摘要:

APRIL, 1916. Vol. XL., No. 469. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. AN ordinary meeting of the Society was held on Wednesday evening, March 3, in the Chemical Society’s Rooms, Burlington House. The President, Mr. A. Chaston Chapman, 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.C. W. McHugo, A.I.C., C. J. H. Stock, B.Sc., F.I.C., G. Tate, Ph.D., F.I.C., and T. E. Wallis, B.Sc., F.I.C., were read for the second time; and certificates in favour of Messrs. Paul Seidelin Arup, B.Sc. (Lond.), A.I.C., A.C.G.I., 31, St. Petersburgh Place, Bayswater, W., chief chemist to the Aylesbury Dairy Company Ltd.; Alexander Scott Dodd, B.Sc.(Edin.), F.I.C., 20, Stafford Street, Edinburgh, Public Analyst for the City of Edinburgh; Harri Heap, M.Sc. (Vict.), F.I.C., Burnside, Lyndhurst Road, Withington, Manchester, Lecturer in Chemistry, Public Health Department, University of Manchester ; and Francis Howard Carr, F.I.C., Edgmont, Derby Road, Nottingham, Director of Boots’ Pure Drug Company, were read for the first time. Mr. D. Mitchell was elected a member of the Society. The following papers were read: “The Structure of Pepper: Some New Features,” by T. E. Wallis, B.Sc., F.I.C.; “The Soluble Chlorides and Total Chlorine in Some English Cokes,” by S. W. Bridge, B.Sc., F.I.C. ; ‘( The Occurrence of Chlorine in Coal,” by A. de Waele ; and The Routine Detection and Estimation of Boric Acid in Butter,” by H. Hawley, M.Sc., F.I.C.

ISSN:0003-2654    

DOI:10.1039/AN9154000141

出版商:RSC    

年代:1915

数据来源: RSC

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142 NOTE ON THE DETERMINATION OF SULPHATES IN FLOUR NOTE ON THE DETERMINATION OF SULPHATES IN FLOUR. BY G. D. ELSDON, B.Sc., A.I.C. (Read at the Meeting, February 3, 1915.) OWING to the use of acid calcium phosphate in self-raising flour, the estimation of sulphates present in flour has become almost a necessity. It is well known that this estimation cannot be made in the ash (compare O’Sullivan, ANALYST, 1914, 39, 425, and Cripps and Wright, ibid., 429); and even when the flour is mixed with lime previous to ignition, the result obtained by the writer has been far from satisfactory.The following method has been used by him and others for some time, and has been found to be fairly satisfactory : Ten grms. of flour are added to 25 C.C. of concentrated hydrochloric acid contained in a 250 C.C.beaker. The beaker is then gently warmed on the water- bath for a few minutes, and the whole frequently shaken until all the flour has been attacked and the liquid is of a deep purple colour. The whole is finally heated on the hot water-bath for about an hour, the beaker not, however, coming in contact with the steam, but being placed on the metal covering.About 100 C.C. of water are added, and after standing a few minutes the liquid is filtered, the filter-paper being washed once with cold water. The filtrate is then heated to boiling, barium chloride solution added, and the resulting barium sulphate weighed. Many samples of plain and self-raising flour have been examined by this proceos. In the case of a plain flour containing 0.4 to 0.5 per cent.of ash, the average amount of barium sulphate obtained in the above manner is 3.5 mgrms.-corre- sponding to 0.021 per cent. of CaSO, or to 0°012 per cent. of SO,. This is somewhat higher than the figures quoted by Cripps and Wright. This may be accounted for either by the oxidation of some organic sulphur in the above process, or by the failure of 1 per cent.acetic acid to extract the whole of the sulphate. The difference is, however, not very serious, and of little consequence in comparison with ths much larger amount of sulphate found in The method has been tested on flours containing known amounts of sulphate- the sulphate being added both as calcium sulphate and as that contained in impure acid calcium phosphate. Quantities of calcium sulphate were added to 10 grms.of flour as below, and the total sulphate estimated. The amounts of calcium sulphate found are corrected for that present in the original flour. phosphatic ” self-raising flours. Calcium Sulphate added. 0*0060 omo120 0.0240 0*0300 Calcium Snlphate found. 0.0055 0 *0110 0,0235 0.0290 0.2 grm. of acid calcium phosphate containing 12.0 per cent.of calcium sulphate was added to 10 grms. of flour and intimately mixed. The total sulphate was then estimated and found to be 0.25 per cent. as calcium sulphate, the amount added being equal to 0.24 per cent.SOLUBLE CHLORIDES AND TOTAL CHLORINE IN SOME ENGLISH COKES 143 When determining the sulphate present in a phosphatic self-raising flour, or in a plain flour which has been 6 K improved,” it will be advisable to allow 0025 per cent. of oalcium sulphate as that due to the sulphate normally present in the flour, as this seems to be the maximum amount likely to be present, except in the case of very low-grade flours. A portion of this work was done in the Birmingham Municipal Laboratory, and I am much indebted to Mi. J. F. Liverseege both for suggestions and for permission to use that part of the work done in Birmingham. MUNICIPAL LABORATORY, REGENT ROAD, SALFORD.

ISSN:0003-2654    

DOI:10.1039/AN9154000142

出版商:RSC    

年代:1915

数据来源: RSC

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SOLUBLE CHLORIDES AND TOTAL CHLORINE IN SOME ENGLISH COKES 143 THE SOLUBLE CHLORXDES AND TOTAL CHLORINE IN SOME ENGLISH COKES. BY STANLEY W. BRIDGE, B.Sc., F.I.C. (Read at the Meeting, Nawh 3, 1915.) DURING some experimental work carried out on the purification of water by percola- tion through coke filter-beds, the chlorine content of the water was found in one instance to have increased from 4 parts per 100,000 to 18 parts per 100,000, and the author was asked if he could supply any figures relating to the amount of soluble chlorides generally present in gas coke.A considerable number of figures have been publishedas to coal, the amount of soluble chlorides and total chlorine in which is a matter of coneiderable importance where the coal is carbonised in gas retorts or coke ovens, inasmuch as the presence of sodium chloride in the coal in material amount has a destructive action on the fireclay material used for the construction of the retorts or oven walls, especially where the coal is carbonised in a moist condition and at high temperatures.In addition, as the chlorine is largely driven off with the rest of the volatile matter in the form of hydrochloric acid, a large proportion of chlorine in the coal brings about difficulties in the removal of the tar and ammonia, owing to the formation of solid ammonium chloride in the condensing plant.Where the coal is burnt in apparatus involving contact of the waste gases with copper alloys, as in the copper fireboxes and brass tubes of locomotive boilers, considerable trouble is experienced with coals high in chlorides from corrosion of the copper-containing materids by the hydro- chloric acid evolved.Search of the literature failed, however, to reveal any information with regard to the chlorine content of coke except in one instance-namely, in a paper by Schreiber (Stahl and Eisen, 1910, 30, 1839)-where an analysis is given of the soluble salts extracted from a single coke sample.In view of the fact mentioned above, that in the case of water purification, when employing fresh coke on filter- beds, erroneous conclusions might be drawn if account were not taken of the144 STANLEY W. BRIDGE: THE SOLUBLE CHLORIDES chlorides likely to be extracted from the coke by the water, it was thought worth while to examine the soluble and total chlorine contents of a number of samples of coke obtained in ordinary practice in gasworks, and in addition a sample of metallurgical coke and a cannel coke prepared at low temperature were examined.The following table gives the results obtained, the chlorine in all cases being calculated as NaCl, and given as percentage of this salt on the original air-dried coke : TABLE I.Description. Gas-coke ... ... ... ... ... ... ... ... ,? 9 3 # ? ? ? 9 ) ? ? I ? 9 , ? ? ... 9 , I , I ? ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... . I . ... ... ... ... ... ... ... ... ... ... ... .. Metallurgick cok'e' . . . . ... Low temperature cannel residue District of Origin of Coal. Soluble Chlorides as NaC1.Derbyshire ,I 9 , I2 Durham Y Y 9 , 9 , $ 9 Lancashire Yorkshire Durgam Flint ,9 Per Cent. 0.262 0.191 0.045 0.040 0.122 0.087 0.055 0.037 0.013 0.056 0.080 0.029 00016 0.007 0.357 Total Chlorine aa NaCl. Per Cent. 0.499 0.341 0.134 0.137 0.344 0.119 0.102 0.086 0.039 0.076 0.144 0.099 0.086 0.071 0.918 The results show the considerable variation in the chlorine content of the coke, and generally the variations in the chlorine in the cokes are much the same as has been found by others in that contained in coal.I t is well known among coke-oven managers that many of the Derbyshire coals are exceptionally troublesome in respect of chlorides, and the average amount found in the Derbyshire cokes is higher than from any other district. The low-temperature cannel residue was very high in both soluble and total chloride, and the same has been found true in the case of several other cannel coals and cokes which have been partly examined.It will be noticed that, in the case of the metallurgical coke, the percentage of soluble chlorides and the ratio of soluble to total chloride ie very low, which would indicate that a greater proportion of the chlorine is driven off from the coal with the volatile matter when the coal is carbonised under coke-oven conditions--i.e., in a moist state, and allowed to remain in the oven till the percentage of volatile matter is very low.In order to obtain some idea as to extent to which the chlorine is driven off from the coal, a few experiments were carried out on the laboratory scale on a sample of coal well known for its high chlorine content, and on two samples of cannel also high in ohlorine.Eaoh of these coals was carbonised (1)jin a fireclay crucible at aAND TOTAL CHLORINE IN SOME ENGLISH COKES 145 Soluble Chlorides as NaC1. temperature of about 400’ to 500’ C., and (2) in a platinum crucible for fifteen minutes over a powerful Meker burner.The soluble and total chlorine were deter- mined in each coal or cannel, and in the low-temperature and high-temperature residue, the chlorine as before being expressed as NaCl; and in the case of the residues this is calculated back to percentage on the original coal or cannel, so that the figures show directly the losses which occur on heating. The results are given in Table 11. : TABLE 11.Total Chlorine as NaC1. Description. ... ... Crtnnel ... ... ... ... Low - temperature residue (volatile matter = 10.77 per cent.) ... ... ... ... --- --- ... Camel ... ... ... ... ... 1 0.077 Low - temperature residue (volatile matter ... = 7-79 per cent.) ... ... ... 0.192 High-temperature residue ... ... 0.068 ... --- 1.141 0.498 0.288 Per Cent. 0.068 ! 0.525 0.357 0.123 Per Cent.0.987 0.918 0.314 ... Coking-coal ... ... ... ... 1 I ::: I ... 1 Low-temperature coke (volatile matter = 13-08 ... ... per cent.) ... ... High-temperature coke (15 minutes) ... High-temperature coke (90 minutes) . , . ‘ 0.092 0.140 0.048 0.048 0.237 0.094 0.091 It will be seen that, in accordance with expectation, the proportion of total chlorine driven off at high temperatures is much greater than at low temperatures.On the other hand, in every case the amount of (‘soluble ” chloride is greater in the low-temperature residue than in the original coal or cannel. This doubtless arises from the fact that the soluble chloride cannot be completely extracted from the original coal when it is well compacted with bituminous matter, whereas after the bituminous matter has been destroyed by carbonisation and the whole mass rendered porous, the soluble chlorides can be much more completely extracted.In the cam of the coal sample, a further test was made to see what effect a more prolonged heating would have on the chlorine content, the sample in this case being heated over the Meker burner for ninety instead of fifteen minutes.As will be seen from the table, the prolongation of the heating does not affect any material change. The analytical methods employed were as follows : Solable ChZorzdes.-Fifteen to 30 grms. of a,n average sample crushed to pass a ten-mesh sieve were boiled with water for one hour in a, flask connected to a reflux condenser, the coke then filtered and washed, and the filtrate on cooling acidified with nitric; acid, followed by slow addition of dilute permanganate till the solution146 SOLUBLE CHLORIDES AND TOTAL CHLORINE IN SOME ENGLISH COKES was just permanently pink.Standard silver nitrate solution (1 C.C. = 0.001 grm. C1) was then added, the silver chloride filtered off, and the excess of silver determined by titration with standard ammonium thiocyanate according to the Volhard method. The addition of permanganate was found necessary, as on the direct addition of silver nitrate to the acidified solution some blackening always occurred. This was a t first thought to be due to soluble sulphides from the coke, but when lead carbonate was added to the coke suspension before filtering the blackening still took place, and appeared to be due to some reducing agent extracted from the coke.The addition of permanganate to the acidified solution entirely obviated the difficulty. TotaE Chtlorim.-2-5 to 5 grms. of the coke were gently ignited with 3 to 6 grms. of a mixture of 1 part pure sodium carbonate and 2 parts pure lime until the carbon was completely burnt, the mass being then boiled with water to which a little lead carbonate was added to remove sulphides. After filtering and washing, the filtrate- concentrated if required-was acidified with nitric acid, and the chlorine determined in the manner described above. To ascertain whether any loss of chlorine took place during the ignition for burning off the carbon, pure sodium chloride was mixed with sugar, charcoal, and the above lime-sodium carbonate mixture, and strongly ignited to burn off the carbon, and 99.8 per cent. of the sodium chloride was recovered in the filtrate. Resublimed monochloracetanilide was also gently ignited with the mixture, and found to contain 20.11 per cent. of C1 instead of the theoretical 20.92 per cent.-an immaterial error for the purpose of the present investigation.

