摘要:

AUGUST, 1916. Vol. XL., No. 473. THE ANALYST. OBITUARY. THE death, on May 31, of Sir Arthur Church, in his eighty-first year, removes from the Society of Public Analysts one of it8 oldest members. Sir Arthur, then known as Professor, Church, was elected a member of the Society on May 5, 1875, in the first year of its existence. He wag at about that time brought closely into touch with the work of the Society by reason of his being commissioned to write a popular guide to the National Food Collection which had been arranged, under the old Science and Art Department, at the Bethnal Green Museum.It was necessary to do a good deal of analytical work in connection with the compilation of this guide, and much of this was done in consultation with the late Mr. G. W. Wigner, the first Secretary of the Society, and one of the most active among its founders. The little book which was the outcome of Professor Church’s labours was reprinted until as many as 6,000 copies had been disposed of, when in 1889, seventeen years after the appearance of the first edition, it was revised and considerably enlarged by the author, assuming the form in which it is still familiar as a convenient and reliable work of reference for analytical and general information about everyday things.The book is, or was, published for the body then known as the Committee of Council on Education, by Messrs. Chapman and Hall, under the title of ‘‘ Food : a Brief Account of its Sources, Constituents, and Uses.” In the various obitumy notices which have come under the eye of the writer no reference has appeared to this most useful book, containing as it did the results of much original work, a8 well as of the diligent gathering together of that of many other investigators.Church’s early education was at King’s College, after which he went to the Royal College of Chemistry and to Lincoln College, Oxford, where he took his degree in the School of Natural Science; and his subsequent versatility was not a, little remarkable.For sixteen years he was Professor of Chemistry at the Royal Agricul- tural College, Cirencester, succeeding the late Dr. Augustus Voelcker, and preceding the present holder of the chair, Professor Kinch. During this time he became recognised as an authority in agricultural chemistry, though his more practical agricultural colleagues were wont to hint that a somewhat fastidious instinct pre- vented him from entering whole-heartedly into some of the paths of investigation which at that time, as to-day, were of fascinating interest in farm economics.A manure-heap, notwithstanding all the riddles that then, even more than now, beset340 OBITUARY: SIR A. H. CHURCH, K.C.V.O., F.R.S., M.A., D.SC.its past, its present, and its future, never came to exercise a real charm for him; and, notwithstanding his long tenure of office at Cirencester, he never quite came to play a part in practical agriculture comparable to that played by some of his colleagues and contemporaries. I t was, perhaps, more by chance than by choice that he took to lecturing to the sons of farmers; and though when at Cirencester he did, as has been said, good work, including the writing of an excellent “Laboratory Guide for Agricultural Students,” it was probably without more than passing reluc- tance that he changed his field of labour.The chemistry of vegetable physiology, however, continued to interest him long after his retirement from Cirencester.In order to pursue his studies in this direction he settled down in the neighbourhood of Kew Gardens, and he made a number of investigations on questions relating to albinism and coloration in leaves ; while in connection with zoology he discovered, and described in a well-remembered paper, the curious feather-pigment known as turacin, with its 7 per cent. of copper. His ((Food Grains of India,” a valuable illustrated work published in 1886, is still regarded as a standard treatise.The mineral kingdom, however, was said by some of his friends to possess more attraction for him than the sister kingdoms, vegetable and animal. He possessed a wide know- ledge, and a good collection, of gems, of which he wrote much, and he made many oontributions to general mineralogical chemistry; and, had he no other sphere of activity, thie work alone might have sufficed to give his name enduring reputation.I t is in another connection yet, however, that Sir Arthur Church will probably be remembered best-namely, as Professor of Chemistry to the Royal Academy, to which office he was appointed after leaving Cirencester, in 1879, continuing to fill it until four years ago.He was thus naturally brought into contact with numerous problems relating to the chemistry of pigments and painting, and he extended the educational work of his lectures to Academy students to the preparation of a well- known textbook on (‘ The Chemistry of Paints and Painting,” which has become a standard work. His position as Professor to the Academy naturally led to his being consulted by the Board of Works and other public departments on questions of the preservation and restoration of frescoes in public buildings, and thence, by an easy transition, to the arrest of decay in the stonework of public buildings and monu- ments and to cognate questions.As might be expected from the variety of his activities, Sir Arthur Church was a man of wide culture, but he was not superhial-or perhaps it would be more correct to say that, while the surface of his knowledge and interests may have been large, he dug deeply and productively even in the most widely separated patches of surface to which he turned his chief attention.His personality was gentle and of much charm, but he was shy and retiring, and for many years past had not mixed freely with his brother chemists. By those who knew him his friendship was much valued, and the writer of these lines-in common, no doubt, with others of what, to Church, was the younger generation of chemists-has grateful recollection of many kindnesses shown by him in days that now seem remote. BERNARD DYER. * * % i * E +

ISSN:0003-2654    

DOI:10.1039/AN9154000339

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

DETECTION OF P-NAPHTHOL IN LYSOL AND SIMILAR PREPARATIONS 34 1 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. NOTE ON THE DETECTION OF P-NAPHTHOL IN LYSOL AND SIMILAR PREPARATIONS. BY R. BODMER, F.I.C. (Read at the Meeting, June 2, 1915.) EAVING recently been engaged in the analysis of British-made lysol and similar preparations, the question arose as to whether P-naphthol had been used to bring up the Rideal-Walker coefhient, I endeavoured, without success, to effect a separa- tion of P-naphthol from cresol, and, failing this, I tried direct tests.Richmond and Miller (ANALYST, 1907, 32, 151) describe three tests for the detection of P-naphthol in milk. One of these, involving the use of a diazotised benzidine chloride solution, answers quite well.The method I adopted was as follows: One C.C. of the suspected lysol wa,~ dissolved in distilled water and made up to 100 C.C. (Lysol should give a perfectly clear solution with distilled water in all proportions.) Side by side with this a solution of lysol free from P-naphthol was made of the same strength. On adding about 1 C.C. of the benzidine reagent the pure lysol gives an orange-coloured solution, but if as little as 0.2 per cent.of P-naphthol is present, a fine red colour is developed. Care must be taken to compare solutions of bhe same strength, so that an approximate knowledge of the proportion of cresol in each is necessary, If the solution of cresol is too strong, a reddish orange colour is produced. I have tried a diazotised solution of phenylhydrazine, but the difference in colour between the pure lysol solution and that containing P-naphthol is not so rn arked .J. Katsyama and B. Ikada (ANALYST, 1915, 164) describe a test for P-naphthol. When a few drops of strong sulphuric acid are added to a weak solution of /3-naphthol (the solvent used is not stated), and then a few drops of very weak sodium nitrite added, when a purple colour is developed.This test is not a good one, as on adding sulphuric acid to the solution of the distillate from the lysol in dilute soda the cresol and @-naphthol are thrown out and the nitrite fails to react. Another test recommended by Richmond for milk is to extract with Chloroform and heat the chloroform solution with sodium hydroxide. This is quite useless, as the chloroform dissolves the cresol as well as the /3-naphthol, By testing the lysol solution in the way I have indicated, and comparing the depth of tint with that given by s solution of lysol containing a known amount of342 DETECTION OF ,%NAPHTHOL IN LYSOL AND SIMILAR PREPARATIONS &naphthol, an approximate idea is obtained of the proportion of the latter present.I have proved by experiment, making up lysol with 50 per cent. cresol and 50 per cent. soft soap, that the presence of the soap does not interfere with the red colour produced by the benzidine reagent. The benzidine reagent is made up as follows : One grm. benzidine, 4 C.C. strong hydrochloric acid, and 1 grm. sodium nitrite, are made up to 100 C.C. with water and neutralised.The reagent does not keep well. DISCUSSION. Dr. RIDEAL said that any method capable of determining the presence of other bodies than cresols in lysol would be helpful. Is seemed, however, as was often the case with proprietary articles, lysol had so many rivals and substitutes producing similar results that at the present time the name had ceased to have any definite meaning, and might well be discontinued.I t would be far better to describe the disinfectant in terms of its disinfecting properties, as expressed by the Rideal-Walker coefficient or some other bacterial test. Mr. J. L. BAKER said that he should have thought that the presence of P-naphthol was rather an advantage than otherwise. Mr. W. PARTRIDUE said that one of the advantages of lysol, possessed by few other disinfectants, was that it yielded a clear, or nearly clear, solution.Although poisonous, it was useful for laboratory purposes, being, for instance, an efficient cleaning agent for microscope slides. Dr. RIDEAL remarked that he believed that a War Office preparation was required under the name of liquor cresoli saponatus fortis,” having a, coefficient of over 10 by the Rideal-Walker test, which must contain other bodies than cresols.The PRESIDENT said that it seemed to him that it could not be regarded as objectionable to increase the killing power of a disinfectant, and he did not think Mr. Bodmer suggested that it was; but in any case thanks were due to Mr. Bodmer for his description of a new method for the detection and approximate estimation of /%naphthol.Mr. BODMER, in reply, said that extravagant claims were made for some of these preparations, One, which was not sold as lysol and did not give a clear solution, was stated to have a Rideal-Walker coefficient of 26, whereas that of cresylic acid was only about 3. He had not been able to find any very definite statement as to the coefficient of ,@-naphthol, but as far as he could make out it was said to be about 11, and it was difficult to imagine that by the addition of a small proportion of such a substance the coefficient of cresol would be increased to 26.He had not expected the method to be quantitative, but within certain limits the differences in colour with different quantities of ,@-naphthol were marked, and by working carefully one could readily distinguish between 0.2, 0.5, and 1 per cent. It was not possible to separate the ,@-naphthol by fractional distillation, since a certain amount of cresylic acid came over even at the end j but if, after fractional distillation, the last runnings were dissolved in soda and the benzidine reagent added, theSEIICHI UENO : COREAN BEESWAX 343 reaction was sharper and more marked than in the original, enabling small quantities to be more easily detected. So far he had not detected @-naphthol in lysol sob7 as such, but in another preparation-the one referred to above-stated to have a, coefficient of 26.

ISSN:0003-2654    

DOI:10.1039/AN9154000341

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

SEIICHI UENO : COREAN BEESWAX 343 COREAN BEESWAX. BY SEIICHI UENO. COREAN beeswax is secreted by the bee Apis indica, Fab. var. Japonica “Rads” (in Corean, The Corean bee is similar to the Japanese bee (in Japanese, ‘‘ Mitsu-hachi ”). The quantities of beeswax +nd honey produced in Corea during the year 1912 Pd ”). were as follows : Province. Kieng-kei . , . Tsiong- tsieng (Northj (South) Tsienlia (North) ...,, (South) ... Kieng-sang (North) Pieng-iang (South) ... Kong-wen ... Ham-kieng (Southj” ? ? (South) ,, (North) . . . . ? 9 (North) Hoang-hai ... ... ... . I . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... Beeswax (Kin).* 12,710 13,585 17,331 21,070 15,853 34,448 17,587 15,343 29,648 137,468 106,040 29,086 367 Honey (Kin),’ 3,289 2,382 3,280 2,968 2,436 5,211 3,060 3,125 3,131 10,842 12,713 1,823 31 -- Totals ...... ... ... 450,536 54,291 The values given on the following page were obtained with samples of genuine The determination of the acid and saponification values was made by Bohrish Shibasaki has examined samples of Japanese beeswax with the following Aoid Ester Saponifica- Iodine Value Corean beeswax exhibited in the Taisho Exhibition, Tokyo, last year.and Kurscher’s modified process (Pharm. Zentratbt., 1910, Nr, 25/20). results : M*-Pt. Value. Value, tion Value. (Wijs). Maximum ... 0.8207 66.5 8.19 95.14 103.34 14-14? Minimum ... 0.8135 64.9 5.61 80.45 86.35 10.18 Average ... 0-8160 65-9 6.40 83.44 89 *85 12.27 Thbe results show that the characteristics of Corean m d Japanese beeswaxea are similar to each other, and they also resemble the characberistics of Indian * 1 kin= 14 lbs.Sp. Gr.344 SEIICHI UENO : COREAN BEESWAX Kong- beeswaxes secreted by A . Jorea, L.; A. dorsata, L.; and A . indica, Fab. (Lewko- witsch, Chemioal Technology and Analysis of Oils, Fats, and Waxes," fifth edition, vol. ii., p. 914). wen { Sample.0*8200 0.8358 Pieng- \ iang (South) 1 kieng (South) I Sp. Gr. (=QQ), O C 0.8149 0.8090 0.8345 0.8350 0.8149 0.8168 0.8345 Average 1 0.8229 Melting Point, O C 65-8 65.4 66.0 65.6 65-9 65.4 65.1 66.0 65.4 65.8 65.0 65.6 66.0 65.6 Re frac tiv Index determine a t 85' C.. calculate( to 40' C. 1 *4580 1.4577 1.4577 1 4584 1.4580 1.4580 1*4580 1.4584 1.4580 1.4580 1.4580 1.4580 1.4580 1.4580 Butyo- Refrac- torneter determine1 at 85' C., calculated to 40' C.48.0 47.6 47.6 48.6 48.0 48.0 48.0 48.6 48.0 48.0 48.0 48.0 48.0 48.0 I Acid Value 6-09 5.70 5-91 6.01 4-46 6-38 6-28 7.70 5.95 6.23 5 0 1 0 5.17 5-01 5.85 Saponi ficatioi Value, 84.32 83.34 83-64 85.04 83.08 87.72 84.73 86.44 83.75 82.30 83.08 82.55 79.24 84.56 Ester Value 78.23 77.64 77-73 79.03 78.62 81.34 78.45 78.74 77.80 76.07 87.98 77.38 74.23 78.71 Ratio Num- ber. 12.85 13.62 13.15 13-15 17.63 12.74 12.50 10.23 13.08 12.50 17-25 14.96 14.82 13.45 Iodine Value (Wijs). 12 -93 10.33 12.18 12.23 11.36 10.04 12-00 11.69 11.64 10-38 10.31 12-43 10.86 11.41 Thus it will be seen that the Oriental beeswaxes which are secreted by the above three species of bees are very different in character from European and American beeswaxes, which are secreted by the A . rneZZi$ca, L. THE IMPERIAL INDUSTRIAL LABORATORY, THE DEPARTHENT OF STATE FOR AGRICULTUEE AND COMMERCE, TOKYO.

