OOC.I t is stated that all ebonites, without exception, suffer from the defect of exuding small drops of acid upon the surface under the influence of light. In “An Investigation into the Inflammability of Flake Charcoal, Decayed Wood, and Insulating Papers, made for Lloyd’s Register of Shipping,” by Dr.Rosenhain and Mr. W. Gemmell, it is shown that flake charcoal used in the insulating partitions of refrigerating chambers does not heat to a dangerous extent as a result of the absorption of gases into the pores of the charcoal, but that when subjected to a current of air such charcoal commences to burn at comparatively low temperatures. The following table contains the results of the experiments made : Material.Flake charcoal.. . ... ... ... ... >, ... ... ... ... Y 9 a * * 9 , ... ... ... ... 9 9 .-. Decayed wood, No. l... ... ... ... ,, No. 2 . . . ... ... ... Brown unvarnished paper ... ... ... Black varnished paper, No. 2 ... ... (‘ Ruberoid ..... ..- ... ... ... 9 , Rate of Air-Supply in Cubic Feet per Hour. 1.2 5-0 62.0 5.0 10.0 5 *O 5.0 5.0 Temperature a t which Ignition occurs.0 c. 111 110 96 180 175 195 216 228 If the air contain as little as 5 per cent. of sulphur dioxide, spontaneous ignition of the charcoal may take place without the supply of any extraneous heat, and there- fore the fumigation with SO, of ships having charcoal-fitted bulkheads is a dangerous proceeding. L. ARCHBUTT.544 REVIEWS DAIRY TECHNOLOGY. By C.LARSEN, M.S.A., and W. WHITE, B.S. New York: This volume, which is decidedly American, and deals with the technique of dairy work principally and, in fact, almost entirely, from the American point of view, is very largely a compilation from many sources, and particularly from the numerous and excellent bulletins of the U.S. Department of Agriculture and of various State Experiment Stations.Though a compilation, it has the rare merit of being compiled by those who are really conversant with their subject, and, consequently, selection has been judicious, and facts and details seem to be in all cases reliable. I t is, indeed, quite refreshing to find at the outset a really good average composition of milk. A very large number of subjects are compressed into a rather small space, and the information is therefore somewhat telegraphic, and might have been a little more diffuse than it is.There is an excellent synopsis of methods which have been used to improve the milk-supply of America, and, naturally, full details of the working of certified milk depots are given. The pros and cons of pasteurised milk are carefully debated in a chapter which is quite up to date, and properly completed by a discussion on (‘ cost.” The details of the ‘; handling ” of milk in American cities are of a practical character. One chapter is devoted to some curious methods of graphic calculation of milk mixtures for the purpose of ‘( standardisation ” of milk.Our American cousins seem to have grasped the fact that milk should be paid for according to quality, and that if a low-grade milk be required, it is quite legitimate to bring down a higher- grade quality to meet the requirement.Such ideas, however, are quite heretical in England. In the second part of the book will be found many really useful little details and hints in connection with dairy products which should be useful to those who handle such.A good deal of space is devoted to ice-cream, and there is probably no such elaborate treatment in any dairy work outside America. A full description of all the various trade products and nomenclature is given, but the manufacture of ice-cream is not of the same extensive nature in England, where it seems to be chiefly in the hands of itinerant vendors from a southern clime.The chapters on milk-sugar, casein, fermented milks (which for some extra,- ordinary reason include clotted cream), condensed and dried milks, etc., are all probably better than anything yet published in any dairy work. The processes given are all ‘‘ live ” processes, as far as the trade will allow its secrets to be published. The final chapter on “ Oleomargarine ” is a little disappointing, but in view of the rapid changes in the composition of this product, it would be clearly impossible to keep descriptions up to date.The book is well printed, and there are many illustrations, taken largely from trade journals and official bulletins. I t is, however, unfortunate that practically no allusion is made to them in the text, and descriptions would have largely increased their utility .John Wiley and Sons. 1913. Pp. 298. $1.50 net.REVIEWS 545 The work will be probably of little interest to the general analyst, but should prove useful to those whose work lies chiefly in the dairy world or comes into coutwt with it. CECIL REVIS. FARINES, FBCULES ET AMIDONS. Par MARCEL ARPIN. Paris : Librarie Polytech- M. Arpin has long been well known as Chemical Expert to the Tribunal of the Seine, and also Technical Adviser to the Syndicate of Baking of Paris and to the General Syndicate of French Bakers.The present work of 190 pages is a practical treatise on the analysis of the substances indicated in the title Among bodiss dealt with are wheaten flour, the flour of rye, barley, and other grains. There is next given a description of bread and bread analysis, and the composition of $fEezcrages, or acces- sory materials of the bakery.Chapters follow dealing with pastries, biscuits, and spiced bread. Regulations dealing with army and navy bread are also included. As an example of the mode of treatment, it may be