ISSN:0003-2654    

DOI:10.1039/AN9154000143

出版商:RSC    

年代:1915

数据来源: RSC

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146 SOLUBLE CHLORIDES AND TOTAL CHLORINE IN SOME ENGLISH COKES THE OCCURRENCE OF CHLORINE IN COAL. BY A. DE WAELE. (Read at the Neeting, March 3, 1915.) A UASE of abnormally rapid corrosion of the tubes of an economiser was brought recently to my notice. The brickwork forming the near end of the flue on its way to the chimney-shaft had been removed for purposes of alteration of direction, so that a very thorough examination was possible.The tubes on examination were found to be deeply pitted in places, and at the time held Etdhering oily-looking yellow drops. Several of the tubes were carefully soraped in order to remove the loose adhering scale and fluid. An examination for sulphuric acid showed the merest trace, but an abundance of ferric chloride was found. It was thus clear that the source of failure was the presence of chlorine in some form in the furnace-gases.A record having been kept for several years of the varieties of coal used on this and other boiler-furnaces, I was able to obtain and examine samples of the coals as further deliveries came in. At the same time, it was found that without exception the coals used were those which had been mined in the brine districts of the Midlands.It was thus possible that the chlorine might be present either wholly or partly as sodium chloride.THE OCCURRENCE OF CHLORINE IN COAL 147 In order to determine this, duplicate determinations of chlorine were made by (1) ignition of the coal in admixture with chlorine-free lime; (2) direct extraction of the powdered coal with water.The former method was carried out by intimately mixing a weighed quantity of the powdered coal with powdered lime in a platinum crucible, and inverting the latter in a larger platinum crucible, this being then filled up to within 4 inch of the top with more lime. The ignition wag then per- formed in a mufle. The contents of the crucibles after ignition were tipped out into 8 beaker, dissolved in dilute nitric acid, neutralised carefully, and the chlorine titrated in the usual way.No difficulty was found in obtaining lime containing but the faintest trace of chlorine. The second method was carried out by exhausting the powdered coal with hot water, filtering through asbestos, and directly titrating the filtrate with silver nitrate. Comparisons of chlorine determinations by the two methods gave the following figures : Sample Number.By Ignition. By Extraction, 1 0.253 0.251 2 0.241 0.240 0.212 3 0.210 4 0.220 0.220 5 0.018 0.019 6 0,344 0.346 It would thus appear as if the whole of the chlorine found were present as soluble chloride. This investigation was followed by examination of another boiler-furnace in which nothing but Welsh coal had been used.The furnace in question had been running for over three years, and although I was not able to accord it quite such a close examination as in the case detailed above, the condition of the economiser tubes was very good, no deliquescence being apparent to any degree, whilst the pitting was very slight indeed. Whilst the coals used on this boiler could not be located as accurately as in the previous case, I was able to obtain samples of the different coals that had been used on this and others of a group of boilers.The results are included in the following table : By Ignition. By Extraction. C1 Per Cent. 01 Per Cent. Sample Number. 1 0.003 0*003 2 - 0.010 3 - 0*010 4 - O*OlO 5 0-007 0.006 6 - 0.011 7 - 0-032 8 0.004 0.007 9 0.011 0.012 10 - 0.004 11 - 0.007 The above figures afford a good confirmation of the supposition that soluble chloride was the cause of failure in the first of the two cases.148 A.DE WAELE: DISCUSSION ON THE Two PRECEDING PAPERS. The PRESIDENT remarked that, while in the case of coal apparently the whole of the chlorine was capable of being extracted by water, in the case of the coke only a portion of the chlorine could be obtained in this way, Did this mean that the portion not obtained was protected in some way, as, for example, by tarry or resinous matter, or that it existed in some different form? In the latter case, could the reader of the paper say what the form was? Dr.LESSING said that, as far as he was aware, nothing was known as to the form of compounds in which chlorine occurred in coke; he thought it highly improbable that in the coking process the chlorine would form insoluble compounds with the organic constituents of the coal.The chlorine in coal, as Mr. de Waele’s figures showed, was all soluble, and as a matter of fact the method of extraction with water was practically the only one in use for the numerous daily determinations of chlorine that were made in many coking works.It seemed quite feasible that any chlorides present or being formed in the process of carbonisation would become so embedded in the softened coal that it was difficult to extract them entirely from the finished coke, however finely this was ground, but it wa8 difficult to imagine the formation of any chlorides insoluble in water or acids.The question of the alkalis present in coal was, as Mr. Bridge had mentioned, a very important one, particularly in connection with the action of alkaline chlorides on the refractory materials of gas retorts and coke ovens, and also in connection with the formation of ammonium chloride, which latter, however, had been turned to remunerative account by its extraction from the liquor.He had met with a case somewhat similar to that described by Mr. de Waele, in which producer gas scrubbers were attacked by hydrochloric acid, formed during the oxidation process. Mr. J. GOLDING said that alkaline chlorides were present in “flue dust,” which was now being tried as a source of potash for manurial purposes. He should like to hear whether there was any actual evidence of the chlorine being given off as hydrochloric acid, and also whether magnesia, was present in any notable quantity in the coal and coke examined.The latter question was suggested by the recollection of a recent paper before the Society (J. O’Sullivan, ANALYST, 1914, 39, 425), in which it was stated that the loss of chlorine which occurred during the ashing of beer was largely due to the presence of magnesia.He (Mr. Golding) had tried the method of burning with lime and alkalis for the determination of chlorine in cheese, and had found that for this purpose it was not satisfactory; and Miss Cornish and he had devised another method, which they hoped to communicate to the Society shortly. Mr. J. H. B. JENKINS said that the peculiar formations called birds’-nests ’’ which sometimes occurred in locomotive fireboxes were ascribed to the volatilisation from the fuel of traces of sodium chloride, which was deposited in some of the cooler places on the crown of the firebox; small particles of silicious matter, mechanically carried over, were caught in the molten sodium chloride and formed sodium silicate.Any action of that kind would presumably result in the formation of hydrochloricTHE OCCURREKCE OF CHLORINE IN COAL 149 acid, but it appeared unlikely that any material condensation would take place in the tubes, seeing that the temperature of the issuing gases was about 700° or 800' F., and he had never heard of any damage resulting from such a cause.The proportion of total sulphur in coal may be taken as from 1 to 1.5 per cent., and in the combustion it might be expected that some sulphuric acid would be formed.He was interested, therefore, to hear that, in the case of the economiser corroded by contact with flue gases, referred to by Mr. de Waele, there was very little evidence of the action of sulphuric acid. Mr. J. A. DEWHIRST suggested that the difficulty of extraction with water might be due to the conversion of part of the originally soluble chloride to an insoluble basic form such as the magnesium salt.Personally he did not see why a little acid should not be used in order to extract any such compounds, if the total chloride was desired, Mr. G. N. HUNTLY said that the presence of chlorides in coal had an obvious bearing on the determination of the ash.Considerable variation was liable to occur in the percentage of ash obtained, according to the temperature at which the coal was burnt ; and this might be partially explained by the presence of 0.25 to 1 per cent. of salt. Dr. COLMAN said that he did not think Mr. Bridge meant to suggest that other methods would not yield a larger proportion of soluble chlorides than he had obtained.The original object having been merely to ascertain what quantity of chlorine might be dissolved from a coke filter-bed, the grinding of the coke was only moderatelyfine, in order that the conditions of the experiment might be roughly comparable with those of a filter-bed. No doubt if the coke were more finely ground larger proportion of soluble chlorine would be obtained.But he very much doubted whether, however fine the grinding and however prolonged the treatment with water, anything like the total quantity of chlorine would be dissolved out, though he was not prepared to say what form the insoluble portion assumed. He could me no reason why some of the chlorine should not be converted into double silicates containing chloride, like some of the insoluble minerals of that class; but this, of course, was only hypothesis.He did not, however, think that any of the chlorine was in combination with carbon. Hydrochloric acid was unquestionably present in the products of combustion from coal-containing chlorides. I t was well known in ordinary gasworks practice that, when carbonisation was carried out in the absence of air, hydrochloric acid was always present in the hot gas and in the earliest portions of the ammoniacal liquor.I t was, he thought, unquestionable that hydro- chloric acid had a far more deleterious action than sulphur on copper and iron because, so long as the temperature was sufficiently high to prevent the deposition of water, sulphur dioxide had no very corrosive action, whereas hydrochloric acid, even in the absence of water, acted rapidly. The method of determination adopted was practically that of Eschka for estimation of sulphur, except that quicklime was used instead of magnesia.I t probably would not be a suitable method for organio substances containing a large proportion of volatile matter. When monochlor- aoetanilide was treated by this method, 20.11 per cent. of chlorine waslobtained, as150 HERBERT HAWLEY: THE ROUTINE DETECTION AND against the theoretical percentage of 20.9, showing that with such a substance the results would be slightly low ; but in the case of a substance in which the chlorine was not readily volatile it might be relied upon to give fairly accurate results, at any rate sufficiently so for the purpose of this investigation. Mr. DE WAELE said that for making Mond gas, coal containing more than 0.3 per cent. of chlorine would be rejected, owing to the corrosive effect on the scrubber. The presence of sulphur was not considered to be so serious. In the first scrubber the temperature, as Dr. Colman had pointed out, was too high to allow the sulphur to have much effect. In the ammonia, scrubber some pitting was bound to occur, as there was here a fairly high concentration of snlphuric acid.

ISSN:0003-2654    

DOI:10.1039/AN9154000146

出版商:RSC    

年代:1915

数据来源: RSC

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150 HERBERT HAWLEY: THE ROUTINE DETECTION AND THE ROUTINE DETECTION AND ESTIMATION OF BORIC ACID IN BUTTER. BY HERBERT HAWLEY, M.Sc., F.I.C. (Read at the Meeting, Narch 3, 1915.) THE usual methods for the estimation of boric acid in butter involve remora1 of the fat, and titration of the acid in the presence of glycerol or mannitol. Though perfectly satisfactory when an accurate estimation of the preservative is required, or for a single sample, the process is somewhat laborious when it has to be applied to a large series of samples.The majority of such samples are either free from boric acid or contain an allowable proportion, the detection and an approximate estimation of which is generally all that is required. The following process gives reliable approximate estimations of the boric acid ; it has the advantage that (1) the portion used for the examination of the fat serves also for both detection and estimation, and (2) a number of samples can be examined together in a very short time.The following reagents are required : Tzcrmevk Reagent.-A mixture of 5 grms. powdered turmeric root and 5 grms. tartaric acid is digested with three successive portions of 150 C.C.warm alcohol (industrial methylated spirit is quite satisfactory). Each digestion should continue for not less than an hour, and each successive portion should be filtered, and the volume finally made up to 500 C.C. with alcohol. (This reagent should be kept in fhe dark.) Dilute HydrochZoric Acid.-Twenty C.C. concentrated hydrochloric acid are diluted to a litre with water. One Per Cent.Standard Boric Acid Soldort.-One grm. boric acid is dissolved in 100 C.C. of the dilute hydrochloric acid. Milk.-For convenience, a sample may be preserved with formaldehyde, which is without effect on the test. Method of Working.-Twenty grms. of each sample of butter me placed in small beakers of uniform size of about 40 to 50 C.C. capscity.The butter may be weighedESTIMATION OF BORIC ACID IN BUTTER 151 in a rough balance, or, more rapidly, the apparatus described at the end of this paper may be used to deliver the sample. The samples are melted in the usual way on a copper tray over either a water-bath or steam oven, and kept warm until the curd and aqueous liquid have separated, leaving the fat clear. The fats are now poured off, as far as possible, on to filter-papers placed in small beakers (care must be taken that none of the aqueous portion of the butters is poured on to the filters), and the constants of the filtered fats examined by the usual methods.To the aqueous residues in the beakers 18 C.C. of the dilute hydrochloric acid are added from a small measuring cylinder. The contents of the beakers are stirred and kept warm for a few minutes.Allowing 2 C.C. for the water in the butter, we now have approximately 20 C.C. of dilute acid containing any boric acid originally present in the 20 grms. of butter, together with curd and a little fat floating on the top of the liquid. Ten C.C. of fat-free liquid are removed from each beaker by means of a, pipette dipped through to the bottom of the liquid.While the liquid is held in the pipette, the residue (fat and aqueous liquid) in the beaker is rejected. The liquid in the pipette is then returned to the beaker. This gives 10 C.C. of an opalescent liquid, which should be almost free from fat, though containing a little curd. The beakers are allowed to cool, and to each is added 5 C.C.of the turmeric reagent. Those samples which contain boric -acid slowly develop a reddish - brown colour, the intensity varying with the amount of boric acid present. To estimate approximately the boric acid, standards prepared as follows are put on at the same time: Two burettes are required, one containing 1 per cent. boric acid solution, and the other dilute hydrochloric acid.Standards represanting 0, 0.1 per cent., 0.3 per cent., and 0.5 per cent. H,BO, in the original butter will be found convenient, and are prepared thus : 0.0 per cent. 0.1 ,, 0.3 ,, 3 9 , ,? 6-5 ? # 2, 0.5 ,, 5 ?, 7, 4.5 9 9 9 , 9.5 C.C. dilute HCl, and 0.5 C.C. milk. 1 C.C. standard boric solution, 8.5 C.C. dilute HCl, 0.5 C.C. milk. To each are added 5 C.C. of the turmeric reagent.The milk gives a slight opal- escence, making the comparison of the standards and samples more satisfactory. The comparison should be made not less than one and a half hours, not more than three hours after the addition of the turmeric. The colour .develops gradually, and after a few hours commences to fade. The reagent gives an unmistakable colour when 0.05 per cent. boric acid is present in the butter, and the percentage up to 0.5 per cent.can be estimated with certainty to the nearest 0.1 per cent. ShouId any samples be found to contain more than 0.5 per cent. boric acid, it is best to determine the quantity by extraction and titration in the usual manner, as with such quantities the colour becomes more intense, but the gradation is not so good. This process has been used for the routine examination of butter in this labora- tory for the past twelve months.The results obtained have been frequently checked by estimation in the ordinary way. The apparatus I have devised will be found useful for measuring out the 20 grms. The agreements have always been good.152 ABSTRACTS OF CHEMICAL PAPERS of butter. inch bore and 6 inch length.A plunger is easily made by boring a hole nearly through a solid rubber bung which will just slide into the tube. A piece of narrow glass tubing with a bulb on the end, and sealed at the other end, is then inserted in the hole, and string tied tightly round the narrow end of the bung. To take a sample, the open end of the tube is pressed into the butter, at the same time lifting the plunger. The latter is then pressed down to the mark (which is adjusted so that the tube then contains 20 grms. of butter), and the butter pressed out into the beaker. I t will be found advisable to cover the inner tube with indiarubber tubing, otherwise when the sample is delivered the inner tube may strike the outer and cause breakage. I t consists of a stout piece of glass tubing of about CITY AKALYST'S LABORATORS, BIRMINGHAM.

