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MAY, 1912. Vol. XXXVII., NO. 434. THE ANALYST. OBITUARY. ARTHUR EDWARD EKINS, J.P., F.I.C. ARTHUR EDWARD EEINS, whose death on March 12 was briefly recorded in our last number, was one of the early members of the Society of Public Analysts. He was the son of a farmer in the Fen country, was .born in the Isle of Ely in 1852, and educated at St. Ives Grammar School and at Melbourn, Cambridge. He was originally trained for pharmacy, and in 1876 established a pharmaceutical business at St. Albans. In conjunction with this he carried on an analytical practice, chiefly in connection with agricultural matters, as Analyst to the Herts Agricultural Society. On the death of Charles Heisch, the County Analyst, in 1892, Mr. Ekins was appointed Public Analyst for the County under the Sale of Food and Drugs Act, shortly after which he retired from his pharmacy in order to devote himself more fully to his profession&l duties, as well as to the municipal work of the Corporation of St.Albans, in which he had always taken an active part. He occupied the position of Mayor of the City in the year of King Edward’s Coronation, and it is recorded that during his mayoralty he attended in his official capacity no fewer than 600 meetings. I n addition to working constantly on the various committees of the Corporation (including the Library Committee, the Assessment Committee, and the Pensions Committee), he laboured assiduously as a Magistrate, Poor Law Guardian, Overseer, Churchwarden, and Manager and Treasurer of tbe local Christ Church School, He also held the position of Chairman of the local County Council School Managers, of the Joint Committee of the Sisters’ Hospital and of the St.Albans Building Society. He took a, prominent part in the masonic life of the county, in which he held honours as a, Provincial Grand Officer. All these forms of civic and social activity left him but little time for active con- tribution to the advancement of chemical knowledge by original work, but he did his work as County Analyst conscientiously and effectively, his duties extending to the annual examination of a considerable number of water samples and sewage farm effluents, in addition to his routine work under the Sale of Food and Drugs Act. I t was very rarely that Mr. Ekins missed his attendance at the monthly meetings of the Society of Public Analysts or at the social gatherings connected with them. He served the Society not only as a member of Council, but as Vice-President, in which166 OBITUARY : JOHN PATTINSON capacities his assiduous attendance at both Council and Committee meetings was rendered the more useful by reason of the sound judgment and business ability which he always brought to bear on the matters under discussion.H e had, moreover, a high sense of professional honour, which gained for him the respect and esteem of his colleagues, while his geniality and kindheartedness equally won their personal affection. BERNARD DYER. JOHN PATTINSON, J.P., F.I.C. JOHN PATTINSON was born at Alston, in Cumberland, on February 13, 1828. His schooldays were spent in his native town, and, as a youth, he was brought to Newcastle by his distant relative Hugh Lee Pattinson, well known as the inventor of the Pattinson process for desilverising lead.Hugh Lee Pattinson was a proprietor of the Felling Chemical Works, and there John Pattinson received his early chemical training. He remained there for ten years, and then went to Middlesbrough, under another north-country leader of industry, Isaac Lowthian Bell, He thus obtained a first-hand knowledge of the processes involved in the alkali manufacture, and in the iron and steel manufacture of the time. I n 1858 he returned to Newcastle, and took over the practice of analytical and consulting chemist of William Crowder, in the Side, out of which the present firm of J. and H. S. Pattinson has developed.I n 1868, along with other devotees of chemical science in the town and district, he took part in the foundation of the Newcastle Chemical Society; he was treasurer of that Society until the date of its absorption into the Society of Chemical Industry in 1882, president in 1874-5, and contributed to it papers on the determination of peroxide of manganese, on the quality of the small coal used on the Tyne, on the determination of arsenic in copper, and on other subjects. When the British Association met in Newcastle in 1863, he read a paper on the pyrites used on the Tyne. His practice dealt largely with iron and manganese ores, and in 1879 he read a paper (J. Chern. SOC., 1879, 365) on the determination of manganese, describing a volumetric method which, with slight modifications (described in J.SOC. Chem. Ind., 1891,10,333), is still widely used, and is probably the most accurate method known. Several other papers and notes appear under his name, alone, or in association with his son the late Dr. H. S. Pattinson or with Dr. Dunn, in the Society of Chemical Industry’s Journal. H e was one of the earliest of Public Analysts ; he was appointed Gas and Water Examiner for Newcastle in 1863 or earlier, Food Analyst in 1871, and later became, under the Food and Drugs Acts, Public Analyst for the town, for the county of Northumberland, and for other boroughs in the district. He had been a Vice- President of the Chemical Society, and Vice-president of this Society; was an original Fellow of the Institute of Chemistry, which he had served as member of Council and as Censor ; and an original member of the Iron and Steel Institute. He was an enthusiastic musician, was a Vice-president of the Newcastle Literary and Philosophical Society, a justice of the peace, and greatly interested in social and philanthropic matters.He kept up all his interests, professional and other, to the last ; and after only a few days’ illness he died on March 28 last. J. T. ‘DUNN.OBITUARY : EDWARD DIVERS 167 EDWARD DIVERS, M.D., F.I.C., F.R.S. EDWARD DIVERS was born in London in 1837, and was educated at the City of London School. He subsequently studied chemistry under Professor A. W. Hofmann at the Old College of Chemistry, Oxford Street, and in 1866 he graduated as M.D., at Queen’s College, Galway.He was in private practice until 1873, when, at the invitation of the Japanese Government, he, with other Englishmen, went to that country to establish a College of Engineering, This College ultimately became part of the Imperial University, and Divers was appointed Professor of Chemistry. I n 1886 he retired, and was made Emeritus Professor ; he received the second class of the order of the u Sacred Mirror,’’ and the third class of the order of the ‘‘ Rising Sun.” On his return to England he at once took an active part in the affairs of the Chemical Society and the Society of Chemical Industry. I n 1893 he was elected a Fellow of the Royal Society. The name of Divers will always be associated with the subject of the oxides of nitrogen and sulphur, and with hyponitrites, of which he was the discoverer. I n conjunction with Shimose, he was the first to show that when tellurium monoxide is heated in hydrochloric acid gas, it is converted into tellurium dichloride. Divers will be missed by a, wide circle of friends, for his charming personality, kindliness, and urbane manners endeared him to many. He died on April 8.

ISSN:0003-2654    

DOI:10.1039/AN9123700165

出版商:RSC    

年代:1912

数据来源: RSC

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OBITUARY : EDWARD DIVERS 167 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE Monthly Meeting of the Society was held on Wednesday evening, April 3, in the Chemical Society’s Rooms, Burlington House. The President, Mr. L. Archbutt, F.I.C., occupied the chair. The minutes of the previous Ordinary Meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messrs. L. Goodban, A.I.C., and R. F. Easton were read for the second time, and certificates in favour of Messrs. Harold Thomas Cranfield, Assistant Lecturer in Chemistry and Assistant Analyst at the Midland Agricultural and Dairy College, Kingston, Derby; Ernest Gabriel Jones, M.Sc. (Victoria and Liverpool), F.I.C., City Laboratories, 36, Dansie Street, Liverpool, Deputy Public Analyst and Deputy Agricultural Analyst for the City of Liverpool; and William Henry Roberts, M.Sc.(Victoria and Liverpool), F.I.C., City Laboratories, 36, Dansie Street, Liverpool, Public Analyst for the City of Liverpool, and the County Boroughs of Blackburn, Preston, Bootle, and Barrow-in-Furness, Official Agricultural Analyst for the City of Liverpool and Borough of Bootle, were read for the first time.168 H. DROOP RICHMOND AND HORACE C. HUlSH: Messrs. M. E. Balston, M.A., H. A. Caulkin, B.Sc., F.I.C., and C. R. Wilkins, B.Sc., were elected members of the Society. The following papers were read : I‘ The Separation of Arsenic from Antimony,” by Stanley W. Collins, B.Sc., F.I.C. ; ‘6 The Estimation of Ferric Iron in Presence of Certain Organic Substances,” by John Theodore Hewitt, M.A., D.Sc., Ph.D., F.R.S., and Gladys Ruby Mann ; (‘ The Relation of the Kirschner and Polenske Values in Margarines containing Cocoanut or Palm Kernel Oils,” by E. Richards Bolton, EL Droop Richmond, F.I.C., and Cecil Revis ; Note on the Milk of a Small Herd,” by Edward Russell, B.Sc., F.I.C. ; and 6‘ A Convenient Apparatus for Obtaining an Average Sample of Gas and for Regulating the Flow of a Gas into an Evacuated Vessel,” by Frank Sturdy Sinnatt.

