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JANUARY. 1912. Vol . XXXVII. No . 430 . Aluminium Antimony . Argon . Arsenic . Barium . Bismuth . Boron . Bromine . Cadmium . Cesium . Calcium . Carbon . Cerium . Chlorine . Chromium Cobalt . Columbium Copper . Dysprosium Erbium . Europium . Fluorine . Gadolinium Gallium . Germanium Glucinurn . Helium . Hydrogen . Indium . Iodine . Iridium . Iron . Krypton . Lanthanum Lead . Lithium . Lutecium . Magnesium Manganese Mercury . Gola . THE ANALYST . INTERNATIONAL ATOMIC WEIGHTS. 1912 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0=16 . . A1 27.1 . Sb 120.2 . A 39.88 . As 74.96 . Ba 137.37 . Bi 208.0 .B 11.0 . Br 79-92 . Cd 112.40 . CS 132.81 . Ca 40.07 . c 12.00 . Ce 140.25 . C1 35.46 . Cr 52.0 . CO 58.97 . Cb 93.5 . Cu 63-57 . Dy 162.5 . E r 167.7 . Eu 152.0 . P 19-0 . Gd 157.3 . Ga 69.9 . Ge 72.5 . GI 9-1 . Au 197.2 . He 3.99 . H 1.008 . In 114.8 . I 126.92 . Ir 193.1 . Fe 55-84 . Kr 82.92 . La 139.0 . P b 207.10 . Li 6-94 . Lu 174.0 . Mg 24.32 . Mn 54-93 . Hg 200-6 0=16 . Molybdenum . . Mo 96.0 Neodymium . . Nd 144.3 Neon . . . Ne 20.2 Nickel . . Ni 58.68 Niton (radium emanation) Nt 922.4 Nitrogin . . Osmium . Oxygen . . Palladium . Phosphorus . Platinum . . Potassium . Praseodymium . . Radium" . Rhodium . Rubidium Ruthenium Samarium Scandium Selenium . Silicon . Silver . Sodium . Strontium Sulphur .Tantalum Tellurium Terbium . Thallium . Thorium . Thulium . Tin . Titanium . Tungsten Uranium . Vanadium Xenon . . . . . . . . . . . . . . . . . . . . . . . . . I . . . . . . . .*. . . . . . . . . . . . . . . . . . . . . . . . . N os 0 Pd P P t K P r Ra Rh Rb Ru S8 S C Se Si Ag Na Sr S T& Te Tb TI Th Tm Sn Ti W U V Xe 14-01 16.00 31-04 39.10 190.9 106.7 195.2 140.6 226-4 102.9 101.7 150.4 44.1 79.2 28.3 107.88 23.00 87.63 32.07 85.45 181.5 127-5 159.2 204.0 232.4 168.5 119.0 48.1 184.0 238.5 51.0 130.2 Ytterbium (Neoytterbium) Yb 172.0 Yttrium .. . Yt 89-0 Zinc . . . Zn 65.37 Zirconium . . Zr 90. 2 OBITUARY PERCY GERALD SANFORD OBITUARY. PERCY GERALD SANFORD. WE regret to announce the sudden death from apoplexy on November 26 of Mr. Percy Gerald Sanford F.I.C. at the age of fifty years. Mr. Sanford was a very old member of the Society of Public Analysts and was Public Analyst for the Borough of Penzance and additional Public Analyst for the Borough of Croydon. He was educated at Dulwich College and at the Royal School of Mines, and was subsequently assistant for three years to the late Dr. C. Meymott Tidy at the London Hospital Medical College. He was also for a time research assistant to Professor Pickering at Bedford College. Mr. Sanford gave much attention to the chemistry of explosives and was for a time resident chemist to the Stowmarket Explosives Company and subsequently at the National Explosives Company’s Works at Hayle Cornwall. He also acted as consulting chemist to the Cotton Powder Company Limited and was the author of a well-known treatise on (‘ Nitro-Explosives.” During later years Mr. Sanford had been engaged in the practice of general analytical and consulting chemistry in London carried on in conjunction with his work as a Public Analyst under the Sale of Food and Drugs Act. He leaves a widow and an infant daughter

ISSN:0003-2654    

DOI:10.1039/AN9123700001

出版商:RSC    

年代:1912

数据来源: RSC

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2 OBITUARY PERCY GERALD SANFORD PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE monthly meeting of the Society was held on Wednesday evening December 6,. in the Chemical Society’s Rooms Burlington House. I n the absence of the President the chair was occupied by Mr. Arthur R. Ling F.I.C. Vice-president. The minutes of the previous ordinary meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messrs. S. G. Agar G. S. Barton S. W. Bridge A.I.C. R. V. Briggs F. A. Mason W. I). Saville, G. A. Stokes and F. C. Dyche-Teague B.Sc. A.I.C. were read for the second time; and certificates in favour of Mr. Herbert Hawley M.Sc. (Birmingham) City Analyst’s Laboratory Council House Birmingham assistant to Mr.J. F. Liverseege F.I.C. ; and Miss Maud Gazdar B.Sc. (Lond.) A.I.C. Fox Hall Upminster Essex assistant analyst to Messrs. Dakin Bros. manufacturing chemists were read for the first time. Messrs. R. D. Carty W. K. Walton and G. F. Wesley Martin were elected members of the Socioty. The following papers were read ‘‘ The Estimation of Small Quantities of Essential Oil in Spices etc.” (Part II.) by J. A. Brown F.I.C. ; “ The Determina-tion of Furfural by Means of Fehling’s Solution,” by Lewis Eynon B.Sc. F.I.C., and J. Henry Lane B.Sc. F.I.C. ; “ The Examination of Petroleum Mixtures,” by J. H. Coste F.I.C. E. T. Shelbourn F.I.C. and E. R. Andrews F.I.C. ; ‘( A Metho PROCESS FOR ESTIMATIKG COCOAX CJT OIL 3 for Determining the Amount of Insoluble Particles in Raw Rubber,” by Clayton Beadle and Henry P.Stevens M.A. Ph.D. F.I.C. ; “ Note on Oil of Male Fern,” by Ernest J. Parry B.Sc. F.I.C. ; “ Note on Ground Almonds,” by G. Cecil Jones, A.C.G.I. F.I.C. and Reginald F. Easton ; I ‘ Note on the Determination of Small Quantities of Methyl Alcohol,” by C. Simmonds B.Sc. ; and ‘( The Composition of Australian (Victoria) Milk,” ‘‘ The Composition of Sweetened Condensed Milk,” and ‘‘ The Aldehyde Figure of Butter,” by E. Holl Miller. The CHAIRMAN announced the Council’s nominations of Officers and Council for 1912 as follows : President.-L. Archbutt F.I.C. Past-Presidents (limited by the Society’s Articles of Association to Eight in, Number).-Edward J. Bevan F.I.C. ; Bernard Dyer D.Sc. F.I.C. ; Thomas Fairley, F.I.C.; W. W. Fisher M.A. F.I.C.; Otto Hehner F.I.C.; R. R. Tatlock F.I.C.; E. W. Voelcker A.R.S.M. F.I.C. ; J. Augustus Voelcker M.A. B.Sc. Ph.D. F.I.C. Vice-Presidents.-W. H. Willcox M.D. B.Sc. M.R.C.P. F.I.C. ; Arthur R. Ling F.I.C.; John E. Stead F.R.S. F.I.C. Hon. Treasurer.-H. Droop Richmond F.I.C. Hon. Secretaries.-A. Chaston Chapman F.I.C. ; P. A. Ellis Richards F.I.C. Other Members of Council.-E. Richards Bolton ; R. M. Clark B.Sc. F.I.C. ; J. Connah B.Sc. F.I.C. ; J. Evans F.I.C. ; Charlee A. Hill B.Sc. F.I.C. ; E. Rinks, B.Sc. F.I.C.; G. T. Holloway A.R.C.Sc. F.I.C.; G. N. Huntly B.Sc. A.R.C.Sc., F.I.C.; G. W. Monier-Williams B.A. Ph.D. F.I.C.; F. Wallis Stoddart F.I.C. ; S. R. Trotman M.A. F.I.C.; S. A. Woodhead M.Sc. F.I.C