ISSN:0003-2654    

DOI:10.1039/AN9154000150

出版商:RSC    

年代:1915

数据来源: RSC

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152 ABSTRACTS OF CHEMICAL PAPERS ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Estimation of Formic Acid in Ketchup. C. A. Peters and L. P. Howdar. (J. Ind. and Eng. Chem., 1915, 7, 35-37.)-From 91 to 92 per cent. of the total amount of formic acid added to ketchup can be recovered and estimated by the process described by Fincke (ANALYST, 1911, 36, 103). The amount of distillate collected should be at least 1,000 c.c., and it is of advantage to fit a Stolzenberg tube (ANALYST, 1908, 33, 485) in the flask containing calcium carbonate, and in which the formic acid is retained, the tube serving the purpose of intimately mixing the distillate with the calcium carbonate held in suspension.w. I?. s. Analysis of Glycerophosphates. 1. Francois and E.Boismenu. ( A m . Falsific., 1914,7, 423-432.)-1n the analysis of sodium and calcium glycerophosphates estimations should be made of the water, ash, phosphorus, and the sodium or calcium, respectively. The quantity of actual monoglycerophosphate present may be estimated by Astruc’s method, in which 0.210 grm. of the substance, dried pre- viously at 150° C., is dissolved in 500 C.C.of water, and titrated with & sulphuric acid, using helianthine as indicator ; the number of C.C. of acid required is multiplied by 10 to give the percentage quantity of the mono-ester. The sample must be dried at 150° C. for the estimation of the water. The quantity of ash yielded by the substance is not of great significance, especially in the case of calcium glycerophos- phate granules, where sugar and other substances are present; the sugar, in this case, also interferes with the estimation of the mono-ester by Astruc’s method, w.P. s. Iodine (Hubl) Values of Alcoholic Liqueurs and Essential Oils. R. Marcille, (Comptes !rend., 1914, 159, 1004-1007.)-1n the estimation of essential oils in liqueurs by the French official method (distilling the sample and estimatingFOOD AND DRUGS ANALYSIS 153 Oil of aniseed in 95 per cent.alcohol ... # ? 2, 50 ,9 9 , ... Oil of turpentine in 95 per cent. alcohol ... 2 9 9 , 9 , 50 9 9 Y ? ... Absinthe liqueur . . . ... ... ... the iodine value of the distillate: ANALYST, 1913, 38, 418), it is essential that, in every experiment, the alcoholic strength of the solution under examination should be brought to some definite limit, say 50 per cent., previous to the estimation, since variations in the strength have a considerable influence on the results obtained.The flasks containing the reacting solution should be kept in a dark place during the time of contact of the Hub1 reagent with the sample, as erratic results are obtained when the mixture is exposed to light.The temperature during the time of contact has also a slight influence on the iodine absorption; for instance, an oil of aniseed yielded a value of 1-21 at 25O C. and of 1-35 at 15O C. The variations in the value due to differences in alcoholic strength and exposure to light are shown in the following table ; the figures express grms. of iodine per grm. of essential oil, except in the case of absinthe, where they show gr.ms.per litre of the liqueur : I I 1.35 1 1.54 1.62 3.19 I 2-67 1.27 i 1.80 1.67 :3€i 1 333i8 1.78 3.1 I Condensed whole milk ... ,, skim milk ... In the , In Dull In Diffused Dark. ; Light. j Sunlight. I 72.6 70.0 10.0 I 8.0 1.0 10.5 7.9 i 7.7 w. P. s. 12.0 41 14.5 42 9.1 -- Manufacture of Condensed Milk, Milk Powders, Casein, etc.R. T. Mohan. (J. Xoc, Chem. Ind., 1915, 34, 109-113.)-Milk for condensing should be rejected if the acidity is above 0.2 per cent., and 10 C.C. of it should stand at least three hours without decolorising 1 C.C. methyleno blue at 46” C. So-called “fermentation tests” are of use in checking the purity of the supplies, the Wisconsin ourd test being a good one. A pint of milk is heated in a sterilised jar to about 9 8 O F., 10 drops of standard rennet extract are added, and the jar closed and incubated for about eight hours at 98’ to 102” F.The jar is then opened, and the odour and appearance of the curd noted, which should be free from smell and the holes indicative of gas-forming organisms. The Canadian standad for condensed milk is not less than 28 per cent.milk solids, and not less than 7.7 per cent. milk fat. The following table represents the average percentage composition of condensed milks : ___ -_ - - - - Solids. Ash. Fat. 1 protein. 1 Lactose. 1 gg. 1- I -_--- - I----- I I I . .-. - -- I 1.6 2.0 1.6 5.6 6.9154 ABSTRACTS OF CHEMICAL PAPERS The greatest difficulty in the manufacture of condensed milk is to prevent the crystallisation of the lactose or cane sugar, which gives rise to “sandiness.” A decrease in concentration to prevent which is impossible, as the successful keeping of the product depends on its having less than 30 per cent. of moisture, and to effect this cane sugar must be added in a proportion of about 41 per cent.Even under the best conditions the milk sugar usually crystallises. A thick gelatinous condition of the condensed milk denotes too much milk solids and not enough cane sugar to make a syrup.Evaporuted milk in Canada is defined a8 milk from which a consider- able portion of water has been evaporated, and contains not less than 26 per cent. milk solids, and not less than 7.2 per cent. milk fat ; it contains no added sugar, and is preserved by sterilisation at 113O to 116O C.for about thirty minutes. The milk is then shaken to make it smooth and uniform, and the tins, after sealing off, are incubated for about three weeks prior to shipping, so that any leaks ” or “ swells ” can be picked out. Hard grains sometimes found in the cans consist of calcium phosphate precipitated owing to over-concentration. Plain cortdensed milk is milk evaporated about 4 : 1, which is filled into barrels and used within a few days or so by ice-cream manufacturers and confectioners.The best method of sampling con- densed milk for analysis, from which sugar may have separated, is to transfer the whole contents of the tin to a large mortar and thoroughly grind and mix it, after which a 40 per cent, solution is prepared.Solids.-For the sweetened condensed milk a quantity of the 40 per cent, solution is evaporated to dryness in vacuo or in a McGill oven (in which the product is dried at 70” C.). For the unsweetened or evaporated milk two methods are available : one by taking the sp. gr. of the 40 per cent. solution, and calculating the solids by a formula ; the other by evaporation and weighing.The determination of fat by the Rose-Gottlieb method is the most reliable of those in ordinary use, but this shows on the average 0.31 per cent. of fat too low, due to the occlusion of minute particles of fat by the precipitated casein. Modifica- tions of the ether extraction and Babcock methods are described, which, it is claimed, give quite accurate results. In the former a weighed amount of the evaporated milk, diluted 4 : 1, is absorbed on a filter-coil placed in an extraction cone, and, without any preliminary drying, extracted in 8 Soxhlet apparatus with 1 per cent.acetic acid for two hours. This removes most of the protein matter, after which the cone is washed with hot water to remove the acetic acid, dried in an air-oven at looo C . for six or eight hours, and finally extracted for eight hours with ether in the ordinary way.The paper concludes with some notes on the manufacture of milk powders and casein. H. F. E. H. Solidifying-Point of Mutton-Tallow. R. Meldrum. (Chem. News, 1915, 111, 98-99.)-The more solid glycerides separated, by means of ether, from mutton- tallow (average solidif.-pt. 41.1” C., with a rise of 2 .4 O C.), solidified at 49.7” to 50.4” C. (Dalican’s method), with a rise of 3.4’ to 4*0° C., and neither the presence of suspended matter, nor the method of stirring, had material influence on the results. The variations in the lowest point (6tzbro”) reached before the “rise” ( 2 * 5 O C.) and in the L 6 rise ” (1-8O C.) were much smaller than in the case of theFOOD AND DRUGS ANALYSIS 155 original tallow (5.5’ C.and 3.8’ C. respectively), the differences being largely due to the influence of the liquid glycerides. Such erratic results are not observed with mixtures of stearic and oleic acids. Experiments described indicated that a constant solidification-point and “rise” could be obtained if the amount crystallised per unit of time were kept constant.The glycerides examined required super-cooling to start rapid crystallisation, and each glyceride appears to have a specific temperature of solidification when super-cooled. The fact that glycerides do not reach their normal solidification-point when super-cooled appears to be due to some molecular change. The latent heat of fusion is insufficient to raise the temperature to the normal solidification-point , especially when the super-cooled mass consists of a mixture of solid and liquid substances.C. A. M. Estimation of Total Tartaric Acid and Potassium in Wines. S. Kling and A. Lassieur. (Ann. FaZsijc., 1914, 7, 410-416.)-The total quantity of tartaric acid and of potassium in wine may be estimated rapidly and accurately by precipitating the former as calcium racemate and the latter as potassium perchlorate.For the estimation of tartaric acid, 25 C.C. of the wine are treated successively with 10 C.C. of a 2 per cent. ammonium I-tartrate solution and 20 C.C. of a calcium acetate solution (16 grms. of calcium carbonate and 120 C.C. of glacial acetic acid per litre of water) ; after standing for twenty minutes, the precipitate is collected on a filter, washed, then dissolved in dilute sulphuric acid, and the boiling solution titrated with potassium permanganate solution which has been standardised against tartaric acid.From the result, expressed in grms. of potassium hydrogen tartrate per litre of wine, is deducted 0-2 grm., to correct for the amount of ammonium I-tartrate retained by the precipitate.To estimate the potassium, the ash of the wine is treated with 10 drops of water and 10 drops of perchloric acid solution (sp. gr. 1*635), and then evaporated until most, but not all, of the excess of perchloric acid has been removed. The residue is stirred with 6 C.C. of 97 per cent. alcohol, containing 0.2 per cent. of perchloric acid; the insoluble portion is collected on a filter, washed with 95 per cent.alcohol, then transferred to a crucible, dried, and heated to redness for ten minutes with 3 grms. of sodium carbonate. The perchlorate is thus converted into chloride. After cooling, the contents of the crucible are dissolved in water, filtered, 10 C.C. of & silver nitrate solution are added, and, after the addition of nitric acid, the excess of silver is titrated with thiocyanate solution. During the titration the precipitate of silver chloride should be disturbed as little as possible, since silver chloride reacts to some extent with ferric thiocyanate (ferric sulphate being used as the indicator). This method estimates the potassium present as salts of organic acids and as sulphate. w. P. s. Detection of Vanillin in Quinine Wines. A. C. Chauvin. ( A m FaZsifi., 1914, 7, 420-422.)-Lecomte has proposed a test which depends on the formation of a red zone when an alcoholic phloroglucinol solution is allowed to come into contact with a mixture of an ethereal extract of the wine and a small quantity of dilute hydrochloric acid, but the author points out that furfuraldehyde and its oxidation derivatives also give the reaction. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9154000152