ISSN:0003-2654    

DOI:10.1039/AN9123700167

出版商:RSC    

年代:1912

数据来源: RSC

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168 H. DROOP RICHMOND AND HORACE C. HUlSH: THE SOURING OF MILK. BY H. DROOP RICHMOND, F.I.C., AND HORACE C. HUISH. (Read at the AIeeting, February 7, 1912.) PART I.-METHOD USED. THE rate of souring of milk is determined by a series of acidity estimations a t intervals, and depends on the difference in the acidity at a given interval from that at the commencement; as milk is a substance in which the concentration of the hydrogen ions is low, the end reaction with the most convenient indicator-phenol- phthaleln-is not very sharp. We have taken the point of neutralisation to correspond with the appearance of a faint pink colour, but we find that under varying conditions of light, and to the eyes of different operators, there is an appreciable variation in the end-point ; between two or more experienced operators who have learned to appreciate the point at which a very faint pink colour appears there may be a difference of as much as 2", and this difference may increase sometimes up to 5' with operators of less experience.Even the same operator does not always make very concordant duplicate determinations if the con- ditions differ. Even using a blank, we do not find that the accuracy of the determination is greatly increased, and we have experimented in several directions with a view of increasing the accuracy of this determination. By colouring the milk faintly green (the colour complementary to pink), it was found that the accuracy was slightly, though not very markedly, increased, especially if a green- tinted blank were used ; but after a prolonged experience of this method we came to tbe con- clusion that it was wrong in principle to try and work from a colour, but that the best method would be to endeavour to work to the appearance of a definite tint.We find that, although the colour given by rosaniline to milk is not exactly the same tint as that yielded by phenolphthalein when made alkaline, it is in very dilute solution sufficiently near to enable it to be used as a standard tint, and theTHE SOURING OF MILK 169 method we now employ is this : Eleven C.C. of the milk to be tested is placed in each of two similar beakers, and to one, which serves as the standard tint, one drop of a 0.01 per cent. solution of rosaniline acetate in 96 per cent. alcohol is added; to the other 1 C.C.of a 0-5 per cent. solution of phenolphthaleln is added, and the milk is titrated with & strontia solution till its tint is equal to that of the standard. The result expressed as cubic centimetres of normal alkali per litre we term '' degrees of acidity" (rosaniline standard), or, more shortly, R. S. We find that nqt only do different operators obtain closely concordant results, but that the nature of the light makes no difference in the end-point. The results are about 1.5" higher on the average than those obtained when titrating to the appearance of a faint pink colour. By the use of the rosaniline standard we have far more confidence in the accuracy of the determination of small increases in acidity, and we may mention incidentally that the accuracy of the determination of the aldehyde figure, which depends likewise on a difference between two titrations, has also been increased.PART II.-THEORETICAL CONSIDERATIONS. In endeavouring to trace the course of the souring of milk we have made certaio assumptions. The first is that it is due to micro-organisms, or that, if due to enzymes secreted, these do not diffuse away from the micro-organisms ipto the liquid ; or, in other words, the amount of acidity produced at any moment id pro- portional to the micro-organisms present at that moment. The second assumption is that the rate of diffusion of the acid produced away from the micro-organisms is rapid compared with the rate of production. These assumptions lead us to the differential equation : (1) dm = kda . . .. . . . . (m = number of micro-organisms ; a = acidity.) If we make the further assumption that the increase in the number of micro- organisms is proportional to the number present at any moment, we may write from this assumption and from (1) the differential equation . . . . . . . da = k'adt (2) (t = time), which leads to the equation which leads to a simple logarithmic curve for the souring of milk. each micro-organism produces acid at a definite rate, the differential equation results, leading to the equation which shows a straight line as the curve. log a=lr't+c . . . . . . (3), On the assumption that no increase of micro-organisms takes place, but that . . . . . . . . da=k"dt (4) a = k t + c ' (51, . . . . . . . If we assume that the micro-organisms do not increase, and that the rate of170 H.DROOP RICHMOND AND HORACE C. HUISH: production of acidity falls off in proportion to the amount of acid already developed acting for a unit of time, we arrive at the differential equation da=k'"Edt t . . . . . (6), which on integrating gives us- loga=k"'log t+c" . . . . (7). The curve of this equation is a parabola, though not necessarily a rectangular parabola. PART 111.-EXPERIMENTAL. From the mean of a very large number of acidity determinations at known periods of time we have constructed the table below. This shows the acidity developed at intervals of five hours from the time of milking, when the milk was kept at a temperature of 68" F. There has frequently been a difference of several units in the acidity developed in different samples, but by averaging the results of a large number we believe we have obtained a fair representation of the average souring of milk.Average Souring of Milk. Time in Hours. 10 15 20 25 30 35 40 45 50 55 Acidity. 0 0.1 0.3 2.3 6.0 13.0 30.0 50 62 67 Calc . 0-2 0.5 1.1 2.5 5.7 13.1 29.9 50.5 61.1 66.8 Time in Hours. 60 65 70 80 90 100 110 120 130 140 Acidity. 71 74 76.5 82 85 88 91 93 95 97 Calc. 77.1 74.3 77.1 81.5 85.0 88.9 90.7 93.1 95-2 97.0 The formula used for calculating the acidity up to 45' acidity is log,, a= 0.072 t - 1.406, which is of the type of (3) ; and that used after 45" is log,, a = 1.621 + 0-184 log (2 - 42*2), which is of the type of (7). It is interesting to note that these two curves do not meet, indicating that there is a short period during which another curve, possibly of the type of (5), expresses the results.The change from one branch of the curve to another is quite sharp, and takes place at 45O, which is the point at which micro-organisms cease to develop in milk (cf. Revis and Payne, J. Hygiene, 3906, 216) ; there is no other break in the curve, that mentioned by one of us and Miller (ANALYST, 1907, 32, 144) at 65O not having a, real existence. To try and elucidate this sudden change in the rate of souring of milk at the point when an acidity of 25O has been developed, we have made 8 number of careful experiments in which continuous observations were made over a period of forty-eightTHE SOURING OF MILK 171 hours, determinations in some cases being made hourly. I t will not be necessary to give these experiments in full.The following is an abstract of the results : 1. In three series of experiments in which milk to which a definite amount of alkali had been added, and milk to which a definite amount of acid had been added, were allowed to sour side by side, it wag found that the point at which the break occurred was advanced or retarded by an amount equal to the quantity of acid or alkali added. Thus, a milk with an acidity of 18.2' was reduced in acidity to 3.3' by the addition of caustic soda, and increased to 2 8 ~ 6 ~ by the addition of hydrochloric acid. The points at which the breaks occurred were 45", 60', and 34O, respectively. 2. It was found in every case that the addition of alkali slightly accelerated the rate of souring, and that of acid slightly retarded it, but to a very small extent.3. Experiments on pasteurised milk to which either pure cultures of lactic organisms or a little stale milk was added showed a greatly increased rate of souring. The greatest acceleration of souring was shown by a sample of milk which was allowed to become partially sour, and was then neutralised with soda, and paeteurised, and inoculated with a trace of the unpasteurised milk. 4. I t was found that in every case, no matter what the rate of souring, the curves were very similar. There were, however, slight differences (best seen on plotting out the logarithms of the acidity against time), In some cases a distinct acceleration of the rate of souring was seen, and in others a very distinct retardation.From them results we conclude that- (a) On growing in milk the organisms developing acidity become more active. (6) The organisms are retarded by the acidity they develop, and in the majority of cases this retardation is balanced by the acceleration due to their growing in milk. (c) At an acidity equal to 45O the retardation becomes very great. The point 45' of acidity depends on the nature of the salts present in milk, as in whey it is about 30°, and in a lactose solution about 20". I t is probable that these acidities represent the same concentration of the hydrogen ions. I t follows as a corollary that the organisms which normally cause the souring of milk are not those whose normal habitat is milk, and it is not improbable that they are of intestinal origin.DISCUSSION. Mr. C. REVIS said that he was glad to hear that the authors did not consider that the ordinary lactic acid organisms found their natural habitat in milk. He (the speaker) had for some time been of opinion that the lactic acid organisms usually found in milk were derived principally from cow-dung, It might be contended that suoh organisms, when found in milk, often came from the udder, but Streptococcus mastitis, which grew in the udder in cases of mastitis, was probably from the same source. One observer, however, considered that lactic acid organisms were derived from the cow's saliva. He thought, however, that the cow-dung was the principal source of the organisms, and that milk was certainly not their natural habitat. The problem from a bacteriological point of view was a very difficult one, there being no172 THE SOURING OF MILK means of ascertaining at any moment how many organisms were present in the milk, how many were active, or at what rate they were dying out. Grimme, in some work on this subject, had obtained curves identical with those obtained by the present authors, shewing that there was at first no measurable increase in acidity, although the organisms must have been multiplying.Was there a stage in the life of the organism which had to be reached before it exercised a certain activity, which after- wards gradually decreased? At the point at which there began to be a decrease in the rate of acid production, it might be that the action of the organisms was inhibited by the acid, but he thought it probable that a greater number of them were dyingout at the same time, and that the decrease in acidity might be due simply to the fact that more of the organisms were caused to die off through the acidity they produced than were being produced by multiplication of those still active.He had found with B. coli that the activity of that organism and the results it produced were profoundly affected by slight changes in reaction of the nutrient medium. The lactic acid organisms were undoubtedly very sensitive to the acid they produced, for if a culture were left for a fortnight or three weeks it would become absolutely sterile. With a pure culture the problem was simpler, but if lactic acid organisms were grown in the presence of other organisms common to milk which did not themselves produce acid, the rate of acid production by the lactic acid organism was often much modified.It had to be remembered that ,up to the point of coagulation of the milk the organisms were not exposed to the same acidity as they were after that point. The lactic acid at first w a ~ neutralised by the calcium in combination with the casein, and although the casein exerted an equivalent chemical activity, it might not be equivalent bacteriologically, and so be less inimical to the development of the organisms. Dr. LESSING mentioned that a method had been published by Dr. Schryver and himself some years ago for measuring bacterial reactions of this kind by means of electrical conductivity. They had found it possible, when the action of the bacteria was inhibited by antiseptics, to see whether the changes went on, and so to ascertain whether the action was due to enzymes alone, or to bacteria alone, or to both toget her. ThePREsIDENT asked whether the Rhape of the curve was not a good dealdependent on the conditions of the experiment. Mr. RICHMOND said that the curve was always of the same shape, whatever its conditions, though its dimensions sometimes varied. The period during which no increase in acidity was indicated was determined by the point at which it was possible to detect acidity. Personally he did not think that less than degree could be detected with certainty, and it was an appreciable time before so much acid as that was produced, so that the production of acid might be going on at its regular rate for some time before it was possible to know anything about it. They had had in mind the method of Dr. Lessing and Dr. Schryver, and intended to make use of it as soon as they could obtain the apparatus and had had sufficient experience of its use.

ISSN:0003-2654    

DOI:10.1039/AN9123700168

出版商:RSC    

年代:1912

数据来源: RSC

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THE ESTIMATION OF AMMONIA IN CARBONATED WATERS 173 THE ESTIMATION OF AMMONIA IN CARBONATED WATERS. BY G. D. ELSDON, B,Sc., A.I.C., AND NORMAN EVERS, B.Sc., A.I.C. (Read at the Meeting, March 6, 1912.) DURING the examination of a series of samples of soda water, our attention W&B drawn to the smallness of the figures which we obtained for free ammonia, even in those waters which contained considerable quantities of dbumenoid ammonia. Only four out of twenty samples contained any free ammonia at all, and of these 0.005 part per 100,000 was the highest. Some typical results are shown in Table I. TABLE I. Sample. A ... ... a , . . I . ... B ... ... .I. ... ... c ... ... ... ... ... D ... ... ... ... ... E ... ... ... ... ... F ... ... ... ... ... Parts per 100,000. Albumcnoid Ammonia.I Free Ammonia. 0~000 0-000 0~000 o*ooo 0-002 0.005 0-040 0.011 0.007 0.009 0.005 0.006 For the estimation of free ammonia, the contents of two syphons were trans- ferred to a Winchester quart, the whole thoroughly shaken to remove the gas, and the ammonia estimated in the nsual manner in 500 C.C. One C.C. of Nessler solution was used to 50 C.C. of distilkte, the Nessler solution containing : Potassium iodide, 6-0 per cent. ; mercuric chloride, 2.5 per cent. ; potassium hydroxide, 15.0 per cent. (Frankland, ‘( Thorpe’s Dictionary of Applied Chemistry,” vol. iii., p. 980). In order to find out whether the presence of carbon dioxide in the distillate affects the estimation of free ammonia, a definite amount of standard ammonium chloride solution (1 C.C.= 0*00001 grm. ammonia) was added to an ordinary potable water known to be ammonia free, This water was then carbonated and the ammonia estimated as usual. Several similar estimations were carried out with results as set out in Table 11. TABLE 11. Sample. A ... ... ... ... ... B (1) ... ... ... ... ... B (2) ... ... I . . ... ... c ... ... ... ... ... After Carbonation. I Original Water. 0-004 0.010 0*010 0.020 0.017 0-017 0.001 0-004 0.005 0-003 0.005 0-007I74 G. D. ELSDON AND NORMAN EVERS: The amount of ammonia found in each 50 C.C. of distillate was very unusual- e.g., in the case of sample D (2) the first cylinder contained 0.000, the second 0-006, the third 0.001, and the fourth O*OOO, suggesting that the carbon dioxide, which would be nearly all driven over into the first 50 C.C.of distillate, affects the colour produced by the Nessler reagent. We observed in some cases a transient yellow oolour as the Nessler solution was added to the first 50 C.C. of distillate, but this entirely disappeared on shaking. On adding further quantities of Nessler solution to these cylinders, a permanent colour was produced in some cases; whilst in other cases, after a few moments' standing, a red precipitate appeared which proved to be mercuric iodide. Efect of Carboia Dioxide on Nessler's Reagent.-Ten C.C. of Nessler solution were added to 500 C.C. of water containing 0.060 parts per 100,000 of free ammonia. The usual yellow colour was produced, but, on carbonating, this colour was immed- iately destroyed and, after a few minutes, precipitation of mercuric iodide began.Two series of standards were made up, each containing 0.5, 1, 2, and 3 C.C. of standard amnionium chloride. The first was prepared with ordinary ammonia free water, and the second with carbonated ammonia-free water. I t was found that on adding 1 C.C. of Nessler solytion no colour was produced in any of the cylinders prepared with carbonated water, although the usual gradation was observed in the others; on adding a second C.C. of Nessler solution to the carbonated series, immediate precipitation occurred in all the cylinders. From the above experiments it was quite obvious that the presence of carbon dioxide in quantity seriously affects the colour produced on adding Nessler solution to dilute solutions of ammonia.Our attention was then directed to the quantities of carbon dioxide which would thus interfere. For this purpose a number of cylinders were taken containing a known fixed amount of ammonia and varying quantities of carbon dioxide, the latter being intro- duced by adding suitable amounts of standard acid and standard sodium carbonate. It was found that the presence of carbon dioxide in quantities exceeding about five parts by weight per 100,000 diminishes the colour produced, and that no colour is produced with quantities of carbon dioxide exceeding about 50 parts per 100,000. When the amounb of carbon dioxide present approaches saturation, precipitation of mercuric iodide takes place in a short time. If a larger quantity of Nessler solution is used, the amount of carbon dioxide necessary to affect the colour is greater, but the tendency to precipitation is increased.It seems probable that the effect on the colour is caused by the reduction of the amount of caustic potash present, as hydro- chloric acid in equivalent quantities has a somewhat similar action. The presence of sodium bicarbonate also interferes with this colour in precisely the same way a s carbon dioxide. Modifications Attempted.-In order to get over the above difficulty, the effect of using a Nessler solution of greater alkalinity was tried. Although the results obtained by this method showed a distinct improvement, they were by no means satis- factory. The removal of carbon dioxide by boiling with a slight excess of hydrochloric acid was then tried, the free hydrochloric acid being driven off by evaporation tQ Sodium carbonate has no effect.THE ESTIMATION OF AMMONIA IN CARBONATED WATERS 175 dryness.The residue was dissolved in 500 C.C. of ammonia-free water, and the ammonia estimated as usual. Process Recommended.-Finally we adopted the following method : After removal of as much carbon dioxide as possible by shaking in a Winchester, 500 C.C. of the water are transferred to the distillation flask end 5 C.C. of f sulphurio acid (or more if the alkalinity of the water requires it) are added. Fifty C.C. are then distilled off and rejected, thus removing the carbon dioxide. An equivalent quantity of standard sodium hydroxide is then added, and the usual amount of sodium carbonate. The estimation of free and albumenoid ammonia, is then proceeded with in the usual manner.Using this process, we have examined a number of samples of water carbonated in the laboratory ; the results are set out in Table 111. The results were good, but the method was tedious. TABLE 111. Waters Carbonated in the Laboratory. Source. Ammonia-free water . . . ... Upland surface water, raw Stream water A ... ... B ... 9 , 9 9 ,, filtered' I , C, filtered ,.. 91 Y 9 1 I 9 , 2 9 Deep well water ... ... 9 ) ,, filtered ... Pond water A . . . ... ... B ... ... ... 9 ... ... ... ... ... ... ... ... ... ... ... Ammonia Parts per 100,000. Original Water. Free. o*ooo 0.003 omool 0.000 0.006 0-025 0.000 o*ooo o*ooo 0.065 0.055 Albu- menoid. 0-000 0.009 0.005 0.004 0.013 0,020 0.006 0.000 0.004 0.065 0-045 Carbonated Water.Ordinar Methoi Free. omooo omooo o'ooo 0 -001 0.003 ODO0O o*ooo 0.055 09017 I - Albu- menoid. o*ooo 0.006 0.006 0.017 0.023 0.010 Oo0O8 0.065 0.045 - - Suggested Method. Free. 0.000 0.003 0.001 0-000 0.008 0.025 0.000 0.000 0.000 0.065 0.055 Albu-. nenoid. owooo 0.009 0.007 0.006 0.019 0 *021 0.002 0-008 0.065 0.045 - From the above table it will be seen that the results obtained for free ammonia by the suggested process agree with those obtained on the uncarbonated water by the ordinary method. I t is obvious that, if the first 50 C.C. of distiIlate obtained from a carbonated water by the ordinary method is divided or diluted for the purpose of Nesslerising, the amount of carbon dioxide present, and therefore the error, will be proportionately less.The albumenoid ammonia is slightly increased by Carbonation, whether it is estimated by the ordinary method or by the suggested method. This inorease in albumenoid ammonia seems to take place immediately on carbonation, and no further176 G . D. ELSDON AND NORMAN EVERS increase takes place on standing. That no slbumenoid ammonia is due to impurities in the carbon dioxide used is proved by the fact that, in the case of ammonia-free water (prepared by distillation with alkaline permanganate), no albumenoid ammonia, was found after carbonation. Acw? E’uents.-It is sometimes necessary to estimate ammonia in effluents containing large amounts of free acid; this is usually done by making alkaline with sodium carbonate and distilling. It is evident that the carbon dioxide evolved may in some cases be sufficient to affect the estimation of ammonia, and to obtain a correct result the water must be made neutral with sodium hydroxide before adding sodium carbonate.Contwrcial Soda- Water.-The following results were obtained with samples of commercial soda-water procured from ordinary sources : TABLE IV. Sample. A ... ... ... ... B ... L.. ... * * . c ... ... ... ... D ... ... ... ... E ... ... ... ... F ... ... ... ... Ammonia, Parts per 100,000. Ordinary Method. Free. 0-000 0.000 o*ooo 0.000 o‘ooo 0-000 0~000 I Albumenoid. 0.006 0.007 0.002 0.010 0-005 0.004 0.004 - Suggested Method. Free. 0-007 0.004 0~000 0.002 0.003 0.002 0-003 0.002 Albumenoid. 0.006 0.009 0.002 0.009 0.006 0.004 0-004 0.002 Note.-Since reeding this paper we have studied the effect of carbon dioxide on Nessler solution prepared both according to the formula given in Fresenius, “Quantitative Analysis,” vol.ii., p. 128, and according to that given in Sutton, (‘ Volumetric Analysis,” seventh edition, p. 465. Although the results obtained show an improvement on those given in our paper, owing to the larger amount of potash present, we find that carbon dioxide in amounts exceeding about fifty parts by weight per 100,000 causes a reduction in the colour obtained; this amount of carbon dioxide is much less than would be obtained in the first 50 C.C. of distillate from a carbonated water. We have also compared the colour produced by the various Nessler solutions (made according to these formulae) with a given quantity of ammonia, and find that there is very little difference between them.THE ESTIMATION OF AMMONIA IN CAR,BONATED WATERS 177 DISCUSSION.The PRESIDENT remarked that, as the Nessler solution contained a large excess of potash, which must already contain some carbonic acid, it seemed rather strange that a small extra quantity of carbonic acid should have so great an effect. If this action occurred in aerated waters which had been shaken to remove most of the carbonic acid, it must occur also in many natural waters which contained considerable quantities of carbonic acid capable of being given off on boiling, so that, apparently, such waters also should be acidified, and the carbonic acid boiled off, before the free ammonia was determined. Mr. W. T. BURGESS said that he understood the authors to say that better results were obtained when the quantity of Nessler solution was increased.His own practice, particularly with waters likely to contain very little free ammonia, was to use, for the 100 C.C. Nesslerised, 6 C.C. of Nessler solution prepared according to the formula of Frankland, containing 62.5 grms. of potassium iodide per litre ; and work- ing in this way he had not noticed any diminution in the free ammonia due to carbonic acid. In carbonated waters as much as possible of the carbonic acid was of course got rid of before the ammonia determination was commenced. Mr. E. M. HAWKINS suggested that' it might be possible to avoid two distillations by adding an excess of recently ignited caustic lime, which would combine with the carbonic acid and render the addition of sulphuric acid unnecessary.From his own experience, he was inclined to think that the use of caustic lime would be attended by satisfactory results, and it would not, as far as he could see, cause any difficulty in the subsequent process of determining the albumenoid ammonia. Mr. A. CHASTON CHAPMAN remarked that, while the authors had undoubtedly shown that some effect was produced on Nessler solution by carbonic acid, he was inclined to think that this effect would not have been noticeable had a more sensitive Nessler solution of the usual composition been used. Mr. EVERS, in reply, said that the neutralisation of only about one-tenth of the potash present was sufficient to lessen the colour. He did not know whether the addition of caustic lime would be advantageous, but, as a matter of fact, the distilla- tion was practically one continuous process. He should imagine that, if a Nessler solution containing more potassium iodide were used, the tendency towards precipi- tation would be greater. Dr. Thresh recommended a solution which gives, on adding it to the distillate, about the same strength as Sutton's as regards potassium iodide, but about one and a half times the strength of potash. With such a solution some colour, at any rate, would be obtained in most cases, but it would be reduced in many cases by the carbon dioxide, and in the ordinary way such a reduction might not be noticed.