ISSN:0003-2654    

DOI:10.1039/AN9154000343

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

FOOD AND DRUGS ANALYSIS 345 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Estimation of Caffeine and Antipgrin in Admixture. W. P. Emery and S. Palkin. ( J . Ind. and Eng. Chem., 1915, 7, 519-521.)-The method proposed depends on the conversion of the antipyrin into iodo-antipyrin (cj. ANALYST, 1914, 39, 480) ; the latter substance, together with the caffeine, is then extracted with chloroform, the extract evaporated, and the residue weighed. Iodine is now estimated in this residue, and the quantity found is a measure of the antipyrin; the caEeine is obtained by difference.A quantity of about 0-25 grm, of the caffeine-antipyrin mixture is rinsed into a separating funnel with two 5 C.C. portions of alcohol-free chloroform (it is essential that the chloroform be free from alcohol, otherwise iodoform is formed which interferes with the estimation), 10 C.C.of water and 1 grm. of sodium bicarbonate are added, and 15 C.C. of iodine solution are introduced in small quantities at a time, while the mixture is shaken continuously; the presence of decided excess of iodine in the mixture should be apparent at the end of the operation. The excess of iodine is destroyed by the addition of a crystal of sodium thio- sulphate, the mixture then extracted with several successive quantities of chloroform ; the chloroform extracts are evaporated in a weighed flask, the residue is dried for thirty minutes at 105' C., and weighed.This residue, consisting of iodo-antipyrin a d caffeine, is dissolved in 5 C.C.of glacial acetic acid, 10 C.C. of concentrated sulphurous acid are added, the solution is diluted to about 200 c.c., and the iodide precipitated by the addition of silver nitrate. After adding a few drops of nitric acid, the mixture is boiled, and the silver iodide collected, and weighed. The weight of the silver iodide multiplied by 0.8012 gives the quantity of antipyrin. The quantity of caffeine is found by subtracting the product obtained by multiplying the weight of silver iodide by 1.3374 from the weight of the caffeine plus the iodo-antipyrin.When the caffeine and antipyrin are mixed with the usual excipients of tablet and pill com- binations, the material should be extracted with chloroform, the chloroform solution evaporated, and the residue obtained used for the estimation, as described.The method yields from 99.2 to 100-5 per cent. of antipyrin actual present in a mixture. w. P. s. Studies on Chicory. V. Grafe. (Biochem. Zeitsch., 1915, 68, 1-22; through Monthly Bull. of Agric, Intelligence and Plant Diseases, 1915, 6, 584-585.)-The chief food value of chicory is due to inulin, and its use as a drug to a bitter principle which it contains.The rootscontain more inulin and bitter principle when grown in sandy or loamy soils than when grown in humus or peaty soils ; at the same time, this differ- ence may also be influenced by general conditions of growth, climate, and weather. Attempts to isolate the bitter principle from the unroasted roots did not yield a chemically pure product owing to the fact that the substmce decomposes very readily. It was found, however, that the substance is a glucoside, the constituent346 ABSTRACTS OF CHEMICAL PAPERS sugar being laevulose, and the non-sugar component a derivative of catechol (pyro- catechin), probably the aldehyde.According to several authorities, the roasting of chicory results in an increase in the amount of reducing sugar present at tbe expense of the inulin; this is not quite correct, as products similar to dextrin are formed instead, and also products of the decomposition of inulin similar to (‘ assamar,” The empyreumatic oil which is formed during roasting is analogous to the caffeol resulting from the roasting of coffee, but of essentially different composition ; the writer proposes the name of chicoreol.Its chief constituent is acetic acid (63.5 per cent.); it also contains valerianic acid (5.4 per cent,), and acrolein (2.5 per cent.), the remainder being furfuraldehyde and furfuralcohol, Roasted chicory yields from 0.08 to 0.1 per cent. of this oil. w. P. s. Tests for Hashish. W. Beam. (TVelZcome Trop. Res. Lab., 1915; Bull. No. 3, Chem. Section.)-In a former publication (Fourth Rep.Wellcome Trop. Res. Lab., 1911, p. 25) the author described a test for hashish which he then believed was oharacteristic for samples of Cannabis indka, whatever their origin. I t consisted of extracting the materia€ with petroleum ether and evaporating the extract so obtained to dryness. To the residue is added a few drops of approximately & alcoholic potash or soda, when, in the presence of hashish, a rich purple or reddish-purple colour gradually develops, which on dilution with water takes on a bluish shade.Petroleum ether is, on the whole, the best solvent to use, but all the ordinary resin solvents are satisfactory; whilst if the material, as is often the case, is sold dissolved in fat or oil, alcohol is the best solvent to employ. I t has since been observed that the ordinary British Pharmacopoeia extract of Cannabis indica reacts but feebly, if at all, with this test, and samples from Ceylon and some from the Sudan and Southern Uganda also failed to give the coloration.I t is thus evident that the influence of soil, climate, and method of cultivation, etc., have more influence on the chemical com- position of the plant than has been suspected.As the cultivation or importation into Egypt of hashish in any form is prohibited, a test for the varieties that do not react in the above described manner becomes desirable, Such a test has yet to be supplied, but the following presumptive test has found to answer with all hashish and cannabis preparations so far examined from India, Sudan, Egypt, Greece, and Uganda.The petroleum ether extract is made as usual, and is evaporated in a short test-tube. To the residue are added a few C.C. of a reagent made by saturating absolute alcohol with hydrochloric acid gas. I n the presence of cannabis extract the liquid assumes a, bright cherry red colour, which disappears on dilution with alcohol or water. Trials made with a number of plant extracts and over 200 alkaloids, glucosides, etc., failed to give a similar reaction.Certain volatile oils-e.g., origanum and santal-give a similar reaction, but the colour is far less intense for similar amounts of material. H. F. E. H. Estimation of Small Quantities of Heroine. R. Miller. (Amer. J. Pharm., 1915, 87,248-250.)-Small quantities of heroine in admixture with cocaine and lactose may be estimated as follows, the method depending on the coloration obtained when heroine is mixed with sulphuric acid and formaldehyde : The substance is extractedFOOD AND DRUGS ANALYSIS 347 in the usual way with an immiscible solvent, the residue of heroine and cocaine is weighed, and then dissolved in such a quantity of 1 per cent.sulphuric acid that each C.C.of the resulting solution shall contain from i& to One C.C. of this solution is placed in a tube and treated with 3 C.C. of a mixture consisting of 600 C.C. of commercial sulphuric acid, 300 C.C. of water, and 25 C.C. of 40 per cent. formaldehyde solution. After twenty minutes, the coloration produced is compared with those obtained with definite amounts of heroine under similar conditions.The coloration varies from straw-yellow for i+a grain of heroine to deep cherry red for + grain ; a difference of GV grain will produce a very perceptible change in colour when Morphine and certain other substances interfere with the reaction. w. P. s. of a, grain of heroine. grain is used. Notes on the Hydrocyanic Acid Content of Sorghum.J. J. Williamson and R. M. West. (J. Agric. Research, 1915, 4, 179-185.)-For the determination of hydrooyanic acid the colorimetric method of Francis and Connell (ANALYST, 1913, 38, 569) was used, with one modification. I t was found that when the macerated tissue was distilled with sulphuric acid according to Francis and Connell's method the distillate became yellow, and when subsequently treated with ferric chloride a greenish or brownish precipitate was formed which masked the colour of the thio- cyanate.Enzyme hydrolysis was therefore resorted to. Slade (J. Amer. Chenz. SOC., 1903,25,55-59) digested the ground tissue for twelve hours at room temperature, making use of the enzyme which is always found in a plant in conjunction with a cyanogenetic glucoside.I t was found, however, that at 40" to 45' C. complete hydrolysis was obtained in two hours or less, as portions of the same sample gave the following results : HCN in 10 grms. of Time of Digestion. Ground Material. ... 2 hours *.. ... 0.00040 grm. 4 ,, ... ... ... 0.00040 ,, 6 J 9 ... ... ... 0*00025 ,, The authors digested in all cases for two hours, and the hydrocyanic acid was distilled and estimated in the usual way.The following conclusions are drawn : When sorghum is grown on poor, infertile soil, added nitrogen may slightly increase the amount of hydrocyanic acid in the plant. With a fertile soil and abundant nitrogen this effect may not be produced. During the first three or four weeks of the plant's life the hydrocyanic acid is concentrated in the stalks.Then it rapidly decreases and disappears there, but apparently persists in the leaves in decreasing quantities until maturity. Climate and variety may be more important factors than soil-nitrogen in determining the amount of the acid in the plant. Complete hydrolysis of the glucoside is obtained by digesting the macerated tissue for two hours at 40" to 45" C. H.F. E. H. Estimation of the Degree of Homogenisation of Milk. Von Sobbe. Milchw. Zentyalbl., 1914, 43, 503-506 ; through Monthly Bull. of Agric. Intelligence and Plant Diseases, 1915,6,622-623.)-Two hundred end fifty C.C. of the homogenised348 ABSTRACTS OF CHEMICAL PAPERS milk are treated with 2 drops of formaldehyde solution, then placed in a, graduated cylinder and allowed to stand for seventy-two hours at the ordinary temperature.At the same time 250 C.C. of the un-homogenised milk are treated similarly. After seventy-two hours the two samples are each divided into three layers-an uppermost layer of 50 c.c., an intermediate layer of 150 c.c., and a bottom layer of 50 C.C. The fat-content of each of these layers is determined separately. The degree of homo- genisation is the fat-content of the lowest 50 C.C.expressed as a percentage of the fat-content of the original milk. w. P. s. Origin of Methyl Alcohol in Brandies. T. von Fellenberg. (Mitt. Schweiz. Ges.-Amt, 1914, 5, 172; through J. SOC. Chem. Id., 1915, 34, 677.)-Brandies prepared from grape-juice fermented in presence of the marc contain more methyl alcohol than those from juice fermented after removal of the marc.I t is concluded that the pectin and protopectin contained in the marc produce methyl alcohol, under the influence of pectase, during fermentation. I n an investigation of a number of cellulosic drugs (Membranindrogen) methoxy-groups were found only in the cellulosins (ligno- and pecto-membranins) containing polysaccharides and in gum tragacanth ; those drugs which contained no polysacchsrides were free from methoxy-groups.Cause of Acidity of Fresh Milk of Cows, and a Method for the Estima- tion of Acidity. L. L. Van Slyke and A. W. Bosworth. (New York Agric. Exp. Stat., Tech. Bull. No. 37, December, 1914, 4-6; through J. SOC. Chem. I~zd., 1915, 34, 678.)-In the estimation of the acidity of whole milk by titration with alkali in presence of phenolphthalein, the calcium should first be precipitated by treating 100 C.C.of the milk with 2 C.C. of a saturated solution of neutral potassium oxalate; otherwise high results are obtained, because dicalcium phosphate present in the milk and formed during titration is hydrolysed to form calcium hydroxide and phos- phoric acid, and the calcium hydroxide reacts with more dicalcium phosphate to form tricalcium phosphate.If whole milk be titrated direct, about twice as much alkali is required as when the serum obtained by filtering the milk through a porous porcelain filter is titrated. This discrepancy is due, not, as is ordinarily assumed, to the acidity of milk casein, but to retention of dicalcium phosphate by the filter; casein is present in fresh milk as a calcium caseinate neutral to phenolphthalein.Methods of Estimation of Lecithin in Milk. N. A. Brodrick-Pittard. (Biochem. Zeitsch., 1914, 67, 382-390 ; through J. Chem. SOC., 1915, 108, ii., 293-294.) -Burow’s method (J. Chem. SOC., 1901, 80, ii., 30) of determining lecithin in milk cocsists in dropping the sample into a mixture of equal parts of alcohol and ether acidified with acetic acid, evaporating the filtrate at a low temperature, extracting with dry ether, and determining the phosphorus in the ethereal extract.The author finds that the process is liable to give inaccurate results if the evaporation residue is not dried before extraction ; drying is conveniently effected with anhydrous sodium sulphate.FOOD AND DRUGS ANALYSIS 349 Estimation of Citral in Concentrated Oil of Lemon.E. Biicker. J. prakt. Chem., 1914, [ii.], 90, 393-404 ; through J. Chem. SOC., 1915, 108, ii., 294.)- Concentrated oil of lemon is adulterated principally by addition of citral derived from lemon-grass oil. The citral-content of these oils may be determined with a considerable degree of accuracy by the sodium sulphite method devised by Burgess (ANALYST, 1901,26,260) ; methods in which sodium bisulphite is used give erroneous results.The proportion of citral present is not sufficient to indicate addition of citral, but, taken in conjunction with the hydrocarbon-content of the oil (compare Bocker, ANALYST, 1914, 37, 185), it will show if the proportion added is large. The highest percentage of citral found in oil of lemon free from terpenes and sesquiter- penes is 66, the content varying inversely with the hydrocarbons present.Con- sequently, if an oil of lemon contains either no hydrocarbons and more than 66 per cent. of citral, or 50 per cent. of hydrocarbons and more than 33 per cent, of citral, addition of the latter must have occurred. Since, however, the genuine hydrocarbon-free oil usually contains less than 66 per cent.of citral, the above method gives no more than the minimal value of the adulteration, and may, unless the latter amounts to about 20 per cent., not detect it at all. Palm-Kernel Oil. A. Heiduschka and A. Burger. (Zeitsch. ofentl. Chem., 1914, 20,361-369 ; through J. SOC. Chem. Ind., 1915, 34,668.)-The following average values are given for palm-kernel oil : Saponification value, 253-4; Reichert-Meissl value, 6.6; Polenske value, 9-4 ; iodine value (Hubl), 15-02 ; and molecular weight of non- volatile fatty acids, 228.2.The non-volatile fatty acids consisted of 17.75 per cent, oleic acid, 23.27 per cent. myristic acid, and 58.98 per cent. lauric acid. The total volatile acids, soluble and insoluble (5.20 per cent.), contained capric, caprylic, and caproic acids.No stearic, palmitic, linolic, or linolenic acid was found. Fachini and Dorta's method of separating insoluble fatty acids by treatment of their potassium salts with acetone is useful as a qualitative test, whilst Heintz's method of fractional precipitation with magnesium acetate gives good results when the quantity of fatty acid is not less than 0.05 grm.Constituents of Horse-Fat. J. Klimont, E. Meisl, and K. Mayer. (Monats. Chem., 1914, 35, 1115-1127; through J. SOC. Chem. Ind., 1915, 34, 668.) -Four commercial samples of horse-fat of about the same consistence were purified, and then gave the following valueB: Iodine value, 74-9 to 78.1; acid value, 1.40 to 2-91; saponification value (three samples), 193.1 to 200.4.The sp. gr. was 0.9373 and 0.9461 at 16O C. for two samples and 0.9148 and 0.9184 at 27" C. respectively for the others; the m.-pts. were 20° to 41° C., 22' to 38' C., 29.5' C., and 33' C. respectively; the fatty acids from two samples melted in both cases at 37' to 39' C. In the liquid portion of the fat oleic, linolic, and linolenic acids were detected.The solid portion, when crystallised repeatedly from acetone to which one-twentieth of its volume of chloroform was added, yielded a glyceride of m,-pt. 60' C. and saponification value 197. The fatty acid separated from this glyceride was identified as heptadecylic acid (margaric acid), m.-pt. 5 7 O to 57fP C., neutralisation value 208. The fatty acid from goose- at, described as an350 ABSTRACTS OF CHEMICAL PAPERS eutectic mixture of stearic and palmitic acids, also actually consists of heptadecylic acid.Modification of Wichmann’s Method for the Detection of Small Amounts of Coumarin, particularly in Factitious Vanilla Extracts. J. R. Dean. (J. I n d . and Eng. Chem., 1915, 7, 519.)-The essential part of Wichmann’s method is the conversion of the coumarin (in the residue obtained by evaporating the ether-extract from a vanilla extract to dryness) into salicylic acid by fusion with potassium hydroxide, and identifying the Salicylic acid by the ferric chloride test.The method, however, fails completely when the extract contains saccharin or salicylic acid, but the following modification eliminates the interfering action of these substances : A de-alcoholised porti0.n of the sample is rendered alkaline with ammonia and extracted with 15 C.C.of ether. Vanillin, salicylic acid, and saccharin are insoluble in ether in the presence of ammonia, whilst coumarin is readily dissolved. The ethereal extract is then evaporated, the residue fused with potassium hydroxide at the lowest possible terriperature, and the mass dissolved in water.This solution is acidified with sulphuric acid, extracted with a few C.C. of chloroform, and the chloroform extract shaken with 2 C.C. of water and a few drops of ferric chloride solution. A violet coloration indicates the presence of coumarin. Attention is drawn to the fact that coumarin would interfere with Durand’s method for the estimation of saccharin (ANALYST, 1914, 39, 86).In using this method, the coumarin should be removed by rendering the substance alkaline and extracting with ether before proceeding with the estimation of the saccharin. w. P. s. Acidity and Ash of Vanilla Extract. A. L. Winton, A. R. Albright, and E. H. Berry. (J. Ind. and Eng. Chem., 1915, 7, 516-519.)-The following ranges in acidity and in ash were found in seventy-seven United States Pharmacopceia extracts prepared from different varieties (Mexican, Bourbon, Seychelles, Mada- gascar, Comores, South American, and Java), grades, and lengths of vanilla beans (all the results are calculated to 100 C.C.of the extract) : Total acidity, 30 to 52 C.C. & alkali solution ; acidity other than vanillin, 14 to 42 C.C. & alkali solution; total ash, 0.220 to 0.432 grm. ; soluble ash, 0.179 to 0-357 grm.; alkalinity of total ash, 30 to 54 C.C. & acid solution ; alkalinity of soluble ash, 22 to 40 C.C. & acid solution, The acidity of vanillin may be determined by direct titration, using phenolphthalein as indicator. Commercial vanillin seems to yield a slightly lower result than that required by theory, 1 grm. requiring 63 C.C. of & alkali solution instead of 65-8 C.C. Whilst the colour present in 10 C.C. of genuine vanilla extract does not interfere with the titration after dilution to 200 c.c., the caramel in imitation extracts may be present in such quantity as to render the end-point indistinct. In the latter case the vanillin may be approximately estimated by titration of the ether solution of vanillin and coumarin obtained by shaking out the lead filtrate, as in the Hess and Prescott method (ANALYST, 1899, 24, 162). The vanillin acidity of a vanilla extract is found by multiplying the vanillin percentage by 65.8, thus obtaining the C.C. of & alkali solution corresponding with the vanillin in 100 C.C. of the extract. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9154000345