出版商:RSC    

年代:1915

数据来源: RSC

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156 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Influence of Hydroxy Acids and Lactones on Estimations of the Chemical Constants of Fatty Acids. C. A. Browne. ( J . Id. and Eng. ChLem., 1915, 7, 30-34.)-The author discusses the influence of laotone-forming hydroxy acids (more particularly the y-acids) on estimations of the acid, saponification, and acetyl values of fatty acids. For instance, if one-half of a sample of hydroxystearic acid should undergo lactonisation, the acid value would be depressed from 186.85 to 96.31, and the saponification value increased from 186-85 to 192.62, whilst the ester value would become 96.31 instead of zero.When a difference between the acidORGANIC ANALYSIS 157 Zanzibar Copal. Madagascar Copal. and saponification values shows that lectones are present in a fatty acid, the mean molecular weight (m) of the fatty acids before lactone formation may be Demerara Copal.calculated by the formula : m= %lo8+ 18'016 (' - '), where a is the acid value and S s the saponification value of the mixed fatty acids. Since lactones in a mixture of fatty acids are derived from pre-existing hydroxy acids, the acetyl value of Benedikt-Ulzer (ester value of the acetylated acids) is a truer measure of the original hydroxyl content of fatty acids than the acetyl number of Lewkowitsch.(potassium hydroxide required to saponify the combined acetyl in the acetylated acids). Thus, y-hydroxystearic acid in the glyceride molecule can be acetylated, and would show an acetyl number by Lewkowitsch's method ; whereas the separated fatty acids would show no acetyl value on account of the formation of stearo-lactone. The original acetyl value, calculated to the acetylated hydroxy acids before lactone formation, may be found from the formula, : + 0,00~07~c - %), where r is the acetyl ester value (Benedikt-Ulzer) and ( the acetyl value (Lewkowitsch).w. P. s. Action of Chlorhydrocarbons on Hard Copals.C. Coflignier. (Bull. SOC. Chim., 1914, 15, 780-781.)-The following amounts of insoluble matter were separated on boiling the copals with the solvents, and allowing the solutions to stand : __ . -. . . . .- . . . . - . - . -. . . . Dichlorethylene . . . ... ... Trichlorethylene . . . ... ... Te trachloret hylene ... ... Tetrachlorethane . . . I.. ... Pentachlorethane .. . ... ... I I Per Cent. 78-70 83.20 79-20 66.50 78.40 Per Cent. 70.90 70-80 88.20 37.80 63.00 Per Cent. 70.50 79.20 64.20 47.70 53.10 Madagascar copal' may be distinguished from the other two copals by the fact that it alone gives a practically complete solution when boiled for not too prolonged a period with tetrachlorethane (cf. ANALYST, 1914, 39, 13). C. A. M. Polymerised Drying Oils.R. S. Morrell. (J. SOC. Chem. Ind., 1915, 34, 105-109.)-Linseed oil from various sources was thickened in bulk or in smaller quantities in the laboratory, and to avoid oxidation this was done in an atmosphere of carbon dioxide or hydrogen. In the case of hydrogen it was found that, contrary to the usual statements, a very slight addition occurred, and eventually only carbon dioxide was used.The oils were heated for twenty-eight to sixty hours at 260" C., and the thickened oil was completely soluble in light petroleum. In the case of tnng oil the temperature and time of heating were 240" C. and twenty minutes respectively, and the heating was stopped as soon as any of the substance insoluble in light petroleum was formed, or, in other words, as soon as gelatinisation begun.158 ABSTRACTS OF CHEMICAL PAPERS 47.5 (240'0.) { 27.8 (2100 C.) - - - 0.567 198.5 765-151 The fall in the iodine value is essentially a function of the temperature, for linseed oil which has been kept at 260' C.for twenty-eight and a half hours can be heated for another twenty hours at this temperature without change; but on raising the temperature to 293' C.for another two and a half hours the iodine value fell to 89-97, and a substance is found insoluble in light petroleum and in carbon tetra- chloride. It is evident that one phase of a change in linseed oil is complete between 260' and 280' C., and above this another appears. Linseed and tung oils, thickened between 260' C. and 280' C., contain two modifications, one insoluble in acetone and the other soluble, but both soluble in light petroleum; but olive oil does not give an insoluble foEm, and in the case of poppy-seed oil the insoluble modification is not formed below 290' C.TABLE I. 46.6 (240' 0.) 72 % (210' C.) 0.9542 1.5114 (11.5' C.) 0.3143 (11.5' C.) 876.2 2.47 192.6 93-140-157 sp. gr. (15'C.) ... ... rnin .. ... ... [TI* ... ...... Molecular weight (in benzene) Acidity ... ... ... Sa onification valire ... IocPine value . . . . . . . Glyceryl per cent. ... Crystalline hexabromide ... 42-60 % 0-9763 1.4964 0.2892 Raw. 41-52 % 0-9527 1.4846 0.3035 0.933 1.4831 0.3053 (15' 0.) 805 0.4 197-203 185 9-62 (19O 0.) 33.5 % Linseed Oil. Thickened in Bulk 260.280" C. 0.9527-0*969 - - 5.15 188-193 103-106 - None Thickened in- Hydrogen (260-280" C.)... -- 0.9654 - - - 2.4 195-196 93-128 - None Linseed Oil. Solubility in acetone . . . . . . Sp. g. (15'C.) . . . . . . . . . CnlD . . . . . . . . . . . . [.ID . . . . . . . . . . Molecular weight (in benzene) ... Acidity . . . . . . . . . . . . Sa onification value ....... I o L e value . . . . . . . . . 100 % 0.933 1.4831 0*3053 805 , 0 '4 TABLE 11.C02 (2& 280" C.). -. -. 0.969 1.4915 0.2998 (15' 0.) 1.7 10.4 None (19' 0.) 1686-1704 200-203 118-134 Thickened Linseed Oil. Insoluble Soluble in Ac'etone. Tung Oil. ._ - - - - . - - Ram. . 0-9405 1'5172 (14' 0 . ) 0.3140 (14' 0 . ) 797 3 *3 192-194 166-168 10.47 None Tung Oil. 100 % 0.9405 1-5174 (12.5' C.) 0'3204 (12.5' 0 . ) 797 3.3 192 168 Thickened. -- 0.956 1.5134 (15' C.) 0'3117 (15' C.) 1431 2.3 8.3 None 190-201 143-171 Thickened Tung Oil.Insoluble Soluble 7 z G FORGANIC ANALYSIS 159 In view of the results obtained from the study of poppy-seed oil, it is concluded that linseed oil (thickened and soluble in acetone) contains the components of poppy- seed oil, which polymerises only slightly at 2508 C., but these components have undergone isomeric change. The chemical properties of thickened linseed oil (soluble in acetone) are similar to, and in some respects identical with, those of heated poppy-seed oil under the same conditions.When linseed oil (soluble in acetone) is heated to 290" C., the part which becomes insoluble in acetone has the same quad- ruple molecule as in the case of the poppy-seed oil. The author concludes that linseed and poppy-seed oils contain mixed glycerides of variable amounts of unsaturated acids in addition to small quantities of saturated glycerides, the acids being inter- changeable and their amounts dependent on the sources, and probably the ripeness, of the seed.Thickening by polymerisation without change in chemical composition occurs when there are at least two pairs of doubly linked carbon atoms in the mole- cules of the acids of the glycerides.Before polymerisation occurs, there is a shifting of the linkages in the molecule, and in the case of tung oil there is some slight evidence of ring formation. The thickening is due to polymerisation of the mixed glycerides, and the first stage is the formation of a product insoluble in acetone, which may be a double molecule of linked glycerides in the case of linseed oil, or a quadruple molecule in poppy-seed oil.The change is dependent on the temperature, ind an equilibrium is established when 50 per cent. of the modification has been formed. At higher temperatures the final stage is the formation of a polymer insoluble in light petroleum, which seems to be determined in linseed oil by the linolenic acid glyceride.H. F. E. H. Estimation of Unsaponiflable Matter Applicable to Ether Extracts, Fats, Oils, and Waxes. J. B. Rather. (J. Ind. and Eng. Chem., 1915, 7, 34-35,)-The following method has been devised for the estimation of unsaponifiable substances in the ether extracts of fodders, etc. It differs from the usual methods in that the fatty acids are separated from the unsaponifiable substances by precipitation from ethereal solution.About 0.4 grm. of the substance is boiled for one hour with 20 C.C. of f alcoholic sodium hydroxide solution; the solution is then evaporated nearly to dryness, 3.5 C.C. of glacial acetic acid are added, and the mixture is warmed with 50 C.C. of ether. Twentyfive C.C. of water are now added, the mixture is warmed for a minute, transferred to a separating funnel, and the flask is rinsed with five successive portions of 20 C.C.of ether. After shaking, the aqueous layer is drawn off, the ethereal solution is shaken with 10 C.C. of warm sodium hydroxide solution (1 : 2), 25 C.C. of warm water are then added, and the aqueous layer is drawn off; the washing is repeated five times with 30 C.C.portions of cold water. The ethereal solution is then transferred to a weighed flask, the ether evaporated, and the residue dried at looo C. to constant weight. When large quantities of fatty acids axe present together with small amounts of unsaponifiable substances, fatty acids may not be completely removed from the ethereal solution by the above treatment; in this case the ethereal solution, before evaporation, is shaken with 20 C.C.of hydrochloric acid, the acid solution is drawn off, the ethereal portion evaporated, and the residue weighed. This residue is dissolved in alcohol and titrated with & sodium hydroxide160 ABSTRACTS OF CHEMICAL PAPERS solution; the number of C.C. of alkali solution required is multiplied by 0.028 to obtain the weight of fatty acid which is deducted from the weight of the residue obtained on evaporating the ethereal solution.With samples containing more than 25 per cent. of unsaponifiable substances the amount of retained fathy acid may be disregarded; it amounts to about 2 mgrms., and is balanced by a corresponding amount of unsaponifiable substance in the soap solution. w.P. s. Proposed Uniformity in Methods of Fat Analysis. W. Fahrion. (J. Amer. Chem. ASSOC., 1915, 10, 7-18; through J. SOC. Chcm. Ind., 1915, 34, 185.)-A report of the work of a Commission appointed by the International Association of Leather Trades Chemists to study analytical methods for oils and fats used in the leather industry. Each member received samples of nine oils.The concordance in results was not 80 good as was expected. The acid values agreed well except in the case of cod oils, which alter during keeping. Mixtures of alcohol and petroleum ether, and alcohol and ether, were tried as Bolvents, using either aqueous or alcoholic alkali for titration. The results were the same as with the usual method. The author recom- mends titrating 5 grms.of oil in alcohol with or alkali. Saponification values are greater the longer the boiling, and the lower the concentration of the alkali. The author recommends using at least 3 grms. of oil and alkali containing less than 10 per cent. water, and claims that saponification is complete with five minutes boiling after a clear solution is obtained. Iodine values by the Hiibl, Wijs, and Hanb methods were reported.Results by the Wijs method were in excellent agreement, whilst the Hub1 results showed differences up to 26. The author recommends the abandonment of the Hub1 method. The values by the Hanus method lie between the results given by the other two methods. In the determination of unsaponifiable matter the author washes the petroleum spirit with 50 per cent.alcohol, which does not dissociate the soap. Unsaponifiable matter from fish oils should not be dried above 100" C. The results obtained in the analysis of dkgras show good concordance. Study of Various Tests on Glue, particularly the Tensile Strength. A. H. Gill. (J. Id. and Eng. Chem., 1915, 7,102-106.)-1n a summary, the author says his experiments described in this paper seem to justify the following conclusions : (1) That the tensile strength, jelly test, and viscosity of glue, bear no relation to each other ; (2) that a, particular method described for measuring tensile strength may be expected to give individual results not differing by more than 10 per cent.from the mean of a, series ; and (3) that the method of testing the strength of glue by measuring the strength which it imparts to bibulous paper is dependable, and gives fairly con- cordant results.Conclusion 1 is fully justified, the viscosity in particular being shown to be in no sense a measure of the useful properties of glue, the best and worst of a, series of glue solutions having viscosities which stood to each other in the close ratio of 100 : 96, whilst other more practical tests pointed to their values standing in the ratio of 100 : 60, or thereabouts.The jelly test, on the other hand, appears to exaggerate the difference in value of two glues, if careful measurements of the tensileORGANIC ANALYSIS I61 strength of glued joints be taken as the true measure of their value. For example, the jelly test suggested that one sample of glue was twice as strong as another, whereas the tensile strength of joints glued with each stood in the comparatively close ratio of 15 : 13.The jelly tests were few in number, and appear to have been carried out before the tensile strength test (applied as standard) had been so far perfected that duplicate results never differed from each other by more than 20 per cent.Conclusion 3 is important in view of the fact that measurements of the tensile strength of joints may be quite misleading unless conducted with elaborate pre- cautions. The author obtained erratic results when attempting to measure the tensile strength of bibulous paper impregnated with glue, and dried. He measures the breaking strength with the Mullen paper-tester, the paper being first dipped in 25 per cent.glue solution, dried in the air for thirty-six hours, and the amount of glue taken up per square inch being estimated by weighing pieces 2 inches square before and after treatment. The results are expressed in pounds per square inch per 100 mg. glue on 4 square inches surface. They are much more concordant than measure- ments of tensile strength of joints, except when the latter are made with elaborate precautions, and in general follow the tensile strength ; but unfortunately there are notable exceptions, Conclusion 2 is supported by the author's experimental results.As worded in the original paper, it might be taken to mean that the valuation of glue by measurement of the tensile strength of glued joints was easy, whereas the main value of the paper lies in the demonstration it affords that such work, to have any value at all, must be conducted with extraordinary care.The author uses a special machine for sawing his test-block in two, the saw, frequently filed, being carefully trued on a mandrel, the block, securely held in a rest, being sawn at a definite rate. Nearly two days are required to make the glue solution.Meanwhile the blocks are dried at 60" C. for two hours, sized and set aside to dry at room temperature for two days. They are again heated to 60" C., glued, trued up in a frame to secure perfect alignment, and placed at once in a drying frame of special construction, such that a uniform pressure of 30 pounds per square inch is secured. I n this frame they are supported on the points of adjustable screws, fitted to centre marks on the lower half blocks, the pressure of a 3-pound weight at the end of a 10-inch lever being transmitted through a steel point 1 inch from the hinge of the lever, this steel point pressing centrally on a steel pin, which in its turn is centred on the upper half block.After twenty-four hours in this frame, the blocks are allowed to dry for 100 hours at; room temperature and then tasted.With all these precautions, duplicate determinations may differ 10 per cent. from the mean ; by the neglect of any one of them duplicate determinations may stand in the ratio 7 : 25. I t appears to be established beyond doubt that a pressure of about 30 pounds per square inch gives the strongest joint, notably stronger than a joint obtained with pressures of 10 or 100 pounds.If the pressure be maintained for only three instead of twenty-four hours, the joint is on the average only 3 per cent. weaker. Artificial drying of the joint at 6 5 O C. tends to weaken the joint, and, for test purposes, is less satisfactory than drying at room temperature for 100 hours. The drying apparatus is figured in detail.G. C . J.162 ABSTRACTS OF CHEMICAL PAPEES Composition of Paint Vapours. C. A. Klein. (J. Id. and Eszg. Chem., 1915, 7, 99-102.) A criticism of the experimental methods employed by Gardner (ANALYST, 1914, 39, 266) in investigating this subject. This criticism is particularly directed to the evidence adduced by Gardner in support of his alleged discovery that paint vapours contain carbon monoxide, a statement that has been repeated, solely on his authority, in the public Press of Europe and America, as well as in technical journals (ANALYST, Zoc.cit. and Oil and Golour Trades Journat, 1914, 45, 1000). For the detection of carbon monoxide, Gardner employed the iodine pentoxide method and the formation of potassium formate by tho interaction of carbon monoxide with heated solid potassium hydroxide, with subsequent confirmation of the formate by the mercuric chloride reaction.But first he sought to free the vapours from any other substances which might render the results of these tests ambiguous (or as he put it, 4 L to destroy all organic vapours ''1 by passing them through fuming sulphuric acid.Now, he himself showed that these vapours included formic acid, and it is well known that formic acid at least is destroyed by fuming sulphuric acid with liberation of carbon monoxide. Gardner's deduction that paint vapours contain carbon monoxide is therefore invalid, and the present author states that no other evidence has ever been adduced in support of such a statement. G.C. J. Determination of Gasoline Vapour in Air. G. A. Burrell and I. W. Robertson. (J. Ind. and Eng. Chem., 1915, 7, 112-113.)-The first and more accurate method depends on liquefaction and fractional distillation of the air. The apparatus illustrated is exhausted, then filled at atmospheric pressure with the air to be analysed, and, after closing the stop-cock, is immersed in liquid air contained in a Dewar flask.After ten minutes, the air is removed with a vacuum pump, the cock is again closed, and the apparatus is removed from the liquid air-bath and allowed to attain the room temperature. The pressure of the residual gasoline is then read off on the manometer shown, the ratio of this pressure to that of the atmosphere giving the volume of gasoline vapour in one volume of the original air.The alternative method described is ordinary combustion anaIysis with calculation of the volume percentage of gasoline vapour from the contraction, or from the carbon dioxide pro- duced, on the assumption that gasoline vapour is substantially pentane. The ratio of the contraction to the carbon dioxide pro- duced, a8 well as the agreement of the results with those obtained by the method first described, show that this assumption is usually justified.In cases where the mean molecular weight of the vapours differed notably from that of pentane, the ratio of the contraction to the carbon dioxide would indicate nearly enough for most purposes how the results should be calculated. G. C. J.ORGANIC ANALYSIS 163 Separation of the Illuminants in Mixed Coal and Water Gas.G. A. Burrell and J. W. Robertson. (J. Id. and Eng. Chem., 1915, 7, 17-21.)-The method of fractional distillation in vacuo at low temperatures previously described (ANALYST, 1914,39, 414) has been used in estimating the illuminants in Pittsburgh artificial gas (3 parts of coal gas with 1 part of carburetted water gas). The con- stituents of such gases may thus be separated into the following groups : Distillates.Liquid Air Temperatures, - 185' C. B. -pt. OC. Methane ... ... -165 Nitrogen ... ... -195 Oxygen ... ... -183 Hydrogen.. . ... -253 Carbon monoxide - 190 Below -140' C. Ethylene . . . . . a -103 Ethane ... ... - 51 Below -120' C. Propane ... ... - 45 Prop ylene ... - 51 Below- 78O C. %-Butane ...... 1 Is0 bu tane ... - 10 Isobutylene ... - 4 - Residues. Ethane Propane %-Butane Isobutane Propane N-butane Isobut ane n-Butane Is0 butane Benzene B.-yt. "C. ... -93 ... -45 ... 1 ... -10 ... -45 ... 1 ... -10 ... 1 ... -10 ... 80 B;-pt. Isobutylene . . . - 4 C. Ethylene ... - 103 Propylene . . . - 51 Benzene ... 80 Propylene ... - 51 Isobutylene ... - 4 Benzene ... 80 Isobutylene .., - 4 Benzene ...80 Complete analysis of the artificial gas gave the following results : Carbon dioxide, 2.63 ; oxygen, 0.81 ; carbon monoxide, 13-25 ; hydrogen, 37-33 ; methane, 31.31 ; ethane, 2.10 ; propane, 0.43 ; ethylene, 6.05 ; propylene, 0.60 ; butylene, 0.11 ; benzene, 1-33 ; and nitrogen, 4.23 per cent. The method is recommended as a simple' means of estimating benzene in artificial gas.C. A. M, Comparison of Various Modifications of the Kjeldahl Method with the Dumas Method of Determining Nitrogen in Coal, with Notes on Errors in the Dumas Method due to Nitrogen evolved from the Copper Oxide. A. C. Fieldner and C. A. Taylor. (J. Id. and Eng. Chem., 1915, 7, 106-112.)