ISSN:0003-2654    

DOI:10.1039/AN9123700173

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

178 G. A. STOKES: A NEW PRESERVATIVE FOR MILK, CREAM, ETC. NOTE ON A NEW PRESERVATIVE FOR MILK, CREAM, ETC. BY G. A. STOKES. (Read at the Xeeting, March 6, 1912.) I HAVE recently examined a number of samples of milk which contained a new pre- servative, consisting of sodium nitrite, formaldehyde, and water, sold under the name of “ Mystin ” (cf. Monier-Williams, ANALYST, 1912, 155). This preparation, owing to the presence of sodium nitrite, fails to respond to Hehner’s test and Schiff’s reagent. I n estimating the fat by the Gerber process, the presence of formaldehyde will generally be detected. By adopting the following methods, as little as 2 drops of preservative per 100 C.C. of milk may be detected : 1. A portion of the milk is coagulated with dilute sulphuric acid, filtered, and a solution of diphenylamine in sulphuric acid added to the clear filtrate.The forma- tion of a deep blue colour shows the presence of nitrite (or nitrate). 2. One hundred C.C. of the milk are acidified with 5 C.C. of strong phosphoric acid and distilled in a current of steam. About 10 C.C. are distilled into an equal volume of Schiff‘s reagent ; if a pink coloration develops within five minutes the presence of formaldehyde is indicated. “ Mystin ” added to milk in the proportion of 3 C.C. per litre was found to be a fair preservative. Thus, after three days the acidity developed was only equivalent to 0.24 per cent. of lactic acid, whereas the same milk unpreserved showed an acidity equivalent to 0.69 per cent. of lactic acid. DISCUSSION. Dr. MONIER-WILLIAMS said that he was very glad to have heard Mr.Stokes’s paper, because it directed attention to one or two new points. I t was curious that the addition in this way of so little as 1 part of formaldehyde in 300,000 should be sufficient to preserve milk for three days. I t was generally understood that, when formaldehyde was used as a milk preservative, a considerably larger quantity than this was required. I t was interesting to note that potassium chlorate and potassium nitrate also interfered with the Hehner reaction. The action of these two substances might very likely depend on a direct oxidation of the colouring matter or of the formaldehyde, and possibly other oxidising agents might have a similar effect, if present in sufficient amount. Mr. W. BACON remarked that possibly the increased antiseptic effect of the formaldehyde in this mixture might be due to the action of the nitrite in preventing condensation of the formaldehyde with the amino-acids of the milk proteids. Mr. STOKES, in reply, said that he ought perhaps to have mentioned that his experiments were made during somewhat cold weather. Possibly in warmer weather the preservative effect might not have been so good. He had met with two cases in which this preservative was present in samples taken under the Sale of Food and Drugs Act.

ISSN:0003-2654    

DOI:10.1039/AN9123700178

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

ESTIMATION OF FERRIC IRON IN CERTAIN ORGANIC SUBSTANCES 179 THE ESTIMATION OF FERRIC IRON IN PRESENCE OF CERTAIN ORGANIC SUBSTANCES. BY JOHN THEODORE HEWITT, D.Sc., PH.D., M.A., F.R.S., -4ND GLADYS RUBY MA". (Read at the Meeting, April 3, 1912.1 RECENTLY, one of the authors of this communication desired to measure the rate at which certain organic substances were oxidised by alkaline permanganate. It was a n easy matter to stop the reaction at any instant by adding an excess of ferrous sulphate and dilute sulphuric acid; it was not, however, quite obvious how the amount of unchanged ferrous salt or of the ferric salt produced could be determined. Determination of unchanged ferrous salt is out of the question, as the residual organic matter may, and in many cases did, act as a vigorous reducing agent on acid solutions of dichromate or permanganate, hence a method for estimation of the ferric salt had t o be adopted.Methods depending on the use of stannous or titanous chlorides had to be abandoned, as the organic substances in some cases contained nitro-groups, and consequently recourse was had to methods involving the use of thiosulphate. The original method, due to Scherer, of considering the reaction finished when no further increase of the violet coloration was noticed on adding the thiosulphate to the ferric solution does not give very sharp results, so that the methods in which the reaction 2Fe*** + 2S,O," = 2Fe.0 + S,O," is allowed to become compIete, and the excess of thiosulphate is determined with iodine were examined.(Kremer and Landolt, J. pr. Chem., 1861, 84, 339 ; Zeitsch. anal. Chem., 1862, 1, 214; Oudemanns, Zeitsch. anal. Chem., 1867, 6, 129; 1870, 9, 342; compare Balling, ibid., 9, 99.) The direct method of adding potassium iodide to the ferric solution, 2Fe*** + 21' = 2Fe** + I,, and titrating the liberated iodine with thiosulphate (F. Mohr, Annaleiz, 1860, 113, 257 ; Zeitsch. anal. Chem., 1863, 2, 243 ; C. D. Braun, J. pr. Chem., 1860, 81, 423 ; Zeitsch. anal. Chem., 1864, 3, 452), would have been sufticiently accurate (see Joseph, J. Xoc. Chem. Ind., 1910, 29, 187; Schatz, Pharm. Zeit., 1910, 55, 292) but for the fact that it was impossible to allow the iodine to remain in contact with the organic matter, which was frequently of unsaturated or phenolic character. Experiments were consequently made with Oudemann's method, various organic substances being added at the same time.Generally 20 C.C. of an iron alum solution, about decinormal (5-585 grms. ferric iron per litre) in strength, were mixed with a solution of the organic compound under examination, then 3 C.C. of 1 per cent. copper sulphate and 1 C.C. of 1 per cent. ammonium thiocyanate added and TG thiosulphate solution run in until the colour of the ferric thiocyanate disappeared. Even with the copper salt as catalyst the end-point was never sharp, and the excess of thio- sulphate was immediately titrated with standard iodine with starch as indicator.180 HEWITT AND MA”: Although the added organic substances are capable of reacting with iodine in many of the cases examined, the velocity of the reaction, I, + 2S,O,” = 21’+ s,o,”, SO far exceeds the speed at which the iodine is used by the organic substance that no difficulty was found in determining the end-point.I t must be admitted that better results are obtained when the operator has acquired practice; a very important point is not to use a greater excess of the thio- sulphate than necessary, and to titrate this excess as rapidly as possible. Mineral acid is added, if required, to break up feebly ionised salts (e.g., ferric acetate) ; on the other hand, any large excess affects the estimation injuriously on account of the decomposition of the non-ionised thiosulphuric acid. I t is as well to standardise the thiosulphate on a ferric solution, since, if the standardisation be carried out with copper sulphate, the results obtained for iron appear to be rather low.The standard iron solution may be made by dissolving 48.22 grms. of iron-ammonia alum in water with the aid of 75 C.C. sulphuric acid and making up to 1 litre; if necessary, the iron may be estimated in this solution gravimetrically. The agreement which may be expected on titrating equal volumes (20 c.c.) of the same iron solution is shown in the following table (1 C.C. iodine= 1.003 C.C. thiosulphate) : 1. 2. 3. Thiosulphate added . . . ... ... 20.10 20.09 20.50 Iodine for back titration ... ... 0.35 0.40 0.76 Thiosulphate consumed by iron ... 19-75 19.69 19.74 The titration might conceivably be affected by- 1. The formation of a non-ionisable ferric compound or of a complex ferric anion.2. Reduction of ferric to ferrous compound by the added organic substance. 3. Reaction of the iodine with the added organic substance as well as with the thiosulphate. Whilst rapid work obviates any trouble due to the second or third causes, it intensifies that due to stability of non-ionisable ferric compounds. In the table of results it will be noticed that a very large excesg of ammonium sulphate bas the expected effect, which is not, however, great enough to make the titration useless unless very large amounts of the sulphate are present. Acetates give no trouble if mineral acid be added, acetic acid itself having but a slight influence. The deep colour produced by salicylates and salicylic acid interferes seriously, and the quantity of mineral acid which must be added to inhibit this is too great to allow of a subsequent safe titration with thiosulphate. The titration was practically unaffected by sugars and not greatly by tartaric acid or citric acid in presence of the amount of mineral acid (75 C.C.f sulphuric acid per litre) used in making up the iron solutions. Twenty C.C. of the ferric solution (0.112 grm. iron) were first directly titrated, and the titration was then carried out with equal volumes of the same solution, the substance which might affect the result being added in gradually increasing quantities. The first column gives the name of the added substance, the second shows the weight thereof, and the third the volume in which the added substance was dissolved. In the fourth column the net volume of the thiosulphate employed in titrating the ferric iron is In the table the results show the effect of the substances added.ESTIMATION OF FERRIC IRON IN CERTAIN ORGANIC SUBSTANCES 181 given-ie., the gross volume of thiosulphate added less the equivalent of the iodine used in the back titration.Name. Ammonium sulphat e Acetic acid . . . ... Sodium acetate ... Tartaric acid . .. Citric acid ... ... Ethyl alcohol (96 p e r cent. by volume). Phenol ... ... Mannitol ... ... Added Substance. Weight. Grms. o*ooo 0.264 0.528 1.320 2.640 0.000 0.240 0.480 1.200 2.400 o*ooo 0.545 1.190 o*ooo 0.150 0*300 0.750 1.500 0~000 0.192 0.384 0.960 1.920 0 5 C.C. 10 C.C. 20 C.C. 0.000 0.094 0.188 0-470 0.9 40 0.000 0.182 0.364 0.910 1-820 Volume of Solution.0 10 20 50 100 0 10 20 50 100 0 10 20 0 10 20 50 100 0 10 20 50 100 - - - - 0 10 20 50 100 0 10 20 50 100 C.C. Thiosulyhate used for Titration. 19.73 19.86 19.59 19.43 18.72 19.90 19.88 19.93 19.52 19.22 19.73 13.55 4.81 19.73 19.56, 19.70 19.65 19-18 18.74 19.73 19.56 19.54 18.91 15.85 19-90 19.93 19.73 19.68 19.73 19.91, 19-97, 19.94 19.87 19.82 19.55 19.90 19.91 19-68 19.54 19.48182 ESTIMATION O F FERRIC IRON I N CERTAIN ORGANIC SUBSTANCES Name. Glucose ... ... Galactose . . . ... Cane-sugar . . . ... Maltose ... ... Lactose ... ... D e x t r i n ( B r i t i s h gum). Added Substance. Weight. Grms . 0.000 0.180 0.360 0.900 1.800 0.000 0.900 0.000 0.338 0.676 1.690 3.380 0~000 1.800 0-000 1.800 0.000 0-162 0.324 0.81.0 1.620 Volume of Solution. 0 10 20 50 100 0 50 0 10 20 50 100 0 50 0 50 0 10 20 50 100 C . C . Thiosulphete used for Titration. 19.73 19.92, 19.84 19.77 19-52 19.73 19-90 19-91 19.73 19.87, 19-78 19-75 19.75 19-72 19.90 19 -52 19-90 19.81 19.73 19.87, 19.89 19-78 19.79 19-51 In conclusion, we desire to record our thanks to Mr. J. L. Baker for his kindness i n supplying us with very pure specimens of maltose, lactose, and galactose. EAST LONDON COLLEGE.

