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DECEMBER, 1013. Vol. XXXVIII., No. 463. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. AN ordinary meeting of the Society was held on Wednesday evening, November 5, in the Chemical Society’s Rooms, Burlington House. The President, Mr. L. Archbutt, F.I.C., occupied the chair. The minutes of the previous ordinary meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messre.J. J. Eastick, B.R.S.M., F.I.C., and J. F. Millar were read for the second time; and certificates in favour of Messrs. Alan Milsom Bailey, A.I. C., Lanhill, Chippenham, Wilts, Second Assistant Government Analyst, Straits Settlements, Singapore ; Arthur Leslie Barton, 20, Hotham Road, Putney Common, S.W., Chief Chemist and Bacteriologist to the Belgravia Dairy Company, Ltd.; Thomas Sidney Haines, A.I.C., 24, Woodfield Avenue, Ealing, Assistant to Mr. Cyril Dickinson, B.Sc., F.I.C. ; and Arthur George Abraham Miller, 1, Pretoria Terrace, Waltham Cross, Herts, Lecturer in Chemistry and Physics at the Sir George Williams College, Tottenham Court Road, London, were read for the first time.Messrs. C. W. Birch, U. R. Evans, B.A., and H. W. Gill, B.Sc., A.I.C., were elected members of the Society. The following papers were read : (‘ The Preparation of Rubber for Analysis,” by L. Archbutt, F.I.C. ; ‘( The Examination of Commercial Gelatins in Reference to their Suitability for Paper-Making,” by R. W. Sindall and W. Bacon, B.Sc., F.I.C. ; 6‘ Some Experiments on Chlorine Compounds of Ethane and Ethylene, with Special Reference to their Application to Analytical Chemistry,” by L. Gowing-Scopes ; and The Detection and Estimation of Benzoic Acid in Milk and Cream,” by Edward Binks, B.Sc., F.I.C.

ISSN:0003-2654    

DOI:10.1039/AN9133800549

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

550 L. ARCHBUTT : THE PREPARATION OF RUBBER FOR ANALYSIS. BY L. ARCHBUTT, F.I.C. (Read at the Meeting, November 5 , 1913.) THE preparation of rubber for analysis is a matter which is not very satisfactorily dealt with by the textbooks, and one does not find a machine for the purpose included in the catalogues issued by the dealers in laboratory apparatus. Weber suggests grinding the sample between a pair of mixing rollers; but the laboratory type of machine which he illustrates is power-driven, and would be heavy and expensive.A method commonly employed, and one that answers well enough for an occasional sample, is to reduce the rubber to powder by rubbing on a coarse file or rasp; but this becomes very tedious when many samples have to be dealt with. Moreover, some soft rubbers, very small tubes, and materials such as the insulating coatings of wires, cannot be dealt with in that way; and even with fairly hard rubbers it takes a long time to rasp any considerable quantity.In the course of my inquiries for a suitable machine I applied to Dr. Schid- rowitz, who informed me that he had found it convenient to pass the rubber first through a pair of finely-grooved rollers, and afterwards to grind the partially broken- up material carefully in an ordinary coffee-mill.Acting upon this suggestion, a small experimental machine was made for me in the Midland Railway Works, from which, the machine, which I exhibit this evening, has been developed. By the simple device of mounting the rollers so as to work either in gear or with one roller fixed, we have found it possible to reduce all the rubber samples we have had to deal with to powder without any other appliance or treatment.The machine is easily operated by hand, quite simple, and can be constructed at the cost of a few pounds. Referring to the figures, A and B are two solid grooved rollers made of hard gun-metal, 4 inches in length by 24 inches in diameter, mounted in bearings in a strong steel frame, C.The grooves are V-shaped, eighteen to the inch, and & inch deep, with rather sharp, smooth edges. The rollers can be geared together in the ratio 2 : 3 by means of the solid brass gear wheels D and E. The wheel E is per- forated with a number of holes, R, shown in the side-elevation, and when moved along its shaft, so that the fixed pin P enters one of these holes, it is thrown out of gear, and the roller is fixed.The distance between the rollers A and B is capable of adjustment, and is regulated by means of the set screws, SS. The shafts of the rollers are lubricated by four small Stauffer lubricators (not shown in the figure), which are screwed into holes in the frame C.THE PREPARATION OF RUBBER FOR ANALYSIS 551 The machine is firmly bolted to the bench, as shown in the figure, and the tray T, which slides into the space underneath the rollers, receives the powdered rubber. The rubber for analysis is cut with scissors or a knife into pieces about + inch thick, These are passed through the rollers about three times with the wheels in gear, which crushes and cuts the rubber without grinding it much.The grinding process is completed by passing the broken-up rubber again through the rollers with RUBBER-GRINDING MACHINE. the back roller fixed, and most samples are in this way reduced to powder. Any large and imperfectly ground pieces are picked out and again passed through the rollers. It sometimes happens with very soft, pure rubber that the particles stick together, but they can generally be easily separated again by the fingers.I have not had any experience in the analysis of raw rubber, but all samples of vul- canised rubber goods which I have analysed have been successfully prepared by this machine. Not more than ten minutes are required to prepare a sufficient quantity of the material for an ordinary analysis.As examples of rubbers prepared in this way I exhibit the following :-552 L. ARCHBUTT: ::$: ~ ~ ~ ~ ~ ; , . I Description of Article. Free Sulphur. Alkali Extract. Washer . . . ... ... ... Sheeting, good quality ... ... ,, low quality ... ... Soft red tubing ... ... ... Motor tyre inner tube ... ... Very elastic black tubing ... Cut up with scissors into thin strips Ground for 10 minutes ...... 9 , 15 ?, ... ... 1 , 30 3 , ... ... Mineral Matter (Ash). Per Cent. Per Cent. Per Cent. 2-69 1.51 1-31 2.85 1.33 1.78 3.06 1 *69 1-56 4.40 1-18 1.56 Per Cent. 52 40 46 11 9 1 Condition when Ground. Fine, non-adherent powder. Somewhat adherent powder. Fine, non-adheren t powder. Somewhat adherent powder. Very adherent particles. 9 9 9 ) Y, Even the last sample of pure vulcanised rubber has been reduced to a condition in which the reagents can attack it without difficulty.I have had some experiments made to ascertain the effect of grinding on the figures obtained by analysis, the material used being a rubber washer composed of about 50 per cent. rubber and sulphur and 50 per cent. mineral matter (calcium carbonate and lead oxide). The prepared rubber was first extracted for eight hours in a Soxhlet extractor with boiling acetone, and the extracted rubber, after carefully evaporating off the whole of the adhering acetone, was boiled for four hours with 6 per cent. alcoholic soda solution.The percentage of saponified organic matter, freed from mineral matter, recovered from this solution is given in the column headed ‘ I Alkali Extract.’, Prolonged grinding, as would be expected, causes changes to take place which increase the percentage of matters extracted by acetone ; but ten minutes’ grinding has not appreciably altered the rubber.The grinding has not caused any chemical changes tending to increase the alkali extract, the higher figures obtained with the ground material being obviously due to the finer division of the sample and the more complete extraction.The ‘‘ free sulphur ” figures are peculiar, and I can offer no explanation of them. They were obtained by my assistant, Mr. W. H. Keys, who is a very careful worker, and I have no doubt they accurately represent the amount of sulphur extracted in each case by the acetone. The conclusion to be drawn from these experiments is that the amount of grinding needed to prepare a sample of rubber with the mill I have described does not materially alter the chemical com- position of the rubber.It may be of interest to place on record some further figures showing thatTHE PREPARATION OF RUBBER FOR ANALYSIS 553 eight hours’ extraction with acetone is sufficient for practical purposes in the analysis of vulcanised rubber goods.Description of Article. Rubber hose, canvas removed ... Rubber washer . . . ... ... Gas tubing ... ... ... ... Total Acetone Ex tract, including Free Sulphur. Eight Hours’ Extraction. Per Cent. 7-92 7.97 4.15 4.03 4.18 2.97 2 -93 Sixteen Hours’ Extraction. Per Cent. } 8.12 ] 4.45 } 3.02 Incidentally, the above figures show how closely concordant are the results of repeated analyses of the same material.Weber and others have laid stress upon the difficulty of obtaining an average sample of a rubber article. Weber goes SO far as to say that the proportion of the varioug constituents is scarcely ever the same throughout the sample, and Henriques some years ago mentioned a case in which the percentage of silicious matter in a rubber sheet varied from 1.4 in one place to 28 in another.These observations do not accord with my experience. I have had occasion to analyse samples taken from successive consignments of many different kinds of rubber goods from various makers, and I have been surprised to find the uniformity in composition of the same kind of goods supplied by the same maker.I could bring much evidence in proof of this, but the following will suffice :- In the Midland Railway specifications for certain kinds of rubber goods we ask for a test-piece to be supplied which is to be made from the same ‘‘ mixing” as the goods and vulcanised under the same conditions. These test-pieces are required for mechanical tests. I almost invariably anelyse them, and compare the composition with that of the goods they are supposed to represent.The number of instances in which the analysis of the test-piece is practically identical with that of a sample of the goods is so great as to prove, in my opinion, that the production of a uniform mixture presents no difficulty to the manufacturer, and that the analysis of a small piece of properly manufactured rubber may be taken as representative of the whole.DISCUSSION. Mr. C. BEADLE said that prolonged grinding caused the particles of some rubbers to mat together, and it might be that the diminution in the free sulphur was due to this cause.554 L. ARCHBUTT: THE PREPARATION OF RUBBER FOR ANALYSIS Mr. A. C. CHAPMAN remarked that the process of extracting with acetone might in the case of certain rubbers be affected to an important extent by the tendency of the particles of rubber to clot together, the surface presented to the solvent being thus reduced.This could be overcome by spreading the finely divided rubber on a piece of wire gauze, rolling this up, and placing the whole in the Soxhlet apparatus. Mr. BEVAN said that the sulphur might act on the bronze of the rollers and be driven off in a gaseous form by the heat produced during grinding.The matting together of the rubber particles might perhaps be prevented by grinding with some inert material. Dr. STEVENS suggested that rollers of chilled steel might be better than bronze. If the rollers became hot, as he should have thought would be the case with one fixed and the other revolving, the heat might alter the composition of the rubber.The exposure of a large area to the action of the solvent during extraction was generally sufficiently attained if the rubber was reduced to a thin sheet having a broken surface, and, in fact, this was what was really obtained on grinding soft rubber, since the very fine particles adhered together again. I n grinding waste rubber the most effective gearing for the rollers was found to be 1 to 4, 5, or even 6, SO that possibly some such ratio might be found more effective than the use of one fixed roller.Mr. ARCHBUTT, in reply, said that various gears had been tried, and 3 to 2 had been found to be the best when both rollers were in gear. With regard to the use of the fixed roller, it was found, accidentally, in the case of a sample which could not be reduced to powder by putting it through the machine with both rollers in gear, that the desired effect was obtained when one roller was fixed.With some samples the preparation was easier with one roller fixed all the time, whilst with others the best results were obtained by first using the rollers in differential gear. Chilled steel might answer equally well, and a hard aluminium or manganese aluminium bronze even better than gun-metal, for the rollers. Steel would be trouble- some to keep clean in the laboratory atmosphere. The gun-metal rollers he had used showed no sign of tarnish or of any action of sulphur, though a very large number of samples had been passed through them. He agreed as to the probable advantage of grinding with the addition of some inert material in the case of pure rubber, though he did not have to examine many such samples. They do not get hot.

ISSN:0003-2654    

DOI:10.1039/AN9133800550

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

DETECTION AND ESTIMATION OF BENZOIC ACID I N MILK AND CREAM 555 THE DETECTION AND ESTIMATION OF BENZOIC ACID IN MILK AND CREAM. BY E. HINKS, B.Sc., F.I.C. (Read at the Meeting, November 5, 1913.) DURIXG the last few years several methods have been proposed for the detection of benzoic acid in milk and cream, notably by H. D. Richmond (ANALYST, 1907, 32, 151), C. Revis (ibid., 1912, 37, 346), and G.W. Monier-Williama (Local Government Board Food Reports, No. 10, 1909). These methods, though certain in their application, require for their performance a larger quantity of material than is often available for analysis, and do not deal with the quantitative aspect. The following methods are now proposed as being of equal, or enhanced, delicacy, with the use of smaller quantities of material, and as leading to quantitative results of a satisfactory degree of accuracy.Qualitative.-Twenty-five C.C. of milk, or from 10 to 20 grms. of cream, are heated with an equal volume of concentrated hydrochloric acid, as in the W-erner- Schmidt method for the estimation of fat, until the precipitated curd is completely dissolved. The cooled mixture is shaken with 25 C.C. of mixed ether and petroleum spirit (see below).The ethereal solution is separated, 1 drop of ammonia solution added, followed by 5 C.C. of water. The mixture is shaken, the aqueous layer separated, heated for a few minutes on the water-bath to expel excess of ammonia, and tested for benzoic acid with ferric chloride in the usual manner. On the addition of the ammonia (before the addition of the water) a precipita- tion of ammonium benzoate takes place in the ethereal solution, if benzoic acid be present.The greater the proportion of petroleum spirit relatively to methylated ether, the more pronounced becomes the benzoate precipitate; but, on the other hand, the less marked is the final precipitate of ferric benzoate. Petroleum spirit alone gives a decreased delicacy as regards the ammonium precipitate, and failure as regards the iron precipitate ; methylated ether alone fails (or nearly so) as regards the ammonium benzoate precipitate, but yields a good iron precipitate.A mixture of 2 vols. of petroleum spirit and 1 vol. of methylated ether gives good precipitates with both reagents, and is recommended for use. Of the two reactions, the ammonium benzoate precipitation, though less characteristic, is the more delicate.If 25 C.C. of milk be treated as above, 0.01 per cent. of benzoic acid may with certainty be detected, a, simiIar order of delicacy being obtainable in the case of cream. A milk or creatn free from benzoate often gives, on the addition of the ammonia, an opalescence, and gradually a slight precipitate, which is, however, readily distinguished from the precipitate yielded by benzoic acid.I n doubtful cases one must proceed to the iron reaction. If reliance be placed on the ammonium precipitate, it is advisable to use 0.880 ammonia solution.556 E. HINKS: THE DETECTION AND ESTIMATION OF &z~alztitatiue.-From 25 to 50 C.C. of milk, or from 10 to 20 grms.of cream, are heated with an equal volume of hydrochloric acid, as in the qualitative test. To avoid possible loss of benzoic acid this operation is conducted under a reflux con- denser, although the loss without a condenser is very small. The cooled mixture is extracted three times with 20 C.C. of a mixture of equal volumes of ether and petroleum spirit ; the mixed separated 6 6 ethereal ” layers are rendered alkaline with ammonia, solution, 10 C.C.of water added, and the mixture shaken; the aqueous layer is separated and the extraction repeated twice, keeping alkaline with ammonia if required. The mixed aqueous portions are made acid with hydrochloric acid and extracted three times with 20c.c. of the mixed ether and spirit as before. The final mixed (( ethereal ” solutions are allowed to evaporate spontaneously and dried in a desic- cator until constant in weight (twenty-four hours is sufficient as a rule for the air-dried residue).The benzoic acid is then driven off by heating at looo C. (an hour or two), and the loss on heating gives the amount of benzoic acid present. Treated in this way, milk and cream free from benzoate give a ‘( desiccated residue ” of only a few mgrms., which should lose only a fraction of a mgrm.on heating at 100’ C. By performing the first part of the volatilisation of the benzoic acid on a hot plate, and covering the dish with a glass, much of the benzoic acid may be recovered and be proved to be benzoic acid in the usual manner, the volatilisation being then completed in the oven at 100’ C.The use of petroleum spirit alone for the extractions is inadmissible; methyl- ated ether alone may be used. A mixture of equal volumes of the two is recom- mended. The following table gives the results obtained by the above method with milks and creams containing known amounts of benzoic acid :- Benzoic Acid Present. Per Cent. 0.010 0.025 0.050 0*050* 0.200 0.100 0.250 0-500 09100 Amount of Milk taken for Analysis.C.C. 50 50 25 25 25 25 20 grms. cream 10 9 , 10 2 9 Benzoic Acid Found. Per Cent. 0-008 0-027 0.052 0.050 0.100 0.191 09098 0 -245 0-495 The method gives a close approximation to accuracy in the second place of decimals. The benzoic acid may also be determined by titration of the final residue, but the sublimation method is to be preferred.The loss that is liable to occur in the various stages of two processes for the detection of henzoic acid referred to at the outset is seen in the following experiments :- * This milk was analysed five months after the addition of the benzoic acid.BENZOIC ACID IN MILK AND CREAM 557 1. To 50 C.C. of milk 0.025 grm. of benzoic acid dissolved in sodium carbonate solution was added.The curd was precipitated by acetic acid (Richmond, Zoc. cit.). The benzoic acid in this curd was (on digestion with hydrochloric acid) found to be 0.004 grm. 2. To 100 C.C. of milk 0.050 grm. of benzoic acid in sodium carbonate solution was added, and the milk treated according to Revis (Zoc. cit.). The benzoic acid was then determined by the hydrochloric acid process in the precipitates and final solution obtained.The calcium precipitate was found to contain 04068 grm. benzoic acid, the copper precipitate 0.0015 grm., and the final solution yielded 0.0413 grni., totalling 0.0496 grrn. As is to be expected, salicylic acid behaves in a manner similar to benzoic, though owing to the very great delicacy of the iron reaction with salicylic acid, smaller quantities of the latter acid may be detected.Salicylic acid appears to require a greater number of extractions by the solvents used in order to insure complete extraction. The butter may be treated direct as in the case of cream, or the aqueous portion separated, the fat shaken several times with hot sodium bicarbonate solution, and the mixed washings and aqueous portions digested with hydrochloric acid.The results of these two trials were :- The presence of boric acid does not interfere with tho method described. Butter.--The method has been applied (in two experiments only) to butter. Benzoic Acid Found. Henzoic Acid Butter taken for Direct Sodium Bicarhonate Present. Analysis. Method. Method. Per Cent. Grins. Per Cent. Per Cent.0.30 10 - 0.28 0.20 10 0.22 0.18 DISCUSSION. Mr. C. REVIS said that this method seemed to be as expeditious as any he knew of, and apparently was free from a difficulty which beset most-namely, the solubility of the benzoic acid in the fat, which probably accounted for the low results often obtained in the case of butter. He should like to hear whether any other substance besides benzoic acid would be obtained by Mr.Hinks’s method of treatment, as his experience was that a certain extract was always obtained in such cases, even in the absence of benzoic acid. Cinnamic acid, for instance, which was now being sold as B cream preservative, gave reactions very similar to those of benzoic acid. Dr. E. K. RIDEAL said that in a recently devised method for the preparation of ammonium salts of aliphatic acids, dry ammonia gas was passed into the acids dis- solved or suspended in a mixture of alcohol and petroleum spirit, the ammonium salts being precipitated in this semi-colloidal form ; and it seemed likely that in Mr.Hinks’s process small quantities of lactic acid, and possibly of other acids of the same series, might be formed. This would account for the small amount of residue left when milk was decomposed in the manner described in the paper.558 A-BSTRACTS OF CHEMICAL PAPERS Mr. RINKS said the residue left in the blank determination was doubtless due to a little lactic acid and fatty acid, but not more than 2 mgrms. should be obtained, which lost only a fraction of a mgrm. on heating. He had not tried whether cinnarnic acid was extracted by this treatment, but he should imagine that it would behave similarly to benzoic acid.