- The most important observation is that low results were obtained in every case where the Kjeldahl digestion was stopped as soon as the liquid was colourless.Heating should be.continued for about two and a half hours after the liquid becomes colour- less, but an hour map be saved, without loss of nitrogen, by allowing to cool for ten minutes when colourless, adding permanganate in small crystals, and reheating for one to one and a half hours. Potassium sulphate and a drop of mercury should be164 ABSTRACTS OF CHEMICAL PAPERS used.Omitting the potassium sulphate not only prolongs the period required to obtain a colourless solution, but also the subsequent period which is necessary to convert all nitrogenous substances into ammonium sulphate. About 15 grm. potassium sulphate per 30 C.C. acid appears to be best ; smaller additions slow the process, whereas the use of much larger proportions is attended with risk of loss of nitrogen.Omission of mercury lengthens the process some one and a half to two hours, whilst the substitution of copper sulphite also loses about forty-five minutes as compared with the use of mercury. Phosphoric anhydride was found less effective than potassium sulphate. None of the coals examined contained nitric nitrogen, the results obtained by Jodlbauer’s method being identical with those obtained by the method above described.Identical results were obtained by a modification of Dumas’ method, which is described in detail. I t involves heating the copper oxide for several hours in vacuo, and cooling it in carbon dioxide before using it for a nitrogen determination. With- out these precautions, Dumas’ method seriously overestimates the nitrogen in coal.Whereas the difficulties, such as they are, of applying Kjeldahl’s process to coal depend on the nature of the latter, those connected with the use of Dumas’ method have their root in the method itself. But whilst the difficulty of freeing copper oxide from nitrogen affects the accuracy of any results obtained by Dumas’ method, the incidence of this source of error is especially heavy in the case of coal, since the percentage of nitrogen in coal is usually small, and Dumas’ method precludes the use of large quantities of substance. G .C. J. New Reaction of /3-Naphthol. J. Katayama and B. Ikeda. (Yakugakuxasshi, October, 1914; through J. Pharm. Chim., 1915, 11, 73-74.)-0n mixing 1 C.C.of a dilute (0.01 to 0.001 per cent. solution of &naphthol with a few drops of strong sulphuric acid, and adding 0-05 C.C. of a 0.01 per cent. solution of sodium nitrite, a violet coloration is produced. The reaction, which appears to be due to the forma- tion of a quinone derivative of &naphthol, is faintly perceptible in solutions con- taining only 0*0002 grm.of P-naphthol per C.C. C. A. M. Volumetric Fehling Method Using a New Indicator. A. M. Breckler. (J. lnd. artd Eng. Chem., 1915,7, 37-38.)-The method is dependent on a constant volume at the end of the titration, a constant time of boiling, and the use of sodium monosulphide as indicator. Ten C.C. of mixed Fehling solution are placed in a large test-tube and the sugar solution is run in, starting with 8.5 c.c.; after the first addition, the mixture is boiled for one minute, counting from the time a bubble of steam first traverses the liquid.The sugar solution is now added 2 C.C. at a time, boiling fifteen seconds after each addition. When the mixture becomes faintly blue, a drop of it is added to a drop of 4 per cent. sodium sulphide solution placed on a tile; the tile is given a slight rotary movement and the colour of the spot noted.The suspended cuprous oxide settles at once as black copper sulphide, leaving a, yellow supernatant liquid. The sugar solution is now added in smaIler quantities, boiling each time for fifteen seconds, until the test with the indicator gives a colour- less supernatant liquid after the copper sulphide has settled.The estimation is thenORGANIC ANALYSIS 165 repeated, adding to the 10 C.C. of Fehling solution sufficient water to make the final volume 30 C.C. and abont 97 per cent. of the sugar solution required in the first experiment. This mixture is boiled for ninety seconds and the titration completed, which can usually be done with two additions of the sugar solution.The presence of proteins and metals which give coloured sulphides interfere with the indicator ; the former may be removed from the sugar solution by means of alumina cream. w. P. s. Estimation of Sulphur in Motor Spirit. W. A. Bradbury and F. Owen. (Chem. News, 1915, 111, 39-41.)-A modification of the apparatus previously described (ANALYST, 1914, 39, 30) enables a volumetric estimation of sulphur in motor spirit to be made within about two hours.The burner passes upwards through the base of an absorption vessel, while an inverted round-bottomed flask with a shortened neck is used as the combustion chamber. Round the neck of the flask is fitted a disc of tinned copper (2g inches in diameter) with rings soldered on each side, the lower one being made to rest upon a constriction near the bottom of the absorption vessel.The circumference of the disc is perforated with holes, and the space between the ring and neck of the flask is fitted with a cork. The two carburettore are respectively charged with 10 C.C. of the motor spirit and with pure benzene, whilst about 50 C.C. of & sodium carbonate solution and 20 C.C.of neutral (10 volumes) hydrogen peroxide are placed in the absorption vessel. Air for the combustion is supplied by means of a water-blower, and by turning the taps may be passed through either carburettor, the connections being secured by mercury joints. The pure benzene is lighted at the burner, and the combustion chamber (flask) lowered over it, until the disc is covered by the liquid in the absorption vessel, and the gaseous products of combustion are bubbling gently through the holes in the disc.The taps are then turned so that the motor spirit is farced from the other carburettor into the burner, where it should burn with a small blue flame, while the platinum coil above the gauze cap of the burner is maintained at its maximum state of incandescence.The water in the beaker is now gradually heated from 27O C. to 43O to 49O C. at the end of the estimation ; and when only about 1 C.C. of the spirit is left, two successive portions of 1 C.C. of absolute alcohol are introduced into the carburettor through a, tap above it, to remove the last traces. The air supplied is then reduced to a gentle current, which is continued until the combustion chamber is cold, after which the absorbing liquid and washings are boiled to expel oxygen and carbon dioxide, and titrated with sulphuric acid, with lacmoid as indicator.Tests made with this apparatus showed that when motor spirit is burned in a lamp the wick has a selective action, and the amounts of sulphur vary at different stages of the combustion. No such action, however, took place during the spontaneous evaporation of benzene through the wick of an unlighted lamp.In the fractional distillation of a sample of benzene containing sulphur (348 grains per gallon) 49 per cent. was present in the first fraction of 20 per cent. C. A. M. Determination of the Specific Gravity of Tars, Oils, and Pitches. J. M. (J. Id. and Eng. Chem., 1915, 7, 21-24.)-For ordinary work standardised Weiss.166 ABSTRACTS OF CHEMICAL PAPERS hydrometers (225 mm. long with bulbs about 24 mm.in diameter) give sufficiently accurate results with creosote oils, If the reading be taken above 15.5" C., it may be corrected by means of the formula- Sp. gr. at 15"/15" C. = Sp. gr. t°C/15.50C. + 0*0008(t°C. - 15.5"C.). In the case of results obtained with the pyknometer or Westphal balance the formula to be applied is- Sp.gr. 15O/15OC. = Sp. gr. to/to x sp. gr. of water at t/15*5"C. + 0*0008(t0 - 15*5'c.) When the quantity of material available is less than 100 C.C. it is advisable to use the Westphal balance, with the addition of a special plummet for fractions of less than 20 C.C. For still smaller fractions a 1 C.C.pipette may be adapted as a pyknometer, the point being closed with a piece of sealed glass tubing. The specific gravity of viscous tars and pitches may be determined by the use of a small platinum pan (20 mm. in diameter and 12 mm. in height) supported by platinum wires meeting at the top to form a hook, which is suspended from the balance by a waxed silk thread. The specific gravity of the tar is found by means of the formula- c - a x= - ..(b+c)-(a+d) where a represents the weight of the empty pan in air ; b, its weight in water ; c , its weight in air when filled with tar ; d, its weight in water when filled with tar. In the case of pitches the formation of pockets is obviated by cooling the melted material in the pan slowly and under a slight pressure.Slow cooling causes a pronounced increase iu the results given by hard pitches, but its effect is negligible in the case of soft pitohes. Only rough results are given by a hydrometer with coal- tar ; but, if used, a correction of 0*000685' for each degree C. above or below 15.5' C. is applied. C. A. M. Determination of the Percentage of Toluene in Commercial Toluol. H.G. Colman. (J. Gas Lighting, 1915, 129, 196-198.)-As the result of a large number of distillations of varying mixtures of known amounts of pure benzene, toluene, and xylene, carried out in an ordinary Wurtz distilling-flask, it was found that if the distillation is carried out under uniform conditions it is possible to ascer- tain with reasonable accuracy the percentage of toluene in these mixtures by the determination of the fractions (a) boiling below 105" C.and (b) boiling above 117' C. Further experiments with similar mixtures of pure benzene, toluene, and xylene, but also containing small quantities of the other substances often present to a limited extent in oommercial toluol, such as carbon bisulphide, paraffin hydrocarbons of similar boiling-point, and cumenes, showed that the presence of these does not materially influence the results obtained.A table constructed from the results obtained with the mixtures of pure benzene, toluene, and xylene may therefore be employed with reasonable accuracy in the determination of the percentage of toluene in commerclial toluol which has been properly washed with caustic alkali and sulphuric acid, this being distilled under the same conditions as were employedORGANIC ANALYSIS 167 with the pure mixtures and the percentages boiling below 105' C.and above 117' C. ascertained. I n the accompanying table the percentage of toluene is found in that place in the vertical column above the figure showing the percentage below 105" C., which is on 8 horizontal line with the figure showing the percentage above 117' C., the quantities of the fractions found in the test being taken as the nearest whole per cent., and the toluene result given in the nearest whole per cent.This table only holds good generally for samples containing from 50 to 75 per cent. of toluene, and for such as give at least 5 per cent. and not more than 50 per cent. either below 105* C.or above 117O C. In the great majority of cases the commercial samples fall within the limits named, but by a simple modification the exceptional samples can also be analysed in a similar manner. The distillation is conducted in a standard Engler 100 C.C. distillation-flask, as employed in the petroleum industry, having the following dimensions : Diameter, 6.5 om. ; neck, 15 x 1.6 cm.; length of side-tube, 10 cm. ; angle of side-tube, 75'. The following apparatus is also required : A round-bottomed flask of 150 to 200 C.C. capacity, a Young 12-bulb pear " fractionating column, an 18-inch Liebig con- denser, a set.of 100 C.C. graduated cylinders, and a thermometer registering from 50' to 150' C., and graduated in one-fifth degrees. The graduations of the 100 C.C.cylinders sold are sometimes incorrect to the extent of 1 0.0. The cylinders employed must be standardised by running into them known quantities of liquid, preferably toluene, from an accurate burette. Each day, before testing, the thermometer car- rection must be ascertained by placing it in a distillation-flask, with the top of the bulb just below the side-tube, and hoiling distilled water in the flask. The difference between the thermometer reading and looo is taken as the correction of the thermometer, This correction includes that due to variations of barometric pressure and inaccuracies of the thermometer.Should the barometric pressure vary considerably during the day, the correction should be reascertained in the same manner.The Engler flask and condenser are washed out with the toluol to be tested and allowed to drain. One hundred C.C. of the toluol to be tested are poured into the flask from the graduated cylinder, the latter being drained out only. Distillation is effected by means of a small naked flame, with a wire gauze screen to protect the flame and the bulb of the flask from draughts. The top of the thermometer bulb should be just below the side-tube of the flask, and the rate of distillation 7 C.C.per minute from the end of the condenser, the distillates being collected in 100 C.C. cylinders. When the thermometer reaches 105' C. (corrected) the heating is stopped, the condenser allowed to drain, and the receiver changed. The distillation is continued till the thermometer reaches 117' C.(corrected) ; the heating is then stopped, the condenser allowed to drain, and the residue in the flask, after complete cooling, drained into a 100 C.C. cylinder. The combined amounts of the two distillates and the residue should not amount to less than 99.5 C.C. From the amounts boiling (a) below 105' C. and ( b ) above 117' C. the percentage of toluene in the sample is found, subject to the correction for paraffin content specified below, by means of the accompanying table.TABLE FOR ASCERTAINING IRE PERCENTAGE OF PURE TOLUENE IN COMMERCIAL TOLUOL FROM THE PERCENTAGES OF THE FRACTIONS BOILING BELOW 105' C.AND ABOVE 117' C. - r 49 48 47 46 45 44 43 42 41 - Zr 38 37 36 35 34 33 32 31 29 - T ~. 28 27ORGANIC ANALYSIS 169 The table only holds for crude toluol samples containing 50-75 per cent.of toluene, and for such as give not less than 5 per cent., or more than 50 per cent., either below 105' C. or above 117' C. Most commercial samples fall within these limits, but in the exceptional cases a modification of the method must be adopted. The exceptional cases are of four classes : 1. The percentage boiling either below 105' C.or above 117' C. may be below 5. In this case 90 C.C. only of the sample is taken and mixed previous to distillation with 10 C.C. of pure benzene if in the first test the distillate below 105' C . has been found less than 5 per cent., or with 10 C.C. of xylene (boiling at 136-143" C.) if the amount, boiling above 117' C. has been found below 5 per cent. The mixture is then to be distilled exactly as prescribed, and the percentage of toluene in the mixture found by the table.The figure thus found is the number of C.C. of toluene in 90 C.C. of the original sample. 2. The percentage boiling both below 150' C. and above 117" C. may be so low that there is no corresponding entry in the table. In this class, which includes samples containing high percentages of toluene, SO C.C.of the sample is taken and mixed with 10 C.C. of pure benzene and 10 C.C. of xylene (boiling at 136-143" C.), and the mixture distilled as prescribed. The figure in the table corresponding to the amounts of distillate found below 105" C. and above 117" C. then gives the number of C.C. of toluene in 80 C.C. of the original sample. 3. The percentage boiling above 117' C. may be so high that there is no corre- sponding entry in the table.In this class, where the fraction boiling above 117' C. is very high, 80 C.C. is taken and mixed with 20 C.C. of pure benzene previous to distilla- tion. The figure found in the table from the percentages below 105' C. and above 117' C., multiplied by 100 and divided by SO, gives the percentage of toluene in the original sample, 4.The percentage boiling below 105' C. may be so high that there is no corre- sponding entry in the table. In this class, which comprises samples containing relatively high percentages of benzene and low percentages of toluene, 80 C.C. of the sample is taken and mixed with 20 C.C. of pure toluene previous to distillation, and the percentage of toluene in the mixture obtained from the percentages distilling below 105" C.and above 117" C. in the prescribed manner. From the figure thus found must be deducted the 20 C.C. of toluene added, and the difference represents the amount of toluene contained in the 80 C.C. of the original sample taken. lChe percentages of toluene determined in the prescribed manner by the dis- tillation test will include paraffin hydrocarbons of a boiling-point approximating to that of toluene, when these are present in the commercial toluol.The amount of such paraffins is determined in the following manner, and a corresponding reduction made from the percentage of toluene as found by the distillation test: 100 C.C. of the sample is placed in a round-bottomed flask of 150-200 C.C.capacity, fitted with a suitable fractionating column such as a Young 12-bulb '( pear " column, and distilled at the rate of 1 drop per second from the end of the condenser. The fraction distilling between 107-115" C. (corrected) is collected separately, and its specific gravity at 15.5" C. ascertained by any method giving results accurate to the third place of decimals.reduction a t the rate of 9 per cent. is to be made on tho amount of toluene found by For every 0.001 that the specific gravity is found below 0.868,170 ABSTRACTS OF ~ ~ E ~ I C A L PAPERS the distillation test. Thus, if the percentage of toluene found by the distillation test is 70, and the specific gravity of the fraction 107-115" C, obtaiBed in the prescribed manner is 0.864 at 15.5" C., 4 x 9- 3 per cont.of the figure shown by the distillation test is to be deducted. The corrected ~ e r c ~ n t ~ e of toIuene, &llowing for p a r & ~ n content, is therefore found by multipl~ing 70 by 200-3, or 97, and dividing by 100 = 68 per cent, Commercial. toluene should comply with the following test: 90 C.C. of the sample, shaken with 10 C.C.of 90 per cent. sulphuric acid for five minutes, should not give more than a light brosn colour to the wid layer, G. c. J. ~ e t ~ r r n ~ n a t ~ o ~ of the Percentage of Toluene in C ~ ~ ~ e ~ ~ i a l Solvent Naphtha. H. G. Colman. (J. Gas ~ ~ g ~ t ~ ~ , 1915, 129, 314315.)-The method consists in carefully distilling off from the solvent naphtha all constituents boiling below 1 8 8 O C., the distillate containing all the toluene in the sample mixed with all other lower boiling subst&nces present in the solvent naphtha, t~gether with xylene and small quantities of higher boiling substances.The amount of toluene in the distillate, and consequently in the volume of solvent naphtha originally taken, is found by the method already described for ascertaining the percentage of toluene in com~ercial toluol.A 150-200 c,c. r o u n d - b o t t ~ ~ ~ d fiask and conde~ser are washed out with the solvent naphtha to be tested and allowed to drain. One hundred C.C. of the solvent naphtha are poured into the flask and distilled, using a Young 12-bulb c6pear" fraction- ating column, the rate of distillation being 1. drop per second from the end of the condenser. The distillate is collected in a, 100 C.C.cylinder, and the distilIatio~ stopped when the thermo~eter reaches 1 3 8 O C, (correcte~ : see preceding abstract^, and the volume of distillate noted after al~ow~ng the condenser to drain. If the amount of distillate up to 138" C. thus obtained is less than 35 c.c., a further 100 C.C. of the sample is distilled in the same manner, and the distillates are combined.If the total volume of distillate then still falls below 35 c.c., the sample may be taken as ~ractically free from toluene, If the volume of dis~illate is 35 C.C. or over, thea! 35 0.c. thereof are taken, and mixed with 50 c,c. of pure toluene and 15 C.C. of pure benzene, and the mixture distilled as described in the preceding abstract, the distillates (1) below 105' C,, (2) from 105" to 117" C., and (3) the residue above 117" C., being collected and measured, and the specific gravity at 15.5' 0.of the fraction 1 0 5 O to 117O C. also det~rmined. From the percentages boiling below 105' C, and above 117O C., the percentage of toluene in the mixture is found by means of the table reproduced in the preceding abstract, In cases where the original sample of solvent naphtha contains parafins of a, boiling-point approximating to that of toluene, the figure thus found is too high, and a correction must be made in the following ~ & n n e r : For each 0.0~1 that the specific gravity of the fraction 1 0 5 O to 117' C. is below 0.868, thr~e-quar~ers of 1 per cent. is to be deducted of the percentage of toluene found bg the table, the remainder giving the corrected percentage of toluene in the mixture. Of this amount 50 c,c. is derived from the pure toluene added to the mixture, and must be deducted, the remainder giving the number of c.0. of toluene in 35 C.C. of the dist~l~ate. This number multi-INORGANIC ANALYSTS 171 plied by the number of C.C. of distillate obtained from the original volume of solyent naphtha taken and divided by 35, gives the number of C.C. of toluene in the total distillate, and also the number of C.C. of toluene in the volume of solvent naphbha originally taken. Thus, for example, 100 C.C. of solvent naphtha on distillation in the prescribed manner gave 53.5 C.C. of distillate up to 138" C. Thirty-five C.C. of this distillate were mixed with 50 C.C. of pure toluene and 15 C.C. of pure benzene, and on distillation in a 100 C.C. distillation-flask gave the following fractions : Up to 105' C., 24 C.C. 105" to 117' C., 53 C.C. of sp. gr. 0.855 at 15.5' C. Above 117' C., 23 C.C. From the table, the percentage of toluene in this mixture is 62 per cent., but as the specific gravity of the fraction 105' to 117' C. is only 0*855--i.e., 13 points below 0.868-13 x Q= 9.8 per cent. of 62 must be deducted for paraffins. The corrected amount of toluene in the mixture is therefore 62 - 9.8 per cent. of 62 = 62 - 6.1 = 55.9 per cent., and, deducting from this the 50 C.C. of pure toluene added to the mixture, leaves 5-9 C.C. of toluene derived from the 35 C.C. of distillate. The total amount of toluene in the 53.5 C.C. of distillate is therefore 5.9 x 53*5+35=9*3 c.c., and the amount of toluene in the original solvent naphtha, taken to the nearest whole number is 9 per cent. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN915400156b