ISSN:0003-2654    

DOI:10.1039/AN9123700179

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

KIRSCHNER AND POLENSKE VALUES FOR MARGARINES, ETC. 183 ON THE RELATION BETWEEN THE KIRSCHNER AND POLENSKE VALUES FOR MARGARINES CONTAINING COCOANUT OR PALM KERNEL OILS. BY E. RICHARDS BOLTON, H. DROOP RICHMOND, AND CECIL REVIS. (Rend at the Neeting, April 3, 1912.) IN a paper published last year (ANALYST, 1911, 36, 333), it was pointed out that the determination of the Kirschner value would enable the presence of small quantities of butter-fat to be estimated in the presence of cocoanut oil, and, further, that in itself it furnished a reliable figure for the percentage of cocoanut oil in the absence of butter-fat. The figures then given for the Kirschner values for mixtures containing no butter-fat fell practically on a straight line, but when the mixture contained butter-fat up to 10 per cent.a somewhat irregular curve was obtained. We have reinvestigated this point, and find that the irregularity was due to the fact that the values obtained for mixtures containing up to 15 per cent. of cocoanut oil were carried out with an Irish butter of very low Reichert-Meissl value (22), while the other values were obtained by using a butter of much higher Reichert-Meissl value (30) ; and we ha.d not at that time recognised how sensitive to the presence of butter the Kirschner value was. We have therefore redetermined the values for those mixtures which contained the butter of low Reichert-Meissl value, with a butter of more normal figure, and are now able to make the following deductions : 1. That for the Kirschner values for both cocoanut and palm kernel oils (with or without admixture of butter-fat up to 10 per cent.) a straight line can be plotted which will represent, with very great closeness, the values experimentally obtained (see curves).Further, for any percentage of cocoanut or palm kernel oils the difference in the Kirschner values for “no butter-fat ” and for any percentage of butter-fat (up to 10 per cent.) will be proportional within very small limits to the percentage of butter- f a t ; the closeness of the agreement indicates that the relation will also hold for higher percentages of butter-fat. 2. On examining the values obtained both for cocoanut and palm kernel oils, it was seen that the Polenske value was practically independent of the amount of butter-fat present, when present up to 10 per cent.in the mixture, and is practically dependent on the presence of the cocoanut or palm kernel oil only. The mean value was therefore calculated from the four values obtained for mixtures corresponding to each different percentage of cocoanut or palm kernel oil (see Table I.), and on plotting these mean values a regular curve was obtained. The following equations have been worked out for these ‘‘ mean value ” curves : x (C.N.O.) = 12.3 (P - 0.45)0*747 ; x (P.K.O.)= 16.72 (P - 0.45) ”‘06 ; where X= the percentage of cocoanut or palm kernel oil.184 BOLTON, RICHMOND, AND REVIS : KIRSCHNER AND POLENSKE TABLE I. Cocoanut Oil. Butter-Fat . 0 per Cent. 2 per Cent. 5 per Cent. 10 per Cent. I 7 0 per cent. Reichert-Meissl . . . Polenske ... ...Kirscbner . . . ... 0.38 0.31 0.18 0.92 0.38 0.81 1.70 0.42 1.49 3.25 0.55 2.70 i 5 per cent. 0.87 0.71 0.22 1.66 0.79 0.74 2.16 0.68 1.31 4.10 0.93 2.85 Reichert-Meissl . . . Polenske ... ... Kirschner . . . ... Reichert-Meissl . . . Polenske , . . . Kirschner . . . ... Reichert-Meissl . . . Polenske ... ... Kirschner . . . ... Reichert-Meissl . . . Polenske ... ... Kirschner . . . ... Reichert-Meissl . . . Polenske ... ... Kirschner . . . ... Reichert-Meissl , . . Polenske ... ... Kirschner . . . ... Reichert-Meissl . . . Polenske ... ... Kirschner . . . ... ... 10 per cent. 1.64 1-17 0.32 2-39 1.20 0.88 3.40 1.37 1.58 4.86 1.26 2.99 i 15 per cent. 2-67 1.73 0.38 3.16 1.80 094 4.27 1.69 1.69 5.52 2 -01 2.99 \ i 25 per cent. 3.91 2.91 0.54 4.85 2.61 1.15 5.53 2-96 1.94 6.54 2.93 3-08 1 50 per cent.6.05 7.06 1.10 6-60 7.16 1-56 7.70 6-90 2-27 9.10 7-30 3-37 75 per cent. 6.97 12-36 1.50 8.34 11.91 1-91 9.20 12-29 2.57 10.50 12.30 3 -68 I I 100 per cent. 8-08 16.02 2.01 These relations show that the influence on the Polenske figure of 1 per cent. of cocoanut oil is the same as that of about 1-75 per cent, of palm kernel oil. The figures obtained from the equations for palm kernel oil are almost identical with the experimental figures, but the agreement is not quite so good in the case of cocoanut oil, and we have not taken into account the value for 100 per cent. in calculating the equation to this curve. The values in the latter case show somewhat irregular fluctuations, which are probably due to the distillation of the volatile insoluble acids in cocoanut oil, on account of their lower molecular weight than those of palm kernel oil, being more influenced by the other constituents of the mixture.The chief difference is in the value for cocoanut oil itself, the experimental value being 16.5 as against 17.05 calculated from the formula. We are, after many experiments, of theVALUES FOR MARGARINES CONTAINING COCOANUT OILS. 185 opinion that it is not possible to obtain the true value for cocoanut oil in the ordinary apparatus, and this point will be referred to later. We therefore point out that the Polenske value acts as an '' indicator," so that, when a margarine containing cocoanut or palm kernel oils is examined by the Reichert-Meissl-Polenske-Kirschner process, reference to this mean curve a t once determines the percentage of cocoanut or palm kernel oil apart from other values.The corresponding Kirschner value obtained from the typical curve then determines the presence or absence of butter-fat, the Reichert-Meissl value acting as a confirma- tory figure, and controlling the small fluctuations which may occur in the Kirschner value occasioned by a variation in butyric acid content of different butters. The tables (11. and 111.) here given for cocoanut and palm kernel oils, with and without admixture of butter-fat, are the typical values obtained from the curves which are also given, and we feel that they will prove a reliable guide provided that the method be carried out under standard conditions laid down in the paper previously referred to, the standard apparatus being also employed (ANALYST, 1904, 29, 155).On account of the similarity of the results obtained for cocoanut and palm kernel oil, the following formula will give the percentage of butter present with either fat for the Kirschner and Polenske values found experimentally : K - (0.262 P"63 + 0.09) .+ Butter per cent. = 0.242 9 or nearly as exactly by the more simple formula : K - (0.1 P + 0.24) 0.244. Butter per cent. The following formuke connect the Kirschner value and percentage of butter-fat when neither cocoanut nor palm kernel oil is present : K = 0.236 B + 0.33, or, with a small increase in the probable error, K = 0.244 B + 0.28, which is practically the formula given above. Exception may be taken to the above formulq on the ground that it supposes a certain fixed value for the butyric acid content of the butter present.While this is undoubtedly true, the variations so caused will not in the vast majority of case8 lead to errors of any great magnitude, and the percentage of butter determined by the formula has usually been within 0.5 per cent. of that actually present. We think it necessary to draw attention to an observation we have made recently. In the standard apparatus, that portion of the still-head which passes through the cork and into the interior of the distillation flask is provided with a, small hole in the side to prevent the collection of condensed liquid in the still-head. * Values of (0.262 PO'"+Of@) : P. 0.5 ... ... ... 1 ... ... ... 2 ... . . I 3 ... ... ...4 ... ... ... 5 ... ... ... 6 ... ... ... I ... ... Value. 0.26 0 *35 0.50 0-61 0-72 0 '81 0-90 0 -98 P. 8 ... 9 ... 10 ... 11 ... 12 . . I 13 ... 14 ... 15 ... ... ... ..* , .. ... ... ... Value. ... 1-06 ... 1'13 ... 1-21 ... 1-28 , . . 1 *34 ... 1.41 ... 1.47 ... 1.53186 KIRSCHNER AND POLENSKE VALUES FOR MARGARINES, ETC. Polenske Indicator Value. 0.45 { 0.76 { 1.22 { 1.75 { ’*” { 7-10 { 12.19 { 16.5 { As originally designed by Polenske, this hole had a fixed distance from the stopper of the flask. Insufficient attention is paid to this point by makers of the apparatus, and we have found that if the hole is much more than 1 cm. from the lower surface of the cork, low Polenske values may be obtained with high percentages of cocoanut oil; and we think that if this method be made a standard one, particular attention should be given to this point.TABLE 11. Butter-Fat. 0 per 2 per ti per 10 per Cent. Cent. Cent. Cent. Kirschner ... 0-18 0.80 1-49 2-70 Reichert-Meissl 0.38 0.92 1.70 3.25 Kirschner ... 0.25 0.75 1-55 2.82 Reichert-Meissl 0.87 1.65 2-15 4.10 Kirschner ... 0-34 0.84 1-60 2.90 Reichert-Meissl 1.60 2.45 3.42 4.90 Kirschner ... 0.42 0.92 1.68 2.96 Reichert-Meissl 2.52 3.15 4-35 5.55 Kirschner ... 0.60 1-08 1.82 3.08 Reichert-Meissl ... 3.92 4-57 5.55 6.55 Kirschner ... 1-02 1.50 2.20 3.38 Reichert-Meissl 6.05 6-88 7.72 8.95 Kirschner ... 1-45 1.92 2-55 3.70 Reichert-Meissl 7-00 8.35 9.20 10.50 Kirschner ... 1.88 Reichert-Meissl ... 8-08 - - - ... ... ... ... ... ... - - - Cocoanut Oil. 0 per cent. 5 per cent.10 per cent. 15 per cent. 25 per cent. 50 per cent. 75 per cent. 100 per cent. THE RELATION BETWEEN THE KIRSCHNER AND POLENSKE VALUES FOR BUTTER-FAT. As the Kirschner value for butter is almost entirely obtained from the butyric acid present, it is evident that ti relation between the Polenske value and the Kirschner value will be more sensitive then the relation, at present accepted, between the Beichert-Meissl and Polenske values. We tentatively put forward the following table with the hope that other workers will criticise or verify the figures : Kirschner Polenske Value. Value. 20 ... ... ... ... ... ... 1-60 22 ... ... ... ... ... ... 2.10 24 ... ... ... ... ... ... 2.65 26 ... ... ... ... ... ... 3.201. Kirschner, 0 per cent. butter. 3. 9 9 5 Y , 1 , 6- 9 9 2 9 7 4.Kirschner, 10 per cent. butter. 2. 9 , 2 7 , ,, 1 5. R.-M., 0 per cent. butter. 7 , 7. R.-M., 5 per cent. butter. 9. Mean Polenske. 8. 7 7 10 9 , , 9 3. 9 9 5 9 , 9 , 6. 2 3 2 Y , ,, 9. Mean Polenske.188 KIRSCHNER AND POLEXSKE VALUES FOR MARGARINES, ETC. A variahion of +_ 1 must be allowed in the Polenske valrie corresponding to any particular Kirschner value, but it would appear that less than 5 per cent. of cocoanut oil will cause the Polenske value to fall outside this limit, except in those cases in which cows have been specially fed for the purpose of upsetting the Polenske process. I n conclusion we desire to express our thanks to Messrs. G. A. Payne and H. R. Burnett for carrying out the experimental part of the investigation. TABLE 111.Butter- Fat. Polcnske Indicator Value. Palm Kernel Oil. 0 per Cent. 2 per 10 per Cent. I I Cent. 0.45 { Kirschner ... Reichert-Meissl . . . 0.18 0.38 0-80 1-49 2.70 0.92 I 1-70 I 3.25 0 per cent. 0.68 { Kirsc hner ... Reichert-Meissl . . . 0-30 0.53 5 per cent. 10 per cent. 1.00 { Kirschner ... Reichert-Meissl . . . 0.35 1 -00 0.85 1.54 2-75 1.62 I 2.50 I 4.00 1-35 { Kirsc hner ... Reichert-Meisd . . . 0.40 1.35 0.90 I i::: I 2.80 2.00 4.35 15 per cent. 1-97 { Kirschner ... Reichert-Meissl . . . 0.48 1.97 0.97 1-65 2.87 2.60 I 3.62 I 4.97 25 per cent. 50 per cent. 4.22 { Kirsc hner ... Reichert-Meissl . . . 0-72 3.50 6-87 { Kirschner ... Reichert-Meissl . . . 0.97 4.55 75 per cent. 9-82 { Kirschner ... Reichert-Meissl . . . 1.07 5.22 100 per cent. DISCUSSION.Mr. W. BACON asked whether, in the form of apparatus with a very large distilling tube, this tube was insulated by some non-conducting material? If not, since the tube was so close to the neck of the flask, a great deal of condensation would be likely to occur. Mr. E. M. HAWKINS asked whether, in a mixture consisting.of cocoanut oil and of butter, of which the Kirschner figure was known, it would be possible, from the Polenske and Kirschner figures, to determine with a fair degree of certainty the proportion of cocoanut oil ? Mr. REVIS said that with the special tube described there was no condensationFOOD AND DRUGS ANALYSIS 189 at all, the distillation being, as a matter of fact, more rapid than with the ordinary form. He should like once again to emphasise the importance of always using the game standard pattern of apparatus. The exact details did not matter, provided they were the same in every case. If that were so, the results obtained by different workers would agree, and the results obtained by each would be consistent and concordant among themselves. They (the authors) had found that the Polenske, Reichert- Meissl and Kirschner processes were all three quite as accurate and definite as an ordinary titration of acid and alkali. The question asked by Mr. Hawkins a8 to cocoanut oil and butter mixtures involved some difficulty, because butter varied so greatly as regards its proportion of butyric acid. As they had pointed out, a much more sensitive relationship was shown between cocoanut oil and butter fat when the Kirschner and Polenske figures were used than when the Reichert-Meissl and Polenske figures were used. They put forward their results quite tentatively, but believed the process to be capable of showing the presence of as little as 3 per cent. of cocoanut oil in butter fat. There must always be some doubt as to the exact quantity of butter fat present in a mixture, because of the varying nature of the butter itself.