ISSN:0003-2654    

DOI:10.1039/AN9123700002

出版商:RSC    

年代:1912

数据来源: RSC

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PROCESS FOR ESTIMATIKG COCOAX CJT OIL 3 NOTES ON SHREWSBURY AND KNAPP’S PROCESS FOR ESTIMATING COCOANUT OIL. BY HERBERT S. SHREWSBURY, F.I.C., AND ARTHUR W. KNAPP, B.Sc., F.I.C. (Read at the Meeting, November 1, 1911.) MESSRS. CRIBB AND RICHARDS, in their paper on ( ( Margarine Analysis ” (ANALYST, 1911,36, 328), make the following statement : ‘‘ Ample illustration of this is afforded by Shrewsbury and Knapp (ANALYST, 1910, 35, 385) and other authors, who show that the differences between the figures for cocoanut oil and butter fat, upon which calculations are based, are not so great as in the Polenske process. The Polenske figure for cocoanut oil (17.5) is between five and six times that of butter (2 to 3%), and, as far as we are aware, none of these other processes will improve on this ratio.” We cannot reconcde the first part of this statement with the figures actually given in our paper. The following table compares our method with the Polenske process in this respect, The figures are strictly comparable, being in both processes the number of C.C. FF alkali required for 5 grms. of fat :4 SHREWSBURY AND KNAPP : Shrewsbury and Knapp.. . Polenske ... ... ... Difference Ratio of Butters* Butter Figures. Figures. gr:nf;"t' ~~~$~~~ between Cocoanut Cocoanut Oil and Oil and Limit Butter Oil. 163.0" 32.0:: 131 5.1 1 7 4 t 3.5t 14 5.0 This comparison shows that the difference between the figures for cocoanut oil and butter fat is not Eess than that given by the Polenske method, but, on the contrary, more than nine times as great; and in practice we find that 5 per cent.of cocoanut oil increases the Polenske figure by about 0.5 c.c., and our figure by 5 C.C. This should be remembered when considering the very interesting figures found by H. T. Cranfield (ANALYST, 1911, 36, 446). He showed that for butters from cows fed on cocoanut cake both the Polenske and our figure indicate the addition of cocoanut oil. Evidently the limit figure for genuine butters needs raising in both processes, to allow for the inclusion of these special butters amongst genuine butters. He showed, further, that genuine butters with a Reiohert-Meissl value of 29-5 may give Polenske figures from 1.7 to 3*7--i.e., a difference of 2. This difference has about the same significance as 20 in our process, for which the greatest variation found by Cranfield was 15.4 (40-1 - 24.7).Again, Lewkowitsch found for edible cocoanut oils Polenske figures from 15.49 to 20.45. This wide range produces the same possible error in calculation as would a, range for our process of 154.9 to 204.5. Happily, the range for cocoanut oils in our process is much less. Whilst our method estimates the bulk of the fatty acids which occur as glycerides in cocoanut oil, the Polenske method depends upon the small percentage of water-insoluble volatile acids that are present. This difference is important, because it is not impossible that cocoanut oil could be treated to remove these, and thus give a Polenske figure approximating to that of butter. That the Polenske figure can be diminished by separating the liquid glycerides by pressure (as in the preparation of cocoa butter substitutes) is illustrated by the following analyses of products so obtained from a specimen of Cochin cocoanut oil : Reichert-Meissl Polenske Shrewsbury and Knapp I Value, I Figure. I Figure.Cocoanut " stearine " A,. . ... I Cocoanut oleine " A ... ... 4.2 8.5 169.0 169.0 Cocoanut " stearine " B.. . ... I 3.9 I 11.1 I 165.3 * Ross, Race, and Maudsley (ANALYST, 1911, 86, 196) found 16.55 to 17-05 for cocoaiiut oil, and t Lewkowitsch found 15'49 to 20-45 for cocoanut oil, and 4.1 for a, foreign butter. 35'5 as maximum for foreign butters.PROCESS FOR ESTIMATING COCOANUT OIL 5 (Cocoanut t L stearine ” B had been subjected to the well-known method of refining with superheated steam before being pressed.) Whilst the Polenske figure is greatly reduced by this treatment, the Shrewsbury and Knapp figure is not affected to any extent.That the figure for “ stearine ’’ A and ‘‘ oleine ’* A should be identical is accidental, and indicates that the figure for the ( 4 oleine ” has been raised by the large percentage of the glycerides of the lower fatty acids to just the same extent as it has been lowered by containing the greater part of the olein present in the original oil. I t has been pointed out that the Polenske method does not give such good results with palm-kernel oil, since its Polenske figure is only about 11. It is, in all probability, still less effective for estimating palm-kernel t L stearine,” which doubtless has 8 yet lower value. An old sample of palm-kernel (( stearine ’’ gave a Reichert value of 4.2, Polenske figure 9.35, and Shrewsbury and Knapp figure 162.9.I t is noteworthy that the insoluble volatile acids were solid. Since the principal con- stituent of palm-kernel oil is laurin, the Shrewsbury and Knapp figure is of similar magnitude to the figure for cocoanut oil. A sample of crude palm-kernel oil gave 163.7. AS modifications of, or additions to, accepted processes are considered convenient, we made one or two experiments on the fatty acids left in the Reichert flask after the usual distillation of the fatty acids. The non-volatile acids from butter were treated as described by our method, but the figures obtained were abnormally high, and seem to indicate that the oleic acid undergoes some change whilst boiling with the sulphuric acid, glycerol, and sodium sulphate.The results were useless for our purpose. Referring to the paper of Messrs. Revis and Bolton (ANALYST, 1911, 36, 334). we cannot see the necessity or advantage of their proposed modifications of our process. Many of these modifications we tried and discarded ; they greatly increase the time taken by the method, thereby rendering it unsuitable as a sorting test, without apparently increasing the accuracy. I n our experience we found the tedious method of cooling, with the production of supersaturated solutions from which the fatty acids crystallise slowly, not so accurate as the rapid separation of the hot liquids. Another disadvantage of the modifications is that the range for pure butters, as the published figures show, is greater than in our process.Under one circumstance our process may require modification-that is, if it is required for giving accurate estimations where large percentages of cocoanut oil are present. I n such cases the absolute control of the final conditions is of greater importance, and, for example, the use of a bath at 37” C. might possibly improve results. However, one of us, working in the tropics, obtained by our method normal butter figures and consistent duplicate results, although the laboratory temperature was 30” C. Evidently the method as it stands can be used under winter or summer conditions for the purpose for which it was intended-i.e., the rapid detection and approximate estimation of small percentages of cocoanut oil.6 PROCESS FOR ESTIMATING COCOANUT OIL DISCUSSION.Mr. C. REVIS said that in hisexperience the Polenske figure could be determined with much greater accuracy than the Shrewsbury and Knapp figure. I n the hands of Mr. Bolton and himself the Shrewsbury and Knapp process, a6 originally published, had not yielded concordant results. When the process was modified as Mr. Bolton and he had suggested, they found that quite concordant results could be obtained by different observers. The final cooling was very necessary in the case of mixtures containing large proportions of cocoanut oil, because the solubility of the final fatty acids in 60 per cent. alcohol depended greatly on the temperature. Mr. T. MACARA agreed with what Mr. Revis had said as to the dificulty of getting concordant results with the Shrewsbury and Knapp process when working at the higher temperature.In an ordinary laboratory it was not always easy to regn- late the temperature exactly, and to be able to work at the ordinary temperature was a great advantage. Mr. E. R. BOLTON said that the experience of Mr. Revis and himself had been that even a slight variation in the time of running off the hot solution of fatty acids was liable to cause considerable differences in the results, and their object in modify- ing the process had been to enable more consistent results to be obtained by inde- pendent workers who merely follow a published description. That being accomplished the process would be found to be a valuable one. I t was to be noted that many of the figures given in the author’s present paper related to the whole fats--cocoanut “stearine,” palm nut “stearine,” etc.Mr. Revis and he, even by the Polenske method, had not obtained very satisfactory results when working on the whole undiluted fats, but with such admixtures as were generally foulid in margarine the results were delicate and accurate, duplicate Polenske figures obtained by different observers commonly agreeing within a tenth of a c.c., and as far as their experience went they considered that the ratio between the Reichert-Meissl and Polenske numbers, reinforced by the Kirschner figure, afforded the best means of estimating cocoanut oil now available (cf. ANALYST, 1911, 36, 333). Mr. KNAPP agreed that an essentially practical process, such as this, ought to be capable of being satisfactorily carried out, after a little practice, by an average worker who simply followed the published description.He thought, however, that some misconception had arisen as to the comparative accuracy of the two processes, owing to the fact that in this process the figures obtained were larger than in the Polenske process, so that an agreement within 0.1 C.C. in the Polenske process would correspond to an agreement within 1 C.C. ill the Shrewsbury and Knapp process. For example, Mr. Cranfield had considered that duplicate results should agree within 0.5 c.c., and he (the speaker) concurred; but to reach a corresponding degree of accuracy in the Polenske process the figures would have to agree within 0.05 C.C. With regard to the question of time, the alcoholic solution of the fatty acids should be run off after three minutes, but it seemed hardly likely that, on one hundred and eighty seconds, a variation of one or two seconds either way would make any import ant difference.SHREWSBURY: NOTE ON A COUNTERFEIT GOLD COIN 7 Mr. RICHARDS pointed out that in the paper referred to, Mr. Cribb and he had stated that none of the other processes improved materially on that of Polenske so far as the ratio employed for calculation was concerned, and the figures given by the present Authors confirmed this, as the difference between 5.0 and 5-1 is negligible.

ISSN:0003-2654    

DOI:10.1039/AN9123700003

出版商:RSC    

年代:1912

数据来源: RSC

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SHREWSBURY: NOTE ON A COUNTERFEIT GOLD COIN 7 NOTE ON A COUNTERFEIT GOLD COIN. BY HERBERT S. SHREWSBURY, F.I.C. (Read at the ,Meeting, November 1, 1911.) ANALYSTS are not infrequently called upon to examine counterfeit coin; but the specimen described below, which was uttered in Trinidad, appeared to be SO unusual in character as to be worthy of a brief description. The sample imitated a twenty-shilling piece of date 1861. I t weighed 122 grains against 123.27 grains for a genuine coin. The milling and design were very good, but the gilding had begun to wear off in places, and the partial exposure of the underlying white metal led to the detection of the false coin. A piece of the white metal, after removal of the gilding, gave a specific gravity of 21.8 (To C.) as against 17.157 for standard gold coinage, and had an approximate composition of: 30 ...... ... Platinum ... ... ... 91.5 per cent. Antimony and traces of bismuth and iron ... 5.0 ,, ,, Copper ... 0 . . ... ... ... ... 3.5 ,, ,, - 100.0 It was quite infusible and unaltered in the hottest part of the flame of a MQker burner. One or two notes on the analysis may be of interest. The metal was somewhat difficult of solution. 0.326 grm. of the white metal required more than three hours’ treatment with aqua regia on the water-bath to effect its solution, and it wap, quite insoluble in nitric acid of any strength. Insufficient notice seems to be taken in most textbooks of the difficulty of solution of platinum sulpbide in ammonium sulphide. Fresenius is a notable exception, and points out that the sulphide precipitate requires prolonged treatment with a large excess of hot ammonium sulphide, and that even under these conditions some of the platinum sulphide is usually left undissolved, A difficulty occurred in the qualitative detection of the copper.The presence of platinum in solution appears to prevent the formation of the characteristic blue coloration ~ i t h ammonia. Some platinum sulphide waB left undissolved with the copper sulphide after solution of the bulk of platinum sulphide and all the antimony sulphide in hot ammonium sulphide. This insoluble sulphide precipitate dissolved in strong nitric acid, forming a yellowish-green solution, but the colour of the solution8 COSTE, SHELBOURN AND ANDREWS : was scarcely affected by the addition of excess of ammonia. Copper was at once detected, however, on treatment of the ignited ammonium platinum chloride precipi- tate with hot nitric acid and application of the usual tests to the green nitric acid extract of the reduced impure platinum. Although the high specific gravity of platinum permits a counterfeit of this nature to be made of the correct weight, it is somewhat difficult to understand how any profits can accrue from the proceeding. The fact of such coins actually being in circulation is corroborated by a notice in the ‘( Counterfeit Detector,” in which bankers are warned of the existence of counterfeit sovereigns made of gilded platinum and dated 1862 and 1863. Possibly at the time of their production the price of platinum was sufficiently low to allow the realisation of a large profit.