ISSN:0003-2654    

DOI:10.1039/AN9133800555

出版商:RSC    

年代:1913

数据来源: RSC

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558 A-BSTRACTS OF CHEMICAL PAPERS ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Calculation of the Quantity of Cocoanut Oil Present in a Butter from the Polenske Value of the' Mixture. T. Sundberg. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 26, 422-424.)-The author finds, as the result of the analyses of numerow mixtures of cocoanut oil and butter fat, that the ordinary method of calculating the quantity of cocoanut oil in the mixture from the Polenske value yields too high results.For instance, a mixture containing 20 per cent. of cocoanut oil yielded a Reichert-Meissl value of 23.7, and a Polenske value of 4-4; according to Polenske's table, a Reichert-Meissl value of 23.7 corresponds with a Polenske value of 1.7, and the quantity of cocoanut oil in the mixture would be : (4.4 - 1-7) x 10, that is, 27 per cent.The formula, however, really gives the amount of cocoanut oil expressed as a percentage of the butter fat present, and the quantity present in the mixture would be: 27 ~ loo or 21.3 per cent. This method of calculation is trust- worthy for mixtures containing up to 40 per cent. of cocoanut oil. For example, a mixture containing 41 per cent.gave 38 per cent., calculated by the new formula, whilst the old formula showed 62 per cent. of cocoanut oil to be present. 100 + 27' w. P. s. Rapid and Accurate Method for Determining Fat in Ice Creams, Cereals, and Chocolate. E. P. Harding and G. Parkin. (J. Id. a,nd Eng. Chem., 1913, 5, 843-845.)-The paper is a continuation of one already published by the authors (ANALYST, 1913, 147), where the method was employed on evaporated milk and milk powders.With the following modifications it can be used for ice cream:-The material is melted by warming to 50" C., and well mixed without churning; 5 grms. are weighed into the 100 C.C. extraction-flask, 5 C.C. of 25 per cent. acetic acid added, and the whole cautiously warmed to about 50" C.When the protein has dissolved, 12 C.C. of carbon tetrachloride are added, followed by 10 C.C. of alcohol and 25 C.C. of petroleum spirit; the rest of the procedure is the same as before. A com- plete determination can be made in an hour or an hour and a half. The percentageFOOD AND DRUGS ANALYSIS 559 of fat is slightly higher, and the fat itself is purer than with the Rose-Gottlieb or Babcock methods, When applied to cereals, fertilisers, and chocolate, hydrochloric acid of sp.gr. 1.12 must be substituted for the acetic acid, since the latter acid will not liberate the oil successfully. With chocolates it is necessary to centrifuge for two minutes to obtain the first separation, and the resulting fat from this last- named material, though slightly smaller in amount than that obtainable by the Bigelow and Albrech method (A.C.A.C.Bull., No. 137, pp. 102-103) used for com- parison, was free from the dirty appearance and adrnixed fibre associated with this method. More than three successive washings with ether are unnecessary. H. F. E. H. Essential Oils from Various Countries. (Bull. Imp. Inst., 1913, 11, 428, 439.)-Samples of essential oils from Cyprus, Hong-Kong, West Indies, and Zanzibar, gave the following analytical values :- Oil.Juniper oil, froni Jmi- p r u s PJmnicin Sage oil, from S d v i a Cypria Laurel - leaf oil, from Laiwus szobilis (three samples) Mint oil, from Meqttha sglvestris Myrtle oil, from Myrkus communis (two sam- ples) Pcppermiiit oil (Hong- KO%) "Ngai Yau '' oil, from Artemisia uulyaris " Petit Grain " oil, Jamaica Pimento-leaf oil ,..Clove-leaf oil, Zanzibar Specific Gravity a t 15'/15" C. 0.8684 0,9263 1.9224 t o 0.940 0.9687 0.9166 0.9302 0.9235 0'9359 CJ*9390 0,8884 1,0260 1.0652 Optical Rotation, 100 mm. a t 200 C. +3" 4' - 6 " 31' .4" 4.5' t -. 11" 32' t 31" 58' +8" 14' + 8" - 44" 8' - 41" 5' - -. 6" 45' - 5" 30' - Saponification Value.Oil. icety- lated Oil. Solubility in Alcohol. 16.8 38.9 - Opalescent solution in 9 vols. of 90% alcohol In 1 or more vols. of I n 1 t o 1.7 vols. of 80% alcollol 80% alcohol 75.5 In 2.5 vols. of 70% 61.5 In 5 or more vols. of - 70% alcohol alcohol In 2.5 vols. of 70% alcol1ol 05 S7 I n 1 vol. of 90% alcohol In 1.~01. I n 1'6 vol. of 70% alcohol alcohol In 1.1 vol. of 70% Cineol, 75% Free menthol, 43.3% and L7*49T/, ; menthol as esters, 14.35% and 16.35% - Esters as linalyl acetate, 30.6% Phenols, chiefly eugenol, 68.6% Eugenol, 85 7% C.A. M. Microscopical Detection of Embelic Acid. G. Hey1 and P. Kneip. (Apoth. Zeit., 1913, 28, 699 ; through Chem. ZentraZbZ., 1913, II., 1342.)-Embelio acid, the active constituent of the fruit (employed as an anthelmintic) of the Indian plant Embelia ribes Burm.(Nat. Ord., iVyrsinacea), may be isolated readily as the560 ABSTRACT8 OF CHEMICAL PAPERS hydroxyquinone derivative by microsublimation, and identified microchemically. The microsublimates obtained by Tunmann's method were partly crystalline bundles and partly tabular crystalline structures, surrounded by a yellowish mass (illustrated in the original).They are insoluble in water, but dissolve with a reddish-violet coloration in a mixture of 1 drop of 15 per cent. sodium hydroxide with 10 C.C. of water ; treat- ment with 15 per cent. sodium hydroxide causes the precipitation of small shining violet plates, after a time, mixed with needles of the same colour. The addition of hydrochloric acid causes the separation of CL flocculent precipitate of embelic acid.Carbonates of the alkali metals produce the same effect as the hydroxides, With dilute ammonia, a light red solution is obtained ; on evaporation, small crystalline bundles gradually separate. The dilute alkaline solution of the sublimates gives an olive-brown precipitate with dilate copper sulphate solution, with dilute barium chloride a grey-brown, with dilute nickel sulphate a green-brown, and with magnesium sulphate a flocculent brown precipitate.The alcoholic solution of the sublimate gives with ferric chloride a red-brown, with copper nitrate a dirty green, with lead acetate a dark green, and with zinc chloride a violet precipitate. Mercuric chloride and silver nitrate cause no precipitation.The violet coloration produced by warming embelic acid itself with sulphuric acid only occurs indistinctly with the sublimate. 0. E. M. Testing Ether. G. Frerichs. (Apoth. Zeit., 1913,28,628-630 ; through Chem. Zentralbl., 1913, II., 1254-1255.)-1n testing ether it may be required to ascertain whether it has been prepared from pure alcohol or methylated spirit. In Germany the denaturing agent is a mixture of crude wood spirit and pyridine bases, the latter remaining in combination with the sulphuric acid when the ether is made.The methyl alcohol and acetone of the wood spirit appear in the product as methyl-ethyl ether and unaltered acetone. The former produces a considerable depression of the boiling-point;. Perfectly pure ether boils under the normal pressure at to 3403~ C.The presence of 1 per cent. of alcohol raises the boiling-point 0.2" C., SO that the boiling-point of 35" C., prescribed by the German codex, would permit of the presence of 4 per cent. of alcohol. Such an ether would, however, show a, density of 0-723 instead of 0.720. The official method for determining the boiling- point is not sufficiently sharp; it is better to distil off the first 50 C.C.from 250 C.C. of ether and use this fraction for the determination of the boiling-point. A still more accurate method is to determine the boiling-point under a reflux condenser. A special form of boiling-flask is employed having two necks, in one of which the thermometer is inserted, whilst the other is connected with the reflux condenser, the two necks being joined together near the top by a branch tube.For the detection of acetone in ether, 100 C.C. of the ether are shaken vigorously with 10 C.C. of water, the two layers are allowed to separate, and the water is collected in two test-tubes. To one portion the sodium nitroprusside test is applied, to the other the iodoform test. J. F. B. Non - Nitrogenous Extractive Matters in Fodder and Foodstuffs.J. Konig. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 26, 273-281.)-The group ofFOOD AND DRUGS ANALYSIS 561 so-called non-nitrogenous extractive matters is of somewhat indefinite composition, since it represents only the difference between 100 and the sum of the percentages of moisture, proteins, fats, crude fibre, and mineral matters, and consequently varies according to the effectiveness of the methods by which all these are determined.To a certain extent the term “ extractive ” matter is a misnomer, because a considerable portion of this group is not extracted directly, but is rendered soluble by hydrolysis more or less profound. Some portions of the group--e.g. sugars, dextrins, starch, inulin, various organic acids-are sufficiently definite and well characterised ; others --e.g.pectins, tannins, bitter principles, colouring matters-are not so well known, but still have a generally defined significance. On the other hand, the pentosans, hemicelluloses, and a portion of the lignin, occur in various degrees of conden- sation, and uiay appear partly in the “extractives” and partly in the crude fibre, according to the methods employed.The pentosans are easily and completely estimated by the distillation method, and it is therefore desirable to adopt means whereby they are totally excluded from the crude fibre value, in order to avoid reckoning them twice over. This object is almost completely effected by the author’s glycerol and sulphuric acid digestion method, which nevertheless gives results practically identical with the Weende method.The reason is that Konig’s crude fibre, though practically free from pentosans, which are readily digestible by animals, includes more of the lignin, which is almost undigestible, than the Weende crude fibre. The cell walls of plants consist of bodies belonging to four groups; pentosans, hexosans, lignins, and cutins.So far as the first three of these are concerned they exist in different degrees of solubility (condensation, or resistance to hydrolysis). These degrees must necessarily overlap, and a sharp separation must be difficult, if not impossible. Portions of all three groups are soluble on digestion with water alone under a pressure of 2 to 3 atmospheres, also on digestion with enzymes such as diastase or pepsin-hydrochloric acid.The members of this group correspond with starch, and are termed by the author protopentosans, protocelluloses (hexosans), and protolignins. The bodies of the second group are rendered soluble by digestion with dilute (2 to 3 per cent.) acids under pressure, or by boiling at 1 3 5 O to 137’ C. These are called hemipentosans, hemicelluloses (hexosans), and hemilignins.Konig’s glycerol-sulphuric acid method affords an approximate separation of the first two groups from the third or ortho group, which constitutes, together with the cutin, the so-called “crude fibre.” The orthopentosans occur only in very small proportions; the orthohexosans, so far, have not been observed to include any anhydrides of mannose and galactose, and may therefore be said to consist substan- tially of orthocsllulose, the ‘‘ true ” cellulose. The ortholignins are oxidisable bodies, and may be separated from the orthocellulose by suitable treatment with ammoniacal hydrogen peroxide; these lignins may be split up into two groups by treatment of the crude fibre with 72 per cent.sulphuric acid. This acid dissolves the ortho- pentosans, the orthocellulose, and SL portion (colourless) of the ortholignins, leaving a residue of dark coloured ortholignins insoluble.The cutin is susceptible neither to hydrolysis nor oxidation under the conditions specified, nor is it soluble in the solvents of cellulose. I n view of the fact that a sharp separation of the groups of various degrees of resistance in impossible, it is highly desirable that an international562 AESTRACTS OF CHEMICAL PAPERS standard method for their approximate classification be adopted, so that the results may at least be comparable.J. F. B. Hop Analysis. 0. Neumann. (Chem. Zeit., 1913, 37, 1317 -1318.)-The author cannot accept the conclusions of Power, Tutin, and Rogerson (ANALYST, 1913, 459), that the petroleum spirit extract of hops does not contain the bitter principles (? resins), but consists mainly of fatty acids.Such conclusions are contrary to estab- lished experience, which leaves no doubt as to the utility of the estimation of bitter principles in hop analysis. The tests for bitter principles and estimations of lupulin always give concordant results. Hops poor in lupulin never show a high per- centage of bitter principles, and those rich in lupulin are never poor in bitters.Seibriger has found that carbon tetrachloride is equivalent both quantitatively and qualitatively to petroleum spirit as a solvent, and possesses the advantage of uniformity of composition; moreover, the time of extraction may be reduced from even hour8 to three hours.The hops are chopped up in a mincing-machine with sharp knives, and 10 grms. are shaken in the cold with the solvent, whether petroleum spirit or carbon tetrachloride. For this purpose an apparatus such as that designed by Wagner for the estimation of phosphoric acid in fertilisers is most suitable. For the titration with alcoholic potassium hydroxide, 100 C.C. of the filtrate are taken.I n order to avoid the separation of layers 80 C.C. of neutral 96 per cent. alcohol are added before the titration. The extraction of the bitter principles can be effected with cold petroleum spirit by shaking for three or four hours. With carbon tetra- chloride one or two hours’ shaking is sufficient. The results with petroleum spirit are slightly lower than with carbon tetrachloride, but the divergences do not exceed the permissible limits.Extraction in the cold constitutes a notable simplification in hop analysis. J. F. B. The speed of rotation is regulated a t 15 revolutions per minute. Direct Iron Estimation in Ferri et suininue Citrus and Extracturn Ferri Pornaturn. F. Lehmann. (Apoth. Zeit., 1913,28, 708 ; through Chem. Zentralbl., 1913, II., 1342.)-The author’s method (Apoth.Zeit., 1911,26,125 ; Chern. Zentralbl., 1911, I., 845) for the destruction of the lactic acid radical in ferrz~m lacticum by means of hydrogen peroxide and sulphuric acid may be applied to the destruc- tion of the organic portion of iron and quinine citrate, and in iron lactate extract. (1) Ferri et Quinina! Citras.-O*4 grm. of the sample is dissolved in 10 C.C.of water, boiled, 30 C.C. of 4 per cent. hydrogen peroxide added, and the liquid shaken and allowed to stand with frequent agitation until gas evolution ceases ; it is then boiled with 5 C.C. of concentrated sulphuric acid, and, after excess of hydrogen peroxide has been removed by means of potassium permanganate added drop by drop, allowed to stand for one hour with 2 grms.of potassium iodide in a closed flask. The iodine is then titrated back with & thiosulphate and starch; 1 C.C. TT thiosulphate corre- sponds to 0.0056 grm. iron. (2) Extracturn Ferri Pornaturn.-The method is the same, 1 grm. of extract being used. 0. E. &I.FOOD AND DRUGS ANALYSIS 563 Detection of Potassium Dichromate in Milk. B. Grewing. (Zeitsck Untersuch.Nahr. Genussm.; 1913, 26, 287.)-Ten C.C. of the milk are mixed with 4 C.C. of a 3 per cent. aniline solution, and the mixture is poured on the surface of sulphuric acid contained in a test-tube. A blue zone develops a t the surface of contact of the two liquids if dichromate is present; a violet zone below the blue zone will also be noticed. When the milk contains from 0.05 to 0.1 grm.of dichromate per litre, a green zone appears first, and changes gradually to blue; with 0.01 grm. of the salt per litre, the coloration obtained is red-violet, and develops after the lapse of about six minutes. The presence of nitrates, formaldehyde, and hydrogen peroxide, does not interfere with the reaction. w. P. s. Detection of Nitric Acid (Nitrates) in Milk.R. Barth. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 26, 339-341.) - The formaldehyde-sulphuric acid test is recommended (cf. ANALYST, 1902, 27, 357) as being capable of detecting as little as 0.5 mgrm. of nitric acid per litre of milk. I n order to prevent the formation of a brown ring at the point of contact of the acid with the miik, snlphuric acid having a sp. gr. of 1.71 should be used.The water employed in reducing concentrated acid to this strength must be free from nitric acid, and, as ordinary distilled water frequently contains traces of nitric acid, it is advisable to re-distil the water after the addition of a small quantity of sodium hydroxide. In carrying out the test, 10 C.C. of the milk are mixed with 5 drops of formaldehyde solution (prepared by adding 10 drops of commercial formalin to 250 C.C. of water), and the mixture is poured carefully on the surface of 5 C.C.of the sulphuric acid contained in a test-tube. With 0.5 mgrm. of nitric acid per litre, the blue ring appears after the lapse of about five minutes; with 5 mgrrns. of nitric acid per litre the blue ring develops almost immediately. w. P. s. Estimation of Phosphorus in Manures and Feeding-Stuff s.C. Duserre and P. Chavan. (Mitt. Lebensnzitteluntersuclz. Hyg., 1913, 4, 261 ; through Chem. Zcntralbl., 1913, II., 1333.)-For the estimation of phosphoric acid the modification of Pemberton’s method recommended by Molinari, consisting in the addition of Peter- mann solution to the liquid to be precipitated, gave good results with superphosphates, but the authors occasionally found high values when working in sulphuric acid solution with Thomas ” phosphate or bone meal.By adding ammonium sulphate instead of nitrate to the molybdenum solution, they obtained accurate ‘‘ results.” The solution was prepared by dissolving 25 grms. ammonium sulphate in 400 C.C. nitric acid of density 1.2, and 75 grms. ammonium molybdate in 500 C.C.of warm water, and mixing when cool. Ta,bles are given showing the distribution of phosphorus-con- taining compounds in hay from a meadow not manured, and from the same meadow manured with superphosphate. The phosphorus present as lecithin was determined by extraction of the hay for one hour with boiling ether, repeated five times, and treatment of the residue from the ethereal extract with a mixture of nitric and sulphuric acid ; the hay exhausted with ether was then extracted for one hour with boiling absolute alcohol, the extract evaporated down, and the residue treated as before.To determine the inorganic phosphorus, the hay thus treated was extracted564 ABSTRACTS OF CHEMICAL PAPERS with 1 per cent. cold hydrochloric acid. The phosphorus present as nuclein was determined by treatment of the extracted hay with nitrosulphuric acid.For the estimation of phosphorus in organic compounds the following is recommended as leading to the least loss of phosphorus : 5 to 10 grms. of the suhstance are heated in a 300-400 C.C. Kjeldahl flask with 15 C.C. of sulpuric acid and 15 C.C. of nitric acid ; nitric acid is added drop by drop when the nitrous fumes have disappeared.Water is added to the clear liquid, and the whole boiled; after cooling, precipitation with the molybdate solution is carried out. 0. E. M. Estimation of Higher Alcohols in Spirits. R. Ofner. (Clzem. Zeit., 1913, 37, 1239.)-The author has used the Komarowsky reaction ( c t ANALYST, 1910, 35, 403) for the estimation of higher alcohols in spirits, and finds that the method is sufficiently accurate for most purposes.For the reinoval of aldehydes, the distilled spirit should be treated with m-phenylenediamine hydrochloride and re-distilled ; a smaller quantity of salicylic aldehyde than that mentioned by Fellenberg (loc. cit.) should be used, and the spirit under examination and the comparison solutions should contain 50 per cent, of alcohol or be brought to this strength by suitable dilution.The following method also yields trustworthy results :-Ten C.C. of the distillate, after removal of aldehydes by nieans of m-phenylenediamine hydrochloride, are treated with 1 C.C. of a furfuraldehyde solution (1 grm. of furfuraldehyde in 1 litre of 50 per cent. alcohol), 10 C.C. of concentrated sulphuric acid are added, and the mixture is shaken and heated for twenty seconds over a flame.After cooling, the coloration is compared with those obtained under similar conditions with known quantities of amyl alcohol dissolved in 50 per cent. alcohol. In the case of cognac, isobutyl alcohol should be used in place of amyl alcohol in preparing the comparison solutions.w. P. s. Turpentine Sold as a Drug. (Bull. 253, Idand Rev. Dept., Ottawa; through J. Xoc. Chem. Ind., 1913, 32, 1028.)-The standards sanctioned for turpen- tine for medical purposes by the Privy Council in 1912 are-(1) I t shall be entirely free from mineral oil. (2) Unless sold as wood turpentine, it shall absorb not less than 340 times its weight of iodine (Hub1 solution and method); if sold as wood turpentine, it shall absorb not less than 240 times its weight of iodine by the same method.(3) The undissolved (unpolymerised) residue on treatment of 10 C.C. with 40 C.C. of a sulphuric acid containing 20 per cent. of fuming acid shall not exceed 10 per cent. by volume of the sample. (4) The refractive index of this residue shall be not less than 1.495 at 20" C.(5) The refractive index of the sample at 20" C. shall lie between 1.468 and 1.473. (6) The sp. gr. of the sample at 20' C. shall not be less than 0.86. (7) The initial boiling-point shall not be lower tban 150" C. under ordinary atmospheric pressure. (8) At least 75 per cent. by volume shall distil below 160OC. (9) The residue on evaporation over a steam-bath shall not exceed 2 per cent.Forty-two samples out of 158 collected were found to contain petroleum, and ten other samples did not comply with the above requirements.FOOD AND DRUGS ANALYSIS 565 Detection of Adulteration of Cider Vinegar with Distilled Vinegar. s. L. Crawford. (J. Ind. and Eng. Chem., 1913, 5, 845-847.)-The volatile con- stituent with a reducing action on Fehling’s solution, which is found in all pure cider vinegars, is absent from distilled vinegar and pyroligneous acid.The fact that it is also absent from fully fermented dry refined cider, six months old (acidity 0.36 per cent.), and from completely fermented first-pressing juice six months old but not refined (acidity 0.75 per cent.), goes to show that this volatile reducing substance is formed during the acetification of the apple juice.The proposed method is to dilute 50 C.C. of the sample to 250 c.c., and distil off 200 C.C. into a 250 C.C. flask, neutralise and make up to volume. The reducing substances are estimated in 50 C.C. of the distillate by Munson and Walker’s method (Bureau of Chem. BUZZ., 107). When reduced to a basis of 4 per cent. acidity (grms. per 100 C.C.of acetic acid), the distillates from nine samples of genuide cider vinegars are shown to contain from 0.111 to 0.149 per cent. of reducing substances calculated as “ invert sugar.” Taken in conjunction with the glycerol values and other constants, indications should be thus obtained as to the adulteration of cider vinegar with distilled vinegar or pyro- ligneous acid. If the latter adulterant has been employed, the vinegar will contain more formic acid than the amount usually found in cider vinegar (0.007 grm.per 100 c.c.), while if distilled vinegar is present the formic acid will be less than this amount to an extent dependent on the amount of cider vinegar present. H. F. E. H. So-called Non-Alcoholic Wines of Commerce. W. I. Baragiola and W. Boller.(Zeitsch. Untersuch. Nahr. Genussm., 1913, 26, 369-408.)-The authors have submitted two samples of commercial ‘‘ non-alcoholic wine ” (pas- teurised and clarified grape-juice) to an exhaustive analytical and chemico-physical investigation, both in their natural state and after fermentation with yeast. The analytical results have been used for calculating ‘( balance sheets ” of extract, acids, and mineral matters, for which purpose the methods of calculation adopted in the case of normal wines was found to be valid, The concentration of hydrogen ions or degree of acidity was estimated by the sucrose inversion method.One of these grape-juices in its original condition, and both of them after fermentation, showed, as compared with natural wines, an abnormally high concentration of hxdrogen ions in relation to the proportion of titratable acid present.This high degree of dissociation of the acids is reflected in the flavour of the “non-alcoholic wines,’’ which, in spite of the presence of sugar, always shows a tendency to be sharp. The sharpness would appear to depend upon a poverty in ammonium salts or organic bases, which have a powerful influence in depressing the ionisation of the acids without reducing their quantity.An investigation of a large number of samples of “non-alcoholic wines,” with regard to the nitrogenous matters in various types of combination, might decide whether poverty in nitrogen is a direct consequence of the process of manufacture. I t is suggested that a better conservation of the nitrogenous com- ponents might be aimed at in the process of pasteurisation and clarification, and might result in an improved and milder flavour.The “wines” before and after fermentation were also investigated according to the conductivity method of Dutoit566 ABSTRACTS OF CHEMICAL PAPERS and Duboux by titration with barium hydroxide, and the relationships of the con- ductivity curves are.discussed in connection with the chemical composition ; the influence of the sugar in the unfermented “wines” reduces the sharpness of the curves. In the determination of the ash it is shown, by mathematical treatment, that the errors are of the same order as in the analysis of ordinary wines. The chemico-physical balancing of the acids and bases was calculated by two distinct methods-Quartaroli’s, and Dutoit and Duboux’s (ANALYST, 1910, 35, 254)-with concordant results, and a representation of the condition of combination of the various organic and inorganic acids has thereby been obtained.The presence of very considerable quantities of tartaric acid in the free state is thus indicated in the grape-juices, whereas,, according to the older methods of wine analysis, such juices would contain little or no free tartaric acid.J. F. B. Wine Statistics for the Years 1911-1912. (Arbeit. Kaiserl. Gesundheit- samte, 1913, I., 555.)-The present report gives the proceedings of the Official Com- mission on Wine Statistics, together with details of analyses of 1,912 samples of wine and 6,087 samples of must obtained from the different wine-growing districts.Details are also given regarding the localities of the vineyards, the soil and manures used, kind of vines grown, insect pests and remedies for the same, vintage, climatic notes, etc. Paxticular attention was paid to the amount of sulphurous acid in the wines ; in most cases the total quantity of the acid was less than 200 mgrms. per litre, but in certain samples the quantity exceeded 300 mgrms. per litre. Deniges’ test for citric acid was found to be trustworthy, but wines containing a, large quantity of tannin must be treated with animal charcoal to remove this constituent before the test is applied. Further experience of the use of nicotine as an insecticide (cf. ANALYST, 1912, 37, 96) has been of a satisfactory nature, and by repeated sprayings at proper intervals it has been possible to eliminate injurious insects from entire districts. w. P. s. Accurate Estimation of the Dry Extract of Wines and Fermented Liquors. P. Malvezin. (Bull. SOC. Chirn., 1913,13,943-947.)-None of the methods in use give constant results owing to the effect of the glycerol, which may or may not be partially removed. To obviate this error the amount of extract free from glycerol is estimated as follows :--Fifty C.C. of the wine are taken, and half of it is heated in a flask connected with a pump, and with a second flask which can be put out of com- munication by a, stopcock. The wine is heated under reduced pressure at 75” to 80’ C., until the residue is pasty, after which the second portion is introduced and the operation repeated. A current of steam is now introduced for an hour from the communicating flask. All the glycerol is thus expelled, and the residue is then dried and weighed. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800558