ISSN:0003-2654    

DOI:10.1039/AN9123700183

出版商:RSC    

年代:1912

数据来源: RSC

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FOOD AND DRUGS ANALYSIS 189 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Chemical Valuation of Digitalis. J. Burmann. (BUZZ. SOC. Chim., 1912, 11, 221.)-The author has already shown (Bull. Soc. Chim., 1910, 7, 973) that in Keller's method of judging of the value of digitalis by the examination of its active glucoside, digitoxin, it is only a pseudo-digitoxin that is estimated, and his results have been confirmed by Kraft (Schweiz. Woch. Chem. PhaTm,, 1911, 12-13). For the estimation of the total glucosides soluble in chloroform, 100 grms. of the liquid, obtained by dialysing the digitalis with 20 per cent. alcohol, are mixed with 60 grms. of absolute alcohol, and made up to 190 grms., with 50 per cent. alcohol. A mixture of 30 grms. of basic lead acetate solution (sp.gr. 1.240) and 30 grms. of absolute alcohol is then added, the liquid stirred and filtered, and 125 grms. of the filtrate (= 50 grms. of the dialysate) treated with hydrogen sulphide, and filtered from the lead sulphide through a Buchner's funnel. The precipitate is washed two or three times with 50 per cent. alcohol, and the filtrate and washings concentrated under reduced pressure (preferably below 50" C.) to about 50 C.C. to expel the alcohol, after which 2 C.C. of 10 per cent. ammonia solution are added, and the liquid extracted with chloroform for one and a half to two hours. The chloroform extract is filtered into a tared 200 C.C. Erlenmeyer flask, the solvent evaporated on the water-bath, and the residue dried at 100" C. in a current of dry air.I t is next taken up with 3 grms. of chloroform, the solution mixed with 7 grms. of absolute ether, and the glucosides reprecipitated by the addition of 50 grms. of petroleum190 ABSTRACTS OF CHEMICAL PAPERS spirit. After standing for some hours, the supernatant liquid is decanted and replaced by the same quantity of petroleum spirit, the flask being well shaken and allowed to stand. Finally, the liquid is again decanted, and the residue dried on the water-bath in a current of dry air until constant in weight. The glucosides thus separated are in the form of an amorphous white powder, and give the reactions typical of Keller's digitoxin. They may be crystallised by dissolving 0-03 to 0-04 grm. in 1 C.C. of absolute alcohol and adding 0.5 C.C.of water. After standing for several hours the deposit will show under the microscope acicular crystals grouped in rosettes (f-digitoxin or Kraft's hydrodigitalin) and prismatic tables (digitoxin). The crystals may be separated by means of their different solubilities in ether and water, and identified by their melting-points respectively). of four dialysates of digitalis : Total glucosides . . . ... ... 0.152 Glucosides by Keller's method ... 0.118 I n this way the following results 1. Per Cent. (145' to 150" C., and 247.5' C. were obtained in the examination 2. 3. 4. Per Cent. Per Cent. Per Cent. 0.148 0.118 0.111 0.116 0.091 0.085 Digitoxin . . . ... ... ... 0.034 Proportion of digitoxin . . . ... 22.5 0.032 0-027 0.026 21.6 22.0 23.4 Physiological experiments upon animals showed that the glucosides soluble in chloroform were more toxic than Keller's digitoxin. C.A. M. Baking Qualities of Flour. Willard and Swanson. (Chem. News, 1912, 105, 97-99.)-Failure to correlate the behaviour of flours with their gliadin-gluten ratios suggested that the differences observable might be caused by substances present in very small amounts. The production of a good loaf depends on the physical properties of the gluten, and these may be much affected by small quantities of associated substances. Such substances may also operate in quite a distinct manner-vie., by favouring or inhibiting the growth of the yeast, and among these would be the amino acids produced from the wheat proteins by the hydrolytic action of the yeast. The addition of unextracted bran to flour had a notably deteriorating effect on the loaf as regards both volume and texture.If the bran were previously extracted with cold or hot water the effect was less marked on loaf texture, and the addition of bran extract to the flour was very favourable. The fact that extracted bran and bran extract each produced better results than when entire bran is used was unexpected but confirmed on repetition. Figures are given showing the effect of various substances on loaf volume. Extracts derived from wheat scourings were, on the whole, undesirable, causing sticky doughs ; peptones had no effect till present in large quantity, and were then deleterious as they produced marked stickiness. Glycocoll was markedly bad in every way, the dough being sticky, runny, and stringy, and resembling that from badly germinated wheat; the loaf volume was reduced and the texture impaired.Leucin produced results like glycocoll, but less pronounced ; it caused the development of a disagreeable odour. Aspartic acid proved slightly favourable, but asparagin was injurious. The latter, while shorten -FOOD AND DRUGS ANALYSIS 191 ing the time of rising (probably by stimulating the growth of the yeast), weakened the gluten and so decreased the oven expansion and loaf volume. Similar effects are observed with flour from germinated wheats, and asparagin is known to be among the products of accompanying protein metabolism (cf. Ford and Guthrie, ANALYST, 1908, 33, 323). Ammonium chloride had a, most beneficial effect even in small traces, and appeared to assist yeast growth, as the time of rising is shortened.Ammonium acetate had a similar but less marked effect, but in larger amounts impaired the texture. Ammonium tartrate and phosphate had but little effect. Sodium bicarbonate was detrimental alike to time of rising and volume of loaf, while sodium phosphate, sodium formate, and potassium nitrate call for no special comment. A detailed study of the effects of germination of wheat on the resulting flour was made, material being prepared from corns germinated for from 1 to 5 days. Up to 3 days little effect wgs produced, but after this time bad effects at once became apparent ; texture of loaf, volume, crumb, and alcohol-soluble protein all being adversely affected. The deleterious influence of flour from germinated wheat was strongly manifested even when only 1 part in 30 of sound flour was employed, while with larger amounts the product showed that the mixtures were quite unfit for bread-making.H. F. E. H. Detection of Fluorine in Foods, etc. A. Sartori. (Chem. Zeit., 1912, 36, 229-230.)-For the estimation of fluorides in wine or fruit-juice, according to the author, 200 C.C. of the sample are treated with a few drops of 20 per cent. sodium sulphate solution and 10 C.C. of 10 per cent. barium acetate, and the mixture is allowed to stand for twelve hours. The precipitate is collected on a filter, incinerated and tested for fluorides by the waxed watch-glass method. The limit of sensitiveness by this method is about 0-3 mgrm. of fluorine.J. F. B. Comparative Study of Methods for Determination of Hard and Total Soft Resins in the Hop. H. V. Tartar and C. E. Bradley. ( J . Ind. Eng. Chem., 1912, 4, 209-213.)-1t is shown that Siller’s method (ANALYST, 1909, 34, 485), though useful enough with Continental hops, leads to over-estimation of the soft resins when applied to seeded hops such as are grown in America or England. This is due to the extraction of fatty oil from the seeds (cf. Briant and Harman, J. Inst. Brew., 1910, 16, 5), which are crushed when the sample is put through a mincing machine as directed by Siller. On the other hand, Briant and Meacham’s method (J. Fed. Inst. Brew., 1897, 3,233) gives very much lower results for soft resins, and correspondingly higher ones for hard resins, than does the latest form of Lintner’s volumetric method (ANALYST, 1909, 34, 53; 1910, 35, 352), or a new method described in the present paper.Lintner’s original method (Zeitsch. f. d. ges. Brauw., 1898, 21, 407) gives results which accord well with those obtained by the method of Briant and Meacham, but both methods are believed to be faulty in that they fail to extract the whole of the soft resin. A hop which shows only 8 per cent. of soft resin when subjected to Briant and Meacham’s process or the original Lintner process may yield 16 per cent. when analysed in accordance with Lintner’s more recent proposals or by the authors’ method. Lintner’s new method differs from the old one only in the fine grinding of192 ABSTRACTS OF CHEMICAL PAPERS the sample, to which no objection can be taken when the final determination is to be made by volumetric process dependent on the acid function of the soft resins.The new method described is as follows : A 10 grm. sample of hops is extracted with ether for eight to ten hours. The ethereal extract thus obtained is filtered, and the filtrate made up to 200 C.C. Half this volume is used for the determination of total resins, the other half for the determination of soft resins. For the determina- tion of total resins, 100 C.C. is placed in a 250 C.C. flask and evaporated a t about 40" C. to very small bulk, the last of the ether being removed in a vacuum desiccator at ordinary temperature. The residue is taken up in alcohol, filtered free from wax, and the filtrate made up to 100 C.C.Of this 100 c.c., a portion of 20 C.C. (equivalent to 1 grm. of hops) is transferred to a tared beaker, and the alcohol removed by evapora- tion in a vacuum oven at 50" C. For the determination of soft resins the remaining 100 C.C. of the ether extract is taken down to dryness exactly as in the determination of total resins. The residue is taken up with about 100 C.C. of petroleum ether (b.p. 40" to 45' C.), stirring with a rod and leaving to stand some time. The hard resin is then removed by filtration, the petroleum ether removed from the filtrate exactly as the ether was removed at an earlier stage, and the residue taken up with alcohol. The alcoholic solution is filtered from wax, made up t o 100 c.c., and 20 C.C. (equivalent to 1 grm. of hops) is transferred to a tared beaker, and evaporated and weighed as in the determination of total resins.When dried in the manner described, there is much less change of composition-as judged by the absence of browning- then when resort is had to higher temperatures, and a constant weight is obtained, which is never the case when a temperature of 80" C. is employed. The authors believe their method to be the most accurate available, but they consider Lintner's modified method to be the best method for commercial purposes, as it is rapid, and yields results which seldom differ by more than a few tenths of 1 per cent. from those yielded by their own method. Even with 10 grm. samples the sampling error cannot with certainty be kept below 0.3 per cent. G. C. J. Tests for Linseed Oil and its Adulterants.J. F. Liverseege and G. D. Elsdon. (J. SOC. Chem. Ind., 1912, 31, 207-208.)-The following modification of the well-known Livache test for quantitatively expressing the drying-power of oils has been found to yield uniform results : Litharge, finely-powdered and passed through a No. 40 sieve, is spread out in a thin layer in an incubator at 20° to 22" C. overnight to become constant in weight. About 10 grms. of this litharge are introduced into a flat-bottomed German silver dish, 3 inches diameter and 1 inch deep, 0.7 to 0.9 grm. of oil added, and after weighing, 5 C.C. of methylated ether (sp. gr. 0.720) are run into the mixture, and the litharge spread out in a uniform layer by thoroughly rocking the dish. The dish and contents are kept in the incubator at 21" C.and weighed after one, two, or more days, until the weight is either constant or diminish- ing, and the weight gained then expressed in terms of percentage of the oil taken. The added ether is volatilised after half an hour, and leaves an inappreciable residue. By this test, raw linseed oil ceases to gain weight in two days, and then usually loses weight. With boiled oils, the oxidation is usually complete in one day. The follow- ing are typical figures :FOOD AND DRUGS ANALYSIS 193 Per Cent. One Sample. Maximum. Minimum. Raw Linseed Oils. Gain after two days ... ... 17.4 18 15 - - ,, ,, three days ... ... 16.9 ,, ,, fourteen days ... 15.9 Gain after two days ... ... 13.6 - - Boiled Linseed Oils. Gain after one day ... .., 14.1 14 12 - - Soya Oil.-Gain = 8.4 to 8.9 per cent. Cotton-seed Oil.-Gain = 6.6 per cent. Elape Oil and .Arachis Oil.--Gain= 2.5 per cent. ; after twenty-one days, Olive Oil (2 sarnples).-Gain=0~6 and 1.4 per cent. in two days; after Resin Oil.-Loss=O-3 per cent, in one day; then gain=9*9 per cent. in Thus, drying oils do not gain after about two days, while non-drying oils may continue to gain for weeks, The gain in weight of oils of a particular class varies with the iodine value, and there is evidence of 8ome relationship between these figures for oils of different classes. rape oil, 5.7 ; arachis oil, 4-1 per cent. twenty-one days, 2.5 and 3.4 per cent. respectively. two days, and 19.4 per cent. in thirteen days. A. R. T. Chemical Composition of some New Zealand Meat Extracts.A. IBI, Wright. (J. SOC. Chem. Ind., 1912, 31, 176.)-Moisture, organic matter, mineral salts, chlorine, fat, and total nitrogen were determined by the methods described by the author (J. Soc. Chem. Ind., 1907, 26, 1229); acidity by titration with potas- sium hydroxide and phenolphthalein and calculating as lactic acid ; insoluble and coagulable proteins (U.S. Dept. of Agriculture, Bureau of Chem., Bull. 107, p. 115) ; proteoses by the zinc sulphate method (ibid.) ; peptone-like bodies and polypeptides by precipitation, with the proteoses, by the tannin salt-reagent, their amount being found by difference (J. Amer. Chem. SOC., 1906, 28, 1485) ; nitrogen as total meat bases by deducting the nitrogen present as ammonia from the nitrogen in the tannin salt filtrate ; ammonia by the magnesium oxide method (U.S.Dept. of Agriculture, Bureau of Chem., BUZZ. 107, p. 9) ; purin bases by Schittenhelm’s method (ibid., 11111. 90, p. 129) ; creatin and creatinin by Folin’s colorimetric method (Zeitsch. physiol. Chem., 1904, 41, 223); phosphoric acid and potash by examination of the ash (U.S Dept. of Agriculture, Bureau of Chem., Bull. 107, pp. 3, 4, and 11). A “burned” flavour and a dark colour impair the commercial value of an extract ; they are shown, by the analyses given of six samples, to be accompanied by undue amounts of peptone-like substances, intermediate between the peptones and the amino acids. The characteristic salts of meat extract are potassium dihydrogea phosphate and potassium monohydrogen phosphate ; in general, the mineral con- stituents show great variations.0. E. M. Acid-Soluble Phosphorus Compounds of some Feeding Materials. Hart and Tottingham. (Twenty-Seventh Annual Report of the Agric. Exp. Sta. Ulziver. Wisconsin, 95-106; through Inter. Inst. Agric., 1912, 3, 398.)-Phytin, which is a complex organic phosphorus salt of potassium, magnesium, and calcium, is widely194 ABSTRACTS OF CHEMICAL PAPERS distributed, particularly in seeds, as a reserve material. I t is present in the entire seeds of maize, oats, and barley, but is largely localised in the outer layers of the wheat seed; it could not be isolated from swedes or alfalfa (Lucerne) hay. Phytin phosphorus forms from 40 to 50 per cent. of the total phosphorus in the afore- mentioned seeds. In alfalfa which was cut at the most favourable stage of growth for forage, the inorganic phosphorus formed 63 per cent.of the total; there is also present about 17 per cent. of phosphorus in some unknown organic combination. H. F. E. H. Estimation of Saccharin in Foods. G. Possetto and G. Issoglio. (Giorn. Earm. Chim., 1912, 61, 5-11 ; through Chem. Zentralbl., 1912, I., 754.)-The separation of the saccharin from the chief constituents of foods by dialysis is recommended. In the case of milk, jams, etc., a portion of the sample is rendered alkaline with sodium carbonate and submitted to dialysis for twenty-four hours ; at the end of this time the dialysed solution is acidified with phosphoric acid, and the saccharin shaken out with ether. The dialysed solution obtained in a similar way from cocoa should be decolorised with animal charcoal before being shaken out with ether.w. P. s. Composition of Scammony Root and of Scammony Resin. F. B. Power and H. Rogerson. (J. Chem. Xoc., 1912, 101, 398-412.)-Scammony root con- tains a small quantity of sucrose, an essential oil and furfuraldehyde, crystalline scopoletin and its glucoside, 3-4-dihydroxy-cinnamic acid, fatty acids, and a resin containing ipuranol, C,,H,,O,(OH),, melting at 285" to 290" C. ; a-methyl-butyric and tiglic acids ; jalapinolic acid and its methyl-ester ; valeric acid ; and traces of other substances. Scammony gum-resin contains tiglic acid, a valeric acid, jala- pinolic acid and its methyl-ester, and glucosides, dextrose, etc. The resins obtained from the root and the commercial gum-resin are thus similar in character, but not identical.A comparison of the resin from scammony-root with that obtained from the root of Ipomsa orizabensis (J. Chem. SOC., 1912,101,1-17), shows that the two products differ considerably in composition. Both the resins are complex in character, but consist to a large extent of the glucosides and methyl-pentosides of jalapinolic acid, C,,H,,(OH)(CO,H) and its methyl-ester. While, however, the methyl-pentose obtained from the hydrolysis of the resin of scammony root appears to be identical with rhamnose, that from the resin of I. orizabensis yields a new crystalline tetra- tlcetyl derivative. The resin from the last source contains also small amounts of hentriacontane, C31H64, and cetyl alcohol, which are not present in the resin from scammony root, and marked differences are observed in extracting the crude resins and the products of their alkaline hydrolysis with various solvents.The names by which these complex resins have hitherto been known, such as jalapin " or (' scammonin " should now be discarded, as they are not individual substances. A. R. T. Inversion of Sucrose by the Enzymes of Honey. 0. Achert, (Zeitsch. Untersuch. Nahr. Genussm., 1912,23,136-139.)-Results of experiments carried out by the author show that honey which has not been heated above 55" C. is capable ofBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 195 inverting added sucrose ; the inversion proceeds at the ordinary temperature and is more or less rapid. For instance, a mixture of honey and sucrose was prepared con- taining 22.0 per cent.of the latter ; after the lapse of four months the mixture was found to contain only 2.2 per cent. of sucrose, When the honey has been heated to a temperature of looo C., it loses its power of inverting sucrose. The quantity of free acids in the honey does not play any part in the process, as neutralised honey inverts sucrose at the same rate as does natural honey. w. P. s. Estimation of Tannin in Wines. P. Malvezin. (BUZZ. SOC. Chim., 1912, 11, 300-303.)-The method described previously (ANALYST, 1911, 36, 412) may be modified slightly in order to render the estimation more rapid, the chief alteration being that the zinc-tannin precipitate is collected on a filter immediately after the wine and precipitant have been boiled for the prescribed period of five minutes. After the precipitate has been washed, it is dissolved in dilute sulphuric acid and the solution titrsted with & permanganate as described. The factor 0.120 should be employed for calculating the quantity of gallotannic acid from the volume of per- manganate solution required for the titration, and the titration should be continued until a, pink coloration is obtained which does not disappear within three minutes. w. P. s. Detection of Small Quantities of Zinc in Wine. A. Straub. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 23, 140.)-The following process is described for the detection of small amounts of zinc in wines, for instance, in wines which have been treated with potassium ferrocyanide and a zinc salt in the fining operation (cf. ANALYST, 1905,30,264). From 100 to 200 C.C. of the wine are boiled, hot sodium carbonate solution is ridded, and the mixture heated for some length of time; the precipitate is then collected on a filter, washed, dissolved in ri small quantity of hydrochloric acid, and the solution oxidised by heating with potassium chlorate. An excess of sodium acetate is now added, the solution is boiled, filtered to remove iron and aluminium hydroxides, etc., and the filtrate then tested with hydrogeu sulphide. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700189