ISSN:0003-2654    

DOI:10.1039/AN9123700007

出版商:RSC    

年代:1912

数据来源: RSC

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8 COSTE, SHELBOURN AND ANDREWS : THE EXAMINATION OF MIXTURES CONTAINING PETROLEUM. BY J. H. COSTE, F.I.C., E. T. SHELBOURN, F.I.C., AND E. R. ANDREWS, F.I.C. (Read at the Meeting, December 6, 1911.) IN Section 3 of the Petroleum Act, 1871, it is stated that “For the purposes of this Act the term ‘ petroleum ’ includes any rock oil, Rangoon oil, Burmah oil, oil made from petroleum, coal, schist, shale, peat or other bituminous substance, and any products of petroleum or any of the above-mentioned oils, and the term petroleum to which this Act applies ’ means such of the petroleum so defined as, when tested in manner set forth in Schedule One to this Act, gives off an inflammable vapour a t a, temperature of less than one hundred degrees of Fahrenheit’s thermometer.” The manner prescribed was the unsatisfactory one of testing, by means of small flame, the petroleum contained in an open cup heated in a, water-bath.Section 2 of the Petroleum Act, 1879, provided that the term “petroleum to which this Act applies” should in future mean petroleum which gave off an in- flammable vapour at a temperature of less than 73’ F. The apparatus then newly designed by the late Sir Frederick Abel was prescribed for use, and the temperature of flash 73’ F., as registered by this apparatus, was intended to correspond to a, flash of 100” F. in the open cup. In 1899 the London County Council appealed against a magistrate’s decision that a composition containing 20 per cent. of petroleum did not come within the meaning of the Acts, and the higher court remitted the case to the magistrate for him to convict.In 1907 the Privy Council, acting on a provision of the Act of 1871, endorsed this view of the law, and strengthened it by an Order ‘‘ that certain parts of the ‘ Acts of 1871 to 1881 ’ the latter being the petroleum (Hawkers) Act should apply to any mixture of petroleum with any other substance or substances which. . . gives off inflammable vapour at a temperature of less than 73 degrees of Fahrenheit’sTHE EXAMINATION OF MIXTURES CONTAINING PETROLEUM 9 thermometer, whether such mixture be liquid, viscous, or solid, in the same manner as if such mixture were petroleum, to which the said Acts apply." Dismissing from consideration several questions which may arise out of the word- ing of the above-mentioned Acts and Order, the points at issue for the analyst in connection with any mixture are (1) Does it contain petroleum as defined by the Acts? (2) Is it to be certified as petroleum to which the Acts apply? I t might be taken from the wording of part of the Order that any mixture in respect of which the answer to (1) was in the affirmative, and which gave off inflamm- nble vapour below 73" F., was zpso fucto within the scope of the Acts ; but this is not necessarily so, as it is stated that (( mixtures of petroleum with other substances present dangers similar to those presented by petroleum without admixture." It is therefore necessary to consider the second question from a somewhat wider point of view than the mere giving off of an inflammable vapour.The fact that petroleum which may or may not flash below 73' F.is used in paints, enamels, paint removers, polishes, solvents, etc., in admixture with alcohol, ether, and acetone which flash below 73" F., and turpentines, carbon tetrachloride, trichlorethylene and tetrachlorethane, whiob do not, renders a decision as to the application of the Petroleum Acts one of greater difficulty than can be solved by the class of officer to whom testing under the Acts is often entrusted. Since the Acts do not apply to mixtures flashing at or above 73" F., it is in all cases convenient to determine the flash-point first, leaving the decision as to whether samples which do flash are! or contain, petroleum within the meaning of the Acts, to be based on subsequent chemical work. Apart from difficulties presented by certain liquids due to their containing chloro- compounds the determination of flash-point is not so simple or satisfactory as might be thought.The three well-known types of apparatus-the original Abel, the Abel- Pensky as used in the Colonies, and the German form of the same apparatus- have recently been very carefully examined and compared by J. H. Harker, and W. F. .Higgins (Nat. Phys. L d . CoZZ. Researches, VIII. 19-39). The following points have been studied by these workers : (1) The influence of variations in the method of testing (a) the frequency of application of the test-flame, ( b ) variations in the time of opening the slide, (c) variations in the water-bath temperature, (d) variations in the depth of immersion of the thermometer ; (2) the temperature distribution in the oil- cup of the various forms of apparatus; (3) the heat from the test-flame, differences of 4' F.may occur even in the most careful work, more especially in the apparatus provided with the oil test-flame ; (4) the difference between the flash-points deter- mined with the different forms of apparatus. These are approximately constant at all temperatures ; the German form gives results about 3.7" F. and the Colonial form 1.1" F. higher than the Abel. The oil test-flame reads about 3" F. higher than the gas-flame. (5) They emphasise the fact that the flash-point of a liquid, as ordinarily determined, is an empirical constant which is largely a function of the particular apparatus used. If a low flash-point establishes a prima facie presumption of the presence of petroleum to which the Acts apply, it is necessary, in the first place, to determine whether the flash is wholly or partly due to the presence of petroleum.The effect of thermometric lag has also been investigated.10 COSTE, SHELBOURN AND ANDREWS : We outline a general scheme which should enable such a decision to be made. I t is obvious that in many cases some of the processes suggested could be omitted or modified, and that at various stages much useful information will be given by the determination of such physical properties as refractive index, boiling-point, and specific gravity, and by the consideration of the relation of these constants to one another. The odour and the nature of the flash given by liquids will often furnish useful qualitative information.A liquid, which on agitation with water is found to be wholly miscible with it, cannot contain any appreciable quantity of the hydrocarbons which are the main constituents of petroleum as known to the law. If any loss of volume occurs, owing to the solution of a portion of the sample, it should be washed with further quantities of water until all soluble constituents (alcohol, acetone, etc.) are removed. These washings, or the water coming over with the steam distillate, may be examined by determining the initial boiling-point of the liquid and the properties of the first portion of the distillate. Tho following example will illustrate the ease with which this can be done: A Russian burning oil flashing at 81" F.was mixed with 10 per cent. of ether. After washing about 80 C.C. with 6 washings, in all 1850 c.c., the flash-point was found to be 82" F., showing that the tendency is rather for traces of petroleum to be lost than for ether to be retained. Viscous liquids which obviously contain fixed oils or solids in solution or suspension can be distilled either alone at ordinary or reduced pressure or with steam in order to obtain a suitable liquid for working on. If this be done, it is necessary to ascertain that the residue contains no matters which were present originally in liquid petroleum-e.g., a sample of ordinary burning oil, flashing at 84' F., was steam distilled, and gave 45 per cent. by volume of a distillate flashing at 69' F. An unwary worker examining a mixture which contained such an oil might be disposed to certify it as containing petroleum within the meaning of the Acts, whereas the process of fractionation was the cause of the low flash.In all doubtful cases it is advisable to wash repeatedly with water, then with sodium bisulphite solution to remove alcohols and acetone, and afterwards to dry with calcium chloride, which should remove any traces of alcohol, and again to take the flash-point (cf. Nash, ANALYST, 1911, 36, 577). Whether the sample has been distilled with steam or alone, or only washed with water, the treatment with sodium bisulphite and calcium chloride should be carried out on the sample or the distillate. Only hydrocarbons and their chlorine derivatives, amyl alcohol or acetate, and carbon disulphide, are now likely to be present.The hydrocarbons may be terpenes, paraffins and cycloparafins, and aromatic hydro- carbons. Terpenes may be removed by Armstrong's method (J. SOC. Chem. Ind., 1882, 1, 480), which has been shown by one of us to be applicable to mixtures of terpenes with both aliphatic and aromatic hydrocarbons (Coste, ANALYST, 1910, 35, 438; Coste and Nash, ibid., 1911, 36, 207). This treatment also removes the amyl compounds mentioned above, but in presence of these substances the acid must be removed before steam distillation, as they separate from solution when the acid is diluted, The remaining liquid can only contain paraffins and cycloparafins, homo-THE EXAMINATION OF MIXTURES CONTAINING PETROLEUM 11 logues of benzene, carbon disulphide, and chloro compounds.If 1 C.C. is poured into a small porcelain capsule, diluted with 2 C.C. of alcohol, and the capsule placed on fhe bottoni of a large beaker covered with a clock glass, which is moistened on the under side with a drop of silver nitrate, the appearance of silver chloride on the drop when the diluted liquid is lighted and the clock glass placed over the beaker will indicate the presence of chlorine, and, by inference, of chloroparaffins, etc. I t is seldom that this treatment is necessary, as a peculiar reddish, smoky flash and an ,odour of hydrochloric acid will usually indicate the presence of any of these bodies, Carbon disulphide is seldom found in admixture with other solvents, and does not need much consideration. Veley (Proc.Roy. Xoc., 1910, B. 82, 217) has examined tetrachlorethane and trichlorethylene, and his values (cf. Gowing ScopeB, ANALYST, 1910, 35, 238) for some of the properties of these are given below with figures for carbon tetrachloride and carbon disulphide : CCI,, carbon tetrachloride . . . (CHCl,),, tetrachlorethane . . . CHCl, IcCl2, trichlorethylene.. . ... CS,, carbon disulphide.. . ... Sp. Gr. - . 12*30 - __ 1.6095 4O 17" - 1.6013 17" 17'5" 1.4702 17.5' '2 1 -2921 4 O Refractive Index. %D (12.3" C.) 1.4656 (17" C.) 1.495587 (17" C.) 1.479141 (20" C.) 1.6277 Boiling-Poin t. 76-77' C. 147.2" C. 87-55' C. 46.0' C. As even the higher fractions of petroleum oil or coal-tar hydrocarbons seldom have a sp. gr. of 0.9, anything above this figure will, unless such substances as nitro- benzene or carbon disulphide are present, indicate the presence of chloro-compounds ; and, conversely, anything below a sp.gr. of 1.47 will indicate the admixture of lighter substances with the chloro-compounds. In any ordinary case if the oil freed from alcohol, ether, and acetone flashes below 73"F., and contains no carbon disulphide, it must contain '' petroleum " in the eyes of the law, since chlorine compounds do not flash themselves, but raise the flashing-point of other liquids. A mixture of carbon tetrachloride and benzene, when tested in the Abel apparatus, shows the inhibitive effect of the chloro-compound on the inflammability of the benzene vapour in a, very pronounced degree. Instead of the bright, almost explosive, flash usually associated with the latter, one observes (probably after the slide has been opened several times), a reddish-coloured flame travel comparatively slowly across the surface of the liquid.No doubt the chloro-compound exerts a double effect i n retarding flashing by diluting the inflammable vapour, and also (owing to its vapour density) by preventing the access of air. From 8r mixture containing possibly both aromatic and aliphatic hydrocarbons and chloro-compounds of the latter, it is easy to remove aromatic hydrocarbons12 THE EXAMINATION OF MIXTURES CONTAINING PETROLEIJM either by careful nitration followed by fractional distillation or by sulphonation. It must be borne in mind that if terpenes have been found in the liquid, the presence of aromatic hydrocarbons to the extent of from 5 to 12 per cent.of the terpenes found is probable, owing to the cymene obtained when turpentines are polymerised. This amount should be deducted from any aromatic hydrocarbons which may be found. The approximate determination of the amount of paraffins and cycloparaffins in admixture with chloro-compounds can be made by a consideration of the physical properties of the mixture and of its probable constituents. We hope at a later date to be able to propose a fairly accurate method of estimation, but at present do no more than make the above suggestion with the warning that the accuracy of all physical methods is dependent on a qualitative knowledge of the constituents of the mixture. We think we have shown that the examination of mixtures under the Petroleum Acts requires an amount of knowledge and judgment that places it above the powers of the ordinary “tester” to carry out efficiently, and is work which might more properly be entrusted to the Public Analyst or other chemical officer of the Local Authority administering the Acts.We have examined several samples of liquids sold as paint removers, and have found them to consist principally of acetone and benzene; smaller amounts of other organic liquids are usually present, and we have identified alcohol, chloro-hydrocarbon derivatives and coal-tar naphtha in different samples. Several liquids labelled ‘‘ non- inflammable solution” were found to consist of a wax or a mixture of waxes dissolved in carbon-tetrachloride and benzene. We have also detected light petroleum in mix- tures sold for lacquering purposes. In these cases it was admixed with amyl alcohol. Amy1 acetate and ethyl alcohol were also present in one instance. I n soine cases the dissolved substance is collodion cotton, and we understand that lacquers of this class are extensively used by silversmiths for protecting articles of silver plate from atmospheric influences. DISCUSSIOK. Mr. ARCHBUTT said that in testing the so-called (‘ non-inflammable ” mixtures he had always found it desirable not to rely simply on the fact of their flashing or not flashing in the official apparatus, but to put some of the material into a larger vessel and test it with a naked flame, and also to warm some of it in a fair-sized porcelain crucible and then test it. Under these conditions it was sometimes found that mix- tures which did not actually flash in the Abel apparatus were nevertheless far from being uninflammable. Mr. COSTE agreed with Mr. Archbutt; but the limitations as to what one might do when testing under the Petroleum Acts were very strict. They did not even allow of the correction of the flash-point for barometric pressure. The necessity for such a correction was only discovered by Sir Frederick Abel after the Act of 1881 was passed, and the Act had not since been amended to allow of it.