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 567 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Micro-Chemical Method for the Estimation of a- and @-Amino Acids and Certain Derivatives in Proteolysed Substances, Blood, and Urine. P. A. Kober and K. Sugiura. (J. Amer. Chem. Soc., 1913,35,1546-1584.)-The principle of the method is the property of a- and #-amino acids, peptides and peptones to dissolve cupric hydroxide quantitatively in the cold to form a metallic complex in a neutral or slightly alkaline solution (C, = 10-7‘O7 to 10--8.8).The reaction is extremely rapid and sensitive, and will give good results with 0*005 per cent. solutions of these substances failure to obtain such a complex being proof of the absence of a- and p-amino-acids and their polypeptides. The extent to which the copper can be precipitated from the complexes of nineteen amino-acids, twenty-seven di-peptides, eighteen tri-peptides, and N four tetra-peptides is given when in equilibrium with m6 barium hydroxide, and it is shown that the amount of copper dissolved by the free amino-acid can be distinguished from that dissolved by the peptides and peptones.Interfering substances are not numerous, the first class being dicarboxylic acids, and the second reducing substances such as the sugars and uric acid.The sugars can all be separated by ammoniacal lead acetate (5 C.C. strong ammonia to 25 C.C. 10 per cent. lead acetate), which does not throw down any amino-acids or peptides in very dilute solutions (I in 25,000). An insoluble cuprous compound of uric acid is precipitated, when 2 C.C.of a 5 per cent. solution of cupric chloride and 0.5 C.C. saturated magnesium aulphate are added to such a body as urine. The method is shown to be applicable to proteolytic cleavage products, blood, and lirine, so far as the accurate determination of amino-acids, pep- tides, and peptones in these materials is concerned, and may therefore be called a ‘ 6 clinical ” method.Two very insoluble copper complexes, n-amino-caproic acid and phenylglycine copper, are described which may be found useful in analytical work with copper. By means of these two amino-acids the copper of all the other com- plexes, including those of the amino-acids and all the polypeptides thus far studied, with the exception of histidine, can be thrown down quantitatively.Therefore by means of these reagents histidine in very small quantities can be accurately apd quickly determined. For following proteolysis the method is best used in conjunc- tion with the nephelometric one of Kober (J. Amer. Chem. Soc., 1913, 35, 290; see p. 571). With this instrument can be estimated the amount of undigested protein at any time, while the total amino-acid nitrogen obtained by the copper method will indicate the amount of hydrolysis at any time.The copper complexes on treatment with barium hydroxide will give the amount of the free amino-acids- the final products of hydrolysis; all this can be done on 0.005 grm. of protein. For fuller details of the technique involved and of the solutions required the original paper should be consulted.H. F. E, H. Amino-Aeids in Blood. A. Constontino. (Biochem. Zeitsch., 1913, 55, 419- &&)--The author recommends removal of proteins by means of an acid mercuric chloride solution before determining amino-acid nitrogen by Sorensen’s formaldehyde method. Blood or serum (100 c.c.) is mixed with 500 C.C. of a 2 per cent. mercuric568 ABSTRACTS OF CHEMICAL PAPERS chloride solution containing 0.8 per cent.hydrochloric acid, vigorously shaken, and after standing with intermittent shaking for one hour is centrifuged, and filtered through a dry filter. A known volume of the filtrate is treated with hydrogen sulphide to remove mercury, the excess of hydrogen sulphide expelled by means of an air current, and the liquid, after being exactly neutralised, concentrated on the water-bath, or preferably at 50" C.under reduced pressure, and then distilled with magnesium oxide under reduced pressure at 45O C. to expel ammonia. E. W. Detection of Blood. B. Bardach. (Chenz. Zeit., 1913, 37, 1190-1191.)-The guaiacum-perborate test described previously by the author and Silberstein (ANALYST, 1910, 35, 439) is rendered more sensitive if the blood solution be treated previously with dilute acetic acid; the addition of pyridine, as rscommended by Leers (cf.Michel, ANALYST, 1912, 37, 506), is also advantageous. Five C.C. of the blood solution (urine) are treated with 3 drops of 30 per cent. acetic acid, allowed to stand for about two minutes, and 2 drops of a saturated alcoholic guaiacum resin solution and 0-5 grm.of powdered sodium perborate are added. Three C.C. of 80 per cent. acetic acid are then added, the mixture is shaken, and 3 C.C. of alcohol are allowed to flow on to the surface of the solution, followed by 2 drops of pyridine. In the presence of blood, a blue zone appears within a few minutes, and then fades gradually. Nitrites yield a somewhat similar reaction, but in this case the lower layer of liquid is coloured blue, and the colour fades very rapidly, whilst with blood the coloration appears both at the junction of the liquids and in the alcoholic layer.Alkaline urines also yield a blue coloration with the test, but the colour develops immediately on the addition of the guaiacum tincture, perborate, and alcohol. When a positive reaction is obtained the presence of blood should be confirmed spectroscopically.The test is less sensitive in the case of urine than with aqueous blood solutions, but 0.017 C.C. of blood in 1 litre of urine gives a distinct reaction. w. P. s. Cyanogenesis under Digestive Conditions. S. J. M. Auld. (J. Agric. Sci., 1913, 5, 409-417.)-Important foodstuffs which produce hydrocyanic acid in con- siderable quantity on maceration with water are linseed and linseed cake, improperly made linseed gruel, Java beans, and other varieties of Phaseolus luizatus and im- mature great millet (Sorghum wulgare).The generally innocuous character of linseed cake was explained by Henry and Auld (ANALYST, 1908, 33, 280) and Dunstan as due to the destruction by heat of the enzyme present during the hot process of expressing the oil; This is, however, not the case, as most linseed cakes do in fact liberate HCN in quantities varying from 0.001 to 0.052 per cent. on maceration with water.At blood heat such cakes will liberate in witro half the available acid in fifteen minutes, and sheep fed with cake containing 0.052 per cent. of available HCN in quantities up to 4 pounds per day suffered no ill effects, although exposed to far more than the lethal dose.Investigation showed that under digestive conditions cyanogenesis is likely to be inhibited by acids and alkalis, digestive juices, cellulose (especially), glucose, molasses, salt, and many other feeding-stuff constituents and adjuncts. Owing to the time the food remains in the digestive tract (one to two hours) before coming to the true stomach or the acid-secreting portion of theBACTERIOLOGICAL, PHYSIOLOGICAL, ETC.569 stomach, normal inhibition of cyanogenesis is chiefly caused by the alkaline character (about &) of the saliva, and this explains the noE-toxic character of linseed cake. Small amounts of hydrocyanic kcid were found in the rumen of a sheep which was killed shortly after feeding on linseed cake, and it may be taken that cyanogenetic feeding-stuffs are most likely to be poisonous when fed with acid-containing or acid- producing foodstuffs, or where the HCN is already present, as in improperly made linseed gruel. Reasons are given for believing that the small quantities of HCN normally produced from cyanogenetic feeding-stuffs may possibly have a beneficial action, from their well-known tonic properties.H. F. E. H. Estimation of d-Lactic Acid in Body Fluids and Organs. J. Yoshikawa. (Zeitsch. Physiol. Chem., 1913, 87, 382-418.)-The d-lactic acid is estimated by measuring the rotation of a solution of its lithium salt. Tables and curves are given showing relationship between lactic acid content and rotation from which the follow- ing formulz are derived : u = - 0.286~ + 0*00342132.. . 0,286 - J0.081796 + 0.01368~ p3=----- ~. , a= -O~2864c+O*O0405c2. . . 0.00684 ,/0-082025 + OT6% 0.0081 c = 0.2864 - p = weight per cent. of d-lithium lactate ; d = density of solution ; of rotation. The presence of inactive lactic acid or acetic acid do not affect was found to be free from d-lactic acid: the efficiency of the with urine to which a known quantity of acid had been added.ether, after acidifying with phosphoric acid, 98.35 - 100.65 per c = p x d ; u=angle the rotation. Urine method was tested By extracting with cent. of the added acid was found. For the extraction of d-lactic acid from muscle, the author recom- mends the method of J. Mondschein (ANALYST, 1912, 37, 403).The material is extracted with boiling water,, and the extract and coagulum treated separately. The extract is concentrated to a thin syrup, and extracted with alcohol. After distilling off alcohol, the residue is acidified with phosphoric acid and extracted with ether, the ether extract distilled, and the residue dissolved in water and converted into lithium salt by treatment with lithium carbonate.The coagulum is dissolved by warming with sodium hydroxide, and the resulting solution freed from proteins by saturating the boiling liquid with salt and acidifying with sulphuric acid. The protein-free liquid is then treated in the same manner as the aqueous extract. E. W. Colorimetric Method for the Determination of Hydrocyanic Acid in Plants, with special reference to Kaffir Corn.C. K. Francis and W. B. Connell. (J. Arner. Chem. Soc., 1913,35,1624-1628.)-The ferro-ferricyanide method gives variable results, and difficulty is experienced in keeping the ferrous sulphate solutions free from ferric compounds. The ammonia-alum (Allen’s Organic Analysis,”570 ABSTRACTS OF CHEMICAL PAPERS 3rd. ed., vol. iii., p.92) and the lead-acetate methods (ibid.) are only applicable when hydrocyanic acid is present in relatively large amounts (0.1 per cent. and over). The thiocyanate method, modified as follows, was finally adopted : Fifty grms. of the finely chopped material are triturated with 100 C.C. of water, and then washed into a litre distilling flask with 100 C.C. of water. Fifty C.C. of concentrated sulphuric acid are then added, and about 150 C.C.are distilled into 50 C.C. of a 4 per cent. solution of potassium hydroxide. The end of the condenser must be beneath the potash solution, or loss of hydrocyanic acid results. The distillate is made up to 250 c.c., and to 50 C.C. portions of this are added 1 C.C. of yellow amnionium sulphide, the whole being then taken to dryness on the water-bath. The residue is taken up with 10 or 15 C.C.of hot water and barely acidified with dilute hydrochloric acid. Free sulphur is removed by filtration, and 0.5 C.C. of dilute hydrochlcric acid is added before boiling the solution for five minutes, after which su_lphur is again filtered off, the boiling and filtering being repeated, if necessary, until the solution is absolutely clear.The solution is then nearly made up to the mark in R 50 C.C. Nessler tube, and 15 drops of a 5 per cent. ferric chloride solution are added, when a bright cherry-red coloration indicates the presence of cyanide in the sample. If too much acid is present the colour will be lemon yellow, and if alkaline, iron will be precipitated. The standard solution of potassium thiocyanate is made to contain 15 grms.of this salt in a litre and standardised gravimetrically with silver until 1 C.C. = 14-92 mgrms. KSCN=10 mgrms. of KCN. Fifty C.C. of this solution are diluted for use in the Nessler tubes, 1 C.C. of the diluted salt being equivalent to a mgrm. of KCN. There is a tendency towards obtaining high results when using this method, but it compares favourably with the silver nitrate gravimetric method, and is very satisfactory for deter- minations of KCN in amounts under 0.5 per cent.Chlorides, bromides, and iodides do not interfere. Some results found by using the method on Kaffir corn plants are as follows :- HCN per cent. ... ... 0.010 Leaves. Plant stunted and frost-bitten . . . ... Stalk and leaves. Plant in good condition .. . ... 0.0007 ... 0.0124 Entire plant without roots. Taken from field in which Plants much stunted and H. F. E. H. stock was poisoned. almost dry from lack of water. Solubility of Milk Proteins in the Constituents of the Serum. L. Lindet. (Bull. Xoc. Chim., 1913,13, 929-935.)-Previous investigations have shown that the albumin of milk can only be distinguished from the casein by its different rotatory power, and the names of a-casein and P-casein are therefore suggested for the casein and albumin respectively.Both of these caseins are soluble in the same proportions in the different constituents of the serum. Estimations of the solubility of a-casein in solutions of the serum constituents of approximately the same concentration as found in milk serum gave the following results : In lactose (5 per cent.), 0.27 ; sodium chloride (0.2 per cent.), 0.605 ; sodium citrate (0.08 per cent.), 0.945 ; and sodium phosphate (0.05 per cent.), 1.636 grms.per litre. This artificial serum Kould thus contain 3.456 grms. of a-casein; and assuming that p-casein dissolves in theBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 571 same proportion, the total amount of caseins dissolved would be 6.9 grms.per litre, or somewhat higher than the average amount usually found (6.45 grms.). If a certain quantity of a solvent (e.g., sodium citrate) be added to milk before coagulation, a serum richer in soluble caseins will be obtained (e.g., 8.94 grms., instead of 6.12 grms. per litre for a 0.4 per cent. solution of sodium citrate).This increase is entirely due t o the a-casein. In ordinary serum there is not more &casein present than can be dissolved by the serum constituents, whereas only a part of the a-casein (about 10 per cent.) is in solution, the remainder being in a state of colloidal suspen- sion. The addition of calcium chloride to boiled milk causes the latter to be coagulable by rennet. This is to be attributed to the salt precipitating a portion of the soluble caseins which have not been coagulated by the heat, and also to the precipitation of calcium phosphate, which mechanically envelops the casein in colloidal suspeusion. The coagulation of raw milk is also rendered more rapid and complete, and the coagulum firmer by the addition of calcium chloride, owing to the fact that part of the soluble caseins is rendered insoluble through the loss of the solvent constituents and the mechanical action of the nascent acid calcium phosphate.C. A. M. Nephelometric Determination of Proteins ; Casein, Globulin and Albumin in Milk. P. A. Kober. (J. Amer. Chem. SOC., 1913, 35, 1585-1593.)- The author describes an improved form of -nephelometer, and the following method of freeing a sample of milk from fat previous to casein estimation is recommended. Five C.C.of the milk are measured into a 250 C.C. graduated flask, and after adding 200 C.C. of water and 10 C.C. of Tn caustic soda solution, water is added t o the mark and the whole is thoroughly sha.ken. Ten C.C. are placed with 2 C.C. of ether (previously washed with 10 per cent.caustic soda solution) in a centrifuge tube, which is then tightly corked and vigorously shaken. After standing till the layers have separated, or centrifuging for a minute or so, 5 C.C. of the aqueous layer are removed with a pipette in such a way as not to disturb the ether, and diluted to 60 C.C. Milk so treated is quite clear and ready for nephelometric estimation.Taking 10 C.C. of this solution and adding 10 C.C. of 3 per cerit. sulpho- salicylic acid, a suspension of casein is obtained which can be matched with the following standard :-5 C.C. of a 0.01 per cent. casein solution mixed with 10 C.C. of 3 per cent. sulphosalicylic acid. The protein so obtained is not all casein, so another portion of milk is precipitated according to the ‘‘ official ” method (dilute acetic acid), and the amount of precipitate obtained in an aliquot portion of the filtrate is then determined nephelometrically by adding four volumes of the reagent.This fraction, called the I ‘ globulin and albumin ” fraction, when deducted from the gross casein, gives the amount of casein precipitated by the (‘ official ” method. Results by the new method agree closely with the official figures, the former, if anything, being n trifle the higher.The ether used in extracting the fat increases the volume of the solution, so for 10 C.C. of diluted milk and 2 C.C. of ether, the factor 0.910 must be employed. For removing fat, hydrochloric acid cannot replace caustic soda, as this acid interferes with the use of sulphosalicylic acid.The standard casein solution must be controlled by a nitrogen estimation, using the factor 6.38, and is made by572 ABSTRACTS OF CHEMICAL PAPERS dissolving 0.1 grm. casein, or its equivalent, in 1 C.C. of Fc caustic soda and making up to 100 C.C. with 2 C.C. toluene. This stock solution keeps for three or four days, and is diluted ten times for use. It is suggested that proteins may be directly estimated neph elom etrically in pot able waters.H. F. E. H. Precipitation of Purine Bases from Meat Extract and Urine by Means of Zinc Salts. E. Salkowski. (Biochem. Zeitsch., 1913, 55, 254-260.)-0n treating a 10 per cent. meat extract solution with ammonia and calcium chloride to remove phosphates, and adding the neutralised filtrate with zinc chloride and sufficient sodium carbonate to make the mixture neutral or faintly alkaline, a considerable precipitate is formed, which is easily filtered and washed.After removing the zinc from this precipitate by means of sulphuretted hydrogen, a solution is obtained in which purine bases can be scarcely detected by ammoniacal silver nitrate. This apparently negative result is due to the presence of colloidal substances which prevent the formation of the purine precipitate.That the zinc precipitate contains purine bases is proved by dissolving the precipitate in hot dilute nitric acid, with the addition of urea, cooling, and adding silver nitrate, when a precipitate of hypo- xanthine silver or a mixture of this substance with hypoxanthine silver nitrate is formed.The presence of purine bases does not interfere with the determination of albumose nitrogen by means of zinc sulphate and sulphuric acid. E. W. Estimation of Sulphur and Chlorine in the Rice Plant. A. R. Thompson. (J. Amer. Chem. SOC., 1913, 35, 1628-1634.)-Sulphur is found in plants in definite chemical organic compounds such as edestin (0.88 per cent. SO,), legumin (0.38 per cent.), and gliadin (1-03 per cent.), as well as in the mustard oils.No organic compound containing chlorine has been isolated from any plant. From the obvious increase of sulphate ion in rice plants grown in sand and fertilised with ammonium sulphate, it is concluded that this salt as such is absorbed by the plant. Total sulphur was determined by Hart and Peterson’s modification of Osborne’s method, the melt being boiled out with water and not acid (J.Amer. Chem. SOC., 1902, 24, 142; Wis. Agri. Expt. Sta. Res. Bull., 14, 2). It is important that both fusions and boilings should be carried out over alcohol lamps. Duplicate determinations usually agreed within 0.02 to 0.03 per cent. InorgFnic sulphur was determined by stirring the sample with 100 C.C.of 1 per cent. hydrochloric acid, and allowing it to stand an hour before filtration. Chlorine was determined by the Volhard official method (U.S. Dept. of Agri. Bur. Chem. BUZZ., 107, 23). Determina- tions of chlorine, total SO,, and mineral SO, were made at three separate stages of growth of the plant, samples being taken both from unfertilised plots and from ground receiving a mixture of ammonium sulphate, superphosphate, and potassium sulphste.Firsst period, before flowering, sample being divided into foliage and roots. I n this series the total sulphur is higher than at any other period of growth, and is equally divided between foliage and roots. Inorganic sulphur is highest in the roots, being almost four times as high as in the foliage, but is still much lower than the total sulphur.Chlorine is also highest at this period, and, like sulphur, is found in highest percentage in the roots. Second series, taken at the flowering period. TheBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 573 sample was here divided into panicles, leaves, stems, and roots. The difference between manured and unmanured plants is nil as regards composition, though the former were much the larger and heavier plants, and the leaves show the highest, and the stems the lowest, content of sulphur.Chlorine, like sulphur, has decreased in percentage amount, and is highest in the roots. Third series, taken at maturity, and divided into chaff, grain, leavee, stems, and roots. Again no effect upon com- position is shown by manuring, total sulphur (as SO,) being very small in the stems and chaff, and about 0.23 per cent.on dry weight in the other parts. Inorganic sulphur is found only in the roots, showing that this form of sulphur has been used up in the formation of organic sulphur compounds. Chlorine is absent from the grain, though high in the stems. The pounds per acre of inorganic sulphur, phos- phoric acid, and chlorine absorbed by the rice plant are as follows : Unlllaaured. Corllplete (as above).so, ... ... ... ... 9.5 11.9 c1 . . I ... ... ... 14.9 21-1 P,O, ... ... ... ... 28-8 42.0 An analysis of the soil showed that the sulphur is present largely in organic form ; no trace of sulphide was detectable. The absence of effect of sulphur fertiliser on the composition of the plant is probably due to the presence of much iron in the soil, with the consequent formation of insoluble basic compounds.In sand pot experi- ments the chlorine absorbed is about twice as great as that absorbed by the rice plant when grown under normal conditions, experiments by the sand method showing that sulphur fertiliser is not rendered insoluble to the plant, as is the case in soil cultures.H. F. E. H. Detection of Albumin in Urine. 0. Mayer. (Zeitsch. angew. Chern., 1913, 26, 639-640.)-Several tests should be made in order to be certain that any given sample of urine contains albumin. Ten C.C. of the urine should be boiled with 6 C.C. of sodium chloride solution (1 : 3) acidified with acetic acid; a precipitate indicates the presence of albumin. Another portion of the urine is mixed with an equal volume of a reagent prepared by dissolving 4 grms.each of mercuric chloride and sodium chloride and 8 grms. of citric acid in 250 C.C. of 6 per cent. acetic acid ; a white turbidity is obtained when the urine contains albumin. Mucin is also precipitated by this reagent, and a, preliminary test should be made by boiling the urine with an equal volume of acetic acid, when any turbidity produced will be due to mucin.A comparison of the two turbidities will show whether albumin is present in addition to the mucin. The quantity of albumin present in urine may be estimated approximately by allowing 5 C.C. of the sample to flow on to the surface of about 10 C.C. of a, solution containing 5 grms. each of mercuric chloride and citric acid and 40 grms.of sodium chloride in 500 grms. of water. When the urine contains albumin to the extent of 0.001 per cent. a white ring forms in ninety seconds at the junction of the two liquids. Should the ring appear in a shorter time, the urine is diluted with water and the test repeated until the ring develops in the time mentioned; the amount of albumin present is obtained from the degree to which the urine has been diluted.w. P. s.574 ABSTRACTS OF CHEMICAL PAPERS Estimation of B. Coli Communis in Water. J. Partik. (Arch. f. Hw., 1913, 79, 301-322 ; through Chem. Zentralbl., 1913, II., 1252-1253.)--A measured quantity of the water to be tested is placed in suitably graduated centrifugal tubes; with ordinary not highly polluted waters, 40 or 20 C.C.may be taken, but with highly polluted samples and surface waters, 10 or 5 C.C. will suffice. Alternatively, the water may be diluted with physiological sodium chloride solution, and a suitable quantity measured off. If 40 C.C. be taken, in the case of soft waters, 20 drops of sterile 10 per cent. sodium carbonate solution and 10 drops of sterile 10 per cent.ferric sulphate solution are added; with hard waters, 16 and 8 drops respectively are employed. The tubes are centrifuged for ten minutes, and the clear liquid is carefully poured off from the precipitate. The latter is dissolved in 1 C.C. of sterile, neutral, 20 per cent. potassium tartrate solution, the liquid is thoroughly mixed and distributed quantitatively among six to twelve Conradi-Drigalski pla,tes, according to the suspected degree of pollution of the water.The walls of the tube are rinsed out with the solvent and the washings also brought on to the plates. The plates, without covers, are first digested for thirty to forty-five minutes in the thermostat at 43" to 45O C. and then kept at 37" C. When the red colonies are sufficiently developed, they are counted, and a few are examined in the usual way to confirm their identity as typical B. coli. The method described is sensitive and permits of the collection and enumeration of all the coli germs in a, measured quantity of water ; the colonies develop on the plates in twenty-four hours, and the organisms are available for further cultural and biological tests. By this method also, other pathogenic organisms of the typhus-coli group, which may be present in the water, can be detected. J. F. B. Bacteriological Methods of Water Analysis, with Speeial Referenee to the Use of the Berkefeld Filter. E. Hesse. (Arch. f. Hyg., 1913, 80, 11-28 ; through Chem. Zentralbl., 1913, II., 1253,)-The author gives a summary of the various methods for counting organisms and the detection of pathogenic bacteria and B. coli. The methods which depend on the employment of the Berkefeld filter and the bacteriological examination of the residue retained by the filter are specially dealt with. The candles supplied by the Berkefeld Filter Company, under the designation (( lo;,'' are particularly suitable ; owing to their larger surface, these filter much more rapidly than the No. 12 candles. Without the use of kieselguhr, 48 per cent. of the organisms present in the water are recovered, but with kieselguhr 91 to 97 per cent. can be retained. A further advantage is that large quantities of the water to be tested can be employed. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9133800567