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年代:1912

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BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 195 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Microscopic Differentiation of Hemp and Flax Fibres. P. Sonntag. (Bey. Deutsch. botan. Ges., 1912, 29, 669; through Chem. Zentralbl., 1912, I., 1@58.)- With the microscope focussed on the upper surface, flax shows a right-hand spiral forming an average angle of 10.21 degrees with the cell axis. With a, deeper focus, a left-hand spiral of a steeper twist is observed. Hemp shows the same double spiral, but at an average angle of only 3-7 degrees. In both cases the structure is only observed in thin bast cells after boiling in water or acetic acid. Observation is best carried out on the broken ends of a, torn fibre. 0. E. M. Seventh Report on Research Work of the Metropolitan Water Board. A. C. Houston, 1912.-This Report consists of the following six sections : 1.Search for pathogenic organisms in raw river water. 2. The comparative vitality of ‘6 culti- vated ” and L 6 uncultivated ” typhoid bacilli in artificially infected samples of raw296 ABSTRACTS OF CHEMICAL PAPERS river water. 3. The comparative vitality of the typhoid bacillus in raw Thames water at different temperatures. 4. On the biological characters of B. coli isolated from (1) raw river water, (2) stored water, and (3) stored and filtered water. 5. On the advantages of passing raw river water through small reservoirs antecedent to storage in large reservoirs. 6. On the advantages of occasionally using precipitation methods antecedent to the storage of raw river water in large reservoirs.Among the conclusions arrived at by the author are the following : 1. The typhoid bacillus and Giirtner's bacillus are not habitually present in small amounts, such as 10 c.c., of raw river water ; and since the water will ultimately be stored for several weeks and then filtered, the margin of security is very great, in view o€ the extremely high death-rate of uncultivated typhoid bacilli when added artificially to river water. 2. In the Sixth Research Report (ANALYST, 1911,36,185) it was shown in a '' girl carrier " case that '' uncultivated " typhoid bacilli perish much more rapidly than '' cultivated " organisms. A '' male carrier " case amply confirms the previous finding, and it may be taken as true that thirty days' storage of river water is tantamount to sterilisation SO far as water-borne epidemic disease germs are concerned.3. Laboratory experi- ments lead to the conclusion that the typhoid bacillus lives longer at low (32' to 41°F.) than at higher (50" to 98-6' F.) temperatures. For seven months in the year the mean river temperature of about 58' F. is specially unfavourable to the sustained vitality of the typhoid bacillus; during the remaining five months of the year the mean temperature of about 41' F. is much less favourable to the rapid death of this organism. Even at freezing-point the reduction of typhoid bacilli by the second week was over 99 per cent., and by the fourth week only one survived out of 3,029 added initially. In the caw of the Metropolitan water-supply the author is of opinion that even in the coldest months of the year four weeks' storage of river water prior to filtration affords reasonable, if not absolute, protection from water- borne diseases.4. This report is of a, highly technical character, and deals with the physiological differentiation of numerous varieties of B. coli, using the direct plating- out method not preceded by cultivation in an enrichment liquid medium. 5 and 6. The author confirms his previous opinion (Third Research Report) as to the desirability of passing the raw river water through small reservoirs before storage. On three separate occasions, when sample8 were examined before and after such treatment, the percentage reduction, when averaged, was as follows : Bacteria, 36, ammoniacal nitrogen 15, albumenoid nitrogen 5.2, permanganate 7, turbidity 19, colour 8.The pre-storage treatment may be advantageously supplemented by the use of coagulants such as sulphate of alumina or alumino-ferric, and among other benefits derivable is the possibility of utilising the worst quality of flood water, and so preventing the depletion of the storage reservoirs under any conditions save those of drought. H. F. E. H. Sterilisation of Water and Dairy Materials by Ultra-Violet Rays. M. Ringelmann. (J. d'Agric, Prat., 1911,75, 619-621; through Inter. Inst. Agric., 1912, 3, 266.)-Ultra-violet rays from a mercury lamp traverse quartz or rock crystal, but not glass and thin layers of air. Water must be free from matter in suspension ; the sterilisation on an industrial scale of liquids like wine, beer, milk, orORGANIC ANALYSIS 197 broth, which contain colloid substances, is not to be expected, owing to the low penetrative qualities of the rays in such media. The walls of the lamp should not be in direct contact with water to be sterilised, since the yield of rays falls off in proportion as the temperature of the lamp is lowered. On a laboratory scale milk has been successfully sterilised by allowing films not exceeding a few millimetres in thickness to flow' between quartz plates, the rate of flow being regulated by the inclination of the plates. Water for butter-making is favourably affected, an impure sample after treatment causing a prolongation in the life of butter made with it from eight days to a month. The most useful application of the rays is in the sterilisation of drinking water. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9123700195