ISSN:0003-2654    

DOI:10.1039/AN9123700008

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

THE AMOUNT OF INSOLUBLE PARTICLES IN RAW RUBBER 13 A METHOD FOR DETERMINING THE AMOUNT OF INSOLUBLE PARTICLES IN RAW RUBBER. BY CLAYTON BEADLE AND HENRY P. STEVENS, M.A., PH.D., F.I.C. (Rend at the Meeting, December 6 , 1911.) CONSIDEBABLE difficulties exist in separating raw rubbers from insoluble extraneous bodies in such a manner that these may be collected, examined and estimated. The most practical manner is to determine the loss on washing, but there is some difficulty in collecting the material removed in the process. For some purposes i t is useful to reverse the operation and to remove the rubber and that which properly belongs to the rubber, and to collect, examine, and weigh the extraneous matter. Washing the material on the rolls in the ordinary way is the best procedure from the point of view of the examination of the rubber, but something is wanted, to supplement this test, and which will permit the examination of those impurities which are discarded and thrown away in this process.Moreover, the samples are at times too small to enable this to be done with advantage on ordinary washing rollers; further, with some kinds of scrap and tacky rubbers, the process of removal of the insoluble impurities is not sufficiently complete without overworking the rubber, and there are many cases in which the whole of the mechanical impurities are not removed even after prolonged treatment on the washing rollers. A very small amount of rubber is required for the test about to be described, and the smallness of the amount may be used as an argument against its adoption, because it may be suggested that so small a quantity cannot be taken .to represent the bulk.This diffi- culty can be overcome by proper sampling. When the whole mass is sufficiently homogeneous, a, portion of the crepe is taken for analysis. The treatment on the rolls should be as short as possible to avoid disintegration of the particles that exist in the rubber. The insoluble constituents may be separated by dissolving the rubbers in benzene and allowing the insoluble constituents to settle out from the solution, or by filtration, but the drawback is the viscosity of the solution obtained, which hinders the sedi- mentation or filtration of the particles. This applies even to very dilute solutions of high-grade rubbers.Many raw rubbers, particularly those in which the determination of the insoluble solid particles would be of most value, are difficultly soluble in naphtha or other solvents without mastication, which, however, has the disadvantage of disintegrating the insoluble matter. The insoluble matter may be estimated by decanting the top half of the solution as recommended by Schidrowitz, evaporating off the naphtha, and determining the weight of rubber. Knowing the total amount of rubber taken in the 5rst instance and subtracting from this twice the weight of dry rubber obtained from the clear solution, the difference is the weight of the sediment. This latter, however, cannot be separated without further washing and filtration. The method we have adopted is a, modification of that employed in the case of vulcanised rubber goods.To bring about a separation of mineral in such materials,14 BEADLE AND STEVENS: A METHOD FOR DETERMINING it is customary to heat the finely-ground rubber with an organic liquid of sufficiently high boiling-point to such a temperature ag to bring about depolymerisation of the rubber and subsequent solution of the latter in a partly decomposed state. For this purpose nitro-benzene was introduced by Weber and subsequently nitro- naphthalene. Both these substances have disadvantages-the poisonous nature of the vapours of the former, and the fact that the latter is solid at ordinary tempera- tures. Subsequently xylol was suggested, the rubber and liquid being heated under pressure, and a further advance on this was a suggestion for using high-boiling petro- leums which render an autoclave unnecessary.Phenetol has also been used, and we have found it very convenient for the purpose. Now it is well known that fully vulcanised mechanicals are much more difficult to treat by this process than soft rubbers. The latter, as might be expected, yield much more easily to the solvent action of the fluid. Raw rubbers are still more easily acted upon, and a very short treatment at a relatively low temperature is sufficient to dissolve the rubber and so. alter its character that, on diluting the product with naphtha, the viscosity of the solution is very much lower than that of the original raw rubber when dissolved in naphtha. For treating raw rubbers we have used nitro-benzene, high-boiling petroleum, and phenetol (of the three we prefer phenetol).One grm. of the finely-cut rubber is placed in a test-tube with 5 to 10 C.C. of the solvent. The temperature should be raised very slowly, so as to give the rubber plenty of time to swell. It is best to heat for about half an hour at 100" C., then to gradually raise the temperature to about 140" C. for one to one and a half hours. The rubber swells until the whole mass is a jelly, then, on gradually heating to a certain point, a rather sudden change takes place, and the thick, jelly-like mass becomes rapidly thin and liquid, During the heating a peculiar smell is given off, resembling hot fat or roasting meat. On cooling, the whole is poured into about 100 C.C. of benzene and the insoluble matter allowed to settle.We find it advisable to wash once or twice with benzene by decantation before transferring to a filter-paper and washing. I n some cases, however, it is preferable to remove the soluble matter by repeated decantation with naphtha, evaporating off the last traces and weighing the residue in a tared dish. We obtained the undermentioned results. The first column shows the total sediment, the second the amount of ash obtained by incinerating the sediment, and the third column the organic matter by difference. The most useful figure, accord- ing to our opinion, is the one given in the first column, but the others are useful in determining how far these insoluble particles are due to organic and how far to mineral constituents. We have also found that a repeat test gives good agreement : 1.2. 3. Grms. Grms. Grms. Hard cure Para unwashed as received ... 1.50 0.66 0.84 ,, ,, ,, washed and dried ... 0.36 0.20 0.16 Plantation crepe ... 6 . . ... ... 0.29 0.05 0.24 Castilloa ... ... ... ... ... 6.80 3.78 3-02 creped ... ... -.. ... 5-90 1-10 4.80 9 , B ... ... ... ... 6-46 1-06 5-40 Gutta.. . ... ... ... ... ... 0.80 0.40 0.40 Negro Head.. . ... ... ... ... 0.48 0.26 0.22 Wili rubber A ... ... ... ... 6*88 2-85 4-03THE AMOUNT OF INSOLUBLE PARTICLES I N RAW’ RUBBER 15 The separated material is available for microscopic examination ; and as it is structurally uninjured by the treatment, it may be possible, where it is considered of service, to determine the nature of the insoluble material. The unwashed hard- cured rubber yielded flocculent material of a membranous character which agglom- erated on drying.The washed hard-cured rubber showed masses of disintegrated material, and in many cases where the sediments were examined under the micro- scope it would appear that they were derived from the bark of the tree. The samples of hard-cured rubber and Negro Head were obtained washed and dried from one of the leading manufacturers. The two samples of Castilloa. came from the same estate. From their appearance it was evident that they were not by any means free from impurities. The method may be employed as a useful check on the washing of rubber. As an instance, two samples of scrap crepe gave by this method (A) 1.7 and (B) 2.5 per cent. of insoluble residue: On rewashing, the amount of residue was reduced to 0.7 and 1.4 per cent.respectively. An examination of the material removed in A showed a mixture of sand with a little bark, and in B, bark only. The ash in the washed rubbers amounted to 0.7 and 0.35 per cent. respectively. As the insoluble impurities in A consisted mostly of sand and grit, with very little bark, A presents a case in which the ash determination gives a fair idea of the per- centage of foreign matter in the rubber. I n B the foreign matter consisted almost entirely of bark dkbris. I n such a case the ash determination gives no idea as to the percentage of insoluble particles. tree scrap” washed and creped, produced by the drying down of latex on the tapping surface after the flow of latex has ceased.The rubber is easily peeled off the wood in a thin strip. There is no reason why such rubber should be contaminated with bark chips to’ any great extent, but it may easily pick up a little sand and grit. Rubber B consisted of “bark scrap”; that is, thin shreds of bark removed by the tapping knife, collected, and macerated wet. The loose pieces of bark were for the most part washed away during the maceration process. Such rubber would naturally tend to retain a little of the bark even after prolonged washing. I t is evident, therefore, that an estimation of ash may be very misleading as regards the amount of insoluble impurities in a sample of rubber. The method we have outlined, although more troublesome than the determination of ash, is nevertheless one which can be carried out fairly rapidly and gives more accurate information as to the character and amount of the insoluble impurities.A consisted of so-called DISCUSSION. Dr. SCHIDROWITZ asked what advantage was possessed by nitrobenzene over benzene as a solvent in this case. He presumed that it was a question of rapidity of solution. He should like to know how the insoluble matter was weighed- whether directly or indirectly-because this was really the most difficult point in the determination. Dr. RIDEAL said he gathered that with nitrobenzene the whole mass became semi-solid, whereas with benzene it remained fluid. From the figures given16 THE AMOUNT OF INSOLUBLE PARTICLES IN RAW RUBBER it seemed to him that the quantities of insoluble organic and inorganic matters in some of these rubbers were very small, and that after all it was the determination of soluble organic and inorganic matters that might have a value in the future.Since rubber from the same species varied in composition from month to month, according to climatic conditions, etc., to so great an extent as to aff'ect the relative price, it seemed unlikely that these small differences in the insoluble matter were to be regarded as of any great commercial importance. Dr. SCHIDROWITZ said that in his experience the determination of insoluble matter was one of the most valuable that could be made in rubber--a good deal more valuable, probably, than the determination of nitrogen. Mr. CLAYTON BEADLE said that the first action of the solvent wag to produce a gel, but as the heat was increased the whole mass became perfectly limpid.These insoluble particles were not rubber, but were derived from the bark or from other sources foreign to the rubber itself. I n the case of impure rubbers, the insoluble particles were to a large extent removed by the manufacturer during the process of washing, ekc. If the rubber was sufficiently transparent, the particles could be seen in it by the naked eye. It was first discovered by Spence that protein in rubber became insoluble when the rubber was treated with benzene and allowed to remain quiescent for a, sufficient length of time, and this has since been confirmed by ourselves and other observers. The process described, however, did not leave the proteins in the insoluble residue. The advantage of using such substances as nitro- benzene, nitronaphthalene, or phenetol and other bodies of sufficiently high boiling- points, was that the temperature obtainable enabled one to bring about depolymerisrt- tion, so that the liquid was rendered less viscous, from which liquid, after dilution with benzene, the insoluble portion more readily settled out. When this thinning down had taken place, the clear liquid, after dilution with benzene, was poured off, and the insoluble matter, after being washed once or twice with benzene, was dried and weighed.