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

574 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Detection of Amy1 Alcohol and other Aliphatic Alcohols and their Esters. T. Takahashi. (J. CoZZ. Agric. Tokio, 1913, 5, 167; through Chem. Zentralbl., 1913, II., 1334.)-In elaboration of his method (BdL. COIL Agric. Tokio, 7,437) and that of Koshino (Pharm. SOC. Jap., No. 351) for the detection of amyl alcohol (fuse1 oil) with vanillin and sulphuric acid, the author gives the followingORGANIC ANALYSIS 575 method : 2 C.C.of a solution of vanillin in 200 C.C. sulphuric acid of sp. gr. 1-84, with 0-5 C.C. of 0.1 per cent. amyl alcohol (Merck) in 15 per cent, alcohol, give a red coloration which increases in intensity until finally the liquid becomes turbid. Water added in drops clears the solution and gives a purple coloration which becomes bluish on the further addition of water, up to 4 C.C. Within ten days a precipitate of similar colour forms, while the supernatant liquid is a light rose-red.In a similar manner the following colours were obtained with other alcohols : Absolute ethyl alcohol (1 c.c.), turbid greenish- blue-light green ; methyl alcohol, dark red-purple; propyl alcohol, purplish-red -red-purplish-blue ; isopropyl alcohol, purplish-red- red-purple ; 12-butyl alcohol, yellow-red-purple ; amyl acetate, red-vermilion- carmine ; amyl formate, light yellow-red-purplish ; am yl benzoate, yellow-pur- plish-red ; butyl ester, green-pink ; amyl ester, red-light purplish-red-purple; butyl isovalerate, red-reddish-yellow-vermilion-purplish-red; propyl valerate, light red-carmine-purplish-blue ; acetic ester, dark yellow-light pinkish-red ; methyl isobutyrate, light red ; methyl propionate, red-purplish-rcd-purple ; methyl lactate, green-dark green--red ; methyl acetate, purplish rose-red ; methyl formate, light red ; ethyl propionate, light red ; caproic ester, yellow-carmine-red ; aceto- acetic ester, green-greenish-red-red (blue precipitate).I n all cases but the first, 1 drop of the alcohol or ester was taken. 0. E. M. Estimation of Small Quantities of Methyl and Ethyl Alcohols in Aqueous Solutions. J. Hetper. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 26, 342-348.)- Methods described previously by the author (ANALYST, 1912, 37, 366; 1913, 56), and based on oxidation with permanganate, may be applied to the estimation of ethyl and methyl alcohols in dilute solution.The solution must not contain other substances which reduce permanganate, and previous to the estimation it must be diluted with water or concentrated by distillation, as the case may be, until it contains from 0.1 to 0.25 per cent. by weight of total alcohols. The solutions required are : Acid potassium permanganate solution prepared by dissolving 16 grms. of potassium perrnanganate and 40 grrns.of crystallised phos- phoric acid in 1 litre of water, and alkaline pernianganate solution containing 16 grms. of the salt and 40 grms. of sodium hydroxide per litre; these two solutions are standardised against oxalic acid solution. A preliminary experiment is made to determine the alcoholic strength of the solution under examination ; for this purpose, 25 C.C.of the alkaline permanganate solution are diluted with 50 C.C. of water, heated on a water-bath, and the alcoholic solution is added in small quantities at a time until the permanganate colour is changed to green. The mixture is heated for a further twenty minutes, 25 C.C. of oxalic acid solution are added, and the excess of the latter is titrated with permanganate.permanganate solution is equivalent to 0.0025 grm. of alcohol. Alkaline 0zidation.-Twenty-five C.C. of the alkaline perrnanganate solution are diluted, heated to 40" C., 10 C.C. of the alcohol solution are added, and the mixture is at once heated on a water-bath, where it is maintained at 94" C. for from fifteen to twenty minutes.oxalic acid Each C.C. of The hot solution is then treated with 25 C.C. of576 ABSTRACTS OF CHEMICAL PAPERS solution, and titrated with the acid permanganate solution. The quantity of permanganate solution reduced should be not less than 7 C.C. or more than 12 C.C. Acid Oxidation.-Thirty C.C. of the acid perrnanganate solution are diluted with water, from 10 to 20 C.C. of the alcohol solution are added, and the mixture is heated under a reflux condenser to 94" C.for two hours. oxalic acid solu- tion are then added, and the excess is titrated with permanganate solution. The volume of permanganate solution reduced should be from 8 to 14 c.c., and 0.1 C.C. is deducted from the quantity used. Let p=grm. of total alcohols in the solution, x=grrn. of methyl alcohol in 100 grms.of total alcohols, y=grm. of methyl alcohol in 100 C.C. of the solution, x=grm. of ethyl alcohol in 100 C.C. of the same, nl=c.c. of alcoholic solution, and v1 = C.C. of permanganate solution used in the alkaline oxidation, n2 = C.C. of alcohol solution, and v2 = C.C. of 2 permanganate solution used in the acid oxidation, then : Thirty C.C. of Simultaneous Estimation of Methyl Alcohol Nicloux.(BUZZ. 806. Chim., 1913, 13, 935-939.)-The y == l-o-o, P X w. P. s. and Formaldehyde. M. method is & modification of the author's dichromate process (ANALYST, 1898,23, 41). The amount of potassium dichromate required for the oxidation of the mixed methyl alcohol and formaldehyde is first estimated, and then in a second estimation the quantity of carbon dioxide produced in this oxidation, For the latter estimation, 10 C.C.of the solution are mixed with sufficient 2N-dichromate solution to give a green tint, and the mixture placed in a small tube which is introduced upright into a reaction vessel containing 15 C.C. of sulphuric acid. The small tube is inverted within the flask after reduc- tion of pressure, and the reaction completed by immersing the apparatus for five minutes in an oil bath at 150' C.The gas is then extracted by means of a mercury pump and measured. If x represent the required quantity of methyl alcohol, y the formaldehyde, and a the weight of carbon dioxide produced by the oxidation of 5 C.C. of the mixture by the quantity b of dichromate- ---+-=a, 32 30 442 44y and 294x 196y 32 +-=b, 30 since 32 mgrms.of methyl alcohol require 294 mgrms. of potassium dichromate for oxidation, and yield 44 mgrms. of carbon dioxide ; whilst 30 mgrms. of formaldehyde require 196 mgrms. of dichromate, and yield 44 mgrms. of carbon dioxide. Hence and 16 (llb-49a) 539 X = 15 (147a - 22b) 1078 Y = C. A. M.ORGANTC ANALYSIS 577 Coals of Canada. (Bzdl. Imp. Inst., 1913, 13, 496-513,)-Analyses of the coals from all the Canadian coalfields are given.C. A. M. Analysis and Examination of Non-inflammable Cellulose Esters. Acetylcelluloses. H. Barthelemy. (Monit. scient., 1913, 3, II., 549-554 ; through Chem. ZentraZbE., 1913, II., 1617.)-The following tests may be applied for the examination of cellulose acetate preparations: Ten grms. of the sample are digested for one or two days, with frequent shaking, with a mixture of 190 grms.of dry tetrachloroethane and 10 grms. of 96 to 98 per cent. methyl alcohol, and the solution is examined for insoluble residue ; the strength and transparency of the film left by the evaporation of the solvent are also noted. From the relative viscosity of the solution an idea may be obtained as to the extent of degradation suffered by the cellulose moIecule in the process of acetylation, The presence of admixtures of nitro-cellulose may be detected by the diphenylamine-sulphuric acid test. The rnoistureis determined by heating 10 grms.of the powdered material at 65" to 70" C. until the weight is constant. A good acetate should not lose more than 1 to 1.5 per cent. under such conditions.The ash should not exceed 0.4 to 0.6 per cent. The percentage of combined acetic3 acid is estimated by saponification of 2 grms. of the material by heating for sixteen hours with 40 C.C. of ;-sodium hydroxide solution at 85" to 90" C., and titrating back the excess of alkali with sulphuric acid. The '' cppper value " (cupric reducing value) is of special importance from the point of view of the practical utility of the acetate ; it is inversely proportional to the tough- ness and viscosity of the material, and should not exceed 10.For testing the stability, 5 grms. of the powdered acetate are heated in a slow current of air free from carbon dioxide for three hours at 123' to 125" C., the air then passing through a flask containing & sodium hydroxide solution, which is afterwards titrated back. The '{ instability value " (grms.of acid, calculated as acetic, split off per 100 grms. of material) should not exceed 0.3. J. F. B. Methods for the Estimation of Natural Gas for the Production of Gasoline. E. S. Merriam and J. A. Birchby. (J. Ind. and Eng. Chem., 1913, 5, 824-828.)-Two empirical tests are described and recommended, and a small testing compressor is illustrated by means of which a direct determination can be carried out.The first test consists in shaking 1 C.C. of kerosene with two successive portions of 100 C.C. of the gas. The shaking is carried out in a Hempel explosion pipette over mercury, and the residual gas measured in each case. The actual volume absorbed from the second 100 C.C.as well as the ratio of the volumes absorbed in the two experiments is significant. As a result of the first shaking, the kerosene is saturated with methane, which is usually present in large amount, and is not very soluble, and nearly saturated with ethane, but is very far from being saturated with the higher paraffins, which are present in smaller amount and freely soluble. The decrease in volume in the second experiment is therefore mainly due to the higher paraffins, and the number of C.C.absorbed gives approximately the number of gallons of gasoline which can be obtained from 1,000 cubic feet of gas. When this number is high ( 5 or more) the ratio of gas absorbed in the first experiment to that absorbed578 ABSTRACTS OF CHEMICAL PAPERS in the second is usually low (2 or thereabouts), whereas when the proportion of liquid hydrocarbons is low (less than 1 gallon per 1,000 cubic feet) the said ratio may run up to 10.A second experiment, which gives useful results, is the following : A measured volume of gas (100 c.c.) is passed backwards and forwards between a gas burette and a Hempel pipette through a tared bulb tube containing 5 C.C.of olive oil, and from the contraction in volume of the gas and increase in weight of the bulb tube the mean molecular weight of the dissolved hydrocarbons is calculated. The olive oil is saturated with methane and ethane before use. Gases containing paying quantities of gasoline (1 gallon per 1,000 cubic feet and upwards) yield hydrocarbons to olive oil with a mean molecular weight of 60 to 73, whereas gases containing only sinall proportions of liquid hydrocarbons give a figure of 48 to 60 when submitted to this test.The third test described is a, direct determination of the liquid condensate which can be obtained from 250 cubic inches of gas. The apparatus consists of a pair of brass cylinders, each provided with a piston, together with a measuring cylinder, the whole tested to 500 pounds working pressure.It is operated by a small boiler- testing pump. Pressures from 80 to 250 pounds per square inch are used in actual large-scale plant for the recovery of gasoline from natural gas. G. C. J. Colorimetric Method for the Estimation of Histidine. M. Weiss. (Chem. Zeit., 1913, 37, 1245.)-The method depends on the property which histidine possesses of combining with diazotised compounds to form a red-coloured substance.The reagents required are : (1) Sulphanilic acid, 4, hydrochloric acid, 40, water, 400 parts ; (2) 0.5 per cent. sodium nitrite solution ; (3) 10 per cent. sodium hydroxide solution. One volume of the sulphanilic acid solution is added to 2 volumes of the nitrite solution to form the diazotised compound.A standard is prepared by treating 10 C.C. of a 0.01 per cent. histidine solution with 1-5 C.C. of the diazotised reagent and 3 C.C. of the sodium hydroxide solution, and histidine solutions under examina- tion are treated similarly, if necessary, after dilution to such an extent that the coloration obtained exactly matches the standard. Tyrosine must not be present in the histidine, its absence being denoted by a negative reaction with Millori’s test.Histidine sometimes contains other substances which interfere with the diazo reaction, since they combine with a portion of the reagent. I t is recommended that portions of the solution be treated with increasing quantities of the reagent until an optimum coloration is obtained, the comparisons being made after the standard and the test solution have been diluted to a volume of 20 C.C.each. w. P. s. New Indican Reaction. A. Jolles. (Chem. Zeit., 1913, 37, 1200.)-The test depends on the formation of EL violet-coloured compound when thymol and an oxidising agent are brought into contact with potassium indoxylsulphonate or with the indoxyl liberated from the latter by means of hydrochloric acid.In applying the test t o urine, 10 C.C. of the sample are mixed with 2 C.C. of a 20 per cent. lead acetate solution and filtered; the filtrate is then treated with 0.5 C.C. of a 10 per cent. alcoholic thymol solution, 10 C.C. of hydrochloric acid containing ferric chlorideORGANIC ANALYSIS 579 (Obermayer’s reagent), and 4 C.C.of chloroform, and the mixture is shaken. The presence of a mere trace of indican produces a violet coloration in the chloroform layer. When shaken with water the colour changes to brownish-yellow, but is reproduced on shaking the chloroform layer with hydrochloric acid. It may happen that when thymol has been added to urine as a preservative, the usual tests for indican may yield a violet or blue coloration; this may be differentiated by the ordinary starch test from the colour given by iodine.w. P. s. Colour Reactions of Triketohydrindene Hydrate (Ninhydrin). W. Halle, E. Loewentstein, and E, Pribram. (Biochem. Zeitsch., 1918, 55, 357-370.)-A number of substances containing primary alcoholic, aldehydic, and ketonic groups give colour reactions on boiling with ninhydrin; thus glycerol, amyl alcohol, and dextrose give blue colorations, ethylene glycol and maltose bluish-violet, lzvulose and lactose reddish-violet, erythritol red, and galactose rose colours.These reactions occur only in highly concentrated and neutral solutions, and do not take place in dilute solutions or in the cold. The sensitiveness of the reaction is greatly increased if the liquid is made alkaline after boiling : sodium, calcium, and barium hydroxides giving blue, ammonia red, and sodium carbonate violet-red colorations.I n the case of dextrose, a distinct blue colour is produced on adding sodium hydroxide after boiling with ninhydrin even at a dilution of 1 in 100,000. The reaction consists in the reduction of the triketohydrindene hydrate to hydrindantin, which substance is an exceedingly sensitive indicator for free hydroxyl ions. The formation of blue colour on boiling ninhydrin with amino-acids differs from that described above, in that it occurs in the cold and even in vacuo, and is not increased by subsequent addition of free hydroxyl ions, whilst addition of sodium hydroxide before boiling prevents the reaction.Hydrindantin also gives a blue colour with amino-acids in the cold. The colour formed from ninhydrin with amino-acids is colloidal, and especially sensitive towards electrolytes, the action depending almost exclusively on the nature of the cation. E. W. Solidifying and Melting-Points of Mixtures of Stearic and Oleic Acids. R. Meldrum. (Chem. News, 1913, 108, 199-201.)-Parallel determinations of the solidification-point of prepared mixtures of commercial stearic ” and L b oleic ” acids by Dalican’s method showed that the results were accurate to within 13.3 per cent.of the solid fatty acid. The error decreased with the proportion of oleic acid present, so that the degree of accuracy with a mixture containing 20 per cent. of stearic ” acid was 11.4 per cent.Thus, whilst the addition of 10 per cent. of oleic acid only lowered the solidification-point by 1 * 5 O C., the addition of 80 per cent. caused a lowering of 0.61” C. for each 1 per cent. of liquid fatty acid present. Again, in the case of a mixture containing 70 per cent. of oleic acid, each 1 per cent. of the latter corresponded to a lowering of 0.46’ C. Similar results, but correspondingly lower, were obtained when the determinations were made without stirring the mixture.The final rise of the temperature varied as much as 0.5’ C. in a, series of determina- tions. When working with large quantities of fatty acids, the rise ” was apparently eliminated owing to the slowness of cooling. As regards the melting-point, the most580 ABSTRACTS OF CHEMICAL PAPZRY constant results were obtained by the thermometer bulb method, care being taken that the coating of fatty acid was of uniform thickness.The conclusion drawn from determinations by four methods is that the results obtained by all the methods are too high, and that for this reason the solidifying-point is only apparently, and not really, lower than the melting-point.C. A. M. ''Wood Oils" from China and Japan. E. H. Wilson. (BUZZ. Imp. Inst., 1913, 13, 441-461.)-About nine-tenths of the wood oil of commerce is derived from Aleurites Fordii, and is exported from Hankow. A sample of the seeds of this tree yielded 58-3 per cent. of oil with sp. gr. 0.940 at 15' C., saponification value, 191.8, and iodine value, 166.7. Chinese wood oil is also obtained from another species, A.montana. The Japanese oil is derived from A. coydata, which has frequently been confused with the two Chinese species. The Japanese oils examined by Chapman (ANALYST, 1912, 37, 551) were stated to be the product of Paulowrtia imperialis, but later examination has identified the seeds from which these oils were obtained as those of Aleurites cordata.The Japanese and Chinese oils differ in polymerising properties, the former remaining fluid under conditions which convert the latter into a hard jelly which becomes a friable powder when crushed between the fingers. C. A. M. Waxes and Resins of Kapok and Akon Fibres. H. Matthes and I,. Streicher. (Arch. Pharm., 1913,251,438-452.)-When extracted with a mixture of alcohol and benzene, kapok fibres yielded 4.97 per cent., and akon fibres 4.63 per cent. of waxes resembling beeswax. These waxes contained 28 and 31 per cent. respectively of unsaponifiable matter (mainly phytosterol and melissyl alcohol) and gave the following values : Melting- Acid Value. Saponifica- Iodine Reichert- Polenske "I D 40' C. Poillt. tioii Value. Value. Value. value. Kapok wax 1-4618 24" C. 58.85 170.14 6944 2.02 0.97 Akon wax 1.4682 30.5" C. 65.09 171.52 70.52 1-76 1.05 The fatty acids of kapok wax consisted of about 15 per cent. of solid acids and 85 per cent. of liquid acids, whilst the corresponding amounts in akon wax were 20 and 80 per cent. respectively. In both cases the solid acids consisted of palmitic acid, whilst the liquid fatty acids contaiued about 61 per cent. of oleic acid, 38 per cent. of linolic acid and 1 per cent. of linolenic acid. Both kapok and akon fibres contained bitter principles, and from the latter a resinous substance resernblng aloes resin was isolated. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800574