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年代:1912

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ORGANIC ANALYSIS 0.22 0.892 - 042O 75-0 197 0.25 0.37 0.891 0.893 - 0.65' + 1.12O 74.0 76.0 ORGANIC ANALYSIS. Detection of Tertiary Alcohols. M. Gwerbet. (Comptes rend., 1912, 154, 713-715.)-A means of distinguishing between primary, secondary, and tertiary alcohols is based upon the differences in their behaviour when heated with potassium hydroxide (cf. Comptes rend., 1911, 153, 1487). A mixture of 3 C.C. of the alcohol and 3 grms. of potassium hydroxide (previously dehydrated by fusion) is heated for sixteen hours at 230' C. in a sealed tube. After cooling, the point of the tube is broken under water, and the gases collected and measured. I n the case of primary or secondary alcohols the amount of gas will be considerable, whereas with tertiary alcohols it will only amount to a few C.C.at most, or there may be absorp- tion of water into the sealed tube. The solid product of the reaction is then treated with water. If the alcohol was primary or secondary, it will have been completely transformed into the potassium salt of the corresponding acid, and will be entirely soluble, whereas in the case of secondary or tertiary alcohols an oily layer of about the Bame volume as the original alcohol will be formed upon the surface of the water. C. A. M. Aromatic Grass Oils. Part 11. (BUZZ. Imp. Inst., 1911, 9, 333-340.)- Part I. of this article (ANALYST, 1912, 61) dealt with citronella oils, and the present part is devoted to lemon-grass oils. These are derived mainly from the two grasses, Cymbopogon Jlexuosus and C. citratus, the former yielding oils soluble in two or more volumes of alcohol (70 per cent.), and the latter giving, as a rule, oils not completely soluble in even ten volumes alcohol (90 per cent.).An oil from C. pendzdus (India) also yields an '' insoluble " oil. Ceylon Lemon-grass Oils.-Three samples distilled from C. citratus gave the following results : I I 2* I 3. Yield of oil, per cent. ... ... Sp. gr., 1 5 O / 1 5 O C. Opt. rotation, 100 mm. 'ai; 200 C: Citral by sodium bisulphite, per cent. ... ... ... ... Solubility ..- ... ...198 ABSTRACTS OF CHEMICAL PAPERS - 0-914 - 0.1" 73.0 Two other oils examined, stated to be fiexuosus oils, were found to be mixtures of such oil with the oil from C. nardus (citronella grass), and gave abnormal results. Indian Lemon-grass Oils.-Four samples yielded results as follow : - 0.906 - 0.1" 76.0 Odour .. . ... ... Opt. rotation, 100 mm. at 20" C. Citral, by sodium bisulphite, per cent. ... ... ... Solubility in 70 per cent. alcohol Sp. gr., 15"/15"C. ... ... Solubility in 90 per cent. alcohol '' Tyrntl " Oil. - 0.902 - 0.7" 72-5 Not completely sol. in 10vols. Sol. in quanti- ties up to 1 vol. ; cloudy on addition of more alcohol. Oil. Fine 0.905 - 0.65" 84.5 Sol.l: 2. More alcohol pro- duced slight turbidity. Sol. in all pro- portions ; ex- cess of alcohol produced slight turbidity. Sol. in quantities turbid on addi- tion of more alcohol. up to 1 vol.; The '' Cochin '' lemon-grass oil thus belongs to the group of '' soluble " oils, Most commercial lemon-grass oils contain from Uganda Lemoiz-g,rass Oils.-The following are typical of six oils (from C.citratus) and is exceptionally rich in citral. 70 to 75 per cent. of citral. examined from this source : Sp. gr., 15"/15" C. ... ... Opt. rotation at 20" C. Aldehydes by sodium bisulphite; per cent. ... ... ... Solubility in alcohol ._. ... 0.872 - 0.1 2" 64.5 Not completely sol. in 1Ovols. of 80 per cent. 0.881 + 0.17" 70-5 Not completely sol. in 10 vols. of 80 per cent. 0.894 - 0.4" 75.0 Insol. in 1Ovols. of 70 per cent. Bermuda Lemon-grass Oil.-A sample of this oil from C. citratus showed on analysis : Sp. gr., 15" C., 0.8689 ; optical rotation a t 20" C., - 0.35" ; citral, 40 per cent. ; not completely soluble in 70 per cent., or in 80 per cent. alcohol. The percen- tage of citral is very low. Montserrat Lemon-grass oil is of the insoluble type, and one sample examined contained over 74 per cent.of citral. A. R. T.ORGANIC ANALYSIS 199 Detection of Carotin. M. Tswett. (Ber. Deut. Botan. Ges., 1912, 29, 630- 636. Through Chem. Zentralbl., 1912, I., 951.)-For colouring matters belonging to the same group as carotin the name carotinoids is suggested. For the detection of carotin an alcoholic or petroleum spirit extract of the colouring matter is first obtained, and its elective solubility in a two-phase system of 80 per cent. alcohol and petroleum spirit is estimated. Should a portion of the colouring rnatter be electively soluble in the petroleum spirit it is possibly carotin. After removal of all alcohol the absorption capacity of the petroleum spirit solution is then tested with calcium carbonate, and should the solution retain its colour in the presence of an excess of the absorbent agent, its spectrum should be examined.The positions of the two principal absorption bands in the spectrum of carotin are somewhat differently placed by different observers. In the author’s experiments with carotin derived directly from the leaves these bands occurred at 492 to 475 pp and 460 to 445 pp respectively. With regard to the micro-chemical detection of carotin, it was found that the potassium hydroxide method of Molisch (Ber. Deut. botan. Ges., 1896, 14, 18) and the author’s resorcinol method (Botan. Centralbl., 81, 83) did not give entirely definite reactions. In the latter method the tissue containing chlorophyll is treated with concentrated resorcinol solution, which dissolves the plasmatic proteins and lipoids.If, then, about 1 per cent. of hydrogen potassium phosphate be added, the lipoids agglomerate into green globules and there separate, here and there, bundles of yellow crystals, which also contain red crystals. These masses of crystals consist of xanthophyllene and carotin. C. A. M. Errors in the Estimation of Cholesterol by the Ritter Method; Effect of Autolysis on Cholesterol. H. J. Corper. (J. Biol. Chem., 1912,11, 37; through Chem. Zentralbl., 1912, I., 1055.)-Ritter’s method of estimating cholesterol (Zeitsch. f. physiol. Chem., 1901,34,430) was investigated, pure cholesterol and ox-spleen being used ; it was found that the use of sodium ethoxide causes unavoidable errors.With too little, the esterification of the fats is incomplete, and the amount of cholesterol is over-estimated ; with too much, the cholesterol cannot be completely extracted from the salt-mixture by ether, and too little is found. The cholesterol content in the spleen of the dog is not materially altered by autolysis. Ox spleen contains about 0-4 per cent. of cholesterol calculated on the moist substance. 0. E. M. Estimation of Citric Acid. D. S. Pratt. (V: 8. Department of Agriculture, BureazL Chem., through Chem. Eng., 1912, 15, 72-74.)-The following method yields satisfactory results in the examination of fruit juices, etc., containing citric and other organic acids in admixture. The citric acid is oxidised to acetone dicarboxylic acid, and the acetone produced is weighed as a mercury sulphate addition-product. Fifty grms.of the juice are treated with 110 C.C. of alcohol (95 per cent.) to remove pectin bodies. The liquid is filtered after fifteen minutes and the residue washed with more of the alcohol. The solution is diluted to an alcoholic strength of about 50 per cent., and barium acetate solution (20per cent. in water) added to precipitate all the citric acid. After stirring, allowing the precipitate to settle, filtering the solution and thoroughly washing the precipitate ou the paper with alcohol (50 per cent.) to remove200 ABSTRACTS OF CHEMICAL PAPERS sugar, the paper and its contents are dried until alcohol is removed. (Ether may be used in place of alcohol at this stage for washing the precipitate.) About 50 C.C.of water and 3 to 5 C.C. of syrupy phosphoric acid are added to the barium citrate, which, on warming, completely dissolves, when the liquid is filtered and the paper and residue washed till the solution measures 100 C.C. An aliquot part of this solution, containing about 0-05 to 0-15 grm. citric acid, is measured into a distilling flask, 5 to 10 C.C. of phosphoric acid added together with 400 C.C. of hot water. When briskly boiling, potassium permanganate solution (0.5 grm. per litre) is run in from a dropping funnel a t the rate of 1 to 2 drops per second till the pink coloration is permanent throughout the liquid. The apparatus used by the author consists of a distillation- flask (500 C.C. capacity) attached to a spiral condenser, the former carrying a funnel, the stem of which extends 9 inch through the stopper, and which is drawn out to a small bore.The distillation-flask contains a glass rod, to the lower end of which is fused a short piece (9 inch) of small tubing, the device helping to produce steady ebullition. As the permanganate is added drop by drop, the acetone produced by oxidation of the citric acid is distilled off as soon as formed, and further oxidation prevented. The receiver contains 30 to 40 C.C. of Denigds’ reagent, prepared by adding, with constant stirring, 200 C.C. of strong sulphuric acid to 50 grms. of mercuric oxide and 500 C.C. of water, heating, if necessary, on the water-bath till solution is complete, and filtering the liquid after cooling and diluting to 1 litre. The distillation is continued till only 50 to 100 C.C.of solution remain undistilled, when the solution in the receiver is boiled gently under a reflux-condenser for three-quarters of an hour after the liquid becomes milky. The solution is filtered hot through a Gooch crucible, washed with water, alcohol, and finally ether, and dried in the water-oven for half an hour. The weight of the precipitate, which is, according to Denigds, (2HgS0,.3Hg0),.4CH3.C0. CH,, multiplied by 0.22, gives the amount of citric acid in the fruit juice taken. I n many cases precipitation of barium citrate and its subse- quent solution in phosphoric acid are unnecessary, but sugar-containing products should be examined as described, since sugar retards the oxidation of the citric acid.Malic and tartaric acid do not interfere with the process. Duplicate determinations agree within 2 or 3 mgrms. of citric acid with the quantities specified. The factor given (0.22) does not correspond with any simple formula, and has been arrived at as a mean of a number of experiments. A. R. T. Analysis of Textile Finishes. E. Schmidt. (Chem. Zed., 1912,36, 313-315.) -The author proposes a scheme for the identification of finishing materials in textiles. The finish is dissolved in as concentrated a form as possible by extraction with organic or inorganic solvents. Fats, resins, and mineral substances are estimated in separate samples. The substance extracted from the cloth and free from fat is dissolved in water. The aqueous solution is treated with a few drops of nitric acid, and the separation of a gelatinous precipitate would indicate the presence of norgin.The precipitate is warmed slightly and filtered; the filtrate is cooled and tested with a neutral solution of ammonium molybdate. If a white flocculent pre- cipitate is formed, either at once or after a short time, the presence of glue is indicated.ORGANIC ANALYSIS 201 After standing, the solution is filtered, neutralised with ammonia, and treated with an excess of alcohol. The formation of a precipitate may indicate the presence of starch, dextrin, gums, plant mucilages, or norgin; dextrose and glycerol remain in the filtrate. J. F. B. Quantitative Estimation of Hydroxy-, Amino-, and Imino-Derivatives of Organic Compounds by Means of the Grignard Reagent, and the Nature of the Changes taking Place in Solution.H. Hibbert. (J. Chem.. SOC., 1912, 101, 328.)-Hibbert and Sudborough's method (J. Chem. SOC., 1904, 85, 933) gives low results with most hydroxy-compounds if phenetole is the solvent used ; the fatty alcohols up to and including propyl alcohol behave quite abnormally in both phenetole and amyl ether. Aromatic and most fatty hydroxy-compounds give accurate results in amyl ether, alone or in admixture with ketones, esters, etc. In phenetole, but not in amyl ether, aromatic amines give low results. Hibbert and Sudborough's method (J. Chem. Xoc., 1909, 95, 477) for the estimation of amino- and imino-groups is not applicable to the lower fatty amines, as these form stable additive compounds with the magnesium methyl iodide, with the result that gas is not evolved, or only slowly, and on heating.Pyridine appears to be the most suitable solvent for hydroxyl compounds, and primary and secondary amines, but investigation of the lower fatty alcohols and fatty amines in this respect has not been carried out. Dimethylaniline may apparently also be employed. 0. E. M. New Method for the Separation of Tertiary from Secondary and Primary Amines. H. Hibbert and A. Wise.' ( J . Chem. Soc., 1912,101,341.)-The primary and secondary amines form additive compounds with magnesium alkyl halides which immediately decompose at ordinary temperatures, with evolution of the corresponding fatty hydrocarbon : (1) R*NH, + MgRI = R*NH( MgI) + RH (2) R, : NH + MgRI = R, : N (MgI) + RH while tertiary amines, having no available hydrogen atom, yield additive compounds incapable of this decomposition.To the mixed amines, alone or dissolved in ether, is. added excess of an ethereal solution of magnesium methyl iodide or bromide, the ether distilled off, and the product heated to 200' to 280' C. in an oil-bath, when the tertiary amine distils over. The other amines are recovered by steam distillation from sodium hydroxide. 