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

INORGANIC ANALYSTS 171 INORGANIC ANALYSIS. Standardisation of Alkalimetric Solutions. F. D. Dodge. (J. Ind. and Eryg. Chem., 1915, 7, 29-30.)-The use of potassium hydrogen phthalate, KHC,H,04, is recommended for standardising alkali solutions employed in volumetric analysis. It may be prepared by dissolving 50 grms. of resublimed phthalic anhydride in about 200 C.C. of water, exactly neutralising the solution by the addition of 50 per cent.potassium hydroxide solution (about 120 grms. of this solution will be required), then adding a further 50 grms. of the anhydride, and heating the solution until a11 the crystals have dissolved. The solution is now diluted with water to about 550 grms., filtered if necessary, and stirred while cooling. The crystals are collected, recrystallised from 300 C.C.of hot water, and dried at 110" C. The salt is anhydrous, Don-hygroscopic, stable, and colourless; it is soluble in 10 to 11 parts of cold water and in about 400 parts of alcohol. w. P. s. Detection of Bromides in the Presence of Thiocyanates, Cyanides, and Ferrocyanides. L. J. Curtman and A. G. Wikoff. (J. Amer. Chem. SOC., 1915, 37, 298-301.)-Thiocyanates, cyanides, and ferrocyanides interfere with the libera- tion of bromine from bromides by chlorine water, apparently owing to the latter having a selective oxidising action upon them.The following method of pre- cipitating them as cuprous salts in the presence of sulphurous acid enables 2 mgrms. of bromine to be detected in the presence of 500 mgrms. of each of the inter- fering substances : The solution, which should be neutral or slightly acidified with sulphuric acid, is mixed with 15 C.C.of a, saturated solution of sulphur dioxide, heated just to boiling, and treated while hot, and with coutinual stirring, with172 ABSTRACTS OF CHEMICAL PAPERS 2N-copper sulphate solution, which is added drop by drop until the supernatant liquid is blue.(A green colour in the case of thiocyanates indicates the addition of insufficient sulphurous acid.) The liquid is filtered while hot, and the filtrate and wash- ings evaporated to 5 to 10 c.c., any slight white precipitate formed in the concentra- fion being disregarded. I t is then tested with 1 C.C. of 3N-sulphuric acid and 1 C.C. of 1 per cent. potassium permanganate (or dilute hydrochloric acid and chlorine water) and shaken with carbon bisulphide.If permangaaate be used, care must be taken not to leave the carbon bisulphide too long in contact with it, since they react and form a small amount of manganese dioxide, which may dissolve and give a colora- tion similar to that given by small quantities of bromine. C. A. M. Comparison of the Gunning-Copper Method with the Kjeldahl-Gunning- Arnold Method for the Estimation of Nitrogen.0. F. Jensen. (J. Ind. and Eng. Chem., 1915, 7, 38-39.)-Estimations of nitrogen in bone meal, dried blood, cyanamide, and linseed-meal by the Gunning-copper method (use of 0.3 grm. of copper sulphate in addition to potassium sulphate) and the Kjeldahl-Gunning- Arnold method (use of metallic mercury in place of copper sulphate) showed that with either method a digestion of from one to one and a half hours gives a quantitative yield of ammonia, except in the case of dried blood, when three hours’ digestion is necessary in the Gunning-copper method.The latter method possesses the advan- tage that the use of sodium sulphide is unnecessary in the distillation part of the process; the copper sulphate also acts as an indicator in adding the sodium hydroxide before distilling, so that a large excess of alkali may be avoided.w. P. s. Rapid Method of Estimating Nitrates. E. Knecht. (J. SOC. Chem. Id., 1915, 34, 126-127.)-The method is a modification of one previously proposed by the author (Ber., 1903, 36, 166) depending on the fact that titanous hydroxide is capable of effecting the complete reduction of nitrates (and nitrites) to ammonia.When caustic soda is added to a solution of a, titanous salt, black titanous hydroxide is precipitated, and this begins to decompose almost at once, yielding nascent hydrogen and the white titanic hydroxide, probably according to the following equations : Ti,( SO,), + 6NaOH = Ti,(OH), + 3Na2S0,. Ti2(OH)6 + 2H,O = STi(OH), + H,.A convenient amount of nitrate for a determination is about the equivalent of 0.1 grm. of potassium nitrate. Ten C.C. of a 1 per cent. solution are measured into a copper flask, excess of caustic soda is added, and then about 20 C.C. of commercial titanous sulphate or chloride. The solution is at once distilled into standard acid, and the liberated ammonia estimated.The reagents must be added in the order stated, or there will be a loss of nitrous or nitric oxide. Pure potassium nitrate showed 99.80 and 99.83 per cent. as the result of duplicate determinations, the cost of which for materials is considerably less than one penny. H. F. E, H.INORGANIC ANALYSIS 173 Comparison of Some Methods for Total Phosphoric Acid in Super- phosphate.C. A. Peters and A. G. Weigel. ( J . Ind. and Eng. Chem., 1915, 7, 39-40.)-The estimation of phosphoric acid by precipitation first as phospho- molybdate and then as ammonium magnesium phosphate gives high results unless the phosphate solution has been previously evaporated to dryness to remove silica. Trustworthy results are obtained by other methods-namely, the volumetric method of Pemberton, and the direct precipitation of the phosphoric acid as ammonium magnesium phosphate in the presence of ammonium citrate or citric acid, and direct weighing of the yellow phosphomolybdate precipitate.w. P. s. Volumetric Estimation of Silver. C. Debrun. (Ann. Falsific., 1914, 7, 407-409.)-1n the Gay-Lussac method for the volumetric estimation of silver, the strength of the standard chloride sodium solution employed is so adjusted that 100 c.c., measured at 1 5 O C., are equivalent to 1 grm.of silver. If measured at other temperatures, a correction must be applied for the contraction or expansion of the solution, rand the author gives the correction for each degree between 0' and 35' C. Thus, 100 c.c., measured at 15' C., will measure 99.953 C.C.at 0' C.; 99.938 C.C. at 5" C. ; 99.956 C.C. at 10' C. ; 100.092 c.0. at 20' C . ; 100.205 C.C. at 25' C. ; 100.328 C.C. at 30' C.; and 100-484 C.C. at 35' C. w. P. s. Analysis of Mine Waters. J. H. Capps and 0. W. Boies. (J. P 7 q ~ Chem., 1915,19, 65-75 ; through J. Soc. Chem. Ind., 1915, 34, 175.)-Free sulphuric acid in mine water cannot be determined directly, owing to gradual hydrolysis of the ferric salt during the titration.Electrolytic reduction of the ferric salt invariably resulted in the liberation of measurable amounts of hydrogen. This source of error was avoided by reducing with cadmium amalgam in an atmosphere of hydrogen. A portion of the mine water (50 c.c.) was first titrated with potassium permanganate (1 C.C. =0*005258 grm.Fe) for ferrous iron. A small separating funnel and a three- way tap were sealed to the central tube and side tube respectively of a Drexel gas-washing bottle, and after introducing a convenient amount of the mine water and exhausting, the bottle was well shaken ; hydrogen was admitted, and the bottle again shaken till equilibrium resulted. The process was repeated twice, the amalgam run in, and the bottle shaken vigorously until the attainment of complete reduction --i.e., till a drop of the solution gave no colour with potassium thiocyanate (about two minutes).One aliquot part of the solution (50 c.c.) was then titrated with sodium carbonate for free acid and another portion (50 c.c.) with permanganate for total iron. Methyl orange indicator was employed in the former operation, the end-point being ascertained by comparison with a standard neutral tint.The absolute end-point of the standard was ascertained by conductivity measurements made during titration of a similar solution in presence of methyl orange. The result- ing tint was permanent when the solution was enclosed in a sealed bulb of clean glass. An artificial '' mine water " containing 0.429 grm.of ferric iron, 0.774 grm. of ferrous iron, and 3.85 grme. of sulphuric acid per litre, also traces of aluminium, calcium, magnesium (as sulphates), and sodium (as chloride) gave, respectively, OD174 ABSTRACTS OF CHEMICAL PAPERS analysis by the above method, 0.427 grm., 0.769 grm., and 3.825 grms. Similar solutions of ferric iron in sulphuric or hydrochloric acids, after reduction (four to five minutes) in the same way with cadminm amalgam, gave extremely concordant results upon subsequent titration with permanganate and bichromate, respectively.In these cases the preliminary expulsion of oxygen from the solutions was unneces- sary, but the air in the apparatus was displaced by carbon dioxide. Zinc amalgam effected a rapid reduction (0.5 minute), but the results were vitiated by the simultaneous displacement of appreciable amounts of iron from the solutions. Separation of Tungsten from Molybdenum.E. E. Marbaker. (J. Amer. C3wm. Soc., 1915, 37, 86-95.)-The tungsten and molybdenum are first obtained a8 a solution of sodium tungstate and molybdate. To this boiling solution, which should not contain more than 0.3 grm.of either metal, a 25 per cent. solution of stannous chloride in concentrated hydrochloric acid is added in the proportion of about 20 C.C. for each 0.16 grm. of tungstic acid supposed to be present. Larger amounts of tin give trouble at a later stage, whilst the separation of tungsten is incomplete unless enough stannous chloride is added. The total volume of the solution should lie between 60 and 300 C.C.After boiling for a few minutes, the blue precipitate of W,Os is allowed to settle, the orange supernatant liquid is decanted through a filter and the precipitate washed by decantation with 5 per cent. hydrochloric acid until the washings give no reaction for molybdenum when tested by the zinc and thiocyanate method. The precipitate is then brought on to the filter, allowed to drain, partially or completely dried, according as it is small or large in amount, and ignited to WO,.The filtrate and washings are evaporated to small bulk, 5 to 10 grms. of 20-mesh zinc is added to throw tin out of solution, and after ten minutes the green solution is decanted through a filter and the tin is washed several times with hot water, which is also filtered and collected.The filtrate and washings are heated to 60' C. and passed through a Jones reductor, through which 50 C.C. of dilute (1 : 40) hydro- chloric acid has first been passed. The filtrate and washings are followed through the reductor by 150 C.C. of dilute (1 : 40) hydrochloric acid, and finally by 150 C.C. of hot water, all the liquid being collected in the flask of the reductor, which has been previously charged with 20 C.C.of a 10 per cent. solution of iron alum and with 20 C.C. of Reinhardt's solution (90 grms. manganese sulphate, 175 C.C. sulphuric acid, 175 C.C. syrupy phosphoric acid, 650 C.C. water). When the green solution enters the ferric solution, the colour changes to red, This red solution is finally titrated with permanganate, an operation attended with no difficulty, as the red colour disappears as the titration proceeds, and the final change is from faint bluish green to pink, The molybdate is reduced in the reductor to Mo203, which reacts quan- titatively with the ferric solution to give molybdate and ferrous salt.The results, both for tungsten and molybdenum, are never more that 0.5 per cent.in error. The method for tungsten, if applied to a solution of pure sodium tungstste, gives low results ; but if a little (0.2 grm.) sodium chloride or potassium sulphate be added, the results are exact. In presence of notable amounts of molybdenum, it is unnecessary to make any such addition. G. C. J.APPARATUS, ETC. 175 Electrolytic Separation of Zino, Copper, and Iron from Arsenic.A. K. Balls and C. C. McDonnell. (J. Ind. and Eng. Clzem., 1915, 7, 26-29.)- For the electrolytic separation of zinc, copper, iron, and small amounts of lead from arsenic, it is essential that the latter should be in the pentavalent condition, since in the lower form of oxidation it will be partially precipitated. Another essential condition, especially when iron is present, is that there should be an excess of alkali (e.g., 10 to 20 grms.per 100 C.C. of electrolyte). Potassium hydroxide is more satisfactory than sodium hydroxide, and the precipitation of iron or copper hydroxides is prevented by the addition of tartaric acid. The addition to the electrolyte of glycerol, or a mixture of equal parts of glycerol and alcohol, causes better adherence of zinc deposits to the basin, which may be of nickel, roughened by etching or a sand-blast.To prevent deposition of carbon with the iron, the ourrent should be maintained below 1.7 amperes per 100 sq. cm., and preferably below 1 ampdre, while the addition of a few C.C. of alcohol will prevent iron oxide from depositing at the anode. In order to make copper deposits adhere firmly, rapid rotation (1,000 to 1,600 revolutions per minute) of the anode is necessary, and an addition of about 2 grms. of potassium nitrate is made.The arsenic may be estimated iodimetrioally in the liquid siphoned off the deposits. C. A. M. APPARATUS, ETC. Fractional Distillation with Regulated Still-Heads. M. A. Rosanoff and C. W. Bacon. (J. Amer. Chem.SOC., 1915, 37, 301-309.)-1t is stated by Brown (J. Chem. Soc., 1880, 37, 49 ; 1881, 39, 517), that in distillation with a still-head maintained at a constant temperature the composition of the distillate is constant, and is identical with that of the vapour evolved by a mixture whose boiling-point equals the temperature of the still-head. When, however, the boiling-point curve of a mixture passes through a maximum or a minimum, Brown's law requires modi- fication.If the boiling-point curve be plotted with the abscises representing the composition of liquid mixtures, the diagram may be divided into two parts by a straight line perpendicular to the composition axis and passing through the maxi- mum or the minimum of the curve, and each part may be regarded as an independent diagram.The composition of the vapour from the regulated still-head will then depend upon whether it fall within the right or left-hand side of the diagram. For example, in the case of a mixture of carbon bisulphide and acetone (where the boiling-point curve passes through a minimum), a mixture containing only a small percentage of acetone was distilled in an apparatus of the type previously described (J. Amer. Chem. SOC., 1909, 31, 448; and ANALYST, 1914, 39, 306). The still-head was kept constant at 40-02O C., and seven consecutive fractions of distillate contained 75.2 to 75.1 per cent. of carbon bisulphide-a composition falling to the right of the perpendicular. In a second experiment the mixture contained 29 per cent. of carbon bisulphide (a composition lying within the left part of the diagram), while the still- head was maintained at the same temperature. Fifteen consecutive fractions of the distillate then contained from 55.4 to 55.3 per cent, of carbon bisulphide. Analogous176 REPORTS results were obtained with mixtures of ethyl acetate and ethyl iodide (boiling-point curve passing through a, minimum) and of chloroform and acetone (boiling-point curve passing through a maximum). C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9154000171