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

580 ABSTRACTS OF CHEMICAL PAPZRY INORGANIC ANALYSIS. Quantitative Ammonia Distillation by Aeration. 111. P. A. Kober and S. S. Graves. (J. Amer. Chem. SOC., 1913, 35, 1594-1604.)-1n two previous papers (ANALYST, 1908, 33, 409, 442), P. A. Kober dealt with the aeration method of dis- tilling ammonia, and the authors now elaborate the method with further details, and cite numerous experiments showing its accuracy and convenience for all classes of ammonia determinations. From 400 to 600 litres of air were found to be sufficientINORGANIC ANALYSIS 581 for the average amount of ammonia obtained in Kjeldahl estimations. The heat of neutralisation, though slightly accelerating the distillation at the beginning, has no effect on the final results.The best quantity of sodium hydroxide is found to be 75 C.C.of a solution of sp. gr. 1.46 to 1.48, and 20 C.C. of concentrated sulphuric acid. Full details, with an illustrated apparatus, are given for the best method of manipulating. the aeration of the Kjeldahl melt after digestion. Using a fairly good pump, 25 C.C. of & ammonia can be quantitatively distilled (by aeration) in about one hour.Litmus-paper is not suitable for the detection of small amounts of ammonia in distillates if used in the ordinary way, but should be allowed to soak with stirring until change of colour is apparent. Boric acid, suggested by Winkler in place of the usual standard acid as an absorbent for the ammonia, is not satisfactory if used for the aeration method (CJ. ANALYST, 1910, 35, 316).H. F. E. H. Electrolytic Deposition of Antimony. W. K. Chaney. ( J . dmer. Chew&. ~ O C . , 1913, 35, 1482-1490.)-The paper is concerned with the deposition of antimony in presence of tin. In absence of tin, it may be deposited rapidly and quantitatively from an electrolyte of sodium sulphide, potassium cyanide, and sodium hydroxide. This method, as well as the method of depositing tin from the solution of its sulphide in ammonium polysulphide, breaks down when both metals are present, as tin is incompletely deposited from a sodium sulphide electrolyte, and metallic antimony is appreciabIy soluble in ammonium sulphide.The author has worked out an entirely satisfactory method for the simultaneous deposition of tin and antimony, and another method which, with care, effects the deposition of antimony alone from a solution containing both metals.The simultaneous deposition of antimony and tin is effected from an ammonium polysulphide electrolyte under conditions that insure that at the end of the electro- lysis the concentration of ammonia and ammonium sulphide is negligible. The initial concentration of ammonium polysulphide is also important.Concentrated aqueous ammonia is saturated with hydrogen sulphide in presence of excess of sulphur, and the filtered solution is mixed with six times its bulk of ammonia, saturated with hydrogen sulphide. This mixture is added drop by.drop to the solution of the chlorides of antimony and tin until a clear solution is obtained. This solution is then diluted to about 125 C.C.in a platinum dish, which serves as cathode. An anode rotating at 400 revolutions per minute is used, and the solution electrolysed at the boiling-point with an initial voltage of 3.5 and N.D,,, = 1 amp., raising the voltage to 4 as the current falls. From 0.2 to 0.3 grm. of antimony may be deposited quantitatively within an hour. At the boiling temperature ammonia and ammonium sulphide are removed or oxidised, and the deposits are like polished platinum.Antimony may be separated from tin as follows: The solution of the mixed chlorides or the suspension of the mixed sulphides in water is treated with hydrogen chloride and boiled. Excess of powdered lime is added,and the mixture is again boiled. Some lime is suspended in boiling water, the mixture saturated with hydrogen sulphide, filtered, and the filtrate added to the contents of beaker containing the sulphides of tin and antimony. The mixture is boiled for ten minutes, allowed to582 ABSTRACTS OF CHEMICAL PAPERS cool to 70" C., and electrolysed at 2.5 volts and N.D,,,=0*2 amp., using a rotating cylindrical platinum cathode 12.5 cm.in circumference and 4 cm. in height, and an anode of platinum iridium wire bent to form a helix, 6 em.in diameter, outside the cylinder, and then to form a smaller (1 cm.) helix inside the cylinder. The success of the method depends on getting the stannic hydroxide precipitated in a compact form. If in a gelatinous form, particles may adhere to the cathode and become reduced. G. C. J. Calorimetric Ash Estimations. F.v. Konek-Norwall. (Chem. Zed, 1913, 37, 1181-1182.)-The ash remaining in the crucible or other contrivance which accommodates the charge in an oxygen calorimeter is always less than the ash obtained by burning the substance in an ordinary open dish. This is known to be partly due to scattering of the charge and partly to other causes. The author finds that the error is particularly large with coals high in sulphur, and may amount to one-third of the ash with Hungarian coals, with 5 per cent.of sulphur. In such cases notable quantities of sulphate of calcium, iron (and the alkali metals), are found in the bomb washings, and the author recovers the lime and ferric oxide by filtering off the precipitate which results from the titration of the bomb washings with sodium carbonate.The washed precipitate is ignited with the paper, and the weight of the ash added to that remaining in the bomb crucible. Even when so corrected, the results are always below the truth, one source of loss being due to alkali oxide, which is lost as sulphate. G. C. J. Estimation of Chlorine in Rag Flock. A. E. Parkes. (Chem. News, 1913, 108, 177.)-Fifty grms.of a representative sample are digested for three to four hours with 500 C.C. of water, and the extract filtered through wire gauze in a Buchner's funnel. The residue is washed with successive portions of 100 C.C. of water, until the filtrate and washings amount to 1,000 C.C. This extract is filtered through paper, and portions of 100 C.C. ( = 5 grms. of flock) are evaporated to dryness in porcelain dishes, and the residues heated until the organic matter is just charred, after which water is added and the chlorine titrated with silver nitrate solution, with potassium chromate as indicator.The method give accurate and concordant results in the case of samples containing known quantities of sodium chloride. In examin- ing unwashed flocks the addition of pure phenol or other germicide to the first extract is advisable (cf.ANALYST, 1913, 469). C. A. M. Estimation of Copper as Sulphide. C. Beck. (Chem. Zeit., 1913,37,1330.) ---For the reduction of cupric sulphide to cuprous sulphide by ignition with sulphur in a Rose crucible, a current of carbon dioxide may with advantage replace the current of coal gas or hydrogen usually employed.The advantage lies in the fact that there is no risk of reduction to metallic copper whatever the temperature em- ployed, and no risk of explosion or of fracture of the crucible lid due to local heating where the hydrogen, etc., escapes and burns. G. C. J. Cathodic Estimation of Lead and Analysis of Lead Alloys. R. Garten- (Chem. Zeit., 1913, 37, 1281-1282.)-Hitherto lead has been estimated meister.INORGANIC ANALYSIS 583 electrolytically only as peroxide on the anode.Conditions are now described under which it may be deposited quantitatively as metal on the cathode. For the estima- tion of quantities of lead up to 1 grm., the electrolyte should contain 2 to 2.5 C.C. concentrated nitric acid, 5 grms. gallic acid, 5 to 6 C.C. alcohol, and amount to about 125 C.C.For quantities of lead from 1 grm. to 2.5 grms., these quantities should be doubled. Larger quantities of lead than 2.5 grms. cannot be deposited free from im- purities by the use of the electrodes described. These consist of a Winkler gauze cathode and a cylindrical anode of platinum foil, 7 mm. in diameter and 40 mm. long. The anode is centred within the cathode, so that the distance fromany point on the anode surface to the nearest point of the cathode surface is almost a constant.The current should not deviate much from 1-2 amps. At 1.6 amps. a non-adherent deposit results, whilst a current less than 1.2 amps. makes the deposition very slow. The electrolyte is maintained at 6 5 O to 75” C. throughout the process, which requires from three to five hours, according to the amount of lead present. The longer time suffices for the deposition of 2.5 grms.lead. The operation should not be prolonged unnecessarily if the most exact results are desired, as a small quantity of a yellow- coloured substance may then be deposited with the lead. The error involved in continuing the electrolysis for five hours with only 0.5 grm.lead present is about 1 mgrm. At the end of the operation the cathode is washed once with tap-water without interrupting the current ; then with distilled water, alcohol, and ether ; and is finally dried cautiously over a flame. I n absence of interfering elements, quantities of lead from 0.4 grm. to 2.5 grrns. can be estimated with an absolute error in no case exceeding 1.7 mgrms., and a percentage error in no case exceeding 0.13 per cent.Copper, if present, is wholly deposited with the lead. Zinc, cadmium, iron, nickel, cobalt, and manganese remain wholly in the electrolyte. Silver, tin, anti- mony, and arsenic interfere with the method, as they are partially, but not wholly, deposited on the cathode. In the important case of alloys of lead with tin and (or) antimony, the metal is dissolved in nitric acid with the aid of tartaric or citric acid ; the solution is made alkaline with solid sodium hydroxide, mixed with a con- centrated solution of sodium sulphide, warmed, and filtered. The precipitate, which contains all the copper, iron, and zinc, as well as lead, is washed with sodium sulphide solution until free from tin and antimony, and then with a strong solution of ammonium chloride containing a little ammonia and ammonium sulphide.It is then dissolved in nitric acid as far as possible, qnd the filter, which obstinately retains some lead, is ashed, and the ash dissolved in nitric acid and added to the main solution, which is next evaporated to dryness. The residue is taken up in nitric acid and electrolysed as described. In the filtrate and washings containing the tin and antimony, the latter is estimated electrolytically by Hollard’s modifica- tion of Classen’s method. The tin in the exhausted electrolyte is precipitated as sulphide, and this is dissolved by means of hydrochloric acid and potassium chlorate, and the solution evaporated to dryness.The residue is dissolved in hydrochloric acid, and the tin deposited from an ammonium oxalate electrolyte by Hollard’s modification of Classen’s method.If the alloy contains tin or antimony, but not both, the method is simplified. G. C. J.584 AESTRACTS OF CHEMICAL PAPERS Analysis of Alloys of Lead, Tin, Antimony, and Copper. D. J. Demorest. ( J . Ind. and Elzg. Chew., 1913, 5, 842-843.)-The novelty of the method here described lies mainly in the titration of antimony by permanganate in sulphuric acid solution free from hydrochloric acid.The combination of methods for deter- mining the four metals has also points of novelty. The drillings (1 grm.) are treated with 20 C.C. hot concentrated sulphuric acid until the sample is nearly decomposed and the lead sulphate white.Free sulphur is liberated, but does not interfere. The mixture is boiled for some minutes, cooled, diluted with 50 C.C. water, boiled several minutes, and, before it has cooled to GO" C., the clear liquid above the lead sulphate is decanted through a Gooch crucible. The lead sulphate is boiled UP with a further 10 C.C. of sulphuric acid, the mixture diluted with 30 C.C. water, boiled, and filtered through the Gooch crucibk.The lead sulphate is washed with hot water, dried, ignited at a dull red heat, and weighed. The filtrate, which should not exceed 150 c.c., is heated to 60" to 80" C., and titratedwith permanganate until a deep red colour appears. More permanganate (2 to 3 c.c.) is added, the solution shaken for a minute, and the excess of permanganate determined by titration with f ~ ~ ~ o u s sulphate.The net consumption of permanganate gives the antimony. To the titrated solution 50 C.C. of hydrochloric acid and about 0.15 grm. antimony (unless this amount is already present) dissolved in 5 C.C. concentrated sulphuric wid are added, and the boiling solution is reduced by means of iron in a current of carbon dioxide, the boiling and stream of gas being continued for thirty minutes after the solution becomes colourless.The stannous solution is cooled in a current of carbon dioxide and titrated with iodine. Another portion of the sample is treated in a similar manner up to, or including, the antimony titration. Tartaric acid (3 grms.) is added, and then ammonia, until the solution is slightly alkaline.The acid reaction is restored by addition of 2 C.C. sulphuric acid, the solution is heated nearly to boiling, 2 grms. sodium sulphite is added, and, when it has dissolved, 10 C.C. of a 10 per cent. solution of potassium thiocyanate. The mixture is shaken, allowed to stand fifteen minutes, filtered through asbestos, and the copper precipitate washed. Copper is then estimated either by the thiocyanate-permanganate method or by the iodide method after ignition of the precipitate and solution of the oxide in nitric acid.The results are accurate to within 0.2 per cent. for lead, tin, and antimony, and to within 0.1 per cent. for copper. G. C. J. Spectroscopic Detection of Magnesium, Calcium, Strontium, and Barium. E. H. Riesenfeld and G. Pfiitzer. (Ber., 1913, 46, 3140-3144.)- By ordinary spectroscopic methods-for example, using the Beckmann biirner- calcium cannot be detected in solutions of lower concentration than 0.2 mgrm.per c.c., strontium in concentrations below 0.6 mgrm. per c.c., barium in concentrations below 14 mgrms. per c.c., and magnesium not at all. By resort to an arc spectrum, far smaller quantities of calcium, strontium, and magnesium can be detected, and the detection of magnesium also falls within the range of this method.The authors figure a suitable apparatus, consisting of a glass cup to accommodate 1 to 2 C.C. of the liquid to be examined, the cup pierced by a platinum wire resting in an eboniteINORGANIC ANALYSIS 585 holder containing a little mercury, into wbich the wire dips.The mercury in the ebonite holder is in electrical connection with a brass binding screw at its base, the holder being suspended by a clamp which grasps it near the top. Above the liquid is suspended an iridium needle, adapted to be put in connection with the other terminal of the source of electrical energy. The whole apparatus is mounted on a stand facilitating vertical and horizontal adjustment of the position of the arc relative to the spectrometer.The liquid in the cup is connected to the positive pole, of Between the negative pole and the iridium needle if3 interposed an adjustable resistance of 300 to 500 ohms, to carry a current of 1 amp. The iridium needle is depressed by means of a micro- meter screw until an arc is established between it and the liquid, and the length and intensity of the arc are then regulated by further adjustment of the micrometer screw and of the external resistance.As little as 0.002 mgrm. calcium, 0.03 mgrm. strontium, 0.006 rngrm. barium, and 0.1 mgrm. magnesium, may be detected easily in 1 C.C. I n these concentrations, calcium shows one brilliant line (423 pp), a, bright line (616 pp), and a faint line between them; strontium two bright .lines (422 and 461 pp) and two fairly bright lines; barium two brilliant lines (455 and 493 pp), two other bright lines, and a fairly bright one; and magnesium a brilliant band composed of three lines (516.8 to 518.4 pp), as well as a fairly bright lins further towards the violet end of the spectrum.The iridium electrode gives rise only to lines which are faint compared with the above.The hydrogen line 656 pp appears as a brilliant line, the line 486 pp as a bright one. No air-lines appear. The apparatus used by the authors, which they believe to be the first simple device for producing Lecoq de Boisbaudran’s arc, is made by Franz Hugershoff, Leipzig. source of electrical energy at 100 to 200 volts. G. C. J.Detection of Nitrous Acid in the Presence of Nitric Acid. A. Leelare. (J. Pharm. Chinz., 1913, 8 , 299.)