ISSN:0003-2654    

DOI:10.1039/AN9123700013

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

16 THE AMOUNT OF INSOLUBLE PARTICLES IN RAW RUBBER NOTE ON THE DETERMINATION OF SMALL QUANTITIES OF METHYL ALCOHOL.* BY C. SIMMONDS, B.Sc. (Read at the Meeting, December 6, 1911.) SMALL proportions of methyl alcohol, especially when in mixture with ethyl alcohol, have hitherto been somewhat difficult to determine readily and accurately. Fairly good approximate results can be obtained by comparative experiments with the well- known method of Riche and Bardy (Compt. rend., 1875, 80, 1076), or with WolPs modification of Trillat’s process (Ann. Inst. Pastew, 1902, p. 8), but these methods are lengthy and rather troublesome. The process described by Thorpe and Holmes (J. Chem. Xoc., 1904, 85, 1) gives good results when the quantity of methyl alcohol is * Communicated with the sanction of the Government Chemist.DETERMINATION OF SMALL QUANTITIES OF METHYL ALCOHOL 17 not too small.It is not well adapted, however, for use when the proportion of methyl alcohol is less than about 2 per cent. of the ethyl alcohol, since the necessary subtractive correction (loc. cit., pp. 2, 3) may in such cases equal or exceed the quantity it is desired to estimate. For determining very small proportions of methyl alcohol the method is quite inapplicable. In such cases satisfactory determinations can be made by applying the principle of colorimetric comparison to Den@’ process for the detection of methyl alcohol (Compt. rend., 1910, 150, 832). The possibility of thus using the process is indicated by Denigits (Zoc. cit., p. 833). The object of the present note is to give the procedure which the writer finds most suitable for utilising the reaction quantitatively in general analytical work-as, for example, in examining spirituous beverages, medicinal tinctures, flavouring essences, and so forth.The alcoholic mixture is first purified, where necessary, either by the method of Thorpe and Holmes (J. Chern. Soc., 1903, 83, 314), or by other suitable means. It is then diluted with water or mixed with ethyl alcohol, as the case may require, until it contains 10 per cent. of total alcohol by volume. To 5 C.C. of this prepared liquid contained in a wide test-tube are added 2.5 C.C. of permanganate solution (2.0 grms. KMnO, per 100 c.c.), and then 0.2 C.C. of strong sulphuric acid. When the reaction has proceeded about three minutes, 0.5 C.C.of oxalic acid solution is added (9.6 grms. crystallised acid per 100 c.c.). On shaking, the liquid becomes clear and nearly colourless. One C.C. of strong sulphuric acid is now run insand well mixed with the solution, which is finally treated with 5 C.C. of Schiffs reagent. A violet colour is developed in the course of a few minutes unless mere traces of methyl alcohol were present, when twenty or thirty minutes may be required. This colour is due, of course, to the reaction of the fuchsine solution with formaldehyde, produced by the oxidation of the methyl alcohol. A sufficient quantity of sulphuric acid is present to prevent the development of colour with any acetaldehyde formed from the ethyl alcohol during the oxidation. A preliminary experiment carried out as described serves to detect the presence of methyl alcohol (if this is not alreadyknown) and to give some idea of the quantity.According to the indications thus obtained, another part of the prepared liquid is further diluted, if necessary, with ethyl alcohol of 10 per cent. strength until it contains from 0.001 to 0-004 grm. of methyl alcohol in 5 C.C. ; and the experiment is repeated side by side with two or more standards for comparison. These contain 0-001, 0.002, 0.003, etc., grm. of methyl alcohol in 5 C.C. of 10 per cent. ethyl alcohol. The colours produced are compared in small Nessler-tubes (25 c.c.) or in a suitable colorirneter. With properly sensitive Schiff’s reagent, 0*0003 grm. methyl alcohol in the 5 C.C. of liquid taken is readily detected. The best depths of colour for comparison, however, are given by the formaldehyde produced in the manner described from quantities of 0.001 to 0-004 grm.of methyl alcohol. I t is convenient to keep a standard solution (1 grm. per litre) of methyl alcohol in 10 per cent. ethyl alcohol. This is diluted as required with 10 per cent. alcohol18 ABSTRACTS OF CHEMICAL PAPERS to form the standards for comparison. This proportion of ethyl alcohol (10 per cent.) is a suitable strength for general work, as the distillates ordinarily obtained are stronger, and can thus be diluted down instead of having to be concentrated. The process has the advantages of (1) being rapidly executed, (2) requiring only a small quantity of material, and (3) being directly applicable to weak distillates. The degree of accuracy obtainable is shown by the following results of a typical series of experiments : GRM. METHYL ALCOHOL PER 100 C.C. Present. 0.005 0.028 0.044 0.072 0.100 0.500 1.000 Found. 0.004 0.029 0.046 0.072 0.104 0.492 0.968 Formaldehyde, of course, must be absent from the unoxidised solution of alcohols, or else its effect must be determined and allowed for. Glycerol must also be absent. GOVERNMEKT LABORATORY, LONUOX.