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

176 REPORTS REPORTS. Report to the Local Government Board upon the Effects of Certain Condensing and Drying Processes used in the Preservation of Milk upon its Bacterial Contents. S. DelBpine. (Food Reports, No. 21, 1914. Price 6d.) -Three methods of preservation of milk as practised at four English factories were investigated : A, Manufacture of sweetened condensed milk; B, drying of milk over heated revolving surfaces ; C, drying by spraying the milk into a current of hot air.The main object of the first set of experiments conducted in 1910 was to ascertain whether tuberculous cow's milk was still capable of conveying tuberculosis after being treated by Methods A and B. In the second set of experiments (1911) special attention was paid to the general effects upon the bacterial contents of milk which followed the use of Methods B and C.Method A.-The milk is pasteurised by one of two methods, either at a tempera- ture of from 75' to 80" C. for twenty to twenty-five minutes with continuous stirring in steam-jacketed cylinders, or in a series of steam-jacketed tubes through which the milk is made to pass at such a rate that before it leaves th9 heater the temperature is raised to about 86O C.It is finally filled, after admixture with 11 to 15 per cent. of cane or beet sugar and condensation, into new and clean, but not sterilised, tins. The finished product is about 31 per cent. of the original milk, and should have a total solids of from 74 to 79 per cent., of which about 57 per cent. is cane-sugar. The crude methods used for stirring, cooling, etc., give rise to opportunities for contamination of the milk subsequent to its partial sterilisation.The following are the results of inoculation tests with tuberculous milk after condensation : Before admixture with tuberculous milk, the fresh milk received at the factory did not, on the day of the experiment, contain an appreciable number of tubercle bacilli, but other bacteria were present which caused inflammatory lesion8 when injected under the skin of guinea-pigs.The heating of this milk to 8 6 O C. reduced to a considerable extent this pathogenic action, while a mixture of 1 part of milk rich in tubercle bacilli with 108 parts of the above non-tuberculous milk produced rapidly extensive tuberculosis in guinea-pigs inoculated with it, and after this mixture had been heated to 77O C.it was still capable of producing tuberculosis, but much more slowly and less extensively than the untreated mixture. Further heating to 92' C. left the mixture still capable of producing tuberculosis resembling in type that produced by milk heated to 77O C. None of the sweetened condensed milk prepared from the infective mixture produced tuberculosis in the inoculated animals, but some of the samples caused inflammatory lesions not produced by the pasteurised milk before sweetening and condensing.A full description of Methods B and C for drying milk, together with diagrams of the plant employed, is given, together with an account ofREPORTS 177 inoculation and feeding experiments made with the finished product.The material, as it was collected from the rollers in B, was exposed to considerable risk of con- tamination from dust and from workmen who wear their ordinary clothes and handle the dried milk with their bare hands. The presence of living tubercle bacilli, as found in the milk dried over cylinders heated to 138" C. to 140' C., is at first sight surprising, but it was found by direct experiment that the milk itself never reached a temperature exceeding 96" C., and that only for a period varying from three to six seconds was it a t this temperature.In Method C the milk, after straining and heating, passes to a separator. The separated milk may be dried separately, in which case the cream is removed. When dried whole-milk is wanted, the separated milk and cream are brought together again in a common channel, which carries the milk to a pasteurising apparatus, where it is heated to 70" to 75" C.The vacuum-condensed milk, after reduction to a little less than half its original bulk, is rapidly carried to 95' C., and then at once cooled to 58" C., and forced under a, pressure of 2,000 to 3,000 pounds, together with a current of air heated to 1 1 5 O C., into a tin-lined chamber the internal temperature of which is 76" to 81" C., where it falls in a layer of granules.About 6,000 gallons of milk were treated daily at the particular factory visited. The total number of bacteria present in mixed COW'S milk such as is usually supplied to town consumers was found to be considerably reduced by treatment according to each of the three methods investigated.The reduction was greatest in the case of Method A, and least in Method C. In each .of the three methods of treatment there was a stage at which the reduction in the total number of bacteria, was much greater than that observed in the finished article ready for sale. The increase in the number of bacteria observed during the final stages is due to recontamination, by which is meant the results of the exposure of .a product partly or completely sterilised to sources of infection by which some of the bacteria removed by sterilisation are reintroduced. Were proper precautions taken, such recontamination might be almost entirely prevented, in which case the total number of aerobic bacteria cultivated by the methods described in the paper should seldom exceed 100 per grm.of preserved milk. The reduction in the total number of bacteria was almost entirely due to the death of Streptococci, Staphylo- cocci, Sarcinca, bacilli of the B. coli type, Streptothrichs, yeasts, etc. At none of the stage8 of preparation was the milk ever found completely sterile, and it was observed that the amount of heat to which the milk was submitted was insufficient to bring .about the death of several saprophytic and of some pathogenic bacteria.Among the .saprophytic bacteria which were invariably found to resist pasteurisation, those most commonly detected were sporing bacilli of the types included under the term B. mesentericus. Some Streptothrichs appeared in some cases to have survived, but the evidence was not conclusive.Of tbe pathogenic bacteria, the tubercle bacillus was the only one the fate of which was investigated. Some living tubercle bacilli of bovine origin were found to have survived treatment under Nethod B. It may safely be assumed that Method C, which yields a product giving a higher total bacterial count than Method B, has even less effect upon tubercle bacilli.The same bacilli resisted the process of pasteurisation forming part of Method A. The tubercle bacilli which had survived pasteurisation in Method A, and drying by178 REPORTS heat in Method B, were still capable of producing progressive tuberculosis in guinea- pigs inoculated subcutaneously with milk containing these bacilli, but the course of the disease produced by these bacilli was very much slower than that produced in guinea-pigs inoculated with the same amount of untreated tuberculous milk.The tuberculosis produced by the heated bacilli was latent or occult for some four weeks. Young rabbits fed with milk containing these modified bacilli did not contract tuberculosis. H. F. E. H. Report on the Work of Inspectors of Foods for the Year 1913-1914. A.W. J. MacFadden. (Abstract from the Annual Report of the Medical Officer of Health of the Local Government Board.)-The Report is arranged under the following headings : 1. Work in Special Relation to the Public Health (Regulations as to Food) Act, 1907.-Inspections were made during the year at the majority of the food-importing ports in England and Wales.Reference is made to the prevalence of lesions of actinomycosis in ox tongues imported from Argentina, but great improvement was noticed in the condition of the tongues received after the attention of the Argentine authorities had been drawn to the matter. Samples taken from cargoes of refrigerated meat treated by the formaldehyde process have been examined, the results showing that the amounts of formaldehyde present were not such as would call for action on public health grounds.Ochonocercissis nodules were found to be present in several consignments of beef from Australia. Bags of sugar arriving in the Port of London from Peru were noticed to be covered with borax, which had been carried in the same hold and had become loose during the voyage.This borax contained considerable amounts of arsenic, and steps were taken for the return of a, portion of the sugar which had already been distributed. Apples received from the United States of America during the early part of the year had a bluish deposit on their skins. This deposit contained traces of copper and arsenic, and was evidently the remains of an insecticide wash.Imports of fresh milk during the year were insignificant in amount, and no samples were taken for bacteriological analysis. Of 51 samples of imported cream examined bacteriologically, all except 2 appeared to have been pasteurised before shipment. Boric acid was present in 30 of the samples, and 11 contained hydrogen peroxide. Attention was drawn in the last Annual Report (cj.ANALYST, 1914, 39, 195) to attempts being made by preservative makers to induce dealers and manufacturers of dairy products to use preservatives which are likely to escape detection unless specially looked for. A “special milk preservative ” which has recently been offered consists of sodium benzoate, 69.5 per cent., and sodium carbonate, 28.1 per cent. 2. Local Arrangements for Food Inspection.-More attention is being paid to the supervision and condition of places where food is prepared, and there is a growing tendency on the part of butchers to notify the local authority at once of meat in their possession which is diseased or unsound.3. Bacterial ~ood-Poisoning.-During the year Beveral minor outbreaks of food- Similar attempts are still being made.INSTITUTE OP CHEMISTRY 179 poisoning came under the notice of the Board, but the only serious outbreak occurred at Newcastle-on-Tyne, This was caused by the milk of a cow infected with septicaemia, following parturition having been mixed with the general milk-supply from a farm.4. Work in Relation to the Sale of Food and Drugs Acts.-Inspectors visited a, number of districts during the year, and made suggestions with a view of increasing the efficiency of the work done under these Acts. Added proof was obtained of the disadvantages attaching to the administration of the Acts by the police in certain districts. The methods adopted were of little use for the purpose of detecting modern fraudulent practices, the number of samples taken was quite inadequate, and in some cases the only notes were kept in pocket-books, which mere liable to be destroyed after a short time. As regards the taking of samples under the Acts, it is suggested that an improvement in administration would be effected by frequent conferences between the medical oflicer of health, the anaIyst, and the sampling officer. Circulars relating to Public Health Regulations (Milk and Cream, and Foreign Meat) are published as an appendix to the Report. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9154000176