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 351 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Comparison of the Microscopical Method and the Plate Method of Counting Bacteria in Milk. J. D. Brew. (New York Agric. Exper. Stat., Bull. NO. 373, 1914, 1-38 ; through Monthly Bull. of Agric. Intelligence and Plant Diseases, 1915, 6, 624.) The number of bacteria was determined in 450 samples of milk by the usual plating method and also by counting the bacteria directly in microscopical preparations of the milk.I t was found that the microscope method almost invari- ably yielded higher figures than the plating method. The relative differences were veryirregular, but were generally greater when the bacteria were few in number. In samples of milk showing plate counts of less than 10,000 per C.C. of milk the count with the microscope showed approximately forty-four times as many indi- vidual bacteria, whilst those samples which gave a plate count of above 1,000,000 per C.C.only showed five or less times as many individual bacteria under the micro- scope. A large number of the bacteria counted under the microscope existed in clumps, and from the results obtained it would appear that each clump only gave rise to one colony.Beyond this, there was evidence that not all the bacteria were able to develop on the nutrient agar medium, and that this inability to develop tended to decrease and disappear as the number of organisms in the milk approached 1,000,000 per C.C. The microscope method, besides being more accurate when the number of organisms is low, has the further advantage of being rapid and relatively simple.w. P. s. Culture Media employed for the Bacteriological Examination of Water. I. : The Schardinger-Dunham Medium for Testing for the Presence of Hydrogen Sulphide forming Bacteria. E. M. Chamot and H. W. Redfield. (J. Amer. Chem. Soc., 1915, 37, 1606-1630.)-Three factors in the Schardinger medium were investigated-(1) Concentration of peptone, (2) that of the inorganic salt, and (3) the nature of the reaction of the medium.Irrespective of the inorganic salts present, and of the acidity of the medium, a concentration of between 3 and 4 per cent. peptone in the final inoculated and incubated medium appears to be best for the most rapid and energetic production of hydrogen sulphide. The addition of beef-broth to simple peptone media slightly increases its sensitiveness, but not in proportion to the increased trouble and labour involved ; it is therefore recommended that it be not included.If sodium chloride is used, the quantity must not be over 1.5 per cent. Cultures to which this salt was added showed an increased hydrogen sulphide production. In 3 per cent.peptone media the presence of from 0.5 to 1 per cent. of potassium chloride had a decidedly beneficial influence, and led to quicker and more uniform results than any other of the inorganic salts tried. Positive results of hydrogen sulphide formation by means of lead acetate paper may be obtained in eighteen hours. No hydrogen sulphide formation is obtainable in as long a period as seventy-two hours from natural waters which are truly ‘( clean,” while much is formed in from twelve to twenty-four hours with contaminated waters.The faeces of domestic animals contain bacteria which are capable of producing hydrogen352 ABSTRACTS OF CHEMICAL PAPERS sulphide from a simple peptone medium in as large amounts as in the case of the bacteria from human fmxs.The large amounts of hydrogen sulphide rapidly pro- duced by organisms of sewage appears to be not due primarily to members of the B. coli group. This group of' hydrogen sulphide producing bacteria do not actively ferment carbohydrates. Hence their presence is a supplementary test for gas- producers, and is of especial value in polluted waters in which the B. coli group is absent.Some evidence has been obtained which apparently indicates that hydrogen sulphide is more rapidly produced in waters containing a mixed bacterial flora than by the isolated pure cultures alone. H. F. E. H. Chemical Detection of Blood. D. Ganassini. (Boll. Chirn. Farm., 1914, 53, 777-781; through J. Chem. Soc., 1915, 108, ii., 295.)-The author has investi- gated Baecchi's test for blood (Arch.Int. Zdd. Ldgale, 1913, 4, 163), which is carried out as follows : Two C.C. of an aqueous alizarin-S-blue solution diluted to a mahogany yellow colour are mixed with about one-half the volume of 3 per cent. hydrogen peroxide solution. A little of the liquid to be tested is then poured slowly down the wall of the test-tube. If blood is present, gentle shaking rapidly renders the liquid intensely blue, the blue colour slowly fading and giving place to a red colour, which is moderately stable.This reaction is stated to give a positive result with 1 part of blood in 20,000, and to answer well with blood which has undergone alteration and become insoluble in water, the blood being then first dissolved in alcohol acidified with hydroohloric acid. Improved Hamin Test for Blood, with Notes on Some Recently Proposed Methods.W. Beam and G. A. Freak. (Bioclzem. J., 1915, 9, 161-170.)-The method described is a modification of that employed by Teichmann for the produc- tion of hemin crystals, and depends mainly on the precautions observed for insuring slow evaporation and crystallisation. A small quantity of the suspected material is placed at the bottom of a flat arsenic sublimation tube about 6 by 3 mm.and 35 mm. long. A few drops of acetic acid containing from 0.01 to 0.1 per cent. sodium chloride are added, and a, very fine cotton-thread adjusted so that its upper end is near the top of the tube and the lower end reaches to the bottom of the liquid. The thread should be everywhere in contact with the tube, to which it adheres readily by being moistened with the liquid.The adjustment is readily made by means of a glass rod, one end of which is drawn out for the purpose. The tube is now placed in a rack, and allowed to remain until crystallisation has taken place. Before placing the thread in position, the solution of the blood may be aided, if desired, by cautiously heating the tube over a small flame, loss of the liquid by violent ebullition being prevented by holding the finger tightly over the mouth of the tube.The clear liquid, filtered by its passage through and along the thread! is slowly drawn up by capillary attraction to the mouth of the tube. Under these conditions evaporation takes place so slowly that, even when the temperature of the atmosphere is above 38' C., it is complete (if the tube is held in an upright position) only after twelve to twenty-four hours or more.The rate ofBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 353 evaporation is readily controlled, within wide limits, by altering the dimensions of the tube and the angle at which it is supported. The crystals usually begin to appear on or near the upper half of the thread, and of sufficient size to be distin- guished with a magnification of 75 diameters, in about half an hour; and they ultimately become so large that, in place of requiring a magnification of 250 to 300 diameters, as usually recommended, they may readily be seen with one of 25 diameters, or even, in many cases, with a good hand-lens. The large size of the crystals is due in great part to the slow evaporation of the liquid ; but it is also a result of the removal, by the thread, of the interfering action of the blood-albumin on crystallisation.Examination of the thread at the end of the experiment shows that the soluble, non-crystallisable constituents of the blood are carried to its upper end, and that the maximum growth of haemin crystals is found lower down.If the solution is sufficiently weak, the first crystals form at the point of greatest concentra- tion-the upper end of the thread; but as the albuminous matter accumulates these cease to grow, and the largest and most numerous crystals are found later about midway down the tube, The following precautions should be observed : The tube should be thoroughly clean and dry, and the thread clean and as fine as can be obtained. The solution of the blood in acetic acid should be of such a degree of dilution that the liquid is faintly pink.If the method is to be applied experimentally to fresh blood, the latter must be completely dried before the addition of the acid, and care should be taken to work with very dilute solutions. Recent methods dealing with the hemin test by W.F. Whitney (Boston Medical and Surgical J., 1912) and C. T. Symons (Biochm. J., 1913, 7, 596) are criticised, and the general conclusions drawn are as follows : Of the reagents which have been recommended for use in Teichmann’s test for blood, acetic acid is the only one on which entire reliance may be placed if the method by evaporation is employed.Acetic acid, without salt of any kind, suffices for the test with blood-stains, fresh or old, provided the stains have not been extracted with water. As a precautionary measure it is advisable to use the reagent containing a minute proportion-about 0.01 per cent.-of sodium chloride. No advantage results from the substitution of other salts for sodium chloride in the acetic acid reagent.Iodides may not be used to substitute chlorides or bromides in the above. This does not apply to the reagent made with lactic acid. Where positive results have been obtained from the use of an acetic acid reagent containing iodide, the effect is apparently due to the chloride naturally present in the blood or as impurity in the reagents. The difficulties experienced with Teichmann’s test when applied to stains, both fresh and old, are due chiefly to the too rapid evaporation of the solvent, end to a less extent to interference of the albuminous matter of the blood with the crystal- lisation.Evaporation should be extremely slow, and when carried out in the manner detailed, which also eliminates the harmful effect of albumin, crystals are obtained with the greatest certainty and of remarkably large size, even though only a minute amount of blood be present.The test as described was found to be equally applicable to old blood-stains (twelve years), stains partially removed by soap and water, or heated to l l O o C., or354 ABSTRACTS OF CHEMICAL PAPERS mixed with earth, or to old stains on rusty iron which had been exposed to strong sunlight and atmospheric conditions for several days.H. F. E. H. Estimation of the Oxygen Demand by the Sodium Nitrate Method in Stoekyards, Tannery, and Corn Products Wastes. A. Lederer. ( J . Ind. and Eng. Chm., 1915, 7, 514-516.)--The method depends on the denitrification of sodium nitrate by the sewage bacteria; the amount of nitric oxygen absorbed during incubation is the same as in the usual method of incubating the sewage with the addition of water containing dissolved oxygen.Quantities of the sewage are treated with successively increasing amounts of nitrate, and, during the incubation period (ten days), the sediment, odour, and gas formation are observed. If the sediment becomes septic ” (ie.? black in colour), the bottle with the next higher nitrate content is selected for the estimation of the residual nitrate-nitrite oxygen.A large excess of added nitrate leads to an increased oxygen consumption, but the excess consumption is insignificant when compared with that obtained by the water- dilution method. The author discusses the application of the nitrate method to works effluent8 such as are met with in the district of Chicago. The effluent from packing-houses is usually mixed with domestic sewage, and the estimation of its oxygen requirement presents no difficulty; sulphurous acid is often present in the effluent from factories where corn-starch and glucose are made, but the injurious effect of this acid and the acidity produced by the fermentation of the carbohydrates may be eliminated by the addition of sodium bicarbonate. Effluents containing alkali hydroxides should be neutralised with hydrochloric acid before the estimation is commenced ; the same applies to lime effluents from tanneries. w, P. s.