0. E. M. Elm-Seed Fat. A. Pawlenko. (Chem. Rev. Fett- u. Harx-Ind., 1912,19,43-44.). -The seeds of the elm-tree contain about 45 per cent. of kernels, which on extraction with petroleum ether yield a greenish-yellow fat (26.1 per cent.) belonging to the cocoanut-oil group. A sample thus extracted gave the following values : Sp. gr. at 20" C., 0.9559 ; solidification-point, 3.5O C.; melting-point, 5.7' C. ; acid value, 5-57 ; saponification value, 277.3 ; Hehner value, 75.45 ; Reichert value, 3.75 ; and iodine value, 32.2. The fat contained 56-2 per cent. of caprio acid with smaller quantities of butyric and oleic acids, and 14.82 per cent. of glycerol. The shells of the nuts also202 ABSTRACTS OF CHEMICAL PAPERS yielded about 2 per cent. of a hard yellow wax-like fat, melting at 59.5O C. and having a saponification value of 187. The kernel fat had a pleasant taste and odour and was apparently well suited for the purposes of food. It also yielded a hard soap which ws,s particularly soluble in cold salt water, but which separated on the surface on heating the salt solution to 713’ C. The extracted residue contained 7.9 per cent.of nitrogen, and ought, therefore, to be a valuable feeding stuff. C. A. M. Characteristics of Cotton Wax. C. Piest. (Zeitsch. angew. Chem., 1912,25, 396-399.)-A sample of crude American cotton (ash, 2.44 per cent. ; Schwalbe’s copper value, 3.57) yielded the following amounts of extract to different solvents : Ether, 0.74 ; benzene, 0.87 ; petroleum spirit, 050 ; and alcohol, 1-20 and 1.27 per cent. The alcoholic extract had a saponification value of 159, and iodine value of 22.1. In the case of nine samples of normal cotton purified for nitration the follow- ing range of values was obtained: Copper value, 0-65 to 1-47; ash, 0.12 to 0.27; wood-gum, 0.32 to 0.90 ; ether extract, 0.09 to 0.37 ; carbon tetrachloride extract, 0-12 to 0.32; and alcoholic (absolute) extract, 0.24 to 0.53 per cent.The cotton wax in the normal purified wool was soluble to the extent of about 50 per cent. in absolute alcohol, whilst about 25 per cent, was soluble in ether and in carbon tetra- chloride. In respect of its melting-point, saponification value, and iodine value, it closely resembled Japan wax. When present in cotton wax it has the effect of increasing the copper value. C. A. M. Refractometric Estimation of the Strength of Formaldehyde Solutions. L. T. Reicher and F. C. M. Jansen. (Chem. Weekblad., 1912,9,104-109 ; through Chem. Zentralbl., 1912, I., 949.)-Experiments with Zeiss’s immersion refractometer have shown that the refractometric reading is a linear function of the concentration of a formaldehyde solution.If 15.5 be subtracted from the reading, and the differ- ence be divided by the factor 3-17, the result will give the percentage of formaldehyde in the solution. C. A. M. Hubener’s Bromide Method for the Estimation of Caoutchouc. F. W. Hinrichsen and E. Kindscher. (Chem. Zeit., 1912, 36, 217-218, 230-232.)- Hubener’s method for the estiniation of caoutchouc in vulcanised rubber (ANALYST, 1909, 34, 170 and 365) by bromination in presence of water has been criticised by various authors, and recently in an adverse manner by Esch (ANALYST, 1911, 36, 558). The present authors had already shown that the estimation of the combined bromine after oxidation with nitric acid involves serious losses of bromine, which, however, may be avoided if the substance be oxidised by fusion with alkali carbonates.It is now shown, however, that if this source of error be eliminated the method devised by Hubener becomes fundamentally unsound, and invariably yields results which are much too high. The investigations of the authors on mixtures of known composition lead to the following conclusions: (1) In the case of soft vulcanised rubbers, complete bromination is very difficult to attain, because the sample cannot be ground sufficiently fine ; there is no means whereby the final point of the bromination in presence of water may be recognised. (2) The precipitatedORGANIC ANALYSIS 203 bromide always contains an excess of bromine above the theoretical quantity, owing to the occlusion either of bromine or brominated compounds. The method of purifying the bromide by washing with alcohol and carbon tetrachloride, recom- mended by Hiibener, is quite insufficient.(3) Superbromination invariably takes place, and the caoutchouc values calculated from the combined bromine are too high. This error is only partially compensated by the opposing error due to loss of bromine when the compound is oxidised by boiling with nitric acid in presence of silver nitrate. (4) The estimation of the uncombined sulphur in the aqueous filtrate from the bromide precipitate is unreliable ; considerable quantities of the combined sulphur are continuously oxidised and are estimated in the aqueous filtrate. (5) Consequently, the percentage of vulcanisation sulphur found in the bromide is always too low. (6) The theoretical basis of Hiibener’s method, differentiating unvulcanised caoutchouc, caoutchouc monosulphide and disulpliide, is therefore left at present without experimental support.J. F. B. Source of Error in the Kjeldahl-Gunning Method. P. A. W. Self. (Pharm. J., 1912, 88, 384-385.)-The author finds that considerable loss of ammonia may take place by volatilisation from the boiling acid liquid when the temperature rises above a certain point, and that this loss is markedly accelerated as the liquid approximates to the composition KHSO,. In some experiments made, practically the whole of the ammonia was lost from highly concentrated potassium sulphate and sulphuric acid mixtures. It is pointed out that there is a limit to the amount of organic3 substance which may be used in an experiment in order to avoid loss of nitrogen, and approximately this is, where 25 C.C.of sulphuric acid and 12 grms. of potassium sulphate are employed, not more than 3.5 grms. of a carbohydrate material, 3.0 grms. of a fatty product containing from 5 to 10 per cent. of oil or fat, and 1-5 grms. containing 80 to 90 per cent. of oil or fat. At least 15 grms. of sulphuric acid should remain at the end of the heating period. A. R .T. Estimation of the Molecular Weight of Small Quantities of Fatty Acids. W. Arnold. (Zeitsch. Untersuch. Nahy. Genussm., 1912, 23, 129-135.)-Full details are given for estimating the molecular weight of small quantities of water-soluble and other fatty acids by titration with potassium hydroxide solution and determining the weight of the resulting soap.An essential part of the process consists in powdering the soap residue before it is dried, it having been found that the last traces of water cannot be expelled from a compact mass of soap. A quantity of the fatty acid is placed in a flask and neutralised by the addition of alcoholic Zc potassium hydroxide solution; in the case of solid fatty acids, a portion of the potassium hydroxide is added, and the contents of the flask warmed to dissolve the fatty acid, the final part of the titration being carried out after cooling the solution, as slightly more alkali is required for the neutralisation when the solution is hot. Phenolphthalein is used as the indicator, and the amount of solid matter introduced by this solution must be estimated separately and an allowance made.The soap solution is then transferred to a weighed platinum basin, evaporated slowly, and the residue dried for forty-five minutes in a water.oven. The residue is now broken up into a fine powder by the204 ABSTRACTS OF CHEMICAL PAPERS aid of a small spatula, and the drying continued for a further two and a half hours. The molecular weight is then calculated from the formula : (s - 2, X f ) x 20000 M= 2, where M is the molecular weight, s the weight of the soap, w the number of C.C. of & potassium hydroxide solution used, and f the potassium equivalent (39-1) - of 20000 each C.C. of the latter solution ; should the potassium hydroxide contain traces of salts, their quantity must be estimated by sulphating a definite volume of the solution, and correcting the equivalent accordingly.Results of experiments with a series of fatty acids, ranging from butyric acid to stearic acid, show that the method yields correct figures ; in over 90 per cent. of the analyses the figures found agreed within 2 units of those required by theory. w. P. s. Method for Determining the Relative Reactivity of Organic Com- pounds. (J. Chem. SOC., 1912, 101, 341,)-The total theoretical quantity of methane is not in general evolved on the interaction of a hydroxy- compound and an excess of magnesium methyl halide in phenetole; the amount is not affected by the presence of ketones, esters, etc. If, however, there is insufficient Grignard reagent, it will be apportioned between the hydroxy-compound and the ketone, according to their relative reactivity for it.To 0.2880 grm. (1 mol.) of a-naphthol was added 3 mols. of the ketone, 6-0 C.C. of phenetole, and 5-0 C.C. of magnesium methyl iodide in phenetole, this being the quantity necessary to react with all the a-naphthol. The methane evolved was measured, and the reactivity- factor calculated as the theoretical volume evolved by 0.2880 grm. of a-naphthol, divided by that found. The known greater reactivity of fatty over aromatic ketones is reflected in the table of results on a series of ketones. H. Hibbert. 0. E. M. Estimation of Oxalic Acid in the Leaves of Conifers. J. Otto. (Zeitsch. anal. Chem., 1912, 51, 296-300.)-Having observed by microscopic examination that the leaves of conifers contained apparently varying quantities of calcium oxalate crystals, the amount varying with the age of the leaves, the author estimated the quantity actually present.Pine leaves (needles) one year old were found to contain from 0.2 to 0.9 per cent. of oxalic acid, whilst older leaves contained up to 2.3 per cent. w. P. s. Preliminary Notes on the Examination of Various Stick-Laes and Shellacs. J. H. Hoseason and 0. Klug. (J. SOC. Chem. Ind., l912,31,165.)-Five kilogrms. of the stick-lac were ground, sifted through a 40-mesh sieve, and mixed; 5 grms. were macerated for twenty-four hours in warm distilled water, filtered, and washed. The dried filtrate is the coloured water extract. The dried residue was macerated with 90 per cent. alcohol, the extract evaporated to a, syrup and dropped on fat-free cotton-wool, and rapidly extracted, after the alcohol had been driven off, with cold ether.The ether was removed by evaporation with alcohol, the liquidORGANIC ANALYSIS 205 made up to 50 C.C. with alcohol, and 5 C.C. taken for (ether-soluble) resin and two portions of 20 C.C. for two Hubl tests. The residue in the cotton-wool was dissolved out with alcohol to 100 c.c., and 5 C.C. taken for (ether-insoluble) resin, and 40 C.C. for two Hubl tests, To insure drying, the film of resin substance in determining the resin must be very thin, The residue from the treatment with water and alcohol was extracted with chloroform ; the wax obtained on evaporating off the chloroform contained a brown substance, included in the wax content. The final residue (woody fibre, insect remains, and probably protein colour compounds) wad dried and weighed.Analyses of a series of stick-lacs, button-lacs, and shellacs are given. The necessity for a standard method of carrying out the Hubl test is emphasised. 0. E. M. New Method for the Determination of the Reducing Sugars. E. C. Kendall. (J. Amer. Chem. Soc., 1912, 34,317-341.)-Briefly, the method consists in modifying Fehling’s reagent by substituting potassium carbonate for caustic soda, and salicylic acid for Rochelle salt. The cuprous oxide is filtered off, dissolved in hot nitric acid, and the copper determined by the modified iodide method as previously described by the author (ANALYST, 1912, 66). Potassium carbonate is shown to be the most satisfactory alkali, and gives more copper than sodium carbonate with the same weight of sugar. Rochelle salt causes some spontaneous reduction of copper, and the citrate solutfon proposed by Benedict (J.Bid. Chem., 1908, 5, 485) is found to be inaccurate owing to depression and variation caused in the reducing power of the sugar in its presence. An alkaline salicylate solution replacing the alkaline tartrate was found to give no spontaneous reduction of copper even after seven hours heating in the boiling-water bath, and changes in the weight present had but very small effect on the reducing power of the sugars. It is not possible to replace salicylic acid by sodium salicylate, although the acid must be present in the alkaline solution as the potassium salt. Numerous experiments are described in which variations in procedure were made in order to obtain optimum conditions. For the preparation of standard tables by the new method, specially purified sugars were used, and their purity carefully checked by the polariscope and otherwise. The author prepared maltose by the barley diastase method of Baker (ANALYST, 1908, 33, 393) ; the other sugars were purchased and recrystallised. The method of reduction was as follows: The sugar employed was measured out in solution of appropriate strength into a, 200 C.C. Erlenmeyer flask, and the total volume made up to 100 C.C. Five grms. of dry salicylic acid were then added, followed by 15 C.C. of copper sulphate solution (equivalent to 2 grms. of CuS0,5H2O) and 25 C.C. potassium carbonate solution (equivalent to 15 grms. of the carbonate) without any agitation of the flask, This order must be adhered to. The flasks are now shaken with a rotary motion. As soon as the salicylic acid has dissolved, the flask is immersed in the boiling-water bath for twenty minutes. The cuprous oxide is filtered on a perforated porcelain dish covered with asbestos felt, and finally dealt with by the author’s method alluded to above. The sugars for which tables are given are glucose, invert sugar, lactose, and maltose. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9123700197

出版商:RSC    

年代:1912

数据来源: RSC