ISSN:0003-2654    

DOI:10.1039/AN9123700016

出版商:RSC    

年代:1912

数据来源: RSC

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18 ABSTRACTS Detection ABSTRACTS OF CHEMICAL PAPERS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. of Caramel in Fermented Beverages. V. Pasquero and A. Cappa. (Gaxx. Chzim. Ital., 1911, 41, 349-358.)-A method of detecting caramel in beer and wine is based upon the distillation of the furfural in the caramel. The results obtained with fifteen samples of different kinds of Italian beer and thirty-one samples of red and white wine showed that although traces of furfural were separated by direct distillation of the sample, the distillate obtained when the liquid was neutralised with magnesium carbonate was quite free from furfural. On the other hand, when caramel was added to each of these neutralised samples the distillate invariably contained furfural. The test is applied by neutralising free acids in the beer or wine by the addition of magnesium carbonate, and distilling 100 c.c., after the addition of a little pumice stone, until 75 C.C.have passed over. The distillate is made up to 100 C.C. and 20 C.C. thereof shaken with 2 C.C. of pure glacial acetic acid, and 5 drops of colourless aniline in a colorimetric cylinder. If the sample contained any caramel, a rose coloration will be produced within fifteen minutes. By means of this test the presence of caramel was detected in three commercial samples of beer and in samples of Msrsala and Coronata wine. C. A. M.FOOD AND DRUGS ANALYSIS 19 Clavicepsin: A new Glucoside in Ergot of Rye. F. M. Zuco and V. Pasquero. (Gazz. Chinz. Itnl., 1911, 41, 368-374.)-From 1 to 2.5 per cent.of a new glucoside, termed '' clavicepsin," was separated from different samples of ergot of rye by extraction with 95 per cent, alcohol. When purified by recrystallisation from water it formed acicular crystals melting at 91' C., which were readily soluble in water. After losing its water of crystallisstion at 100" to 105' C., it melted at 198" C. I t s elementary composition corresponded with the formula C18H34016 + 2H,O. It did not reduce Fehling's solution until hydrolysed by acids, when it was decomposed into 2 molecules of dextrose and 1 of mannite. C. A. M. It had [a] D20 = + 142.27", and yielded an osazone melting at 205" C. Method for Separating Mixtures of the Seven Coal-Tar Dyestuffs allowed (U.S.A.) to be employed for colouring Foodstuffs.T. M. Price. (U.S. Dept. Agric. Bureuu of Arrzimal Iqzdustry, Circular No. 180 ; through Chem. Zentralbl., 1911, II., 1556.)-The dyestuffs which are permitted in the United States to be employed for colouring sausage-skins, etc., are amaranth, ponceau 3 R, erythrosin, orange I, naphthol yellow S, light green SF yellowish and indigo-disulphonic acid. An investigation of their solubility reactions led to the following method of separa- tion : About 0.2 grm. of the mixture is triturated with a supersaturated solution of ammonium sulphate, filtered, and washed with ammonium sulphate solution ; the filtrate contains amaranth and a little naphthol yellow S, which may be separated by shaking with ethyl acetate. The residue from the treatment with ammonium sulphate is dissolved in water, acidified with acetic acid, and shaken out with ether, which extracts the erythrosin.The aqueous layer, freed from ether, is salted out hot with sodium chloride; the filtrate contains the light green SF and the naphthol yellow S, the latter being separated from the former by shaking with acetone. The aqueous solution of the dyestuffs precipitated by salt, when shaken three times with ethyl acetate, yields the orange I in that solvent. The aqueous residue is heated to expel the ethyl acetate, cooled, and diluted with a 25 per cent. solution of calcium chloride, a solution of stannous chloride is added, and ponceau 3 R is thus precipitated, whilst, the leuco compound of indigo-disulphonic acid remains in solution, and may be re-oxidised by hydrogen peroxide to the blue dyestuff.J. F. B. Determination of Gliadin or ' Alcohol-soluble Protein in Wheat Flour. R. Hoagland, (J. Ind. and Eng. Chem., 1911,3,838-842.)-As usually recommended, 70 per cent. alcohol is used for this determination; but the author points out that whether this refers to weight or volume is seldom stated, and does, in fact, considerably influence the results obtained, as has been shown by Shutt (Bull. 57, Central Expr. Farm, Ottawa, 1907), who obtains a gliadin number of 47.4 with 70 per cent, by weight alcohol, and 53.4 when using 70 per cent. alcohol by volume. Snyder (Bull. 105, Bureau of Chem. U.S. Dept. of Agriculture) quotes Teller as finding the amount of protein extracted by 40-55 per cent. alcohol by volume to be practically constant in amount, and the author defends the use of such strength alcohol as will extract the maximum amount of nitrogen from flour.This strength he finds by experiment to be from 45-5520 ABSTRACTS O F CHEMICAL PAPERS per cent. by weight ; 75 per cent. alcohol by weight extracts about the same amount of protein as distilled water, No advantage is obtained by using hot or boiling alcohol. The method used by the author is as follows : Weigh approximately 2 grms. of flour into an 8-ounce stoppered bottle, add 100 C.C. neutral 50 per cent. (by weight) alcohol, shake in a machine for one hour, centrifuge ten minutes, filter and determine the nitrogen in an aliquot portion of the filtrate by the modified Kjeldahl method. Tables are given of the differences obtainable by varying the method of extraction, and show that as much protein can be obtained by vigorous shaking in a rocking machine for sixty to ninety minutes as when the sample is shaken frequently by hand for three or four hours, and then allowed to stand eighteen hours or less.I t is recommended that extraction with 70 per cent. alcohol either by weight or volume be discontinued. H. F. E. H. Hydnocarpus Fat. K. Lendrich, E. Koch, and L. Schwarz. (Zeitsch. Untersuch. Nahr. Genussm., 1911, 22, 441-458.).-The fat used in the preparation of a certain class of margarine which produced cases of poisoning (cf. ANALYST, 1911, 36, 65) was found to be identical in its properties with the fats obtained from the Hydnocarpus species. The fat is known $is cardamom or maratti fat, and consists of fatty acids of the constitution C,H,,-,O, ; from these fatty acids, chaulmoogric acid and hydnocarpic acid have been separated and identified.It does not contain fatty acids of the formulz : C,H,,O, and C,H,,-,O, ; the absence of palmitic acid is noteworthy, as Power and Barrowcliff (Chem. Soc. Proc., 1905, 21, 175) found this acid to be present in Tnraktogenos (Hydnocarpus) Kurzii fat and in Hydnocarpus anthelmintica fat, but not in H. Wightiana fat. The external appearance of the seeds of H. Wightiana and venenata inebrians is very similar to that of Ceylon cardamoms, and this is probably the reason why the fat in question is termed cardamom fat. When administered to dogs Hydnocarpus fat caused vomiting and convulsions. The poisonous properties of the fat appear to have a certain relation to the presence of an ethylene linkage in the structure of the optically active fatty acids of the fat.The authors do not agree with the statement of Thoms and Muller (cf. ANALYST, 1911, 36, 542) that cardamom (maratti) fat is obtained from Taraktogenos (Hgdnocarpus) Kurxii; Thomas and Muller do not state how they separated the palmitic acid found, nor do they appear to have established the identity of the hydnocarpic acid. The authors have also examined the fats obtained from the seeds of H , anthezmintica and H. AZpina, the fats being extracted by means of chloroform. H. AZpina fat consisted of a yellow, butter-like mass, without any particular taste or odour ; it gave the following physical and chemical results on analysis : refractometer value, at 40" C., 67.5; acid value, 5.6; saponification value, 209.1; iodine value, 84.5; [a],,,,+49*0. Its physiological action was similar to that of the other Hydnocarpus fats. w.P. s. Analysis of Candied Lemon Peel. F. Hartel and A. Kirschner. (Zeitsch. Untersuch. Nahr. Genussm., 1911,22,350-353.)-Lemons intended for the manufacture of csndied peel are imported packed in brine, the fruit being cut into two parts before being thus pickled. After washing with water, the fruit is boiled for about twoFOOD AND DRUGS ANALYSIS 21 hours, then cooled rapidly in cold water, and the pulp is removed. The peels are next steeped in water for one day, and then air-dried for a day or placed in direct sunlight. They-are now immersed in a sugar solution of sp.gr. 1.074, and afterwards in a sugar and starch-syrup solution of sp. gr. 1.115 to 1.383, in which they are allowed to remain for about four weeks; the quantity of starch-syrup employed is from 15 to 25 per cent. of the weight of the total sugars in the solution. The peels are finally glazed with concentrated sugar solution. Twenty samples of candied lemon peel examined yielded the following results : Ipsoluble substances, 2.89 to 5.22 per cent. ; soluble extractives, 60-83 to 79.22 per cent. ; acidity (as c h i c acid), 0.04 to 0.20 per cent. ; sucrose, 14.30 t o 48.50 per cent. ; starch-syrup (anhydrous), 9.45 t o 25.30 per cent.; ash, 0.37 to 3.09 per cent.; sodium chloride, 0.02 to 0.09 per cent. w. P. s. Detection of Nitric Acid in Watered Fruit Juiees.R. Cohn. (Zeitsch. offeiztl. Chenz., 1911, 17, 361-363 ; through Chem. Zentralbl., 1911, II., 1613-1614.)- About 75 C.C. of the juice are made alkaline with sodium hydroxide, evaporated nearly to dryness, and the residue is extracted for several minutes with alcohol at a tempera- ture of 40" C. The residue froin the alcohol, which, if it is still syrupy, should again be extracted with alcohol, is dissolved in about 10 C.C. of water and tested for the presence of nitric acid by the diphenylamine reaction. I n the case of pure natural raspberry, cherry, and currant juices, a positive reaction was never encountered. I n the case of bilberry juice the test cannot be used, since this fruit contains a body which gives a blue coloration with sulphuric acid alone.I n presence of bilberry juice the test for nitric acid in the aqueous solution of the alcoholic extract, prepared as .above, may be carried out with nitron. I n the extracts from pure natural raspberry, cherry, currant, and bilberry juices an acetic acid solution of nitron produces no precipitate ; in presence of nitric acid a separation of nitron nitrate soon takes place. J. F. B. Changes in the Composition of the Nitrogenous Constituents of Meat- Extracts. A. M. Wright. (J. Xoc. Chem. I d , 1911, 30, 1197-1198.)-The action of hot water, in presence of the sarco-lactic and other acids of flesh and of salts, on the meat causes a certain amount of hydrolysis, the collagen of muscle-fibre yielding gelatin, and later soluble gelatin and other gelatinoids, and the albumin yielding small quantities of albumoses.During concentration, under a partial vacuum, the amount of organic matter slightly decreases (relatively), while the mineral salts increase, and a small proportion of peptons-like bodies are produced. Concentration in an open pan yields very different results, profound changes taking place, The amount of organic matter is considerably decreased, while there is a corresponding increase of mineral matters. The total nitrogen remains about the same, but the forms in which it occurs are different, about three-fifths of the insoluble and coagu- lable proteins being converted into soluble nitrogenous compounds. Proteoses and mest-bases are decreased in amount, while peptone-like bodies appear in considerable quantity, and the acidity is notably increased.These peptone-like bodies impart a bitter taste to the extract in the cases of those containing them to the extent of, say,22 ABSTRACTS OF CHEMICAL PAPERS Estract Conceiitrated in I Liquor. I Open Pan. 1 2 per cent. or over. The " burned " flavour of certain meat-extracts is doubtless due to this method of concentration. The following analyses illustrate the differences noted. The " open " concen- tration was carried out by evaporation for forty-eight hours at 212" F., the resulting extract containing 17.6 per cent. moisture. The other method, followed on a portion of the same original liquor, was by a partial vacuum of 15 inches at 180" F. for three and a half hours, the resulting extract containing 18.36 per cent.moisture. All the results hive been calculated to a standard Sasis of 20 per cent. moisture for comparison purposes : Concentrated under Partial Vacuum. Moisture ... ... 0 . . Organic matter . . . ... ... Mineral salts ... ... ... Per Cent. 20.00 65.60 14.40 Per Cent. 20.00 60-48 19.52 Per Cent. 20.00 63-04 16.96 Acidity as lactic acid . . . ... Total nitrogen . . . ... ... Insoluble and coagulable pro- teins ... ... ... ... Pro t eo Be s ... ... Peptone-like bodies and poly- peptides ... ... ... Total meat-bases ... , .. Ammonia a .. ... ... 8-00 7.82 2-65 13.34 nil 14.19 0.85 10.30 7 a92 1.16 12.37 8-69 12.53 0.80 8-20 7.86 2.63 13.08 0.3 1 13.76 1-08 A. R. T. Detection of Saponin and Glycyrrhizin in Lemonades by Means of Vamvakas' and Frehse's Tests.A. Behre. (Zeitsch. Uiatersuch. Nahr. Geizussm., 1911, 22, 498-506.)-The two tests mentioned in the title were found to be unreliable. Vamvakad test (ANALYST, 1906, 31, 232), yielded positive results (precipitates with Nessler reagent) with lemonade which was free from saponin and glycyrrhizin, a s well as with other samples containing these two substances; the colour of the precipitates was not characteristic and evidently depended on the presence of sub- stances other than saponin and glycyrrhizin. Frehse's test (ANALYST, 1900, 25, 10) failed owing to the fact that pure saponin is insoluble in ethyl acetate (the solvent recommended for its extraction), and the residue obtained on evaporating the solvent gives no coloration with sulphuric acid. Lemonades containing impure saponin, or so- called saponin, yielded a residue which gave a doubtful reaction with sulphuric acid. w.P. s. Estimation of Saponin and Saccharin in Oil Emulsions. E. Carlinfanti and P. Marzocchi. (Boll. Chinz. Farm., 1911,50,609-615 ; through Chem. Zeiztralbl., 1911, Il., 1488-1489.)-0ne hundred grms. of the oil emulsion are diluted with anFOOD AND DRUGS ANALYSIS 23 equal volume of water, and then gradually treated with 400 C.C. of 95 to 96 per cent, alcohol with constant shaking, which is frequently repeated during two hours, after which it is allowed to stand for twenty-four hours. The clear supernatant liquid is decanted, and the residual fatty mass filtered through linen, again extracted with 60 to 65 per cent. alcohol, and again filtered.The united filtrates are neutral- ised with sodium carbonate and concentrated to 100 C.C. on the water bath. Aromatic compounds are now extracted with ether, and the residual liquid shaken with 20 grms. of sodium sulphate and 9 C.C. of phenol, this treatment being repeated several times, until the whole of the saponin has been extracted by the phenol. The united phenol extracts are then shaken with a mixture of 100 C.C. of ether, 30 C.C. of water and 5 C.C. of alcohol, and left for twenty-four hours, after which the upper layer containing the saponin is separated and evaporated, and the residue extracted with acetone. The ethereal extract, containing the aromatic compounds, is shaken with water acidified with phosphoric acid, the ether evaporated, and the saccharin estimated in the form of alkali salicylate. C .A. M. Separation and Identifieation of Saccharin and Dulcin in Beverages, Foods, and Drugs. S. Camilla and C. Pertusi. (Giorn. Farm. Chim., 1911, 60, 385-393 ; through Chem. Zentralbl., 1911, IT., 1269-1270.)-The material is treated with an excess of barium hydroxide solution, warmed, filtered, and the filtrate extracted with ether after being acidified with sulphuric acid; the saccharin and dulcin crystallise out when the ethereal solution is evaporated. For the identification of these two sweetening materials in the presence of salicylic acid, the sample is mixed with magnesium oxide, evaporated to dryness, and the residue extracted with acetone containing 10 per cent. of water. The acetone solution is filtered, evaporated, the residue dissolved in water, and the solution extracted with ether ; dulcin goes into solution.The aqueous solution is then acidified with sulphuric acid, and the saccharin is extracted by means of a mixture of ether and petroleum spirit Should salicylic acid be present, the aqueous solution containing the saccharin must be evaporated to dryness, the residue dissolved in 10 per cent. sulphuric acid, and the solution treated with an excess of potassium permanganate ; after filtration the saccharin is extracted from the filtrate with a mixture of ether and petroleum spirit (cf. ANALYST, 1910, 35, 436). Alteration of the Acid-Content of Distilled Vinegar when Stored in Wooden Casks. A. Behre. (Zeitsch. Untersuch. Nahr. Genussm., 1911,22,506-509.) -The acidity of a cask of vinegar increased in the course of nine months from 7.10 to 9-12 per cent.; the total solids also increased from 0.30 to 0.39 per cent., and the con- centration of these constituents was evidently due to the more rapid diffusion of the water through the pores of the wood. Further experiments were made in which acetic acid solutions of various strengths were exposed to the atmosphere in glass vessels.I n glass cylinders solutions containing from 7 4 4 to 61.2 per cent. of acetic acid scarcely altered in strength during ten weeks, but when exposed in flasks having narrow necks the more concentrated solutions remained unaltered, whilst those con- taining less than 19 per cent. of acetic acid increased in strength to a slight extent.24 ABSTRACTS OF CHEMICAL PAPERS Considerable changes took place when the solutions were exposed in open beakers ; the stronger solutions lost large quantities of acetic acid, whilst the weaker solutions became stronger.Under these conditions, a vinegar containing 3.17 per cent. of acetic acid was found to have 4.68 per cent. after the lapse of four weeks ; a, solution containing 19 per cent. of acetic acid did not alter in strength; whilst a solution containing 61.2 per cent. lost 2.2 per cent. of acetic acid during this period. w. P. s. Estimation of Phosphorus in Wine. J. Dormane, (Bull. Assoc. Chinz. Sucr. Dist., 1911, 29, 63-67 ; through Chek. Zentralbl., 1911, II., 1376-1377.)-Three samples of Burgundy wine yielded the following results : Total phosphorus (as P,O,), 0.231 to 0.461 ; phosphoric anhydride (P205), 0.160 to 0.390 ; phosphoric anhydride plzis phosphorus in organic combination (as P,O,), 0.205 to 0.422 grm. per litre. The total phosphorus was estimated by igniting the total solids of the wine in the presence of calcium oxide and potassium carbonate ; the phosphoric anhydride (phosphate) by extracting a further quantity of the total solids with cold, dilute hydrochloric acid ; whilst the phosphoric anhydride plus the organically combined phosphorus was obtained by boiling the total solids for two hours with concentrated hydrochloric acid. The solutions were then treated in the usual way for the precipitation of the phosphoric acid. I t is evident that wine contains phosphorus compounds which are not decomposed by hydrochloric acid.