ISSN:0003-2654    

DOI:10.1039/AN9154000351

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

354 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Estimation of Methyl Alcohol in Presence of Ethyl Alcohol. W. A. R. Wilks. (Sudan Government, Wellcome Tropical Research Laboratories, Chemical Section, Bull. No. 1, 1914, pp. &)--An improvement in the method of Thorpe and Holmes (J. Chem. Soc., 1904,85,1) is described. The author finds that the correction, necessitated by the fact that the formation of carbon dioxide from pure ethyl alcohol cannot be wholly inhibited, is not EL constant, as the experiments of Thorpe and Holmes led them to believe, but depends on the exact experimental conditions.Thorpe and Holmes gave this correction as 0.01 grm. carbon dioxide per grm. of ethyl alcohol present, neglect of the correction leading to the apparent discovery of 0.7 per cent.of methyl alcohol in pure ethyl alcohol. M7ithout departing from Thorpo and Holmes’ experimental conditions, so far as these authors thought it necessary to define them, pure ethyl alcohol may be made to give rise to 2.4 times as much carbon dioxide as is stated above, with the result that the application of the method of Thorpe and Holmes, including their supposed constant ” correction, may lead to the apparent discovery of 1 per cent.of methyl alcohol where none is, in fact, present. Such results as these are obtained when the materials are rapidly mixed at the ordinary temperature, so that the heat of reaction gives rise to a considerable rise of t emperst ure.ORGANIC ANALYSIS 355 The author has tried to reduce as far as practicable the correction due to the fact that some ethyl alcohol is always oxidised to carbon dioxide when treated with dichromate and sulphuric acid, Low temperatures, low acid concentration, and the substitution of a weaker acid for sulphuric acid, all tend to reduce the magnitude of the correction.The order in which the materials are mixed is also not without influence. The method finally recommended is a compromise, some alternative methods, which kept the correction somewhat lowor, requiring too much time for the complete oxidation of methyl alcohol, or introducing other sources of error, or being inconvenient in their application.The procedure recommended is as follows : Thirty grms. of potassium dichromate are dissolved in 150 C.C. of water in the distillingflask, and the solution cooled in a mixture of ice and salt.To the cooled mixture, containing much crystallised dichromate, 50 C.C. of the suitably diluted spirit to be examined (cf. Thorpe and Holmes, Zoc. cit.) are added, and finally, in small quantities at a time, a mixture of 20 C.C. sulphuric acid and 20 C.C. water, previously cooled in ice and salt. The flask, connected of course to the train of drying and absorption apparatus, is allowed to stand until next day, the freezing mixture not being renewed.Finally the mixture is heated to the boiling-point, and the carbon dioxide swept out of the apparatus and into the soda-lime tubes by means of a current of air (cf. Thorpe aud Holmes, Zoc. cit.). Under the above conditions the subtractive correction for each grm.of ethyl alcohol present is 0*0040 grm. carbon dioxide. The test numbers are excellent. G. C . J. Detection of Methyl Alcohol in Ethyl Alcohol. V. Pazienti, (Annuli Chim. Applic., 1915, 3, 279-281.)-Five C.C. of the alcohol are diluted to 50 C.C. with water, and oxidised by means of 3 grms. of sodium persulphate and 10 C.C. of 20 per cent. sulphuric acid. The flask is connected with a condenser, the liquid dis- tilled, the distillate collected in fractions of about 2 c .~ . , and the fractions tested for formaldehyde with Schryver’s reagent. To 10 C.C. of distillate containing formalde- hyde are added 2 C.C. of a 1 per cent. recently filtered solution of phenylhydrazine hydrochloride, 1 C.C. of freshly prepared 5 per cent. potassium ferricyanide solution, and 5 C.C.of strong hydrochloric acid. h roae coloration is obtained in the presence of 1 : 1,000 of methyl alcohol. By treating the unfractionated distillate with the reagent 4 per cent. of methyl alcohol can be detected. When the colour reaction is very faint owing to the presence of excess of formaldehyde, the test should be repeated after dilution of the distillate.C . A. M. Method for the Titration of Small Amounts of Halides. F. C. MeLean and D. D. Van Slyke. ( J . Amer. Chem. Soc., 1915, 37, 1128-1134.)-For the titration of small quantities of halides Volhard’s method is not entirely satisfactory, requiring one drop of Tc solution to determine the end-point, The authors describe a modified method for titrating back the excess of silver, in which the far more delicate reaction between iodine and starch is employed as indicator, using & or i& potassium iodide standardised against the silver solution.The halide is precipitated in presence of a known amount of free nitric acid (preferably about 1 grm. of HN0,- 1 C.C. of the acid of 1-42 sp. gr.). In the case of chlorides and bromides, it356 ABSTRACTS. OF CHEMICAL l’APEl18 is necessary to remove the precipitated silver halide by filtration to avoid its subse- quent reaction with the iodine.Coagulation of the colloidal precipitate is most effec- tively brought about by shaking the liquid with one or two drops of caprylic alcohol, and a perfectly clear filtrate obtained. To the filtrate is added a rnixed reagent con- taining sodium’ nitrite to liberate iodine, starch, and a sodium salt of a weak acid equivalent to the quantity of free nitric acid known to be present.The reagent is composed of trisodium citrate (Na,C,H,O, + 54H,O), 446 grms. ; sodium nitrite, 19.0 grms. ; soluble starch, 2-5 grms., with water to 1 litre. Of this, 4 C.C. are added to the clear filtrate, immediately before titration, for each 1 grm.of free nitric acid present, the total volume of the liquid being preferably not more than 50 C.C. Under them conditions, on titration of the excem of silver nitrate with zG potassium iodide the end-point is indicated with perfect sharpness, one drop producing a distinct coloration owing to the liberation of iodine and its reaction with the starch. The titrations may be made either with the entire filtrate and washings of the precipitate, or with an aliquot portion of the filtrate passed through a dry filter, discarding the first portion.Results of analyses quoted show a maximum error of 3 per ccnt. in the case of small amounts (0.7 mgrm. of C1 and 2-6 mgrms. of Br) down to 0.1 per cent. in the case of substantial amounts (70 mgrms. of C1 and 33 mgrms.of Br). J. F. B. Optical Activity of Mineral Oils. C. Engler and W. Steinkopf. (Ber., 1914, 47, 3358-3362 ; through J. Chcm. Soc., 1915, 108, i., 205-206.)-Sporadic optical activity in mineral oils can be attributed to contact with optically active animal or vegetable matter, but universal activity is a strong argument in favour of an organic origin. In examining oils for optical activity they should be separated itno as large a number of fractions as possible, and these frequently require to be redistilled ; otherwise optically active constituents disseminated through the mass of the oil may escape detection, particularly if both dextro- and laevo-rotatory con- stituents are present.Mineral oils readily lose their activity, wholly or in part, when exposed to a high temperature ; distillation should be effected, therefore, under the smallest possible pressure and from small vessels, superheating being carefully avoided.The authors have found some portions with distinct optical activity in every mineral oil which has been investigated. Use of Nitric Acid as a Solvent for Compounded and Vulcanised Rubbers. H. W. Jones.(Rubber Industry, London, 1914, 189-190 ; through J. SOC. Chenz. Tnd., 1915, 34, 671.)--The author suggests the use of nitric acid of sp. gr. 1.42 as a means of separating carbon black from rubber and of obtaining an indication of the presence of (‘ hydrocarbons.” Estimation of Bitumen in Rubber Mixings. B. D. Porritt and E. Ander- son. (Rubber Indzislry, London, 1914, 181-188 ; through J.SOC. Chcm. Ind., 1915, 34, 672.)-Neither pyridine nor carbon disulphide gives sufikiently trustworthy results when used as solvent for the estimation of bitumen in rubber mixings.ORGANIC ANALYSIS 357 Attempts were made to effect a separation of the bitumen based upon the observa- tion that it is apparently unaffected by heating with nitric acid (sp. gr. 1.355 at 19-1O C.) for fifteen minutes at 100" C.A portion of the bitumen, however, is rendered insoluble in solvents by the action of the acid, and tho method fails, partly, at least, for this reason. Method of Estimating Small Amounts of Carbon Dioxide in Rubber Goods in Presence of Sulphides. (Iiubber Industry, London, 1914, 191-192 : through J. SOC. Chem. Ind., 1915, 34, 672.)-The separated insoluble portion of the rubber sample is heated in a flask with 10 C.C.of hydrochloric acid and 10 C.C. of water. A current of air, free from carbon dioxide, is aspirated through the flask, and the carbon dioxide is collected in two flasks, the first contain- ing 30 C.C. and the second 15 C.C. of the following reagent: barium chloride, 30 grms. in 180 C.C. of water ; ammonia (sp.gr. OoS80) 36 C.C. ; water '( sufficient to measure 300 c.c." The precipitated barium carbonate is rapidly collected, dissolved in hydroohloric acid, and converted info barium sulphate. H. W. Jones. I n this reagent sulphides are held in solution. A Simple Method f o r the Estimation of Mineral Natter in Vuleanised Rubbers. H. W. Jones. (-Rubber Idustry, London, 1914, 199-201 ; through J.SOC. Chem. Ind., 1915,34, 672.)-Two grms. of the sample are heated with 40-50 C.C. of nitrobenzene in a 200-300 C.C. flat-bottom flask, connected to a reflux air-con- denser. When solution of the rubber is complete, the flask is allowed to 0001, the contents diluted with acetone, stirred with a glass rod, and allowed to stand. The mineral matter is deposited rapidly and is separated by decantation, transferred to a weighed filter-paper, and washed well with acetone.I n some cases it is advanta- geous to wash further with alcohol and chloroEorm, then to moisten the filter with water so as to obtain a moist and uncaked residue for further examination. Little or no carbon dioxide is eliminated from calcium or magnesium carbonate by boiling for one hour in nitrobenzene. Estimation of the Mineral Matter in Rubber Mixings. B. D. Porritt and R. Wheatley. (Rubber Idastry, London, 1914, 193-199; through J. SOC. Chem. Ind., 1915,34, 672.)-Ozone was passed over dry, powdered, vulcanised rubber in a flask, which was shaken repeatedly in order to expose a fresh surface; the sample was then extracted with acetone, and the ash estimated in the extracted residue. I t was not found possible to render the whole of the organic matter soluble, and in many instances the mineral matter was chemically altered.