mentioned that the section on the analysis of wheaten flour contains directions for the determination of mois- ture, gluten, water of hydration of gluben, fatty matters, acidity, and ash.Micro- scopic analysis and the introduction of mineral matters into the flour are also dealt with. Then follows an account of the interpretation of the results of analysis. One of the most striking features of the book is the minute attention to the details of analytical methods shown throughout.Thus, in giving directions for the performance of a gluten estimation, stress is first laid on the fact that numerous causes influence the constancy o€ the results. Thus, they are affected by the compo- sition of the water employed, the temperature of the water, the time the dough is allowed to stand before the gluten extraction, and the duration of the process of extraction. In making the estimation the author prefers to use water containing about 0.1 grm.of total lime per litre, of which from eight to nine-tenths should be in the form of carbonate. Directions are therefore given to take 0.1 grm. of quicklime pre- pared from marble, to grind this finely, and make up to a litre. This water should be used at a temperature between 15' and 17' ; 33.33 grms. of flour are to be used for each dotermination and mixed with 17 C.C.of water. This is made into a per- fectly smooth dough, and then, for reasons given by the author, the washing out of the gluten is commenced immediately. The most important of these reasons is that the hydration of gluten proceeds for a considerable time, attaining its maximum at the end of about four hours.Therefore, logically, the dough should be allowed to stand this length of time before the extraction is made. As it is inconvenient to wait the whole time, the author prefers, therefore, not to wait at all. I n support of this decision be points out that this manner of procedure possesses the great advantage of indicating the quality of the flour, for the gluten which does so is all the better for the baker which absorbs the greatest quantity of water in the least time, and which is the most elastic, homogeneous, and cohesive.Minute directions follow for the manipula- tion of the dough during washing and freeing from surplus water, which it is stated nique BBranger, 15, Rue des Saints-PAres. Price 6 f.546 RE VIEWS should altogether occupy twelve minutes.The gluten is then weighed in the wet state, placed on a nickel plate, which has been treated with a trace of vaseline and dried at 105’ C. for about twenty minutes. A number of incisions is then made in the mass of gluten so as to facilitate the escape of moisture, and the drying is continued for twelve hours. The gluten is then again weighed.Other analytical operations are described with the same minutice of detail. One cannot altogether agree with N. Arpin in his reasons for immediately washing out the gluten on preparing the dough. The result most instructive to the baker would be obtained by allowing the dough to remain as long as it usually does before going into the oven, since that is the crucial time when the effects of the gluten are of service.The dough of Durum wheat flour would yield very little gluten on being first made ; and yet after softening and hydration a considerable quantity of gluten is obtained from such flour. The present writer has obtained some very interesting gluten results from washing fermented dough taken from loaves just ready to be put in the oven. Elsewhere reference has been made to the fact that in an abstract of Arpin’e method of gluten estimation, appearing in the Journal of the Society of Chemical Inclzcstry (1902,21,1417), it is mentioned that, ( ( although there are numerous sources of error in the separation of gluten, the valuation of a flour on the basis of its content in moist gluten has not yet been suppressed.” I t is significant that, in 1913, M.Arpin, with his extensive experience, still adheres to the gluten-washing process, and gives no methods for determining protein, nitrogen, or gliadin, or glutenin in a flour. With all its possibilities of error, the extraction of gluten, not merely for its weight percentages, but largely because of the information given by its physical appearance and character, is a test which affords most valuable guidance to both the miller and baker.&I. Arpin’s book will form a valuable addition to the library of the food analyst. WILLIAM JAUO. THE CHEMISTRY OF RUBBER. BY B. D. PORRITT, B.Sc., F.I.C. Pp. 87 + Contents + Bibliography + Index. London : Gurney and Jackson. 1913. Price 1s. 6d. This little work is one of a series of Chemical Monographs edited by Dr.A. C, Cumming, and intended primarily for advanced and honours students. It is divided into six sections, of which those on Constitution and Derivatives (11.) and on Theories of’Vulcanisation (IV.) are by Mr. F. D. Miles, B.Sc., A.R.C.Sc. The other sections are as follows : I. The Properties of Crude Rubber; 111. Methods of Vul- canisation ; V. Waste Rubber and its Utilisation ; VI.Synthetic Caoutchouc. Mr. Porritt has set himself the task of giving a concise and accurate account of the chemistry of rubber within a very brief compass, and he has accomplished this task by adhering closely to the subject matter as indicated by the title. The monograph should be useful for the class of realder for whom it is intended. The work has been done on scholarly and scientific lines, although slips are noticeable here and there, Thus, on page 2 there is a reference (172) to the ANALYST which is not correct ; and on page 3 we read Kickxia where Castilloa was, no doubt, intended.P. SCHIDROWITZ.REVIEWS 547 THE VOLATILE OILS. By E. GILDEMEISTER and FR. HOFFMANN. Second edition by E. Gildemeister, translated by Edward Kremers.Vol. I. With two maps and numerous illustrations. 