ISSN:0003-2654    

DOI:10.1039/AN9123700018

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

24 ABSTRACTS OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Detection of Albumoses in Urine. E. H. Fittipaldi. (Deutsch. Ned. Woch., 1911, 37, 1890-1891 ; through Chem. Zentralbl., 1911, II., 1489-1490.)- From 10 to 20 C.C. of the urine are treated with six times the quantity of absolute alcohol, and the resulting precipitate separated by decantation after twenty-four hours, and dissolved in the smallest possible quantity of 31 to 32 per cent. sodium hydroxide solution. This alkaline solution is tested with a freshly-prepared ammoniacal solution of nickel (equal parts of strong ammonia and 5 per cent. nickel sulphate solution), and in the presence of albumoses or peptones gives an immediate orange-red coloration. The reaction is not obtained with albumins, uric acid, cyanuric acid, xanthin, hypoxanthin, sarcosin, or urobilin.The method may also be used €or the detection of albumoses in blood, after the latter has been heated with animal charcoal, cooled, and filtered. The reaction is not given by C-deutero- albumose or A-peptone, but neither do these bodies give the biuret reaction. Albu- moses may thus be detected in urine in cases of albuminuria, especially when large amounts of albumin are excreted. This is attributed to the presence of proteolytic enzymes in the urine. C. A. M. Application of the Biochemical Method to the Analysis of Uva-Ursi Leaves. A. Fichtenholz. (J. Pharrn. Chzim., 1911, 4, 441-446.)-The leaves of Arctostaphylos Uua-ursi are the source from which the glucoside srbutin is extracted commercially.The biochemical method, depending on the hydrolysis of the arbutinBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 25 b y emulsin after the extract has first; been subjected to the action of invertase, may be applied advantageously to the analysis of the dried leaves. The leaves are first extracted with boiling 90 per cent, alcohol, the extract is evaporated to dryness under reduced pressure, the residue is taken up with water, the solution is clarified with basic lead acetate and filtered, the precipitate being washed on the filter. The excess of lead in the liquid is removed by sulphuretted hydrogen, and the solution is then concentrated at a temperature not exceeding 45" C. under reduced pressure. Alcohol is added, and evaporation continued to dryness. The residue is dissolved in thymolated water, the solution is filtered and polarised; the cupric reducing substances calculated as dextrose are also estimated.If the presence of free hydro- quinone is to be feared, this solution should be exhausted by ether ; it is then ready for treatment with enzymes. It is first treated with 0.15 grm. of invertase (top- fermentation yeast, treated with 95 per cent. alcohol and dried), and is digested at 15" to 18" C. for about five days. The flask is then placed in a boiling water-bath for twenty minutes, cooled, and the emulsin (0.15 grm.) is added. During the whole period of digestion samples are taken at intervals and polarised, the cupric- reducing value being also estimated. After the action of the invertase, the IE?VO- rotation of the liquid will have increased, but when the emulsin begins to act the lwo-rotation decreases ; the results are calculated on the assumption that under the action of emulsin a decrease of 60' corresponds to the hydrolysis of about 0.5 grm.of arbutin per 100 C.C. The action may continue over ninety-five days. From the comparative rise in cupric-reducing value, some idea may be obtained of the relative proportion of methyl arbutin also present. J. F. B. Composition of Hens' Eggs. K. Kojo. (Zeitsch. physiol. Chew., 1911, 75, l-2.)-Fluid white of egg was found to contain an average of 87*71 per cent. of water, 11.88 per cent. of organic substances, and 0.4 per cent. of ash; the nitrogen-content was 1-75 per cent., whilst the quantity of dextrose amounted to 0.55 per cent., or 4.64 per cent. calculated on the organic substance.The fluid yolk contained 49-73 per cent. of water, 48.83 per cent. of organic substances, and 1.44 per cent. of ash; 2.49 per cent. of nitrogen, and 0.27 per cent. of dextrose were present. Calculated on the organic substance, the percentage of dextrose was 0.55, a much smaller proportion than was present in the white of egg. Only traces of creatinine were found. w. P. s. Tests for Ascertaining the Freshness of Milk. W. Morres. (Zeitsch. Untevsuch. Nahr. Genussm., 1911, 22, 459-464.)-The alcohol test for milk, which depends upon the fact that milk containing upwards of 8 degrees of acidity (Soxhlet-Henkel) usually curdles when mixed with twice its volume of 70 per cent. alcohol is not always a reliable test of the acidity of milk, as the curdling may be caused by means other than the formation of lactic acid. For instance, milk may be on the point of curdling owing to the presence of rennet produced by bacteria, although it may contain but little free acid.Various strengths of alcohol have been proposed for use in the test, and the author considers that the use of 50 per cent. alcohol will afford useful information. A more stringent test with 68 per cent.26 ABSTR,ACTS OF CHEMICAL PAPERS alcohol may be applied when the milk is intend.ed for feeding infants, etc. The coloration produced when milk is treated with a solution of alizarin in 68 per cent. alcohol gives an indication of the kind of fermentation which has taken place in the milk. Should the milk curdle, but the coloration remain lilac or red, the milk contains only rennet products ; acid formation is shown by a yellow coloration.w. P. s. Relations between the Reductase Test, Acidity, and Alcohol Test in Milk. W. Morres. (Milchw. Zentralbl., 7, 441-445 ; through Chem Zentralbl., 1911, II., 1614.)-The alcohol test in combination with alizarin, which the author calls the alizarol test, gives easily and rapidly the most reliable indication of the degree and nature of the decomposition of the milk. A comparison of the reductase test with the alizarol test showed: (1) That the alizarol test is equivalent to the reductase test both as regards the degree of curdling and the change of colour in t h e case of pure lactic acid fermentation ; (2) that the smallest degree of decomposition which the alizarol test will show definitely (8 degrees of acidity) corresponds to decolorisation time of sixteen minutes at 40" C,, corresponding to more than 20,000,000 germs per 1 C.C.In the testing of milk from a hygienic point of view it is desirable to express the results in terms of its contamination with germs. Milk "rich in germs" would be one which decolorises the test in from five to fifteen minutes at 40" C., whilst '( very rich in germs '' would describe a sample which decolorises in less than five minutes at 40" C. Such milk can be very surely detected by the alizarol test more rapidly than by the reductase test. In the cam of samples poor in germs, which require more than fifteen minutes for decolorising the methylene blue, the reductase test is the only practical method for the estimation of the approximate contamination with germs.As to the nature of the bacteria, present, the fermentation test, or the fermentation-reductase test, of Orla-Jensen affords further information. Since, in practice, the carrying out of the reductase test at 40" C. presents certain difficulties, the author recommends that the test be performed at about 20" C., and the results calculated at 40" C. by multiplying them by +. J. F. B. New Method for Determining the Tryptic Value of Pancreatin. C. F. Ramsay. ( J . Iizd. and Eng. Chem., 1911, 3, 822-823.)-The United States Pharmacopaeia method for determining the tryptic value of pancreatin is unsatis- factory owing to the uncertainty of the end reaction, and consists in finding the amount of enzyme preparation capable of peptonising milk to such a degree that no coagulation follows the addition of nitric acid.The results depend on the amount of acid used, since a little acid gives no precipitate; more acid will always give a precipitate, and still more acid redissolves it. However long the digestion, acid will always cause a precipitation in peptonised milk. The author's method consists in finding the amount of the enzyme preparation which in fifteen minutes will so peptonise milk that no coagulation or precipitate is formed on the addition of slightly acidified rennin solution. The milk is rendered slightly alkaline with sodium bicarbonate to prevent the pancreatin curdling the milk. The materials required are :BACTERIOLOGICAL, PHYSIOLOGICAL, ETC.27 (1) 0.5 grm. pancreatin diluted to a volume of 50 C.C. with distilled water, (2) 900 C.C. milk containing 1-8 grm. of sodium bicarbonate; and (3) 2 grms. of rennin Rnd 1 C.C. of 6 per cent. acetic acid (U.S.P.) added to 50 C.C. of distilled water. The pancreatin is first tested at wide ranges of strength, such as 1 grm. to 700 C.C. milk or 1 grm. to 1,000, and a second series is then carried out over a, narrower range. I n each of several tubes of 100 C.C. capacity are placed 50 C.C. of the milk ; the tubes are placed in a bath at 40" C., and varying volumes of the enzyme preparation are added corresponding to (say) 1 in 600, 1 in 650, 1 in 700, etc. After fifteen minutes' digestion, 5 C.C. of the digested milk are withdrawn, 3 C.C.of the rennin solution added, and the whole well shaken. No precipitation indicates that the casein is all peptonised, and the enzyme is stronger than the dilution tested. The amount of acid in 3 C.C. of the rennin solution will exactly neutralise the amount of bicarbonate in 5 C.C. of the milk; the rennin then acts under favourable conditions, since no precipitate is formed in an alkaline solution. Pancreatin in neutral solutions deteriorates rapidly, and consequently should only be made up immediately before use. The author claims an accuracyof 2 to 3 per cent. for the method, and suggests a standard of 1 to 800 or 1 to 1,000 as being a, suitable strength for pancreatin pre- parations. Commercial samples showed variations of from 1 to 120 to 1 to 1,750. H.F. E. H. Estimation of Urea. Desgrez and Feuillie. (Comptes rend., 1911, 153, 1007-1010.)-The following modification of Bouchard's method, which is based upon the decomposition of urea by Millon's reagent- CH4N,0 + HNO, + HNC, = N,+ CO, + NH4N0, + H,O -is rapid, and requires only simple apparatus. The ureometer is immersed in a, cylinder containing chloroform or carbon tetrachloride, and having round its exterior a metal band with a projection, which may be heated. After the lower part of the ureometer has been filled with chloroform, there are introduced successively 1 C.C. of the urine, about 5 C.C. of water, and 8 to 10 C.C. of Millon's reagent, and the chloro- form is then brought to 30" to 35" C. by heating thc metal projection. Decomposition of the urea is effecked within twenty to twenty-five minutes by shaking the ureometer from time to time.As soon as the volume of gas ceases to increase, the tube is transferred to a cylinder of water, and the gas washed with sodium hydroxide and water, after which the tube is removed to a second cylinder of water, where the last traces of carbon dioxide are removed, and a final washing is given before measuring the quantity of nitrogen. If the temperature of reaction is not allowed to exceed 35' C., no decomposition of ammonium salts, uric acid, amino acids, creatin, creatinin, hypoxanthin, xanthin, tyrosin, leucin, or guanin takes place. Allantoin, however, begins to decompose at that temperature ; but since human urine contains only about 0.014 grm. of that substance after twenty-four hours, this does not interfere with the applicability of the method to human urine, whatever the case may be with herbivora.The non-dialysable substances extracted from several litres of urine did not yield m y trace of nitrogen when treated with Millon's reagent under the conditions of the estimation. C. A. M.28 ABSTRACTS OF CHEMICAL PAPERS Urobilinogen of Urine and Ehrlich’s Reaction for Aldehydes. H. Fischer and F. Meyer-Betz. (Zeitsch. physiol. Chew., 1911, 75, 23%26l.)-The crystalline urobilinogen which may be separated from pathological urine is identical with hemibilirubin. Non-stabile pyrroles (dimethylpyrrole, hsmopyrrole, phonopyrrole, carboxylic acid, etc.), to which class of substances belong the crystalline blood- pigment derivatives and the bile-pigment derivatives, are converted in the body into urobilin, and all these pyrroles give a reaction with Ehrlich’s reagent (p-dimethyl- aminobenzaldehyde in hydrochloric acid solution). After the administration of these substances, a positive reaction does not necessarily denote the presence of urobilinogen and urobilin in urine ; at the same time, urine may contain considerable quantities of urobilinogen and fail to give a reaction with the test. The substance which yields the reaction with Ehrlich’s reagent is a dipyrrylmethane colouring- matter derived from the leuco-bases. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700024