ISSN:0003-2654    

DOI:10.1039/AN9154000354

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

ORGANIC ANALYSIS 357 INORGANIC ANALYSIS. Precipitant for Ammonia. (Substitute for Nessler’s Reagent.) S. S. Graves. (J. Amer. Chem. Soc., 1915, 37, 1171-1181.)-The alkaline solution of the double salt of mercuric and sodium chloride8 gives a white precipitate with ammonia, analogous to the coloured compound formed with Nessler’s reagent, but which is358 ABYTKACTS OF CHEMICAL PAPERS considerably more stable.For the estimation of minute quantities of ammonia the degree of turbidity produced is determined by means of tho nephelometer, for which purposg agglutination of the precipitate must be prevented for a suficient length of time by the presence of a protective colloid--e.g., soluble starch. For the prepara- tion of the reagent, water free from ammonia, obtained by distilling tap-water acidified with sulphuric acid, is employed.To 80 grms. of sodium chloride are added 130 C.C. of water and 100 C.C. of a cold saturated solution of mercuric chloride. When the salt is practically all dissolved, 70 C.C. of a saturated solution of lithium carbonate are added slowly while shaking, so that no mercuric oxide forms on the sides of the flask.The solution is usually cloudy, and should be filtered clear after shaking with a little talc powder. I t may be used at once, and is permanent in stoppered bottles. The starch solution should be freshly prepared eaoh day by boiling 1 grm. of soluble starch with water and diluting to 100 C.C. The standard solution of ammonium sulphate is prepared by mixing 10 c,c. of a solution contain- ing 100 mgrms. of the pure salt per litre with 10 C.C.of a solution of potassium sulphate (75 grms. per litre) and making up to 100 C.C. The standard turbidity for the nephelometer is usuallymade up with 10 C.C. of this ammonium sulphate solu- tion, 15 C.C. of a 0.003 per cent. solution of starch and 5 C.C. of the reagent. Details of the nephelometric instrument, calculations and manipulation, have been described by Kober (ANALYST, 1913, 38, 571).Determinations carried out with known quantities of ammonia have shown that the precipitation is complete, and that the method is available for the estimation of ammonia either alone or in presence of organic matter. It is also available for the estimation of nitrogen by the Kjeldahl method without the necessity of distilling over the ammonia.I n the latter case copper sulphate must not be used as catalyst, and some caution is required in neutralising to avoid any large exoess of alkali hydroxide. In all experiments controls should be carried out on the water used as well as on the reagents. J. F. B. Inter-Relationships between the Constituents of Basic Slag. S. H. Collins and A.A. Hall. ( J . SOC. Chnz. I d . , 1915, 34, 526-530.)-The results of analysis of a number of samples of basic slag are subjected to mathematical treat- ment, and although the probable error of the calculated coefficients of correlation is shown to be large, the fact that there is a fairly close correlation between citric solubility and lime content is brought out plainly. That citric solubility and fine- ness would be found to be correlated was to be expected, but that the lime content has more influence on citric solubility than has the fineness, a point established by these results, is more striking, especially as Robertson has shown (ANALYST, 1914,39, 146) that with some other materials than slag the lime content and citric solubility move in opposite directions.I t seems also established beyond doubt that both silica and magnesia tend to diminish the citric solubility. An attempt is also made to correlate some field results (yield of hay) with the constituents of the basic slag used as manure. The various slags were used in such quantity that the dressing of phosphoric anhydride per acre was the same in all experiments. The coefficient of correlation for any single constituent is very smallINORGANIC ANALYSIS 359 -in no case twice as great as the probable error attaching to it, and in many cases its sign is in doubt.On the other hand, when the results are plotted on a system of rectangular co-ordinates some suggestive figures result. The figures are irregular, but indicate very strongly that for the soils on which these experiments were made slag of average quality is best, the curves with crop yields for ordinates and per- centages of lime, iron, or oxide of manganese as abscisst-e, showing maxima at about the mean value for these percentages.The conclusion drawn is that a certain balance of the minor constituents of slags is desirable, and that for the particular soils experimented with, the analyses of which are given, this balance is attained .in the average steel works, slags most closely approximating average composition giving the best results, and slags abnormal in any respect less satisfactory ones. I t is pointed out that this conclusion does not necessarily extend to soils of different character. I t is remarkable that the curve connecting crop yield with citrate solubility also shows a maximum at about the mean value for the latter.G. C. J. Estimation of Boron in Iron. J. M. Lindgren. (J. Amer. Chem. Soc., 1915, 37, 1137-1139.)--For the estimation of small proportions of boron in iron, Gooch’s method, by the distillation of the methyl ester, was found impracticable, but good results were obtained by following the principles of the method described by Wherry (ANALYST, 1909, 34, 34).Two to three grms. of iron are dissolved in a mixture of 10 C.C. each of nitric acid (sp. gr. 1.4), hydrochloric acid (sp. gr. 1.2), aud water, the product is then neutralised with calcium carbonate. Certain precautions are neces- sary to prevent the separation of the precipitate in a colloidal form. The volume of the liquid is approximately 30 C.C.; to this is added, all at once, about double the quantity of dry calcium carbonate necessary for complete neutralisation, and the mass is vigorously agitated until it forms a pasty golid; hot water is then poured in, and the ferric hydroxide should separate as a dark brown, granular Precipitate. The whole is boiled with 250 to 300 C.C.of water under a reflux condenser for at least thirty minutes to insure complete expulsion of carbonic: acid. Before filtering, the liquid is mixed with a considerable quantity of washed asbestos fibre, which has been digested for several hours on a steam-bath with dilute hydrochloric acid. The washed asbestos is added moist to the iron precipitate, using about 50 C.C. of the pulp, and the mixture boiled for a few minutes, then filtered on a Buchner funnel through a double thickness of paper.The solid matter is washed with boiling water, and the filtrate again brought to the boil by closing the flask and exhausting. After the addition of phenolphthalein a pink colour is established with sodium hydroxide, 1 grm. of mannitol is added, and the liquid titrated until the pink colour reappears. The titration should be controlled by a blank experiment with pure iron treated in the same manner.Estiiiiations have shown that the whole of the boron, in mixtures containing from 0.04 to 0.85 per cent., can thus be estimated with satis- factory accuracy. J. F. B. Battery Assay of Copper. W. B. Price and Others. (J. Ind. and E’ng. Chem., 1915, 7, 546-547.)-This is a report of the Sub-Committee on Methods of Analysis of360 ABSTKACTd OF CHEMICAL YAl'EltS Nan-Ferrous Alloys of the American Chemical Society, and embodies methods generally accepted in the United States for standard analysis by both producers and Consumers of copper and copper products.SampZing.-Detailed directions are given, the most important points being that ingots should be drilled right through and slowly enough to prevent oxidation.The material removed by the first twist of the drill is rejected, as it is desired to exclude the superficial layer of oxide from the sample. No lubricant should be used, but the ifigot may need to be cleaned with ether before starting. The drillings are sifted on a @mesh (per lineal inch) sieve to remove material which has been ground between the drill and the hole, are freed from iron by means of a mignet, and preserved in air- tight bottles.WeQhts and Weighings.-Detailed directions are given to insure the elimination of errors not tolerable in an assay where an accuracy of 1 in 10,000 is demanded. Electrodes.-The cathode is a sheet of platinum, 5 x 10 cm., bent to form an open cylinder-that is to say, the edges are not welded. The stem is riveted and soldered with gold to the middle of the sheet.The anode is made from 1 mm. platinum wire, formed into a helix of seven turns, with a diameter of 12-13 mm. and 8 height of 38 mm., the stem being straight and 125 mm. long. Assay of Ebctrolytic and Low Resistance Copper.-The method described is essentially that of Heath (ANALYST, 1911, 36, 172).I t is to be used for all such grades of copper as are included in the specifications of the Anierican Society for Testing Materials as Electrolytic and Low Resistance Lake Copper. Silver is deposited with copper, an arrangement that works well, provided the silver content does not exceed 100 ozs. per ton. The drillings (5 grms.) are dissolved in 42 C.C.of a stock solvent, made by mixing water, sulphuric and nitric acids in the proportiom 25 : 10 : 7 by volume. The beakers used are 100 to 125 mm. high and 55 mm. in diameter at the base, and hold 225 to 300 C.C. When action has nearly ceased, the beakers are placed on a steam-bath so that the contents may attain a temperature of 80" to 90' C., and left there until solution is complete and red fumes have disappeare'd.The cover and sides of the beaker are washed down, and the solution diluted to 150 C.C. and electrolysed overnight with a current of 1 ampere, which will require about 10 volts if the a,ssays are arranged in parallel. After fifteen hours, cover- glasses, beakers, and electrodes are washed down, and the current reduced to 0.6 ampere. At the first sign of gas evolution (the assay should finish if possible without decided gas evolution) the current is reduced to 0-4 ampere, and 1 C.C.of the electrolyte tested with 2 to 3 drops of fresh hydrogen sulphide water. If any discoloration occurs, electrolysis is continued until a further test shows no discolora- tion. Without interrupting the current, the electrolyte is syphoned off, the beakers being simultaneously filled with water.The cathodes are quickly removed, immerrsed once in water, twice in alcohol, twirled to centrifuge off moat of the alcohol, the rest of the latter ignited, and the cathodes cooled and weighed. Heath's rapid method (Zoc. cit.) may be used by those possessed of the necessary apparatus and experience, but rapid methods require considerable experience before satisfactory results can be obtained, and in any case they require more of the analyst's time.Duplicate assays by the slow method above described should not differ by more than 0.015 per cent.INORGANIC ANALYSIS 361 Assay of Low Grade or Casting Copper.-The following methods are recommeuded for the assay of all grades of copper not included in the specifications of the American Society for Testing Materials.I n presence of very small quantities of impurity, the assay is carried out as already described, the copper redissolved in 42 C.C. of the stock solvent diluted with water, and the copper redeposited as described. A method of more general application consists in dissolving the drillings as described, evaporating until all nitric acid is expelled, redissolving in water, adding 3 c.0.of ferric nitrate solution (1 C.C. =0*01 grm. iron), precipitating the iron from the hot solution with ammonia, and filtering and washing the filter. The precipitated hydroxide is twice redissolved in sulphuric acid and reprecipitated, the filtrates being added to the main copper solution, which is concentrated to convenient bulk, made acid with sulphuric acid, and electrolysed after addition of 2 C.C.of nitric acid. A third method is specially suited for the assay of copper containing only traces of antimony or bismuth, but sufficient selenium or tellurium to interfere. The drillings are dissolved as described, and the solution evaporated until fumes appear or the residue is white.The latter is redissolved in 60 C.C. water, the solution heated to boiling and saturated for ten minutes with sulphur dioxide, removing the source of heat when the gas is started. After a few hours, the solution is decanted through a filter and the precipitate washed with hot water. The filtrate is boiled to expel most of the sulphur dioxide, whilst the filter is ignited to volatilise selenium and tellurium, the oxidised residue being dissolved in 2 C.C.of nitric acid and added to the main solution. This is then electrolysed. Copper high in arsenic, but comparatively free from other impurities, may be assayed successfully by the method given for low resistance copper without further modification than the use of 60 C.C. of stock solvent instead of the usual 42 C.C.G. C. J. New Test for Copper. W. G. Lyle, L. J. Curtman, and J. T. W. Marshall. (J. Amer. Chem. SOC., 1915, 37, 1471-1481.)-An aqueous solution of normal amino- caproic acid is an exceedingly sensitive reagent for the detection of copper, a solution containing 0-004 mgrrn. of copper in 1 C.C. giving an unmistakable precipitate within five or ten minutes.The sensitiveness is much less in presence of even traces of mineral acid, such as are liberated when the reagent is added to solutions of the sulphate, etc., of copper, and the figure given above is the results of experiments with 1 C.C. of copper solution, 1 C.C. of 40 per cent. sodium acetate, and 1 C.C. of a saturated solution (about 0.6 per cent.) of the reagent. Mercury and zinc are the only other common metals that yield difficultly soluble arninocaproates, but the necessity of using sodium acetate in amount sufficient to neutralise any mineral acid present introduces difficulties when silver, bismuth, antimony, tin, iron, aluminium, chromium, nickel, or cobalt are present, The greater part of the paper ie occupied with the detailed description of means whereby all these metals can be eliminated without co-precipitation of the trace of copper to be detected.Ammonium salts, glycine, synthetic leucine, casein and citrates inhibit the reaction, but tartrates in relatively large amount do not interfere. G. C. J.362 ABSTItAC’I’S OF CIIEMJCAT, I’APEKS Estimation of Copper in Commercial Copper Sulphate. G. Incze. (Zeitsch.anal. Chcm., 1915, 54, 252-255.)--The copper sulphate solution is treated with an excess of thiosulphate solution containing thiocyanate ; the copper is thus reduced and precipitated as cuprous thiocyanate, and the excess of the added thio- sulphate is then titrated. 8CuSO,+ Na3S,O3 + 5H,O = 4Cu,S04+ Na,S04 + 5H,S04, and The thiosulphate solution used is propared by dissolving 19.878 grms.of the salt and 8 grms. of ammonium thiocyanate in 1 litre of water ; the iodine solution employed for titrating the excess of the thiosulphate contains 1-0178 grms. of iodine and 5 grms. of potassium iodide per litre. One C.C. of the thiosulphate solution should require exactly 10 C.C. of the iodine solution. Ten grms. of the copper sulphate are dissolved and diluted to 500 c.c.; 50 C.C.of this solution are treated with 52 C.C. of the thiosulphate solution, starch solution is added, and the mixture titrated with the iodine solution. The percentage quantity of copper sulphate in the sample is found by subtracting 20 from the number of C.C. of iodine required for the titration and dividing tho remainder by 5. The presence of iron salts in the copper sulphate does not interfere with the estimation.w. P. s. The reactions proceed according to the equations- 4cU,so4+ 8NH4CNS = 8CuCNS+ 4(NH4),S04. Analysis of Hypochlorite Solutions. IBI. L. Griffin and J. Hedallen. (J. SOC. Chem. Ind., 1915, 34, 530-533.)--For the purpose of an investigation of the factors influencing the stability of hypochlorite solutions, the results of which are published in this paper, the authors found it necessary to submitl to a critical examination the most approved methods of determining available chlorine.Bunsen’s original method-delivery of the bloach liquor into an excess of potassium iodide, addition of acetic acid, and titration of the liberated iodine with thiosulphate-was found to be the most exact as well as the quickest.For purposes of works control, Penot’s method--titration of a known volume of the bleach with alkali arsenite, using iodide and starch a8 indicator-and Mohr’s more convenient modification of it-adding excess of arsenite, and titrating the excess with standard iodine-are more economical of iodide, and make use of solutions the titer of which remains constant for long periods, but neither method is exact.Under the conditions obtaining in the authors’ experiments, the results by either method were uniformly 0-6 per cent. low, duplicates agreeing well. For some technical purposes this error would be tolerable ; whilst if greater accuracy is required, the correction to be applied to the results can be readily determined, once for all, in a, given laboratory by comparing a few results with duplicates obtained by Bunsen’s method.I t is probable that the results are much less influenced by small changes in the experimental conditions than has sometimes been alleged, and that the correction is never very different from 0.6 per cent. In particular it has been alleged that the results are dependent on tho time occupied in performing the titra- tion, and-in Mohr’s method-on the excess of arsenious acid employed.The authors, experimenting over a wide range, were unable to get any evideiic~ of such dependence. G. C. J.INORGANIC ANALY8IS 363 Valuation of Commercial Arsenate of Lead. R. H. Robinson and H. V. Tartar. (J. Ind. and Eng. Chem., 1915, 7, 499-502.)-The presence of water- soluble compounds of arsenic in arsenical insecticides is objectionable, as such compounds are injurious to foliage, and the laws of the United States set a limit (0.75 per cent. As,O,) to the amount that may be present in arsenate of lead sold for agricultural purposes.As in most cases where a soluble constituent has to be estimated in admixture with a much larger quantity of insoluble material, and especially in the administration of a penal statute, it was necessary to prescribe a, particular method of analysis.The authors show that the present official method does not extract as much as 70 per cent. of the soluble compounds of arsenic, and describe a method which gives results on the average 50 per cent. higher than those yielded by the official method. I t is also shown that the new method does actually extract soluble compounds, and that the higher results are not due to hydrolysis or other chemical action.The new method consists in macerating the sample (5 grms.) with water, transferring the mixture to a filter, and washing it with nearly 1,000 C.C. of hot water free from carbon dioxide and ammonia. The soluble arsenate is then estimated in an aliquot portion of the filtrate in any convenient manner.G. C. J. Volumetric Estimation of Nickel. G. Zuccari. (Amali Chim. AppZic., 1915, 3, 277-279.)-The solution of the nickel salt is slowly titrated with a solution of sodium nitroprusside (50.771 grms. per litre ; 1 C.C. =0.01 grm. Ni) with constant agitation, until the compound NiFe(CN),(NO) has been completely precipitated.The end of the reaction is indicated by a spotting test of the filtered liquid with sodium sulphide, a slight violet fugitive coloration being obtained when all the nickel has been precipitated. I t is essential that the solution should not contain less than 1 to 1.5 per cent, of nickel, and that no trace of the precipitate should pass through the filter-paper in the spotting test.To insure complete precipitation of nickel, the test should be repeated after the liquid has stood for five minutes. The titra- tion is preferably done in acid solution. The method is applicable to the direct deter- mination of nickel in its common salts, even in the presence of other metallic salts auch as those of ferric iron, zinc, tin, aluminium, lead, manganese, etc. Nickel nitroprusside is very soluble in ammonia, forming a yellowis h-brown solution.It gives a, lemon yellow compound with potassium hydroxide, and is soluble in potas- sium cyanide solution. The corresponding cobalt salt, CoFe(CN),(NO), is rose- coloured and insoluble in acids. I t is insoluble in ammonia, but combines with it to form a brown compound. Ammonia can therefore be used to separate it from the nickel salt.The volumetric method does not give good results with cobalt, owing to the solubility of the precipitate being too great. C. A. M. Determination of Nitric Nitrogen in Soils. E. R. Allen. (J. Ind. a d Eng. Chem., 1915, 7 , 521-529.)