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

INSTITUTE OP CHEMISTRY 179 INSTITUTE OF CHEMISTRY. PROFESSIONAL CHEMISTS AND THE WAR. THE Thirty-Seventh Annual General Meeting of the Institute of Chemistry was held on March 1 at the new premises of the Institute, 30, Russell Square. Professor Meldola, the retiring President, in referring to the work of the year, indicated the activities of professional chemists in connection with the war.The Council of the Inetitute had supported the counter manifesto to which many British scholars and public men had subscribed in answer to the document emanating from analogous circles in Germany. The Institute had also been instrumental in directing the attention of the Government to the desirability of appointing a Special Committee to deal with the question of supplies of chemical products for which the country had hitherto been dependent to a preponderating extent upon German factories.Dealing with the question of dyestuffs, Professor Meldola reminded the members of the warning he had given in the last paper read before the Chemical Section of ths Society of Arts in 1886. Systematic inquiries made among the consumers revealed the fact that even at that time 90 per cent.of the dyestuffs then in use here were of foreign manufacture. No lost ground had been regained, and'before the outbreak of the war we were still importing nine-tenths of our colouring matters from Germany and Switzerland. The development of this industry abroad had been due to the recognition and utilisation by manufacturers of the results of chemical research.Early in August the President of the Board of Trade appointed a Committee, under the Chairmanship of Lord Haldane, for the purpose of advising the Government with respect to the means of meeting the national requirements, and from this Committee180 INSTITUTE OF CHEMISTRY there was subsequently formed a Sub-Committee, under the Chairmanship of Lord Moulton, for dealing especially with the manufacture of dyestuffs.A scheme formu- lated by the Government in consultation with a Committee representative of the great dye-using organisations was put forward early this year, and, after full discussion by those immediately concerned, was finally referred back for modification. The scheme was considered unsatisfactory, but the Government determined not to allow the project to fall through, and a new scheme, which differs from the first in certain important particulars, was subsequently launched.A considerable number of the dye-consuming companies appeared to be favourably disposed towards it. I t should be clearly understood, however, that neither the Board of Trade Advisory Committee nor the Dyestuffs Sub-committee was in any way responsible for either of those schemes, The grounds on which public action was imperatively called for were set forth most clearly in an address delivered by Lord Moulton at Manchester on December 8 of last year.He had stated explicitly that he only held himself responsible for the advice that the Government should take action, but not for the particular shape or form which that action should assume.The principle had been adopted that there should be established a company in which the consumers should be the chief shareholders, and which the Government should subsidise by advancing capital at a certain rate of interest, to the extent of ~1,000,000. The scheme was in a way a co-operative one, and, for the first time in this country, a distinct proposal was made for the establishment of a State- aided industry. In view of the great interests at stake, the policy appeared to be a sound one, and this was admitted by both political parties when the proposal was mentioned in the House of Commons, in November, by the President of the.Board of Trade. It was a matter of importance to the representatives of the chemical profession that their aspect of this great industry should be kept well to the fore in the scheme, and in any other scheme that might hereafter be put forward. They desired to see the restoration of the coal-tar colour industry to this country, and not only restored, but permanently retained after the war. The discussions of the Government schemes in various parts of the country by dye-consuming organisa- tions, Chambers of Commerce, and so forth, had all centred round political or economic questions ; the vital principle-viz., adequate chemical control-had been subordinated or left out of consideration altogether. While there was much wrang- ling over the question 8s to the method by which the industry should be established and maintained here, whether by free trade or protection, or subvention, or by any other device, the consideration of the questions whether a few years hence there would be anything in the way of dyestuffs worth protecting, whether there would be a sufficient basis of material products left for the politicians and economists and business people to wrkngle over, was overlooked.I t was not a purely business problem which the Government had undertaken to solve; it was primarily a chemical problem.It was not even a business problem in the ordinary trade sense, because the main object was at first to supply our own wants, and the chief consumers were to be the chief producers. The question of business in the sense of outside trade was, for the present, remote. The conditions which had to be met, if this country was to be once more theINSTITUTE OF CHESIISTRY 181 home of the colour industry, were certainly imperfectly understood by the public.Even those most concerned-those who were invited to subscribe to the capital- appeared in most cases to have an idea that all that was necessary was to find the money, secure the Government aid, appoint a board of business directors, and lo! the industry would forthwith spring into existence, ready to cope with all emergen- cies. What were the facts of the case? About five hundred different dyestuffs of definite composition had been given to tinctorial industry as the products of chemical research.Of these a certain number only could be and were being made in this country, The total output of our factories was, at present, inadequate for the requirements of our textile industries.The first step to be taken, therefore, was to enlarge and develop existing factories, so that the dyes which could be made here should be turned out in larger quantities. This necessity had been provided for in the Government scheme, and “so far so good.” If the extension of the existing factories still produced insufficient supplies, new factories must be erected and equipped.That also was provided for in the scheme; but if we want to establish the industry here permanently we must look beyond all this. Where should we be left after the war? We should be in possession of processes for making a certain number of dyes, and the supply of their products might possibly be sufficient for the particular purposes for which they were required.But there would still be an outstanding number of other products which had never yet been made here, and for the working out of these processes no combination of ( I business ” talent was of the slightest value. It was not a business question, but a chemical question, and it was by chemical research alone that our colour industry could be saved.The German colour industry has been built up by the utilisation of the results of research carried on in the factories and Universities and technical schools for a period of over forty years! To suppose that we could retrieve our position by starting a company, the directorate of which was to consist solely of business people, was ludicrous. The large and representative body of dye-users and producers which form the Dyeware Supply Inquiry Committee of the Society of Dyers and Colourists fully endorsed this view, and forwarded to the Board of Trade a resolution, passed at Manchester last month, in support thereof.It was satis- factory to learn that there were dye-consuming organisations which had grasped the situation scientifically. To imagine that a dyer, however skilful he might be, was by virtue of his ocoupation necessarily competent to direct the affairs of a company concerned with the manufacture of the dyes which he used was about as sensiblo as the assumption that a person who could tell the time by his watch was thereby qualified to undertake the direction of a factory for the construction of chronometers.One feature of the new scheme which the chemical profession would view with favour was the distinct recognition of research as a necessity for the development of the industry.The Government ‘( will, for ten years, grant not more than 6100,000 for experimental and laboratory work.” That was certainly a concession which marked an advance in official opinion for which they were grateful.It would be for the satirist of the future to point out that it required a European war of un- paralleled magnitude to bring about this official recognition of the bearing of182 INSTITUTE OF CHEMISTRY science upon industry. Who was to direct this research? A directorate of purely business people would certainly be incompetent ; a board composed of dye-users could do no more than indicate what dyestuffs were needed.True, it was proposed that the company should take powers to secure the assistance of a committee of experts, but this appeared to be simply a reversion to the policy of “ drift.” The experts were, as usual in this country, to be subordinated and their assistance W ~ S to be invoked at the discretion of a Board, the members of which could have no real knowledge of the conditions necessary for prod-acing the materials they required.Would they be competent to point out dangers ahead? The “ staple products” upon which they were asked to stake their capital might, a few years hence, be superseded by the products of subsequent discovery. The policy of attempting to run a highly specialised and rapidly developing branch of organic chemical industry by a company of business people, with expert assistance when required, was fatal if it wae intended to establish the industry permanently here.The group of industries which had arisen from the products of the tar still was not going to remain stagnant after the war, and it was scientific guidance, and not mere assistance, that would keep them alive.I t was the expert, and the expert only, who could foresee the course of development, who could keep in touoh with the progress of research, and direct with intelligence the campaign against competitors. If such scientific direction was withheld, all schemes were sooner or later bound to end in failure. If this second warning to the country, after a period of about thirty years, were unheeded, it would be so much the worse for the country ! To other branches of manufacture in which our dependence upon foreign products had been forcibly revealed by the war, professional chemists were able to render considerable service.It had long been known that laboratory glass and porcelain apparatus and filter-paper had been mainly supplied from abroad, and that large quantities of pure chemical reagents and of the special chemicals required for analytical or research work had borne non-British labels.This state of affairs called for prompt action, and the Councils of the Institute of Chemistry and the Society of Public Analysts had acted conjointly as a Committee for dealing with this matter of such vital importance to the profession.The inquiries instituted by this Committee soon brought the fact that failure in the supply of laboratory glass apparatus would not only cripple the work of the chemists, but would also influence to a serious extent certain important industries the dependence of which upon supplies of suitable glass had not a t first been foreseen. In connection with these inquiries it was at a later period considered necessary, in view of the great national interests involved, that the Institute should take part in giving practical aid to would-be manufacturers.For this purpose ’a Glass Research Committee was appointed, and was still carrying on its work. Formulas supplied by members of the Committee had been made in the laboratory of the Institute and submitted to the recognised tests.The experiments had perforce been carried out on a smdl scde, but the co-operation of a number of glass manufacturers had been secured, and the results would be tested on a fairly large scale under oomplete expert control. Not the least important of the glass problems was the production of a, suitable glass for miners’ safety-lamps, the necessary protecting shades for which had also beenINSTITUTE OF CHEMISTRY 183 hitherto mainly imported from abroad.This particular kind of glass was of pressing importance in relation to coal-mining, and it was certainly humiliating to learn from the makers of these lamps that for glass of the required quality capable of complying with the Home Office tests we have been so largely dependent upon foreign glass manufacturers.The action of the Institute throughout had been governed entirely by patriotic motives; the work was being carried on as a national duty, and the results were placed unreservedly at the disposal of all manufacturers who wished to avail themselves of them. The efforts which were made by certain firms, as well as by our own Committee, were leading to results which held out a good prospect of the manufacture of many kinds of chemical glassware being established on a permanent footing in this country, so that at no distant future British laboratories would be stocked with home-made apparatus. With respect to porcelain it W ~ S satisfactory to be enabled to report that crucibles and dishes equal to the best Berlin ware were now being produced in this country at practically the same price.I t W&S equally gratifying to know that the filter-paper problem had also been practically solved-thanks largely to the assistance given by our paper experts-and that British filter-papers of all the required qualities, and in every respect equal to those which had been associated with foreign labels, would surely be manufactured in British mills.With respect to the supplies of chemical reagents, the Joint Committee found it necessary to entrust to a special Sub-committee the somewhat arduous task of compiling a list of all the commonly used reagents, with indications of the standards of purity required and the tests necessary for ascertaining whether the required standard had been reached. The list had been published as a pamphlet, and had been sent to many firms and companies of manufacturing chemists with a view to ascertaining which reagents of their own manufacture they were prepared to supply.When the replies had been received, the Joint Committee would know the require- ments of the profession that could be met by British manufacturers. I n all the branches of their work the Joint Committee had received most cordial assistance from manufacturers and dealers.The manufacturers of chemical reagents were doing their best to meet the needs of the profession. It was most earnestly hoped that sooner or later laboratory supplies both of apparatus and materials would be entirely of British origin. The manufacturers were-in some cases a t considerable cost-developing lines of industry which were of the nature of new departures for this country.I t was the solemn duty of consumers and users-in fact, of every branch of the profession-to do their utmost to encourage and support these new home industries. Patriotism and the credit of our country alike demanded that, after the war, they should help those who were helping them by insisting upon having nothing but the products of British manufacture.They should not only assist in tbe development of these industries now, but insure their prominent retention after the declaration of peace. With the achievement of this result there would be removed the reproach that the nation which gave to chemical science Priestly, Black, Boyle, Cavendish, Davy, Dalton, Faraday, and Graham, the country which founded the coal-tar colour industry, and which had taken the lead in the manufacture of ‘‘ heavy chemicals,” allowed her184 INSTITUTE OF CHEMISTRY laboratory work to be dependent upon foreign materials, and her great textile and metallurgical industries to be threatened through the stoppage of supplies from inimical countries.Continuing, Professor Meldola referred to the large number of Fellows, Asso- ciates, and Students who had for the time being relinquished their professional work or their studies in order to give their services to the country in the field of war.I t was of interest to learn that during the present campaign a, mobile chemical laboratory has been in use at the front. Professional chemists were also serving with the Army Service Corps, and with the Sanitation Companies of the Royal Army Medical Corps.Members also were engaged in laboratories and factories under Government control, and concerned with the testing or production of the various war materials and supplies. The Institute, in brief, had done its best in the present emergency to discharge its functions as a national professional organisation.The Government Departments early in August received intimation that the services of technical experts and the accommodation of the Institute’s laboratories were at the disposal of the Government if needed, and the names of many members were included in Government and other Committees carrying on work of supreme importance to the welfare of the country at the present time, While he recognised that, under bhe existing conditions of strain upon all State officials, individual interests had to give way to national requirements, he felt that the Government departments did not hold that official view of the status of the chemists which they should. He referred to the advertisement recently issued by the Chief Inspector at the Royal Arsenal, Woolwich, inviting applications from temporary assistant chemists, the candidates being expected to have a thorough training in inorganic and organic chemistry, to be accnrate analysts, preference being given to University graduates, or to members of the Institute. The remuneration offered for the positions was expressed as ‘( wages 62 0s. 6d. per week.” A more direct discourage- ment to entry into the profession of chemistry, or a, more certain method of securing incompetence for the service, could scarcely be imagined. I t was particularly un- fortunate that such degrading terms should be offered at a time when the nation’s need for skilled chemists was being made manifest from so many different quarters, and when this necessity was just beginning to be realised.

ISSN:0003-2654    

DOI:10.1039/AN9154000179

出版商:RSC    

年代:1915

数据来源: RSC