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

28 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Champaca Oils. B. T. Brooks. ( J . Anzer. Chem. Xoc., 1911, 33, 1763-1772.) -A quantity of the yellow flowers of MicheZia champaca L. yielded 0.37 per cent. of an oil containing phenyl-ethyl alcohol (free and as ester), cineol, iso-eugenol, benzyl alcohol, benzaldehyde, and benzoic and acetic acids, with a small quantity of a fluorescent substance (? methyl anthranilate). The oil had the following characters : I. 11. Sp. gr., 3Oo/3O0 C. ... ... 0.9040 ... 0.9107 Refractive index [n],, 30" C. ... 1.4640 ... 1.4688 Ester number after acetylation - ... 199.0 Ester number ... ... ... 124.0 ... 146-0 On standing, the oil deposits comparatively large quantities of a crystalline unstable ketone, melting at 165" to 166" C., and optically active ([u: 30" C.= - 82.5' in alcohol). The white flowers of champaca (MicheZia Zongifolia L.) yielded 0.08 per cent. of an oil free from fluorescence, and containing linalol, the methyl or ethyl ester of methylethyl-acetic acid, and methyl-eugenol. No crystalline ketone was present. The oil had the following characters : Sp.. gr., 30"/30" C. ... ... ... .., 0.897 Ester number ... ... ... ... ... 180 Refractive index [n],, 30" C. ... ... ... 1.4470 The flowers of both species of Michelia contain an oxidase. A. R. T. Behaviour of Invert Sugar in the Presence of Alkali and Hydrogen Peroxide. A. Jolles. (Biochem. Zeitsch., 1911, 36, 389-393.)-When a 2 per cent. invert sugar solution in + N sodium hydroxide solution is treated with an excess of hydrogen peroxide, and heated to a temperature of 317" C., the optical rotation of the sugar diminishes gradually.After an hour or so the rotation becomes nil, then slightly dextro-rotatory, and finally nil again. This is due to the laevulose being more rapidly oxidised than the dextrose. w. P. s.ORGANIC ANALYSIS 29 Analysis of Lactic Acid. A. A. Besson. (Chem. Zeit., 1911, 35, 1209-1210.) -In the estimation of anhydride in commercial lactic acid it is sufficient to add an excess of 2-5 C.C. of sodium hydroxide solution to the neutralised lactic acid (1 grm.), allow the mixture to stand for ten minutes, neutralise the alkali, and to heat the solution just to boiling with an excess of 1 C.C. of p sulphuric acid in order to obtain the quantity of anhydride present (cf.ANALYST, 1911, 36, 235, 556). w. P. s. Determination of Malic Acid. P. B. Dunbar and R. F. Bacon. (J. Ind. and Eng. Chem., 1911, 3, 826-831.)-The authors have worked out a polarimetric method for the estimation of malic acid on similar lines to that described by Yoder (ANALYST, 1911, 36, 498), based on the increase of rotation produced by the addition of uranyl acetate. The acidity of the solution is first titrated on a, separate portion with standard alkali in presence of phenolphthalein; 75 C.C. of the solution are then placed in a 100 C.C. flask, together with the requisite quantity of standard alkali; if dark in colour, 10 C.C. of alumina cream are added, the liquid is made up to the mark and filtered. Twenty-five C.C. of the filtrate are treated with sufficient powdered uranyl acetate, so that a small amount remains undissolved after two hours; 2.5 grms. are generally sufficient, unless the quantity of malic acid is large.After two hours with frequent shaking, the solution is filtered and polarised, if possible, in the 200 mm. tube. The remainder of the original filtrate is treated with powdered lead acetate until no further precipitation results. The liquid is cooled in ice, and filtered clear ; the filtrate is rewarmed to the ordinary temperature, and a crystal of lead acetate is added to determine whether precipita- tion is complete ; if so, the excess of lead is removed by anhydrous sodium sulphate, and the liquid is filtered and polarised, the result being called reading (2). The lead acetate precipitates the malic acid, but as lead malate is soluble in excess of lead acetate, care is necessary in performing this operation.Solutions which contain loss than 10 per cent. of reducing sugar may be polarised without treatment with lead. If reading (2) is negative, a portion of this solution is treated with uranyl acetate as above described and polarised; this is called reading (3). If (2) is positive, reading (3) need not be made. All readings are made with white light on the Ventzke scale, and calculated for the 200 mm. tube. If reading (3) is less numerically than reading (2), reading (3) is accepted, otherwise reading (2) is used. Then the algebraic difference between reading (2) or (3), whichever be used, and reading (1) is multiplied by the factor 0.036, and the product represents the percentage of malic acid in the solution polarised.For this determination the most favourable limits of concentration lie between 0.2 and 2.5 per cent. of malic acid ; the error seldom amounts to more than 5 per cent. of the malic acid present. Reading (3) is intended to correct the slight lowering effect of uranyl acetate on the rotation of the sugars. If less than 10 per cent. of reducing sugar and more than 0.25 per cent. of malic acid be present, reading (3) may be dispensed with; in presence of large amounts of sucrose, reading (2) gives better results than reading (3) The method cannot be used for the estimation of malic acid if d-tartaric acid be also present. J. F. B. The result is called reading (1).30 ABSTRACTS OF CHEMICAL PAPERS Fluorescence Test for Mineral and Rosin Oils.P. H. Walker and E. W. Boughton. (J. Ind. and Eng. Chem., 1911, 3, 816.)-The Outerbridge method for the detection of mineral and rosin oils in fatty oils is based on the observation that the fluorescence of mineral and rosin oils is greatly magnified by per- forming the examination by the light of an enclosed electric arc, and that samples which appear non-fluorescent in sunlight become strongly fluorescent when observed in the proper light. The test may be made quantitative by comparison with a set of standards. The authors have confirmed the fact that the light of an enclosed arc has the effect described, but they show that fluorescence in an oil does not necessarily prove the presence of mineral or rosin oil.Out of sixteen samples of linseed oil of authenticated purity, only eight showed no fluorescence, three showed slight fluores- cence, and five showed marked fluorescence. A number of other samples of fatty oils of known purity, some having been cold-pressed from the seed, showed marked fluor- escence, in some cases as strong as that of many mineral oils. A pure linseed oil which showed no fluorescence was heated to 300" C., and, after cooling, was found to be strongly fluorescent. I n the case of turpentine oils also, many show nc fluorescence; some known to contain mineral oil likewise show no fluorescence, whilst others, certainly pure, show marked fluorescence. J. 3'. B. The same occurred with a pure olive oil after heating. Catalytic Action of Light on the Oxidation of Phenolphthalin to Phenol- phthalein.G. Rossi. (Giorn. Farm. Chzim., 60,433-436 ; through Chem. Zentralbl., 1911, II., 1659.)-Phenolphthaleln is reduced by nascent hydrogen to phenolphthalin. The reversed,reaction is used by the author for the detection of blood. Hydrogen peroxide is employed as the oxidising agent ; any blood which may be present acts as a catalyser ; in the absence of blood the oxidation is extremely slow and only takes place after some days. The procedure is as follows : An alkaline solution of phenol- phthalein is decolorised by shaking with zinc dust, the solution is filtered and added, together with a few C.C. of 12 per cent. hydrogen peroxide, to the liquid to be tested. If blood be present, a pink or red coloration will be developed within three hours.The prolonged action of light will also bring about a similar acceleration of the oxida- tion of the phenolphthalin. According to the author's experiments the light of an electric arc will cause the liquid in a sealed tube to turn red within two hours. J. F. B. Colorimetric Estimation of Phenols in Effiuents. H. Baeh. (Zeitsch. anal. Chem., 1911, 50, 736-740.)-Small quantities of phenols in effluents--e.g., from coke by-product plants, etc., may be estimated colorimetrically, in absence of salicylic acid, by means of Millon's reagent. As a preliminary test, 10 C.C. of the effluent, 0.2 C.C. of Millon's reagent, and 0.1 C.C. of strong nitric acid are heated to boiling-point in a test-tube, in such a way that none of the liquid spurts up.If a faint pink or pale red coloration is developed, the effluent is fit for the test ; if it shows deep red it must be suitably diluted, and if only a faint yellowish-colour is developed, 100 C.C. of the water are treated with 5 C.C. of concentrated sulphuric acid, and 20 C.C. are distilled off, of which 10 C.C. are tested. If the last case indicates that a, concentration of theORGANIC ANALYSIS 31 phenol is required, 1 litre of the efluent is made alkaline with 5 to 10 C.C. of strong caustic potash lye and evaporated t o 50 C.C. The residue is placed in a flask, cooled, acidified with 10 to 20 C.C. of strong sulphuric acid, diluted to 150 c.c., and 100 c.c are distilled over ; the phenol is thus concentrated ten times. For the colorimetric test, the above-mentioned quantities of the effluent and reagents are heated in a test- tube as described; if the coloration is yellowish to pale pink, 0-2 to 0.7 mgrm.of phenol is present in 10 C.C. ; if pale pink to medium red, 0.8 to 1.8 mgrm. ; and if medium to deep red, 1-8 to 3 mgrms. These colours change on cooling, but the above indications are sufficient for the preparation of the standard tests, which are made up in a similar manner with a solution containing 0.1 mgrm. of pure phenol per 1 C.C. No comparisons are made until all the tubes are quite cold ( i e . , after half an hour), when the colorations become stable and remain fixed for several hours. Comparisons should be made against a white ground both by reflected and transmitted light. With some practice, the quantity of phenol may be estimated with an accuracy of a few mgrms.per litre, unless the effluent is extremely dilute. J. F. B. Estimation of Water in Soap. R. M. Fitzpatrick. (Chem. News, 1911,104, 247.)-One grm. of the soap is treated with 50 C.C. of absolute alcohol, a fragment of porous tile added, and the liquid heated on a water-bath under a reflux-condenser till solution is complete. After partial cooling, the liquid is filtered through filter-paper, the soap, etc., remaining in the flask being transferred to the filter by the addition of 20 C.C. of absolute alcohol and warming, and the residue on the paper also washed with absolute alcohol. The residue on the paper is dried and weighed, and the amount of alcohol-insoluble matter thus found. Five grms. of anhydrous sodium sulphate are next added to the cold filtrate, and the closed flask allowed to stand for a t least twelve hours. If the solution shows any tendency to form soap jelly, more alcohol must be added before the sodium sulphate is put in. The solution, after standing, is filtered into a flask weighed with a small portion of porous tile, and the sodium sulphate washed several times with warm absolute alcohol. The alcohol is evaporated off, the residual soap dried for fifteen minutes at 100" C. and weighed. The weight of anhydrous soap, plus the weight of alcohol-insoluble matters, subtracted from the weight of soap taken, gives the weight of water in the soap. A. R. T. Qualitative Reactions of Vegetable Tannins. E. Stiasny and C. D. Wilkinson. (Collegizrm, 1911,318-324,325-333 ; through Chem. Zentralbl., 1911, II., 1384-1386.)-The behaviour of some thirty-four different tannin solutions towards various reagents is described ; amongst the latter were ammonium acetate, tartar emetic, lead acetate, bromine, copper sulphate and ammonia, and formaldehyde.

ISSN:0003-2654    

DOI:10.1039/AN9123700028

出版商:RSC    

年代:1912

数据来源: RSC