-This paper is concerned only with the quantitative reduc- tion to ammonia of nitric nitrogen contained in aqueous solutions, which may also contain much organic matter of the type yielded to water by soils.The considera- tion of the extraction of nitrates from soils is deferred, as is consideration of the364 ABSTRACTS OF CHEMICAL PAPERS separation of the ammonia, nitric and organic nitrogen of soils. I n contradiction to Burgess (Univ. of California Publications in Agr. Sci., 1913, 1, No.4), the author confirms the older view that the aluminium reduction process, as applied to potable waters, breaks down utterly in presence of much organic matter of the type above referred to, 40 per cent., and even more, of the nitric nitrogen being unreduced. The method finally recommended depends on reduction by Devarda’s alloy, and is based on a study of two earlier methods, due to Mitscherlich (Landzo.Jahrb., 1909, 38, 279) and Valmari (Helsingfors dissertation, 1912). Both these authors used Devarda alloy, the former in strong, the latter in weak, alkaline solution. Mitscher- h h proved that reduction was complete under his conditions, and his apparatus eliminated errors due to the carrying over of alkaline spray which the rapid evolution of hydrogen tends to bring about.The use of strong alkali (4 to 5 - 2 9 , however, as used by Mitscherlich, makes it almost impossible to separate nitric from organic nitrogen ; hence the investigation of Valmari’s method. In absence of any consider- able quantity of organic matter, Valmari effected reduction in a solution no more alkaline than that resulting from the addition of a little magnesia (about i$m)* Under these conditions, the method yields excellent results, and Valmari’s simple apparatus is adequate, as the evolution of hydrogen is so slow that there is no danger of spray going over.In presence of much organic matter, however, Valmari found it necessary to add sodium hydroxide. He only made his solutions about &, but even this concentration revives the spray difficulty.With the provision of adequate means for dealing with this spray, the author finds this modification of Valmari’s method satisfactory. A higher concentration of alkali than & is unneces- sary, is more likely to bring about decomposition of organic nitrogenous compounds, and requires more Devarda metal to insure complete reduction. On the other hand, reduction is incomplete when the alkalinity is as low as ;a in presence of much organic matter.Reduction is effected in a 500 C.C. Kjeldahl flask, the stearn and ammonia, issuing from this being led up through a spray trap and down to the bottom of a round-bottomed 250-C.C. Jena flask containing 40 C.C. of water, a pinch of magnesia and of magnesium sulphate, and fitted with a double-bored rubber bung.Through the second hole in this bung issues a quartz tube bent twice at right angles, the distal limb dipping into 25 C.C. of standard acid and 60 C.C. of water contained in a 300 C.C. Jena Erlenmeyer flask. The distal end of thequartz tube, as well as that of the glass tube dipping into the scrubbing flask, terminates in a bulb-shaped enlargement, perforated with 1 mm.holes. The purpose of the magnesium sulphate in the scrubbing flask is to decompose any sodium hydroxide brought over as spray, d i d magnesium hydroxide being much less likely to go forward than sodium hydroxide. The scrubber and receiver being charged, 250 C.C. of the soil extract are placed in the Kjeldahl flask with 2 C.C. of 50 per cent. sodium hydroxide and boiled for thirty minutes to expel ammonia, mechanical loss of liquid being prevented by a, small f.unnel in the mouth of the flask.The contents of the flask are made up again to 250 C.C. with cold water and cooled. Devarda alloy (1 grm. of 60 mesh) and a small piece of paraffin are added, connection made with the rest of the apparatus, and distillation continued for forty minutes.No heat is applied to the contents of the The procedure recommended is as follows :INORGANIC ANALYSIS 365 scrubber. attaching to the measurement of the standard solutions. The =curacy of the method is limited only by the unavoidable error G. C. J. Permanganate and Iodimetric Estimation of Iodide in Presence of Chloride and Bromide. 0. L. Barnebey. (J. Amer. Chem. SOC., 1915, 37, 1496- 1507.)-In the original method of Pean de St. Gilles for titrating iodide in presence of chloride and bromide, with permanganate, the results are erroneous because of the liberation of free bromine or chlorine or formation of hypochlorous acid.The presence of manganese sulphate and phosphoric acid in the ferrous solution allows the removal of the excess of permanganate and manganese dioxide without liberation of bromine or chlorine from the halides, as well as insuring a correct permanganate titration of the excess of ferrous salt.Iodide can also be determined in presence of bromide and chloride by addition of potassium iodide to the final solution obtained by the modification of Pean de St. Gilles’s method outlined above, followed by titration of the liberated iodine with thiosulphate.The sample (0.05 to 5 grms. according to its probable content of iodide) ie dissolved in 100 C.C. of recently boiled water, I C.C. of sodium hydroxide is added, the mixture heated to boiling and kept hot and shaken, whilst standard perman- ganate or stronger) is added, 5 to 10 C.C. at a time, until a, permanent red or green colour is imparted to it.The contents of the covered flask are maintained just below boiling-point for five minutes, more permanganate being added and the solution reheated if the colour disappears. The solution is cooled, and to it is added, all at once with agitation, 15 C.C. of manganese solution (200 grms. manganese sul- phate crystals and 350 C.C. phosphoric acid of sp. gr. 1.7 per litre) and suficient standard ferrous sulphate to react with all the manganese dioxide and excess of permanganate and leave an excess of 10 to 15 C.C.As soon as the manganese dioxide has dissolved completely, the solution is diluted to 300 to 400 C.C. and titrated with permanganate. The percentage of iodide in the sample is calculated from the amount of permanganate required to oxidise it to iodate. For the iodimetric titration, a, few drops of ferrous sulphate are added to remove any excess of permanganate, 1 grm.of potassium iodide is added, and the liberated iodine is titrated with standard thiosulphate. The percentage of iodine in the original sample is then calculated from the amount of thiosulphate required to react with the iodine produced by the interaction of this amount of iodine, in the form of iodate, with excess of iodide.If the iodimetric method only is to be followed, naturally the strength of the permanganate and ferrous sulphate need not be known exactly. The two methods have about equal merit, except when applied to extremely small quantities of iodide, when the iodimetric method is preferable. G. C. J. Permanganate Estimation of Iron in the Presence of Fluorides.Analysis of Silicates and Carbonates for their Ferrous Iron Content. 0. I,. Barnebey. (J. Amer. Chem. Soc., 1915, 37,1481-1496.)-Dittrich and Leon- hard (ANALYST, 1912, 37,146) have shown that the uncertain end-point in the titra- tion of solutions obtained by treating silicate rocks with hydrofluoric acid may be366 ABSTRACTS OF CHEMICAL PAPERS overcome by addition to the solution of sulphuric acid, together with large quantities of precipitated silica and potassium sulphate.The author shows that sulphuric acid alone between the concentrations of F and 5N gives very satisfactory results. With less or more acid present, the pink tint of a fully titrated solution is less permanent. Freshly precipitated silica is useful, as is titanium dioxide, whilst acid sulphates act like sulphuric acid ; but the only neutral sulphates found effective were magnesium and ferric sulphates, the latter an inconvenient reagent because of its colour when added in excess, as is necessary.The most convenient reagent for arresting the tendency of the pink colour to disappear when the titration should be complete is boric acid, which has the added advantage that ferrous fluoborate is remarkably stable towards atmospheric oxygen (air bubbled through the solution for an hour does not lower its titer), whereag ferrous fluoride is very unstable.Moreover in presence of boric acid the customary manganese phosphate solutions may be used to counteract the influence of hydrochloric acid if simultaneously present, whereas in absence of boric acid either manganese salts or phosphates tend to make the end- point very uncertain if hydrofluoric acid is present, Notes are given on the solution of silicate rocks in a mixture of sulphuric and hydrofluoric acids under such conditions that ferrous salts are not oxidised, an operation requiring great care. The method is eseentially that of Cooke (Amer.J. Sci., 1867, [a], 44, 347). When decomposition is complete, the solution is diluted some- what with cold, recently boiled, distilled water, and an excess of solid boric acid immediately added. The subsequent titration with permanganate can then be conducted at leisure, after filtration from solid organic matter, if necassary. G. C. J. Estimation of Sulphuric Acid and Potassium, especially in Potash Salts.W. Vaubel. (Zeitsch. ofentl. Chem., 1914,20,426-434 ; 1915,21,1-6; through J. SOC. Chem. Ind., 1915, 34,658.)-The author recommends estimation of the sulphuric acid by the benzidine method and of potassium by the cobaltinitrite method. The acid sulphate solution is diluted till it contains 0.1 to 0-2 per cent. sulphuric acid, and precipitated with an equal volume of a solution of benzidine hydrochloride prepared by dissolving 6.7 grms.of the base in 20 C.C. of hydrochloric acid of sp. gr. 1.12, and diluting to 1 litre. The solution should not contain more than 10 mols. HCl, 15 mols. HN03, 20 mols. CH3C0,H, 5 mols. alkali salts, or 1 to 2 mols. ferric iron per mol. H,SO,; when one or more atoms of sulphur are present per atom of ferric iron, reduction to the ferrous state is not necessary.For the estimation of potassium Zaleski’s method (ANALYST, 1914, 39,47) is recommended, using a reagent prepared by pouring a solution of 30 grms. of cobalt nitrite in 1 litre of water and 250 C.C. of nitric acid of sp. gr. 1.2 into a solution of 300 grms. of sodium nitrite in 1 litre of water, the mixture being agitated, allowed to stand for twenty-four hours, and filtered. Precipitation of Phosphorus as Ammonium Phosphomolybdate in Presence of Sulphurie Acid.K. G. Falk and K. Sugiura. (J. Amer. Chem. Soc., 1915, 37, 1507-1515.)-A critical examination of Neumann’s method for theINORGANIC ANALYSIS 367 estimation of phosphorus in organic matter. Neumann (Zeitsch, Physiol. Chem., 1902, 37, 115 ; 1904, 43, 35) oxidised the material with sulphuric and nitric acids, and estimated the phosphoric acid by a method which was substantially that of Pemberton-namely, precipitation as ammonium phosphomolybdate, and titration of the washed precipitate with sodium hydroxide.Under some conditions Pemberton's method is exact, but it is well known that in presence of many substances (e.g., sulphuric acid) the composition of the molybdate precipitate varies with the concen- tration of these substances and other experimental conditions, so that in such circumstances accurate estimations can only be made by working the method as an empirical one (cf.ANALYST, 1914, 39,100). The present paper emphasises these facts, it being shown that precipitates obtained under Neumann's conditions always retain sulphate after washing until the wash-waters are neutral, that their exact composi- tion is also dependent on the concentration of the other constituents of the medium in which they are formed, and that consequently each analyst must determine the NaOH : P,O, factor corresponding to his own particular set of conditions.G . C. J. Estimation of Phosphorus Hydride. H. Reakleben. (Zeitschz. anal. Chem., 1915, 54, 241-252.) - For the gasometric estimation of phosphorus hydride in mixtures of this gas with hydrogen (such a mixture, for instance, as is obtained by the action of potassium hydroxide on phosphorus), the following solutions may be employed for absorbing the phosphorus hydrido : $ iodine solution, hypochlorite ~olution, hypobromite solution, concentrated potassium iodate solution, silver nitrate solution, mercuric chloride solution, and mercurous salt solutions.Equally accurate results are obtained by the use of chlorine water (this must not contain more than 0.16 per cent. of chlorine, or an explosion is liable to occur), saturated bromine water, acidified bromide-bromate solution, ammoniacal silver solutions, cuprous chloride solution containing hydrochloric acid, and acidified permanganate solution, but it is necessary to treat the residual hydrogen with a suitable reagent to remove volatile substances (chlorine, bromine, ammonia, etc.) introduced from the solutions.A mixture of phosphorus hydride and hydrogen may be stored over saturated sodium chloride for a long time without undergoing change ; this solution should be used in the measuring burette.w. P. s. Detection of Sodium. E. C. Mathers, C. 0. Stewart, H. V. Houseman, and I. E. Lee. (J. Amer. Chem. Soc., 1915, 37, 1515-1517.)-For many purposes the flame test for sodium is too sensitive. Nost other methods are troublesome. The method recommended depends on separation of potassium as perchlorate or fluoborate and detection of sodium by the insolubility of the fluosilicate in alcohol.An advantage of the method is that the previous separation of magnesium, a troublesome operation, is unnecessary. Lithium does not interfere. Pure perohloric acid is preferable to fluoboric acid for separating potassium, but, being more difficult to prepare, the UBB of the latter is recommended.Excess (about 35 grms.) of boric acid is added to 100 C.C. of 48 per cent. hydrofluoric acid in a lead or platinum dish, the mixture being tested with lead nitrate to insure absence of368 ABSTRACTS OF CHEMICAL PAPERS unchanged hydrofluoric acid. When cold, an equal volume of alcohol is added and enough hydrofluosilicic acid (see below) to precipitate any sodium which may have been present as impurity in the boric acid.Large excess of hydrofluosilicic acid must be avoided. Hydrofluosilicic acid is prepared by pouring hydrofluoric acid over excess of sand. At the end of some hours the solution is tested to insure absence of unchanged hydrofluoric acid, and diluted with an equal volume of alcohol. The reagents must be stored in wax, etc., receptacles, but do not noticeably etch test-tubes in the course of analysis.The solution to be tested, having been freed from all metals save magnesium and the alkali metals, is evaporated to dryness and the residue ignited to expel ammonium salts, which would interfere. The residue is dissolved in about ten times its weight of water, the solution mixed with an equal volume of alcohol and an excess of the fluoboric acid solution. The potassium fluoborate is filtered off, and the filtrate treated with the alcoholic solution of hydrofluosilicic acid.One mgrm. of sodium in 5 C.C. of 50 per cent. alcohol can be readily detected. For the detection of small amounts of sodium in presence of much potassium, the filtrate from the potassium fluoborate is evaporated, the residue ignited, taken up in 50 per cent.alcohol, and tested as described. G. C. J. Note by Abstractor.-In separating potassium by means of perehloric acid, said by the authors to be preferable where available, it should be noted that certain specimens of this acid, sold for analytical purposes, are liable to contain sodium (Thin and Cumming, J.Chm. Soc., 1915,107, 361). New Method of Estimating Sodium and Potassium in a Mixture of their Salts. K. Okada. (Mem. Coll. Science, Kyoto Imp. University, 1915, 1, No. 2; through Chem. News, 1915, 111, 300.)-On mixing sodium hydrogen tartrate with a solution of potasaium and sodium salts and keeping the temperature and volume of the liquid constant, the concentration of the tartrates remaining in solution is a function of the percentage of potassium present.Hence, by plotting this function as a curve and estimating the concentration of the tartrates left in solution, the composition of a mixture of sodium and potassium salts may be ascertained with approximate accuracy. In the author's experiments the standard curve was determined by dissolving 1 grm.of the mixed chlorides of known composition and 2.4 grms. of sodium hydrogen tartrate in water, diluting the solution to 50 c.c., and keeping it at 25" C. for five hours. A measured quantity (20 c.c.) of the clear liquid was then evaporated, the residue ignited at red heat, and the alkalis extracted with a measured quantity of standard hydrochloric acid, the excees of which was subsequentIy titrated.The quantity of acid required was placed on the ordinate and! the weight of sodium chloride on the abscissa axis of the curve. By means of this method the double sulphate of sodium and potassium has been found to have the formula, K*Na(SO,),. I t is soluble as a, solid solution in sodium sulphate, but not in potas- sium sulphate. C. A. M.INORGANIC ANALYSIS 369 Analysis of Spelter.W. B. Price and Others. (J. Ind. and Enq. Chem., 1915, 7, 547-548.)-A Report of a Sub-committee on Methods of Analysis of Non- ferrous Alloys of the American Chemical Society. The methods reoommended are those actually in use in the laboratories of the more important producers and consumers of zinc in the United States. Spelters are olassified as A , High Grade; B, Intermediate; C, Brass Special, and D, Prime Western, the last a low grade used chiefly for galvanising.Sampling.-A number of slabs should be sawn in half, and the sawdust used as the sample. Fine drillings may be used. In neither case should a lubricant be used, and the drillings must be freed from iron by magnets. Lend.-For the estimation of lead electrolytically, the sample (8.643 grms.) is covered with wafer in a 400 C.C.beaker, and 30 C.C. of nitric acid are then added gradually. The factor 8.643 differs from the theoretical factor (8.66) slightly, because lead dioxide cannot be dried completely. When action is complete, the solution is boiled to expel nitrous fumes, transferred to a 200 C.C. electrolytic beaker, diluted to 125 c.c., and electrolysed with a current of 5 amperes, Deposition is complete in thirty to forty-five minutes.To insure complete deposition, the covers and beaker are rinsed down with sufficient water to raise the level of the liquid 0.5 inch, and electrolysis continued for fifteen minutes. The newly exposed surface should remain bright. The anode is washed three or four times with distilled water, once with alcohol, and dried at 210° C.for thirty minutes. The number of decigrams of lead dioxide corresponds directly to the percentage of lead. The electrodes are cylinders of 20 mesh (per lineal cm.) platinum gauze. The anodes &re 30 mm. in diameter and 30 mm. high, the cathodes the same height, but only 18 mm. in diameter. Both have stems of stout wire 10 cm.long. In the absence of electrolytic appliances, lead is estimated as follows: The drillings (25, 15, 10, or 5 grms., according to grade) are treated with 300,180, 120, or 60 C.C. (according to weight of drillings) of “lead acid”-that is to say, dilute sulphuric acid saturated with lead sulphate, prepared by mixing 300 C.C. of con- centrated acid with 1,800 C.C. of water, and adding to the hot solution 300 C.C.of water in which 1 grm. of lead acetate has been dissolved. The “lead acid” thus prepared is allowed to settle several days and then filtered. After all but 1 grm. of zinc has dissolved, the solution is filtered, the undissolved residue washed with 6 4 lead acid,” then washed back into the beaker and dissolved in a small quantity of hot dilute (1 : 1) nitric acid. The resulting solution is evaporated with 40 0.0.(( lead acid” until fumes arise. When cool, 35 C.C. of water are added, boiled, the first filtrate containing most of the zinc and a trace of lead is added, and the mixture left over- night. The lead sulphate is filtered on a Gooch crucible, washed with (‘ lead acid,” then with dilute (1 : 1) alcohol, and finally with strong alcohol.The Gooch crucible is placed in a porcelain crucible and ignited for five minutes, The solution is boiled, diluted to 300 c.c., ammonium chloride (10 grms.) is added, and ammonia, in sufficient amount to redissolve the zinc hydroxide, The mixture is boiled and filtered through a 11 cm. I ‘ black ribbon” paper, which is washed with dilute ammonia and hot water. The ferric hydroxide is dissolved in hot, dilute (1 : 4) sulphnric acid, Irom-The zinc (25 grms.) is dissolved in 125 C.C. nitric acid.370 ABSTRACTS OF CHEMICAL PAPERS the solution passed through a Jones's reductor, which is washed with 150 C.C. of dilute sulphuric acid and 100 C.C. of water, the reduced solution being finally titrated with -&& permanganate. Using such dilute permanganate as this, it is essential to run a control with the same amounts of acid and water. Cadmium.-The drillings (25 grms.) are covered with 250 C.C. water and 55 C.C. hydrochloric acid and left overnight. More acid is added, 2 C.C. at a time, with an interval between each addition, so as to dissolve all but about 2 grms. of zinc with a minimum use of acid, about 60 C.C. in all usually sugcing. A piece of the undis- solved zinc is transferred to a filter, the liquid is filtered, and the undissolved matter is washed with water, rejecting filtrate and washings. The undissolved matter is dissolved in nitric acid, and the solution evaporated with 20 C.C. of dilute (1 : 1) sulphuric acid until fumes ariee. The residue is taken up with 100 C.C. of water, the mixture boiled and allowed to stand overnight. The lead sulphate is filtered off and discarded. The filtrate is diluted to 400 c.c., 10 grms. ammonium chloride are added, and the solution saturated with hydrogen sulphide (one hour). I t is sometimes necessary to add a drop or two of ammonia to start the precipitation of cadmium sulphide. The impure cadmium sulphide is filtered off on a Gooch crucible and dissolved in 60 C.C. (more if necessary) of dilute (1 : 5 ) sulphuric acid by boiling for thirty minutes. The solution is filtered from asbestos and lead sulphide, diluted to 300 C.C. and cadmium reprecipitated as sulphide in presence of 5 grms. ammonium chloride. When much cadmium is present, a third precipitation may be necessary. The precipitate is dissolved in hot dilute (1 : 3) hydrochloric acid in a platinum dish, the solution evaporated to fuming with sulphuric acid, diluted, any filter fibres destroyed by addition of nitric acid and heating, which is continued to dryness and finally to 500 to 600" C., or to dull redness, the cadmium being weighed as sulphate. An alternative electrolytic method for cadmium is described. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9154000357