-The test is based upon the fact that citric acid liberates nitrous acid from its salts, but does not affect nitrates. The solution under examination is treated with an equal volume of a syrupy solution of citric acid, and a little of a 3 to 4 per cent. solution of ferrous ammonium sulphate pipetted on to the surface of the liquid.The characteristic brown ring is obtained in the presence of 1 part of nitrous acid per 10,000, whilst concentrated solutions of nitrates give no coloration in twenty-four hours. A preliminary treatment with zinc acetate, followed by filtration, is necessary when sulphides are present. C. A. M. Electrometric Titration of Dichromate Ion with Ferrous Iron.G, S, Forbes and E. P. Bartlett. (J. Amer. Chem. SOC., 1913, 35, 1527-1538.)-Certain reducing agents increase the oxidising potential of the dichromate ion on platinum by amounts up to 0.2 volt. No other oxidising agent tried exhibits a similar effect. The potential increases up to the very endpoint of the reaction, and is highest when the dichromate concentration is least.A final drop of & reducing agent often depresses the potential by 0.5 volt. Them observations have suggested an improve- ment in the electrometric method of titrating dichromate and ferrous salts which makes it both more rapid and more accurate than the ferricyanide method.586 ABSTRACTS OF CHEMICAL PAPERS The solution to be titrated is placed in B. The platinum electrode E is sealed to the glass tube T, which is preferably arranged to be rotated mechanically by a pulley, P.Connection is made between E and L by filling T with mercury. C is a calomel electrode containing mercury, mercurous sulphate, and potassium chloride. The plunger F serves to sweep out the syphon N just before the end of a titration. QR is a thin wire stretched over the wood-strip W.The connection to the battery l' is made by a piece of wire of such length that the sliding contact S is near 2 at the start of a titration. To titrate a dichromate solution with ferrous salt, the galvanometer is first brought to rest by moving S, then ferrous salt is run in, and S moved towards Q sufficiently to neutralise the anomalous increase in potential.If ferrous salt is to be titrated, a slight excess of dichromate is added, and the mixture titrated back with ferrous G is a mirror galvanometer and M its mirror. I I V solution of known strength. Very soon a nearly constant maximum potential is reached, so that the operator can abandon the sliding contact and occupy his hands solely with the burette and his eyes in watching the spot of light reflected by the galvanometer.Finally, a single drop of Fc ferrous solution in excess drives the spot of light right off the scale. The improvement claimed for this 'method over those previously described lies in the constancy of the E.M.F. right up to the endpoint, and the simplicity of apparatus and method which can be employed in consequence. Taking the results obtained by this method as establishing the true endpoint in titrations of ferrous ion by means of dichromate, it is shown that the disappearance of the ferricyanide reaction, when used as a spot-test in the usual way, does not indicate absence of ferrous iron, but a reduction of the concbntration of ferrous iron to 0.0003 grm.per 100 C.C. This last drop is subtracted from the volume used.G. C. J. Iodimetric Estimation of Iron. C. Beck. (Chsm. Zeit., 1913, 37, 1330- 1331.)-The reaction between ferric salts and hydrogen iodide does not proceedINORGANIC ANALYSIS 587 quantitatively unless one of the products of the reaction is removed continuously. If the resulting iodine is removed by distillation, however, the reaction proceeds to completion, and the iron may be estimated with an error not exceeding 0.2 per cent.by titrating the iodine with thiosulphate. The author introduces the ferric solution into an appropriate distillation apparatus, and adds, in the following order, some broken pot, 2 grms. potassium iodide, 1.5 grms. marble in small pieces, 40 to 50 C.C. water, and 20 C.C. concentrated hydrochloric acid. The apparatus is promptly closed, its contents are distilled nearly to dryness, and the iodine is received in a solution of potassium iodide and titrated with thiosulphate.G. C. J. Determination of Phosphorus in Vanadium S tee1 and Ferrovanadium. C. F. Sidenerand P. M. Skartvedt. (J. Ind. and Eng. Chem., 1913,5,838-839.)- The method depends on the separation of phosphorus from vanadium by precipitation as aluminium phosphate under closely defined conditions.The sample is dissolved in dilute nitric acid, aided, if necessary, by a little hydrochloric acid. The solution is evaporated to dryness, and the residue is baked to decompose nitrate of iron, and then dissolved in concentrated hydrochloric acid, to which about 0.02 grm. aluminium is added in the form of chloride.The solution is nearly neutralised with ammonia, heated nearly to boiling, and the iron reduced by addition of ammonium bisulphite solution. When reduction is complete, ammonia is added until a sIight permanent precipitate of ferrous hydroxide results. This is redissolved by addition of a few drops of ammonium bisulphite solution, and 1 to 2 C.C. of phenylhydrazine is next added drop by drop with constant stirring.If no precipitate appears, ammonia is added drop by drop until one forms, and this is followed by a few drops more of phenyl- hydrazine. The mixture is boiled for two minutes, and the precipitate allowed to subside and then filtered off. It consists of aluminium phosphate and hydroxide, more or less contaminated with vanadium. I t is washed with hot water until the washings develop no cloudiness with mercuric chloride solution, and is then dissolved in dilute nitric acid, the solution being caught in the original beaker.The vanadium is oxidised by a little hydrogen peroxide, and a slight excess of sodium carbonate is then added. The solution is boiled for five minutes, and the phosphorus re-precipitated as aluminium phosphate by gradually adding dilute nitric acid until the solution no longer gives an immediate brown tinge to turmeric-paper.The precipitate is filtered off and washed with 1 per cent. ammonium nitrate. I t is then dissolved off the filter with dilute nitric acid and tested for vanadium with hydrogen peroxide. If the original steel contained less than 1 per cent of vanadium, no trace of colour will develop, showing absence of vanadium, and the precipitation of the phosphorus as molybdate may be proceeded with.With more than 1 per cent. of vanadium present, a pinkish-yellow colour may develop, whilst with 5 per cent. present a deep red colour will probably appear. In such cases a second precipitation with sodium carbonate and nitric acid is necessary, and ferrovanadium with high percentages of vanadium may call for it third precipitation.An ordinary vanadium steel with 0.15 per cent. vanadium and (according to the U.S. Bureau of Standards) 0.035 per cent. phosphorus was found to contain 0.0340 and 0.0356 as the extreme values of a series of analyses, With high-grade ferrovanadium (30 per cent.) the588 ABSTRACTS OF CHEMICAL PAPERS method may give results nearly 10 per cent.in error, but on such material the exact percentage of phosphorus is less important and its determination difficult by any method. G. C. J. Colorimetric Method for Titanium in Iron and Steel. C. R. McCabe. ( J . Ind. and Eng. Cheni., 1913, 5, 735-736.)-The method described is the ordinary peroxide method, with extraordinary precision in compensating for the colour of ferric salts, which, in the case of titanium steel, may be more intense than that due to titanium.The sample (2 grms.) and an equal weight of titanium-free steel are dissolved in separate flasks by heating with 80 C.C. of dilute (1 : 3) sulphuric acid. Nitric acid (2 c.c.) is added to the contents of each flask, and boiling continued unt*il the solutions are free from fumes. The cooled solutions are washed into similar Nessler cylinders, filtering the test solution through a plug of cotton if the sample under examination is cast iron.The colours will either match, or that of the standard steel, selected for its high content of iron, may be slightly more intense. In this case a little of it is rejected until the solutions viewed from above appear identical in tint.Hydrogen peroxide (2 C.C. of a 3 per cent. solution) is added to the contents of each cylinder, when a distinct difference in tint will be noticed if the sample under examination contains 0.02 per cent. of titanium. The tints are again equalised by adding a standard solution of titanium to the control solution in the usual manner, taking care, unless the amount of titanium be very small, to secure equality of volume between the comparison liquids before making the final comparison.When less than 0.02 per cent. of. titanium has to be looked for and estimated if found, it is best to make an ether separation of the greater part of the iron. The sample and control steel are dissolved in 50 C.C. hydrochloric acid, and each solution is oxidised by means of nitric acid and evaporated to about 10 C.C.I t is then washed into a separator with about 15 C.C. hydrochloric acid (2 : l), and extracted with 50 C.C. ether. The acid layer is run off into a beaker, making the separation with care that not more than a drop of the ethereal solution passes into the beaker in either experiment, The solution is diluted with 200 C.C.hot water, made alkaline with ammonia, boiled, and filtered. The precipitate is washed free from chlorides and dissolved by placing the filter in a dish and treating it with 10 C.C. dilute (1 : 3) sulphuric acid. The solutione, which have a light maroon colour, due to a little iron, are filtered into comparison tubes, and the analysis completed as usual.Hydrogen peroxide discharges the maroon colour of the control solution, which gives place to a very pale green. The test solution, in presence of titanium, develops the colour characteristic of that metal, of which as little as 0-001 per cent. can readily be detected. When using this refined method to discover the ultimate distribution of very small quantities of titanium, which, though used in course of manufacture, do not necessarily appear in the finished iron or steel, the insoluble matter from cast iron must be ashed, freed from silica, fused with sodium carbonate, and the acid solution of the product of fusion added to the main solution.The insoluble matter from cast iron always contains titanium, if titanium is present in the iron, but in ordinary technical work the amount may be neglected.The paper describes a method for the preparation in bulk of standard titanium solution with commercial ferrotitanium as starting-point. G. C. J.INORGANIC ANALYSIS 589 Estimation of Vanadium in Steel by the Hydrogen Peroxide Colour Method. C. R. McCabe. ( J . Ind. and Eng. Chem., 1913, 5,736-738 )-For the deter- mination of vanadium, even in the difficult case where this inetal is accompanied by titanium and molybdenum, the author has already described a method (ANALYST, 1911, 36, 473).This method is still recommended in such cases, and in the equally trouble- some case of a steel containing a small aniount of vanadium with much chromium. In most cases, however, satisfactory results can be obtained by simpler means.I n absence of chromium, 2 grms. of the vanadium steel and an equal weight of a non- vanadium steel are dissolved separately in 40 C.C. dilute (1 : 1) nitric acid. About 0.1 grm. permanganate is added, and the mixtures are digested for two minutes. The solutions are then clarified by addition of atxinoniuni bisulphite, and boiled to expel sulphur dioxide. They are next cooled, made equal in volume, and their colours, which should be identical, compared.Into each tube 1 C.C. of 3 per cent. hydrogen peroxide is added, and, to the control solution, a standard solution of vanadic acid until the colours match, adding water to the assay from time to time to keep the volumes approximately equal. I n presence of chromium, 2 grms. of the vanadium steel is dissolved in 80 C.C.of dilute !1 : 3) sulphuric acid, and 2 grins. of steel free from vanadium or chromium is dissolved in an equal quantity of acid, to which potassium bichromate, equivalent to the, chromium in the assay, has been added. When nearly dissolved, 25 C.C. of concentrated nitric acid is added, and tlie mixture heated for ten minutes. Vanadium is not completely oxidised by a small amount of nitric acid such as would oxidise the iron.The method overcomes difficulties which arise from the fact that the colour and intensity of colour of chromium compounds vary with the acidity of the solution and other factors not readily determined. The analysis is then finished as in absence of chromium. G. C. J. Estimation of Zinc in Treated Ties (Railway Sleepers).F. C. Frary and M. G. Mastin. (J. Ind. and Eng. Chenz., 1913, 5, 738-739.)-Railway sleepers, treated with zinc chloride, are usually sold to a specification of 8-oz. zinc chloride per cubic foot, or 0.5 per cent. metallic zinc. Except with oak, the estima- tion of zinc may be accomplished by charring borings with sulphuric acid, adding nitric acid a few drops at a time, continuing the heating until all organic matter is destroyed and nitrous fumes driven off, dilution, removal of iron, precipitation of zinc as sulphide, and final weighing as oxide.With oak sleepers, especially red oak sleepers, the above method fails, for the treatment with acid, no matter how prolonged, does not destroy all organic matter, and the precipitation of the zinc in the dark coloured solution is so incomplete that the estimation may be 50 per cent. in error. All kinds of wood yield to the following treatment : The borings (2 grms.) are weighed into a 200 to 300 C.C. nickel dish, moistened with water, and warmed to insure saturation. About 30 grms. of potassium hydroxide is added, and the mixture heated to fusion. Whilst stirring with a nickel wire, the heat is increased until the mixture boils vigorously. Lumps of gummy substance, which separate, gradually disappear, and the fusion begins to foam. When spurts of inflammable gases appear, about 0.1 grm. of potassium590 ABSTRACTS OF CHEMICAL PAPERS nitrate is added, and similar additions, perhaps five in all, made, with conatant stirring, until the fusion becomes transparent, colourless, and tranquil. The cooled mass is dissolved in water, 15 to 20 C.O. bromine water added, and the mixture boiled for a, minute. Nickel hydroxide, thus precipitated, is filtered off on a Gooch crucible, and the filtrate and washings transferred to a large (750 c.c.) dish, and made faintly acid with concentrated hydrochloric acid. Excess of sodium sulphite is added-a little at a time, until the first violent effervescence ceases-and then 10 to 20 C.C. of concentrated hydrochloric acid. The solution is diluted to 400 c.c., heated to boiling, and titrated with ferrocyanide, using a saturated solution of uranium nitrate as outside indicator, or zinc may be determined by any other method. Enough sulphite must be used to reduce all oxidising compounds, which might otherwise decompose ferrocyanide, and the latter must of course be standardised under approximately identical conditions as regards dilution, acidity, and saline concentration. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9133800580