8vo. Pp. xii + 677. London : Longmans, Green and Co. 1913. Price 20s. net. The work by Gildemeister and Hoffmann may be regarded as a classic in the special field of literature which it represents. On account of its authoritative character as a source of information concerning the large and important group of natural products known as the volatile or essential oils, it may be assumed that it is now quite familiar to all who are interested in the subject.It may, indeed, be considered to have become indispensable as a work of reference, not only for the analyst or consulting chemist, but also for those engaged in the strictly scientific study of the essential oils and their numerous constituents.Since the first appearance of the English version of this work thirteen years have elapsed, and during this period great advances have been niade in the depart- ment of knowledge of which it treats. Many new volatile oils have in the meantime been obtained and described, and the constituents of many others have been more completely determined and characterised, whilst the methods for their examination have been correspondingly improved. I t is therefore not surprising that the present revision of the work has necessitated a very considerable expansion of its contents.The extent of this development is evident from the fact that, although the portion of the first edition which treated of the theoretical principles of steam distillation, as applied to the volatile oils, has been issued as a separate treatise, the material com- prising the principal part of the work could now only be adequately considered by its division into three volumes.I n order to indicate the scope of the volume now under notice, the following brief survey of its contents may be given. I t includes : I. An historical introduction (241 pages) ; 11. a chapter on the production of flower perfumes by extraction, enfleurage, and maceration (23 pages); 111.an enumeration and description of the principal constituents of volatile oils and natural and artificial perfumes (280 pages). These constituents comprise such diverse compounds as the hydrocarbons, aliphatic, aromatic, and alicyclic, together with the sesquiterpenes ; alcohols, aldehydes, ketones, phenols and phenol ethers, acids, esters, lactones, oxides, and compounds containing nitrogen and sulphur.IV. The examination of volatile oils (64 pages). This last section, which is particularly important for the analyst and for all who require to ascertain the purity and quality of essential oils, includes the determination of their physical properties and the chemical methods of examination.I t is accom- panied by very complete tables for computing the percentage of alcohols and the ester value, a second copy of the tables having also been added in such a form as to permit of their separate use in the laboratory. An excellent index is likewise prcvided. It would be difficult to consider in further detail the contents of this very comprehensive work.Its completeness and accuracy render it in all respects a thoroughly trustwortby source of information on the subjects of which it treats, and it therefore merits the highest Commendation. The translation of such a work from548 REVIEWS the original German into English could by no means have been an easy task, and the admirable manner in which this has been aocomplished is also deserving of recognition.F. B. POWER. TABLES ANNUELLES DE CONSTANTES ET DONR~ES NUMERIQUES. Vol. II., Annde 1911. Gauthier, Villars, Paris ; Akademische Verlagsgesellschaft m. b. H., Leipzig ; J. and A. Churchill, London; University of Chicago Press, Chicago. 1913. XI + 759. Cloth. Price 24s. net. The first volume of this very important annual was reviewed in the ANALYST for 1912 (37, 483), and the new volume, giving constants determined in 1911, has recently made its appearance; it is up to the high level of its predecessor.The list of compilers contains the following well-known English names : M. P. Appleby, S. L. Archbutt, A. W. Porter, L. J. Spencer, and N. T. M. Wilsmore; and as their foreign colleagues are of equal rank, one is assured that the work is well looked after. These compilers have been assisted by a large staff of abstractors, the British Empire and Germany being prominent in having furnished the larger number. After introductory notes explaining the use of the tables, one encounters an index of chapters (1 page) and a table of contents (18 pages), so that even without an index information given about some particular property is easily obtained. I t i s interesting to note the extent to which different branches of science engage the attention of chemists, and the influence of fashion, which is certainly not confined to articles of attire. Thus ‘‘ colloids ” and (‘ adsorption ” occupy 30 pages in Volume I. ; in Volume 11. the space has grown to 44 pages, whilst, on the other hand, crystallo- graphy and mineralogy are reduced from 52 to 32 pages. The printing and get-up generally are excellent. The tables should be readily accessible to all chemists, and should be found in every library attached to a, chemical laboratory having any pretensions. J. T. HEWITT.

ISSN:0003-2654    

DOI:10.1039/AN9133800542

出版商:RSC    

年代:1913

数据来源: RSC