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

370 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. Rapid Organic Combustions. 1. Reimer. (J. Anzer. Chem. SOL, 1915, 37, 1636-1638.)-The use of cerium dioxide as contact substance for rapid organic com- bustions has been suggested by Bekk (ANALYST, 1913, 38, 519) in place of the more expensive platinum of Dennstedt. The following modifications are recommended by the author. Instead of the large quantity of asbestos impregnated with cerium dioxide as employed by Bekk, a layer of cerium dioxide asbestos only 3 cm.long is placed in the centre of a combustion-tube of the usual length; following this is a 20 cm. layer of cupric oxide in wire form, held in place by 8 cupric oxide gauze plug. The cupric oxide furnishes oxygen for the burning substance in case the supply of gaseous oxygen is insufficient, or if the vapour of the substance has been carried too fast over the catalyst and prevents the dust of the cerium oxide from being carried forward in the tube.In the back end of the tube is the usual 10 cm. cupric oxide gauze spiral. This serves to break the stream of oxygen and does away with the necessity for the ‘‘ double oxygen ” apparatus of Dennstedt and the glass tube surrounding the boat used by Dennstedt and Bekk.The combustion boat should be placed not more than 2 cm. from the cerium dioxide asbestos, as explosive mixturesAPPARATUS, ETC. 371 of gaes form if there is any considerable space in which the vapours of the sub- stance and oxygen can mix before they come in contact with the catalyst. The method cannot be used for the simultaneous determination of carbon, hydrogen and halogens as can the Bekk method, where no cupric oxide is used.I t is availablefor the analysis of compounds containing nitrogen if a longer empty space is left s t the forward end of the tube for the boats of lead peroxide and care is taken to keep that end of the tube fairly cool. H. F. E. H. Analytical Suetion-Filter.J. Takamine, jun. (J. Amer. Chem. Soc., 1915, 37, 1519-1520.)-A stout glass jar, shaped somewhat like a lipped beaker, with a ground upper edge and a ground glass cover to fit. In the centre of the cover is a tubulure for the accommodation of a cork, Gooch crucible, etc. A side tube for con- nection to the pump is attached to the side of the jar near the top. Halfway down inside axe three projections which support a removable plate.On this plate a small beaker or basin may be set to catch small quantities of filtrate, where it is desired to oollect them without unnecessary dilution, such as would follow from rinsing them out of an ordinary pump flask. By removing the plate a, larger beaker may be introduced into the apparatus, or the lipped jar itself may be treated as a beaker.G. C. J. Gas-Washing Apparatus with Enclosed Filter. E. R. Weaver and J. D. Edwards. (J. I'd. and Eng. Chem., 1915, 7, 534-535.)-Two of the gas-washing appliances figured enclose a filter, by means of which a precipitate, such as barium carbonate or copper acetylide, may be washed without exposure to air. Little description is necessary, but it is pointed out that the absorption-tube (in Figs.1.and 11. the upper horizontal tube; in Fig. 111. the helical tube) should not be too small, 8 to 10 mm. being a suitable diameter for gas rates up to 500 C.C. a minute. The tip372 ABSTRACTS OF CHEMICAL PAPERS of the inlet-tube should be 1 to 2 mm. in diameter, Fig. I. illustrates an apparatus designed to wash gas with a minimum of liquid, and requiring very little pressure behind the gas.The bulbs along the absorption-tube aid absorption, but do not prevent the apparatus from draining completely, These bulbs are omitted from Fig. II., as they would tend to hold precipitates such as this apparatus is designed to collect on the filter above the drain-cock. This filter is of asbestos supported on a perforated plate, and protected by glass beads or another plate from being loosened by the circulating liquid.Washing liquor is introduced through the tap funnel. Fig. 111. illustrates a modification less liable to breakage, and occupying less space. With gas flowing at the rate of 100 C.C. a minute, bubbles remain in the helix seven seconds. G. C. J. Use of the Interferometer for the Analysis of Solutions.L. H. Adams. (J. Amer. Chem. SOL, 1915, 37, 1181-1194.)-1n the interferometer, two beams of light from a single source passing through two rectangular slits are caused to con- verge on a screen, where they produce a system of interference fringes. The inter- position of a transparent medium in the path of one of the bgams causes a shifting of the central bright band to an extent depending on the thickness and refractive index of the medium.When different media are inserted in the paths of the two beams a measure is obtained of the difference in refractive index of the two media, and a far more delicate measure may be obtained of the concentration of a solution than is possible with the simple refractometer, while the correction necessary for the temperature coefficient becomes practically negligible.With simple precautions the concentration of a solution may be determined with an accuracy of 2 parts per million. The optical construction and manipulation of the Zeiss water interferometer are described and illustrated. The interferometer may be used for the examination of solutions in two ways : (1) As a direct reading instrument ; (2) as a zero instrument.In either case the zero reading of the instrument is first obtained by bringing the fringes to coincidence when water or the same solution is contained in both vessels, and this reading is subtracted from the final reading when the contents of the two chambers are different. When following the first method, a series of solutions of the substance of known concentration is made up, and these are compared in one chamber with a sample of the water used for making the solutions in the other chamber, and a calibration curve of concentrations is plotted, with the aid of which unknown solutions may be analysed.In the second method the solution of unknown concentration is compared directly with two known solutions, one of slightly higher, and the other of slightly lower concentration.This method is free from certain sources of error which appear in the first method, where water is used, owing to changes in optical dispersion which cause an apparent shifting of the com- parison band. The sensitiveness and range of the instrument depend on the length of the water-chamber, which is supplied in four sizes, from 5 to 40 mm.in length. With the 40 mm. chamber one division corresponds to 1.5 to 3.0 parts of solute per million for most aqueous solutions, and there are altogether the equivalent of 3,000 divisions ; the greatest differences of concentration whioh can be directly com- pared, therefore, range between 0.45 and 0.9 per cent. An increase of range can beAPPARATUS, ETC.373 obtained by using a shorter water-chamber, with corresponding loss in sensitiveness, or by calibrating the instrument with a standard solution of the salt in plaoe of water. The interferometer was originally designed for the examination of sea- water; it has also been applied to the examination of colloidal solutions and the standardisation of volumetric solutions.I t may be used for the analysis of mixtures of two solid salts by comparing solutims of equal concentration of the mixture, and of one of the components. J. F. B. Substitute for the Twin - Bulb Trap in Toluene - Mercury Thermo- P. B. Davis, (J. Amer. Chem. Soc., 1915, 37, 1198-1199.)-whilst Regulators. toluene, on account of its high coefficient of expansion, is to be preferred to all other liquids for use in thermo-regulators, with mercury for the electrical contact, the usual form of twin-bulb apparatus of this type suffers from certain defects in use and, once set, is not readily adjusted for higher temperatures.The apparatus illustrated has been designed to overcome these defects. I t is simple to construct, compact, and not easily broken. The arrangement (see Fig.) consists of a bulb, a, attached at the bottom of the tube b to the toluene reservoir, which may be of any desired form, Exactly opposite to b is a corresponding tube, c, which carries the capillary and the sealed-in platinum contact.Inside the bulb a the two small tubes e and j are prolongations of c and b respectively, having a length nearly equal to the diameter of the bulb.These tubes are inclined at an angle of about 30" from the perpendicular. The short side- tube d is used in filling the regulator, and is in exact alignment with f. To prepare the apparatus for use, mercury is poured in through the capillary until the bulb a is from half to three- fourths filled. A tube drawn out to a, small diameter is then inserted through d and f into b, and toluene is introduced until the reservoir is filled, also the space in a above the mercury. The tube d is then sealed, and the regulator set for any desired temperature by adding or withdrawing mercury to adjust the contact level in the czapillary. The instrument may be constructed with a range of 50° C., all adjustments being made through the capillary, which should be of 1-5 to 2 mm. bore, according to the b capacity of the toluene reservoir. All danger of the toluene creeping into the capillary is avoided, since the tubes e and f terminate in the same liquid as is con- tained in them. J. F, B.