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

590 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. Mechanical Agitator. V. Grignard. (BUZZ. Soc. Chim., 1913, 13, 952-955.)-The ap- paratus here shown will be found useful for the agitation of flasks while connected with a reflux condenser. It consists essentially of a circular iron or copper plate, which revolves horizontally on a vertical axis. A slight oscillating movement (about 5 to 6 em.) is communicated to it by means of a crank beneath, which is connected with an ordinary laboratory turbine.The upper part of the reflux condenser is supported in a ring of wide diameter. The surface of the plate is covered with asbestos, and is pierced with openings to receive the flask, which may thus be made to oscillate over a flame or an electric lamp. The apparatus may be obtained from Lequeux, 64, Rue Gay-Lussac, Paris.C. A. M. Bomb with Stirring Gear for the Measurement of Reaction-Velocity in a Heterogeneous System at High Pressures. New High-pressure Reducing Valve. L. Stuckert and M. Enderli. (Chem. Zeit., 1913, 37, 1288.)-The bomb consists of an upright Mannesmann tube, closed at each end by a conical plug forced into its seat by tt threaded cap.The liquid and gas are admitted or removed through capillary copper tubes passing through glands, All joints are made tight by the method of F. Haber and R. Le Rossignol (Zeitsch. Elektrochem., 1913, 19,57). In the axis of the upper plug a sleeve is fitted gas-tight by means of a reverned conical seating; the axial bore of this sleeve is enlarged into two oil-chambers, and carriesAPPARATUS, ETC.591 a nicely fitting steel shaft, the upward thrush of which is taken on a ball thrust- bearing. Absolute tightness is secured by a slightly conical Kiingerite washer at each end of the sleeve. Side-pull from the driving-band is prevented by outboard bearings above and below the pulley. A double-walled oil-intercepting cup and a, Witt stirrer are carried at the lower end of the shaft.The heating with pressures up to 80 atmospheres at 2,000 revolutions per minute for runs of five to ten hours was so small that kinetic determinations at constant temperature could be carried out. The new valve is constructed on the principle of the Haber and Le Rossignol joint. I t gives a large opening for a small movement of the spindle ; its packing consists of easily renewed vulcanised fibre disks, and it is not subject to erosion of the valve seat. 0.E. M. Apparatus for the Continuous Evaporation of Large Volumes of Liquid under Diminished Pressure. W. A. Davis. (J. Agric. Sci., 1913, 5, 434.)-The apparatus was speci- ally devised for dealing with alco- holic plant extracts which have a tendency to froth, and it can be left without attention when once started, so long as the liquid in the distilling flask A is renewed from time to time from the drop- ping funnel A l .B serves as a froth trap, the copper gauze seen at the base of it serving to break up the froth and insure its return through the side tube L to the distilling flask A. The large reser- voir P takes small variations in the water pressure, and so in- I sures a steady vacuum, which is maintained by an ordinary water injector pump connected through B Hutchinson regulating valve, J (ANALYST, 1912, 37, 480), with the bottle E, and thence with E and G.The combination E and G allows of the distillate being removed at any time, the vacuum being meanwhile maintained by closing the cock on E and the screw clamp S.G can then be emptied and replaced, and by first opening S alone the vacuum in G is soon re-established. H. F. E. H. Apparatus for Determining the Density and Internal Friction of Gases. M. Hofsass. (J. Gasbeleuchtung, 1913, 56, 841 ; through Chrn. Zentralbl., 1913, II., 1353.)-The apparatus, arranged as a bye-pass in the gas-supply, consists essentially of a chamber provided with a manometer and a fine jet controlled by a cock, and closed at the ends by stopcocks.The gas, collected in it under pressure, is allowed to flow out through the jet ; the time required for the manometer liquid to fall from one mark $0 another is observed by a stop-watch, and affords a measure of the density, which is proportional to the square of the time of flow. If the service-592 ABSTRACTS OF CHEMICAL PAPERS pressure is insufficient, gas enclosed in a second chamber may be forced into the first by a levelling vessel.To determine the internal friction, a capillary is substituted for the jet. 0. E. M. Apparatus for Extracting Carbon Monoxide from Blood. M. Nicloux. (Bull. SOC. Chim., 1913, 13, 947-952.)-The u6e of the apparatus shown in the figure obviates the necessity of a mercury pump for extracting carbon monoxide from blood.The flask A , which has a capacity of 40 to 200 c.c., according to the quantity of blood available, is charged with phosphoric acid (40 c.c., or one and a half times the volume of the blood) and 25 C.C. (or the volume of blood) of water, and is connected with the refrigerator M. The tube t is filled with water, the tap R closed, and the tap R' opened.The flask is then three parts immersed in a calcium chloride bath at 110' C., and a vacuum created by means of a water-pump attached to X, after which the tap R' is closed, and water is intro- duced into the upper part of the tube t'. The blood (25 c.c.) is now introduced into E , and allowed to fall very slowly into the flask through the tap R, the tubes E and t being subsequently washed with 15 C.C.of water. I n con- tact with the phosphoric acid the blood parts with its carbon monoxide, whilst a part of the pigment and proteins is dissolved. To remove froth from the neck of the flask, the apparatus is withdrawn from the bath, cooled with a jst of water, and 10 to 15 C.C. of hot water are introduced from the basin C by rapidly turning the tap R'.If neces- sary, this operation is repeated two or three times. After fifteen to twenty minutes the extraction of the carbon monoxide will be complete, and the flask is withdrawn from the bath. Hot water is now admitted through the tap R until there is no longer a vacuum. The basin C is then filled with water, a measuring cylinder placed over X, the tap R' opened, and the gas collected and measured.I n addition to its use for the examination of blood in cases of carbon monoxide poisoning, this apparatus may be used for the collection of any gas insoluble in water generated by the interaction of two substances. C. A. Rrz. Simple Gasoline Gas Generator for Sulphur I: eterminations. C. E. Waters. ( J . Ind.and Eng. Chenz., 1913, 5, 853-854.)-The apparatus consists of a glass tube 25 cm. high and nearly 5 cm. in diameter, closed at both ends, but with a tube sealed through the top and extending nearly to the bottom, and another tube sealed on to the side near the top. The tube is charged for a third oE its height with glass beads, and for another third with petroleum spirit, or a mixture of this with gasoline ; gasoline alone is unsatisfactory.The apparatus is supported in 8r suitable stand, and the long glass tube which extends to the bottom of the layer of beads is connectedAPPARATUS, ETC. 593 to a supply of compressed air at a pressure of about 40 inches of water, and the side tube is connected to a gauze-topped safety burner. Black rubber tubing is used for the connections.The object of the beads is to break the stream of air up into small bubbles, without which it would be impossible to obtain a steady flame. The size of flame is easily regulated by a cock on the burner or clip on the tube near it, the supply of compressed air behind the generator being always full on. The apparatus has been in use for several years without accident in the laboratory of the U.S.Bureau of Standards, the only precaution necessary being to extinguish the flame before turning off the supply of compressed air. G. C. J. Apparatus and Method for Determining Hydrogen Sulphide in Illuminating Gas. E. P. Harding and E. Johnson. ( J . Ind. and Eng. Chem., 1913,5, 836-838.)-The 300 C.C. bulb, A, of the apparatus figured is charged with 100 to 150 C.C.of a strong solution of cadmium chloride, of which 5 to 6 C.C. are tilted over into the bulb attachment J. The stopcock, D, being closed, and E and F open, M is attached to a meter and E to the supply of gas to be tested, the speed of which is adjusted to 1 to 1.5 c.ft. per hour. If the liquid in 0 develops a coloration, the gas is cut off and the meter read.I n testing par- tially purified gas, 0.1 c.ft. is a convenient quan- tity to take; but if no precipitate is visible in -4 when 0.1 c.ft. has passed, the experiment is con- tinued until one appears. The final reading of the meter having been taken, the apparatus is disconnected from the meter and gas-supply, D is opened, and the liquid in 0 tilted into &4. Wash-water is then drawn into A through M by applying suction at B, and more wash-water is similarly sucked in through E.The gas above the solution in A is next replaced by air by applying suction at B with F open; some starch solution is run into A through B, and the air in A is placed under diminished pressure by suction applied at B. Concentrated hydrochloric acid is run into A through B until the precipitate of cadmium sulphide is dissolved.A small excess of acid is allowed to run in, and the liberated hydrogen sulphide iu finally titrated with a weak solution of iodine delivered from C. For unpurified coal-gas gV is a convenient strength for the iodine solution, a solution one-tenth as strong serving well for purified gas ; or the strength may be adjusted so that each C.C.corresponds to 10 grains or 1 grain of hydrogen sulphide per 100 c f t . , when 0.1 c.ft. is taken for the test. The results are about594 ABSTRACTS OF CHEMICAL PAPERS k 5 per cent. lower than those obtained by the gravimetric cadmium chloride methcd, which is admitted to be more accurate. On the other hand, the gravimetric method is slow, and includes sulphur compounds other than hydrogen sulphide.G. C. J. I I means of the central tube, d. ths tubulure, g, which is closed by a rubber stopper. The reagent is introduced through To the On I 1 I ! I t e side-tube, e, a rubber balloon is fixed and filled with air. 1 1 1 4 /' \ I 1 I I ; B ' I I I I I I I '1 ' 1 ' ,,,_j I \ / C A , and when the latter is full the capillary tap is closed, and the apparatus is ready for use.When in use, the gas is admitted into the vessel A , displacing the reagent, which flows at first down the tube, d, and later through two sinall holes situated at the 'bottom of this tube, through which the gas bubbles up. Absorption begins at once, and is continued by closing the capillary tap leading to the burette and squeezing the rubber balloon sharply.This has the effect of projecting a spray of the reagent up the central tube, d, against the baffle-plate, f. Thtj liquid flows back again down the walls of the vessel, and in passing back into the chamber B, through the small holes at the bottom of the tube, d, it comes into intimate contact with the displaced gas. After repeating the operation a few times absorption is complete, as may be confirmed by means of graduations on the outer tube, k ; the gas is then returned to the burette. This type of absorption vessel may be fitted to Orsat's apparatus ; it has the advantage of holding double the quantity of reagent contained by the ordinary vessel ; the whole quantity of the reagent takes part in the absorption, and the danger of some of the liquid being driven over into the measuring-tube is minimised.J. F. B. Use of the Sense of Smell in Volumetric Estimations. J. F. Sacher. (Chem. Zeit., 1913, 37, 1222.)--Certain substances possessing a distinct odour, the neutral salts of which are odourless, may be titrated without the use of an indicator, the disappearance of the odour being taken as the end-point of the titration. The author has observed, however, that the appearance of an odour can be more readily detected than its disappearance, and the substance should therefore be treated with a slight excess of the neutralising reagent, and this excess titrated back again. Approxi- mately correct results may be obtained in the case of valerianic acid, acetic acid, andLAW REPORT 595 ammonia; but in many cases, especially that of the higher phenols, the hydrolytic action of atmospheric carbon dioxide renders the method useless. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800590