ISSN:0003-2654    

DOI:10.1039/AN9154000370

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

374 REVIEWS REVIEWS. TECHNICAL METHODS OF CHEMICAL ANALYSIS. Edited by G. LUNGE, Ph.D. English Vol. III., Parts I. The value of this work to British chemists has necessarily suffered from its having been primarily produced for German readers, and although the British editor and his collaborators have done their work of translation and revision, upon the whole, very well, it would have been much better had the editors collaborated from the start and produced two independent treatises, one in German for the Germans, and the other in English for British chemists.One bas only to compare the articles on “Brewing Materials and Beer” and on “Vinegar,” which have been entirely rewritten, with some of the other articles in the volume, to see the force of this contention.translation edited by C. A. KEANE, D.Sc., Ph.D., F.I.C. and 11. 1914. London : Gurney and Jackson. Price $3 3s. net. The volume is divided into twenty-three sections or monographs. “Mineral Oils,” by D. Holde, translated, etc., by the late J. Lewkowitsch, contains about as much useful matter as could be compressed into the short space of 57 pages. As an instance of the compression necessary, only one page is devoted to liquid fuel for internal combustion engines.The calorific value of petrol is directed to be carried out in a bomb calorimeter, and the reader is referred to Vol. I. for the method; but reference to Vol. I. shows no mention of petrol, though the combustion of a highly volatile liquid in a calorimetric bomb is a delicate opera- tion, in regard to which the analyst consulting this work might have been glad to find detailed information.The table on p. 23, due to Marcusson, is unintelligible without reference to the original paper. The statement that all methods of estimating petroleum substitutes in admixture with oil of turpentine other than Marcusson’s are inaccurate, is too sweeping, as Armstrong’s method is quite good.Burton’s method is highly dangerous, but no warning is given. The very brief reference to Harker and Higgins’ important investigations of flash-point apparatus might with advantage have been expanded. Freedom from moisture is mentioned on p. 43 as one of the chief requirements of transformer oils, but no test of adequate delicacy is described. Forty-six pages only are devoted to t L Lubricants,” by the same authors, of which nearly two are taken up with a description of Holde’s apparatus for determining the expansion of eight samples of oil a t one time, whilst the much more important subject of (6 absolute viscosity ” is dismissed in less than a dozen lines.Nevertheless, there is a great deal of useful information in these brief pages. ‘‘ Oils, Fats and Waxes ” (pp.105-153) and l C Special Methods of Analysis employed in the Oil and Fat Industries” (pp. 154-209) are dealt with by the late J. Lew- kowitsch, and contain in a very much condensed form the principal matter treated by the author in his standard treatise on these subjects. The section on Resins, Balsams, and Gum Resins ” (pp. 210-222), by K. Dieterich, revised by J.Lewkowitsch, comprises in a series of tables the char- acteristic values of the chief of these commercial products, with the methods of determining their values. I n 1 6 Drugs and Galenical Preparations ” (pp. 223-258),REVIEWS 375 by H. Dieterich, translated by F. B. Power, a brief account is given of the principal vegetable drugs and extracts, the methods of analysis described being chiefly those of the author and the German Pharmacopoeia.“ Essential Oils ” (pp. 259-280), by E. Gildemeister, revised by F. B. Power, contains a good description of the physical and chemical methods used in the examination of these oils, with the constants and properties of those of greatest industrial importance. Articles follow on “ Tartaric ” and ‘( Citric Acids,” by Dr.Klapproth, revised by W. A. Davis, in which the methods of analysis of the raw materials and finished products are given (pp. 281-300). “ Organic Preparations ” (pp. 301 -397) are dealt with by J. Messner, of Merck and Co. (C. A. Keane, translator and reviser). The section appears to be well done, with copious references. Pages 398-451 are devoted to “ India Rubber and Rubber Goods,” by Frank and Marcwald, translated by W.A. Caspari, including the principal rubber substitutes and accessories. There is no reference to synthetic rubber, other- wise the subject appears to be well treated in the brief space. “ Vegetable Tanning Materials” (pp. 452-474), by the late Professor C. Councler, revised by H. R. Proctor, contains an account of the latest approved methods for tannin estimation, including the standard methods of the International Association of Leather Trades’ Chemists ; and in the article on ‘‘ Leather” (pp.475-510), by J. Paessler, also revised by H. R. Proctor, a brief but clear description is given of the methods of analysis of the raw materials used in leather manufacture not dealt with in other sections, and of the finished product.The composition, analysis, and methods of testing inks are briefly treated in the article on “Ink,” by C. Schluttig, revised by C. A. Mitchell (pp. 511-538). Part 11. (really Vol. VI. of the entire work) opens with a very complete monograph on ‘‘ Sugar ” (pp. 539-657), by von Lippmann, revised by A. R. Ling, in which methods are given for the analysis and valuation of the raw materials, pro- ducts, and accessories of the beet and cane sugar industries, followed by a useful article on “ Starch and Dextrin ” (pp.658-687), by von Eckenbrecker, also revised by A. R. Ling. In the next section, on ‘‘ Alcohol, Potable Spirits, and Liqueurs’’ (pp. 688-740), by A. Ebertz and G. Schiile, revised by G. W. Monier-Williams, some overlapping occurs, several pages being devoted to methods for the estimation of starch already described in the preceding article, and the methods for the examina- tion of malt and barley being to some extent repeated in the section on “Brewing Materials and Beer.” Such redundancy is, however, preferable to the cross-references sometimes met with in works of this kind, which end in blind alleys.The reviser of this section has done his work well, and produced a most useful article.(‘ Vinegar ” (pp. 741-754), rewritten by G. Cecil Jones, is also a useful, practical article. The following section, on Wine” (pp. 755-805), by K. Windisch, translated by P. Schidrowitz, is almost wholly based on the official regulations in force in Germany, and nearly all the references are t o German literature and German wines. DuprB’s work is not mentioned, and there is not a single table showing the composition of wines and the characteristics of the various descriptions of wine produced in different countries.Brewing Materials and Beer ” (pp. 806-837), rewritten by A. R. Ling and G. Cecil Jones, is brief but thoroughly practical, and is one of the best sections in the volume.“Paper,” by W. Herzberg, revised by Messrs. Cross, Bevan, and Bacon, is376 REVIEWS a suggestive article, somewhat unduly brief (pp. 838-863). Textile Fibres ” (pp. 864-909), by R. Gnehm, revised by J. Hubner, contains very complete directions for the qualitative and quantitative identification of fibres used in the textile industry, with excellent photo-micrographs, The concluding section on Inorganic Colours ” (pp.910-1017), by A. Eibner, revised by H. J. L. Rawlins and A. Rule, contains information on and methods for the analysis of a great variety of pigments. Although the toxicity of paints is a subject apart from their technical analysis, yet, as the poisonous nature of white lead is referred to, one would have expected to find some brief discussion of recent work on the alleged poisonous properties of paint made with white lead.But there is nothing more than a reference in a footnote to the papers by Baly and by Armstrong and Klein read before the Society of Chemical Industry. Under L‘ Permanent White’’ no mention is made of blanc $xe, but the term appears on p. 917 and subsequent pages as synonymous with permanent white, though not in the index.Some authoritative statement as to whether the term is applicable to all forms of precipitated barium sulphate, or only to those produced in a particular way, would be useful. No less than five pages are devoted to the analysis of lithopone, a comparatively simple matter, which might have been disposed of in two had the authors sifted the various methods, good and bad, which they describe, instead of leaving the reader to wade through them all.Under Ochre and Umber the analyst will not find much guidance of a practical nature. Some analyses of genuine samples might have been given, also in pigments of this kind, whose oolour and staining power are of chief importance, the method of estimating these should be described.The German impress of this section is particularly marked in the description of the red oxide of iron pigments, prominence being given to German names rather than English, and the general description conveying a foreign impres- sion to those familiar with the industry in this country. The finest and purest oxide (Indian red), containing from 97 to 98 per cent. of Fe,O,, is made in this country in very large quantities by calcining copperas in special gas-fired furnaces.Salt is not used as a rule, if ever. The lightest shades of pure oxide are known as Turkey reds. Venetian red is never known here as English red or Prussian red. I t always contains gypsum in large quantity, and is recognised as a (‘ reduced red.” A useful feature of the work is the Appendix, in which are reprinted for handy reference all the tables included in the text. This volume completes Drs.Lunge and Keane’s work, the publication of which has extended over six years. There seems no reason why the six substantial volumes of which it consists should have been published as three, each consisting of two parts, as there is no more connection between the parts of each volume than between the different volumes.The general plan of the work is excellent, consisting, as ii does, of a series of monographs each written and revised by experts of repute. As a work of general reference it will be found of value by all analysts. L. ARCHBUTT. TECHNICAL GAS ANALYSIS. By GEORGE LUNGE, Ph.D. 1914. London: Gurney Thirteen years have elapsed since the publication of the second edition of Dr.Lunge’e well-known English translation of Winkler’s ‘‘ Handbook of Technical and Jackson. Price 15s. net.REVIEWS 377 Gas Analysis.” The death of Winkler in 1904, and the quantity of new matter published in the interval which has led to the development of new methods and modifications of the older ones, decided the author: to start de novo and write an entirely new treatise, using Winkler merely as one source of information, apart from his own tesearches.The present thoroughly practical volume is the outcome of this resolution. There can be only one opinion as to its merits and usefulness to every analyst who has to make gas analyses. It will rank as one of the best, if not the best, of textbooks on gas analysis in the English language, containing in a volume of moderate size, clearly printed and well illustrated, all the best methods up to date for sampling, collecting, transporting, and analysis of gases, including burette calibrations, estimation of suspended solids, tar, naphthalene, and other vapours, etc.L. ARCHBUTT. ORIUINAL GRAVITY TABLES, computed to Hutzdredths of a Degree from the Table attached to the Finance Act, 1914.By G. CECIL JONES, F.I.C., and JULIAN L. BAKER, F.I.C. 1915. London : Brewers’ Journal. Price 2s. 6d. net. The new Origins1 Gravity Tables of Sir T. E. Thorpe and Dr. Horace T. Brown, substituted by the Finance Act of 1914 (this Journal, 1915, 191) for the old tables of Graham, Hofmann, and Redwood, authorised by the Finance Act of 1870, are of great importance to all connected with the brewing industry or brewing analysis.The authors have therefore done a great service in issuing these tables in such a convenient and extended form. The tables in the Act are only given to tenths of a degree, and the authors’ interpolations to one-hundredths thus obviate calculations. The tables are clearly printed and arranged, and are mounted on a folding and cloth-bound card, which, when open, presents the whole tables on a card 14 by 11 inches.METALLURGICAL SMOKE. L. T. THORNE. C. H. FULTON. United States Bureau of Mines, Bulletin A discussion of the general aspects of the smoke problem is followed by detailed description and illustration of many of the appliances which have solved it more or less satisfactorily in certain localities.The enormous scale of American metallnr- gical operations has led to some publicity being gained in this country for American methods of precipitating dust and fume, but stress has generally been laid more on the magnitude of the units than on the principles underlying the methods. Thus many references can be found to the dust-precipitating plant at Great Falls, to the fact that it involved the use of 600 tons of wire and the expenditure of nearly a quarter of a million sterling, a capital expenditure that returns considerably over 10 per cent,, besides securing the abatement of an intolerable nuisance.Now, in addition to such statistics, one can for 20 cents get a sufficiently detailed set of drawings of this plant to be really helpful to anyone desirous of applying the principle to somewhat different material and on a different scale.There are also drawings of plant for the electrical precipitation of fume, another principle of more or less general application. By the application of these two principles-that of the dust chamber with or without wire baffles, and that of electrical precipitation-together with the simple principle underlying bag-house practice, serious nuisance from dusb 84.Pp. 94. Price 20 cents.378 REVIEWS and fume is nearly always avoidable, and the precipitating plant can usually be made to pay for itself, if not to yield a large profit. But with the great preponderance of sulphide ores in America, and American methods of smelting, it is probable that even in the days when a single stack was allowed to discharge nearly 100 tons of dust and fume daily, less damage was done by this than by the sulphur dioxide simultaneously discharged.At any rate, serious damage may be occasioned by the discharge into the air of vast quantities of sulphur dioxide, and for this there is no panacea in sight at present, nor does it seem likely that one will be devised.Every case needs separate consideration, locality being perhaps the most important factor because a permanent one, whereas the concentra- tion of the furnace-gas, though important, can be to some extent controlled, When, in 1911, the Tennessee Copper Company produced 150,000 tons of sulphuric acid from smelter smoke, increasing their production to nearly 200,000 tons in 1912, there were sanguine persons who considered the smelter smoke question finally solved.Yet not only is the success of this process dependent on the concentration of sulphur dioxide (and carbon dioxide) in the furnace gases, and on the capacity of the market to take indefinite quantities of sulphuric acid, but it is still more dependent on the locality of the plant, especially in a country of great distances, like America, where a low-priced product such as sulphuric acid, a thousand miles from a possible user, may be worth nothing at all.Similar criticism attaches to the more recent proposal to produce elemental sulphur from sulphur dioxide, though sulphur will stand heavier freight charges than oil of vitriol. These processes will doubtless receive extended application in suitable localities, but for many years the commoner problem will be that of reducing nuisance without any hope of a direct profit.The author of this bulletin shows that some methods directed to this end, which have been applied on a comparatively small scale in certain localities in Germany, have no prospect of wide adoption in America.The only general method in sight is the old one of diluting the gases before they leave the works and seeking to secure their subsequent rapid diffusion, and for this purpose there is an increasing body of evidence, though perhaps it cannot yet be regarded as conclusive evidence, that a large number of low stacks are better than one great one. & 6 * * + 5 INSTITUTE OF CHEMISTRY. G. CECIL JONES, PASS LIST : JUNE-JULY (1915) EXAMINATIONS. OF eleven candidates who presented themselves for the Intermediate Examination, seven passed: C. E. Corfield, A. Hancock, T. Hopkins, J. McLeod, J. Ogilvie, Agnes Shore, and A. Stewart. In the Examination in General Chemistry for the Associate- ship (A.I.C.), E. R. Taylor passed. Of twenty-four candidates who presented them- selves for the Final (A.I.C.) Examination, sixteen passed : I n the Branch of Mineral Chemistry : E. Arundel; in the Branch of Organic Chemistry : G. M. Bennett, A. J. Boyd, R. C. Denington, H. Hepworth, I. Hopper, G. L. Hutchison, C. H. Lumsden, J. W. Porter, and 9. H. Tucker; in the Branch of the Chemistry (and Microscopy) of Food and Drugs, Fertilisers and Feeding-Stuffs, SoiIs, and Water : G. A. Bracewell, P. Cheng, A. 0. Jones, C. H. Nanley, C. C. Roberts, and 5. Emsley.

ISSN:0003-2654    

DOI:10.1039/AN9154000374

出版商:RSC    

年代:1915

数据来源: RSC