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

LAW REPORT 595 LAW REPORT. Demerara Sugar: Anderson v. Britcher. (High Court of Justice, King’s Bench Division, Divisional Court, November 12 ; before Mr. Justice Darling, Mr. Justice Avory, and Mr. Justice Atkin.)-This was a special case stated by a Metropolitan Police niagistrate sitting at Clerkenwell Police Court. blr. Barrington - Ward appeared for the appellant, and Mr. G. Elliott, K.C., and Mr.Guy Lushington appeared for the respondent. On July 23 last an information was laid by the appellant against the respondent under Section 6 of the Sale of Food and Drugs Act, 1875, for that on June 30 he unlawfully sold to the prejudice of the purchaser a certain article of food-to wit, 4‘ Demerara sugar,’’ which was not genuine Demerara sugar, but cane-sugar crystals coloured with an organic dye foreign to genuine Demerara sugar, so that the sugar was not of the nature, substance, and quality demanded.The magistrate dismissed the information. The following facts were proved or admitted : The respondent was a grocer carrying on business at King’s Cross Road. On June 30 the appellant called at the shop and asked the respondent for 1 pound of Demerara sugar, and received from him 1 pound of sugar, for which he paid 2+d.The appellant had it analysed, and the analysis showed that the sugar was cane-sugar crystals coloured with an organic dye foreign to genuine Demerara sugar. It was, in fact, a crystallised cane-sugar grown in Mauritius. Sugar grown in Demerara and in other West Indian Islands is a crystdlised cane-sugar.Originally it is white, but it is treated so as to become yellow. The colour has been varied from time to time to suit the taste of the public. The colour was formerly obtained by the action of chloride of tin, which converted portions of the sugar into caramel; but that process left traces of tin in the sugar, and a later process was treatment with a colouring matter known as (6 golden bloom,” which contains an organic dye.Large quantities of that colouring matter are exported from England for use in Demerara and the West Indian Islands. The sugar in this case was coloured by the modern process with an organic dye, the colouring matter being infinitesimal in amount and quite harmless. Before the magistrate evidence was given tbat the sugar was equal to the best grade of West Indian cane-sugar, and that the public expect under the designation of Demerara sugar a yellow crystallised cane-sugar without reference to its place of origin.The appellant admitted that the term ‘‘ Demerara sugar ” might be properly applied to similar sugar produced in Jamaica, and other West Indian Islands, but not else- where. No disclosure was made to the appellant at the time of purchase that the sugar, though sold as Demerara, was not in fact produced in Demerara or in the West Indian Islands.596 LAW REPORT The appellant contended that the name implied that the sugar had been produced in Demerara, and that as no disclosure had been made that it was not so produced, an offence had been committed. He contended also that the nature and quality of Demerara sugar depended on the peculiar climate and soil of the particular district, so that, though the description might be applied to sugar pro- duced in the West Indian Islands as well as in Demerara, it could not properly be applied to sugar produced elsewhere.For the respondent it was contended that the Act aimed at securing that the article purchased should be of the nature, substance, and quality demanded, and that the place of origin was immaterial.And it was further contended that “ Demerara sugar” had become a generic term, referring to a process of manu- facture, and not to a place of production; and the magistrate accepted these contentions. Mr. BARRLNGTON-WARD now pointed out that there was no question under the Merchandise Marks Act, and he had to show an offence under the Sale of Food and Drugs Act, 1875.The magistrate had so stated the case that he could not say the article was defective in either substance or quality, but he submitted that it was defective in nature. The point under the Act was not what the purchaser expected to receive, but what the seller was bound to supply. The true meaning of ‘‘ nature ” included a reference to place of origin.Mr. ELLIOTT pointed out that a, Bath bun or a Cambridge sausage was not an article produced only at Bath or at Cambridge. JUDGMENT. Mr. JUSTICE DARLING said that the appeal must fail. The magistrate had so stated the facts that argument was hopeless. Demerara sugar had become a con- ventional term, and this sugar was Demerara sugar in every single respect except that it was not grown in Demerara. Indeed, if a purchaser asking for Demerara.sugar were offered genuine sugar grown in Demerara in its natural state and colour, he would probably refuse it. No one supposed that a Brussels carpet was necessarily made in Brussels, and Demerara sugar might be so without being grown in Demerara. Mr. JUSTICE AVORY concurred, but said that he wished to guard against being taken to say that sugar grown anywhere might be called Demerara, merely because it was cane-sugar and coloured yellow. Mr. JUSTICE ATKIK concurred. Solicitors : Messrs. W. T. Ricketts and Son ; Messrs. Neve, Beck, and Kirby.- Times Financial Supplement, November 13, 1913.

ISSN:0003-2654    

DOI:10.1039/AN9133800595

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

REVIEWS 597 ALLEN’S COMMERCIAL ORGANIC ANALYSIS. By DAVIS and SADTLER. Vol. VII. In this volume the article on Vegetable Alkaloids has been written by G. Barger, Glucosides by E. F. Armstrong, Animal Bases by A. E. Taylor, Ptomaines or Putre- faction Bases by G. Barger, Animal Acids by J. A. Mandel, and Lactic Acid by W. A. Davis. Cyanogen and its Derivatives, by Herbert Philipp.-In the preparation of an article on the commercial analysis of any group of substances, the compiler has a far from easy task.Not only is he confronted by the usual difficulty of the selection of the most suitable methods from a very large number, but there is the further disadvantage that many of the methods in use are published in special journals which may not be readily available for reference, whilst others regularly in use for com- mercial analysis, and modifications of methods whereby increased rapidity and accu- racy are obtained, are frequently not published at all.After making every allowance for these obstacles, however, it must be confessed that the article on cyanogen and its derivatives in the new L g Allen ’’ is, in many respects, very disappointing.Of the 106 pages covered, over a third are taken up with a textbook description of the properties of a large number of cyanogen derivatives and references to their methods of manufacture. Whilst it is doubtless advantageous to mention the properties and methods of manufacture of the occurring commercial salts, so far as these have a bearing on the methods of analysis, it seems to be a waste of valuable space in a work such as this to describe derivatives not occurring in commerce, which information any analyst can look up equally well in the usual books of reference.Further, whilst the statements made as to properties are generally correct, a number of errors occur. Thus, for example, Conroy’s table of the solubility of sodium ferrocyanide is reproduced on p.506, but the decimal point has been mis- placed throughout, so that the solubilities given are only one-tenth of the correct figures. Again, it is stated that the ferrocyanides of magnesium and the alkali earths are “somewhat” soluble in water, which is only true of the barium salt, those of magnesium, calcium and strontium being exceedingly soluble in water, more so than those of the alkali metals.The paragraph on the constitution of the various LLPrussian blues” remains as in the last edition, no reference being made to the investigations made since then by I(. A. Hofmann and others. Where any inform- ation is given as to methods of manufacture, it is for the most part very un- satisfactory, as, except for one or two slight additions, such information remains the same as in the 1896 edition of Allen,” although during the past eighteen years the whole industry of the cyanide, ferrocyanide, and sulphocyanide manufacture has undergone a complete change.So far as analysis proper is concerned, the most satisfactory part of the article is that relating to the analysis of the simple cyanides, in which 8 good account is London : J.and A. Churchill, 1913. Price 21s. net.REVIEWS given of the methods of analysis of the commercial products for their cyanogen content and the commonly occurring impurities, and also for the analysis of cyanide solutions in gold works for the control of the extraction process, the methods for the latter purpose given by Clennel in ‘‘ The Cyanide Handbook ” being fully described.That part of the article dealing with the commercial analysis of ferrocyanides is most disappointing, and the same is true to a lesser extent in the case of the thio- cyanates, and here it cannot be said that the statement in the General Preface to the new edition is complied with. It is there stated that “obsolete methods are omitted; what little of the old text remains has been carefully revised.” I n fact, most of the methods mentioned in the 1896 edition of Allen, at a time when comparatively little had been done on the subject, are reproduced in the present edition, including some errors occurring in the former book.Some new methods have been added, which in many cases appear to have been copied from an abstract, and not from the original paper.A number of the methods given are quite obsolete, and others, though still in use, have been considerably modified to increase their speed and accuracy. I n the case of the Knublauch method for the estimation of ferrocyanide by titration with copper sulphate solution, which is largely used for commercial purposes, the author gives a full account of the precautions required so far as these were given by Knublauch in 1892, but makes no mention of the further precautions which later experience has also shown to be necessary.I n addition, although mention is made of the existence of carbonylferrocyanides, and a description of their properties is given, nothing is said as to their presence in the ferrocyanide products obtained from crude coal-gas, and of the influence which these have in analysing such products.So far, therefore, as the commercial analysis of ferrocyanides and thiocyanates is concerned, It must be concluded regretfully that the article is not likely to be of much use to analysts who are dealing with these products, and still less to those unacquainted with the special subject who are desirous of obtaining information on the matter.HAROLD G. COLMAN. Non-Glucosidal Bitter Principles, by G. C. Jones.-The name of Mr. G. C. Jones at the head of this section, a considerable part of which is concerned with the chemistry of hops, is a sufficient guarantee that it has been written with a dis- criminating and well-informed pen. The somewhat indefinite character of certain of the bitter principles in question and the voluminous and confused literature in which their properties are described make it a matter of great difficulty to distinguish between the true and the false, and between what is really useful to the analyst and what is, at best, of merely academic interest.To say that Nr. Jones has succeeded well is to pay him a high compliment. Since this volume was published, or perhaps while it was in the press, several papers dealing with the chemistry of hops have appeared, and consequently a few of the statements stand already in need of revision. The statement at t.he top of p.165, for example, could hardly be made with the same assurance since the publication of Professor A. J. Brown’s recent paper. Brown has shown (what others have long suspected) that the preservative properties of hops and the percentage of so-called “soft resin” do not stand in any direct proportionality, and that aREVIEWS 599 period of extraction quite insuficient for the solution or removal of the resins will suffice to extract the substance or substances on which the preservative properties of hops depend.Notwithstanding this, there can be no doubt that the estimation of the “ soft resins ” is of considerable importance, and that it still affords one of the best criteria of the brewing value of a sample of hops.The origin and nature of the y-resin is of considerable interest, but, as Mr. Jones points out, it is certainly not derived from the essential oil. Power has recently shown that the resinous constituents of hops include a considerable amount of fatty acids, and on this ground has cast a good deal of doubt on the accuracy of the results obtained by Lintner’s titration method.We must, however, suspend judgment on this point for the present, since there are still very many points in connection with the complex and elusive substances constituting the resins of hops which must be cleared up before the final word is spoken.With regard to the estimation of arsenic in hops, the reviewer’s experience has been that, as a rule, higher results are obtained when working directly on the hops than when the organic matter is destroyed by the ignition method described. With Mr. Jones’s conclusions as to the significance of arsenic in hops and what may be called the permissible ‘‘ advisory ” limit, the reviewer is in complete agreement. The detection of hop substitutes in beer is a matter of little or no practical importance, and, recognising this fact, Mr.Jones has wisely condensed this portion of the subject into a couple of pages, which is in reality more than sufficient. In conclusion, the reviewer is of opinion that this section of the seventh volume will prove a trustworthy guide to any analyst who, not being a specialist, is desirous of obtaining reliable information as to the analytical chemistry of the non-glucosidal bitter substances with which it deals. A.CHASTON CHAPMAN. THE APPLICATION OF PHYSICO-CHEMICAL THEORY. By R. KREMANN. Translated by The present volume is one of a series of monographs on the manufacturing methods of technical chemistry, and this fact bears witness to the increasing impor- tance of physico-chemical theory for the rational control of laboratory and factory processes.In the nature of things physical chemistry has been, and still is, very largely a theoretical branch of the science, but in its later developments it has co- ordinated in a, remarkable manner the empirical observstions of technology, and formulated definitely the conditions under which alone various technical operations can be successfully carried out. It is true that the majority of these processes to which physico-chemical theory has been thus applied had already been worked out empirically to a successful issue, but cases can now be quoted where the physical chemist has made a definite contribution to the solution of a technical problem.The synthesis of ammonia is a notable instance of this, but, curiously enough, it is not dis- cussed in the present volume. An introductory chapter on the two laws of thermodynamics is followed by con- sideration of reaction velocity and catalysis, the law of mass action, and the phase rule, various technical processes and problems being discussed at the appropriate H.E. POTTS. Constable and Go. 1913. Price 8s. 6d. net.600 REVIEWS place. I n this way the Deacon process, the drying of linseed oil, the vulcanisation of rubber, the sulphuric acid contact process, vitrification and devitrification, the setting and hardening of cement, the iron-carbon alloys, the reactions of the blast furnace, the manufacture of soap, the ammonia-soda process, the theory of dyeing, and other matt ere, are treated from the ph y sico-chemical st andpoint.The volume is thus a fairly comprehensive survey of the practical bearings of physical chemistry, and will be found highly suggestive by those who are already to some extent familiar with this branch of the subject. The author cannot be said to cater for beginners, and there is a lack of clearness sometimes, both in expression and in the arrangement of the material.The following definition of adsorption (p. 1’76) furnishes an instance where this fault may be found : “ Adsorption really signifies that when a colloidal precipitate is brought in contact with s solution, it takes up a certain part of it. The compound so produced is called an ‘ adsorption compound.’” Further, there might have been incorporated with advantage more of the actual ex- perimental data which show the applicability of general formuke to particular cases.From the standpoint of the average reader, such data contribute not a little to the interest and clearness of the treatment. J. C. PHILIP. LIQUID AIR, OXYGEN, NITROGEN.By GEORGES CLAUDE. Translated by HENRY E. P. COTTRELL. With a Preface by D’ARSONVAL. Pp. xxv+ 418. J. and A. Churchill. Price 18s. net. Until the appearance of this work, no very recent book had appeared in England dealing with the liquefaction of gases, and the commercial production of oxygen and nitrogen had been left almost untouched. Referring to the growing use of these elements, the translator remarks in his foreword that “ this reason, even if no other existed, would have afforded a sufficient inducement for providing a standard work on this subject in the English tongue, an acknowledged want which the present translation, it is hoped, will help to satisfy.” The reviewer has sometimes speculated as to the utility of translating foreign technical works ; in this particular case he is glad that the work has been done, for the book will now be necessnrily stocked in this country and thus be generally accessible, which was certainly not the case even a year after the appearance of the original French edition in 1909.Anyone desiring sn up-to-date exposition of the methods by which oxygen and nitrogen are usually prepared commercially would do well to consult either the original or the translation ; and if the reader has any sense of humour, he will forgive occasional irrelevances on account of the amusement he will get out of Claude’s descriptions of his own mistakes.Perhaps the third person used in the translation is not quite as attractive as the first person of the original, but the translator is to be heartily congratulated on the way in which he has rendered the sense and style of M.Claude’s French. The nineteen chapters of the book fall into four parts, dealing respectively with the Liquefaction of Gases, the Commercial Liquefaction of Air, the Preservation and Properties of Liquefied Air, and the Separation of the Air into its Elements. The first part deals with the scientific history of liquefaction from the time of Monge and Clouet to the helium cycle of Kammerlingh-Onnes.Not only is actualREVIEWS 601 liquefying apparatus dealt with, but vapour-tension of liquids, heat of vaporisation, the critical point, etc., are explained in an elementary manner. The second part, which is concerned with the commercial liquefaction of air, begins with a long chapter (IV.), in which the insufficiency of a multiple cycle process on a commercial scale is pointed out, and the reasons why cold is produced during gaseous expansion explained.The necessity of exchangers is dealt with, and the machines of Hampson and Linde described. Whilst these workers relied on the work done during the expansion of a gas against the attraction of the molecules for reduction in temperature, Claude’s ambition was to cool the gas by making it do external work which could be utilised in balancing some of the work done in compression.How success was eventually obtained is described .later in Chapter VII., probably the most interesting chapter in the book. One realises the difficulties of lubrication at low temperatures, and must admire the idea, of using petrol at the temperature of liquid air for purposes which at ordinary temperature usually require a cylinder oil.It is interesting to know that Claude succeeded in 1912 in doing away with lubrication by substituting stamped leathers for the metallic rings of the pistons ; apparently the leather receives some preparation before stamping. The preservation and properties of liquid air are dealt with in a decidedly popular manner in Part III., whilst Part IV.gives an account of the separation of oxygen and nitrogen from the air. As far back as 1892 Parkinson had the idea of separating the constituents by utilising their difference in vapour-pressure, and he had the sound idea of recuperating the cold produced when the liquids evaporated.Linde and Hampson patented the first successful processes; these and other methods based on fractional distillation are described. Recent advance has been more in the direction of fractional condensation, or rather in a combination of the two. The reason is not far to seek-the first drops of liquid which separate on con- densing air contain 47 per cent. of oxygen.The production of pure nitrogen by auto-progressive rectification was patented in 1903 almost simultaneously by R. Levy (who was drowned in the Titanic disaster) and Linde; the method has become of great importance with the introduction of the cyanamide industry. The paper and printing are admirable, and the French blocks which have been employed for the illustrations have come out excellently.The work is, however, defective in that, like the original, it contains no index ; this might well be added in another edition, and several misprints eliminated a t the same time. Misprints are not generally a serious matter, but become annoying when introduced into mathe- matics-e.g., the integral on p. 132. The book will doubtless be widely read and much appreciated.J. T. HEWITT. THEORIEN DER ORGANISCHEN CHEMIE VON DR. FERDINAND HENRICH. ZUGLEICH ZWEITE AUFLAGE PER NEUEREN THEORETISCHEN ANSCHAUUNGEN AUF DEM GEBIETE DER ORGANISCHEN CHEMIE. Braunschweig : F. Vieweg und Sohn. 1912. Pp. xiv + 401. 13 Abbildungep. Price 10 marks. This book, as indicated in the subsidiary title, is, under a new name, the second edition of the author’s well-known work on (‘ Recent Theories of Organic Chemistry.”602 REVIEWS The new title affords a better description of the scope of the work than did the old, since in both editions the discussion of the latest theories is introduced by a carefully wriften historical review of the early development of theoretical organic chemistry.In the fourteen chapters devoted to the more recent theories the author’s endeavour has been to discuss as many as possible of these, with the result that some degree of inequality of treatment has crept in, less than justice being done to some highly interesting subjeots. However, difficulties of selection always ‘abound in the treat- ment of a literature so voluminous ILEI that of theoretical organic chemistry, and .on the whole a fair picture of the modern position is presented. The author cannot, however, be acquitted of ‘( insularity ” of treatment, and has in many cases confined himself*much too exclusively to the literature of his own country. What is to be thbught of an account of colour and constitution without mention of Armstrong, of fluorescence and constitution without the name of Hewitt, and of discussions on tautomerism, the Walden inversion, and the relations of optical rotation and oonsti- tution, with no reference to the work of Lowry, McKeneie and Frankland, and Patterson respectively ? The author has the gift of lucid expositioa, and possesses a lively and trenchant style which greatly adds to the pleasure af the reader. A. HARDEN.

ISSN:0003-2654    

DOI:10.1039/AN9133800597

出版商:RSC    

年代:1913

数据来源: RSC