摘要:

AUGUST, 1909. Vol. XXXIV., No. 401. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. NOTE ON A PROPOSED TEST FOR HALOGENS.* BY G. B. NEAVE, M.A., D.Sc. (Rend at the Meeting, June 9, 1909.) IK the estimation of nitrogen in triazo compounds by shaking with mercury and concentrated sulphuric acid, with alcohol as the solvent (H. D. Richmond, ANALYST, 1908, 33, ISO), it was noticed that when halogen was present, a precipitate of mer- curous halide was formed. The following are the results of some experiments made to determine whether this reaction is general, and also if it could be used for the estimation of halogens. The method of procedure was to dissolve the substance in the smallest possible quantity of alcohol, and shake the solution with some mercury and a little concen- trated sulphuric acid in a small stoppered bottle.About forty substances have been examined, but only in‘the case of some iodine compounds was the precipitate large. With all the other substances the precipitate was very slight, in some cases amount- ing to little more than a dimmiDg of the surface of the mercury. The influence of the quantity of sulphuric acid present seemed to be small. IODINE CoJIPouNDS.-~vith methyl, ethyl, propyl, and methylene iodides, a good precipitate was produced ; but with iodoform and iodobenzene the precipitate was very slight. BROAIINE Com?ouNDs.-These included ethyl bromide, ethylene dibromide, bromoform, acetylene tetrabromide, bromethylene bromide, tribromacetic acid, monobrombenzene, p-dibrornbenzene, 21-bromtoluene, nz-brombenzoic acid, dibrom- anthracene, and bromtriphenylmethane. In all cases only a slight precipitate was formed. CHLORINE COMPOUNDS.---AS in the case of bromine compounds, so with chlorine compounds, only a very slight precipitate appeared. Among the substances examined were chloroform, carbon tetrachloride, chloral, ethylidene chloride, acetyl chloride, * This work was carried out in accordance with the terms of the “ Analytical Chemistry Investigation Scheme.”346 THE ANALYST. benzoyl chloride, the three chloracetic acids, benzyl chloride, benzal chloride, benzo- trichloride, p-chloronitrobenzene, dichlorphthalic acid, dichloranthracene. The conclusion drawn from the experiments is that the proposed test answers fairly well qualitatively, but that it would not be suitable for the quantitative determination of halogens. DEPARTMENT OF CHENISTRY, TECHNICAL COLLEGE, GLASGOW.

ISSN:0003-2654    

DOI:10.1039/AN9093400345

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年代:1909

数据来源: RSC

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346 THE ANALYST. THE SABATIER-SENDERENS TEST FOR DISTINGUISHING BETWEEN PRIMARY, SECONDARY, AND TERTIARY ALCOHOLS.* BY G. B. NEAVE, M.A., D.Sc. (Bead at the Meeting, June 9, 1909.) SABATIER and Senderens (Bzdl. Xoc. Clzim., 1905 [iii.], 33, 263) propose to distinguish between primary, secondary, and tertiary alcohols by making use of the catalytic action of finely divided copper at 300’ C. on the vapour of the alcohol. Primary alcohols are decomposed into hydrogen and aldehydes, secondary alcohols into hydrogen and ketones, and tertiary alcohols into water and unsaturated hydro- carbons. The apparatus employed consists of a hard glass tube about 28 inches long and 8 inch in diameter, containing a layer of finely divided copper 24 inches long. The copper is prepared from powdered copper oxide by reduction in a current of dry hydrogen at 300” C.To one end of the hard glass tube is attached a bent capillary, to the vertical part of which is fixed by means of a cork a piece of glass tubing about 3 inches long and 4 inch in diameter. The other end of the hard glass tube is connected with a receiver, which is cooled by a mixture of ice and salt. A space of 4 or 5 inches next the capillary is kept free from copper, so that the alcohol may be vaporised before coming into contact with the finely divided metal. To regulate the temperature it has been found convenient to use a cylindrical air-bath about 26 inches in length, with two small holes on the top, about 12 inches apart, carrying two thermometers. For the heating of this air-bath three Ramsay burners were used.When the tube has attained a temperature of 300” C., 2 or 3 C.C. of the alcohol to be examined are poured into the short wide tube connected to the capillary, through which the liquid slowly flows into the heated tube and is vaporised. The vapour, which contains some unaltered alcohol, condenses in the cooled receiver. To a, few drops of this distillate a solution of magenta, decolorised by sulphur dioxide, is added, when a red coloration indicates the presence of an aldehyde. If no red colour appears, a solution, containing 1 gram of semi-carbazide hydrochloride and 1 gram * This work was carried out in accordance with the terms of the “Analytical Chemistry Investigation Scheme.”THE ANALYST. 347 of potassium acetate to 6 C.C.of water, is added to a second sample. A white precipitate formed immediately, or only after some time, shows the presence of a ketone. Finally, an unsaturated hydrocarbon can be detected by its power cjf decolorising bromine. The following thirty alcohols, which were obtained from Kahlbaum, unless other- wise stated, have been examined, and have all answered the test. Before passing them over the heated copper, they were shown to be free from aldehyde and ketone. PRIMARY hcoHoLs.-*Methyl alcohol .- I n this case the vapours from the heated tube were passed directly into the solution of magenta decolorised by sulphur dioxide. *Ethyl alcohol: The sample was practically absolute, having been distilled over caustic potash and lime, and then several times over metallic calcium (L.W. Winkler, Ber., 1905, 38, 3, 3613). Sabatier and Senderens (Comp. Bend., 1903, 136, 738 and 921) recommend their method for the preparation of acetaldehyde. I t has been found that a yield of about 50 per cent. of aldehyde can be obtained. "Propyl alcohol : This method can be used with advantage for the preparation of the aldehyde.-*But$ alcohol -*Isobutyl alcohol -*Amy1 alcohol-Active amyl alcohol-Heptyl alcohol-Octyl alcohol-Cetyl alcohol : I n this case the alcohol was contained in a porcelain boat and placed in the hard glass tube, which was then closed with a cork at the end formerly connected to tho capillary.--::~Allyl alcolzol- Glycol--':'Be?zxyl alcohol. SECONDARY ALCOHOLS.-:;'~SO~YO~~~ alcohol .- The product gave no indication of aldehyde, but a precipitate was at ouce formed on the addition of the semi-carbazide solution.- Seconclury butyl alcohol (methylethyl carbino1)-Secondary amyl alcohol (methylpropyl carbinol).-Secoizdary anzyl alcohol (diethyl carbinol) : This was pre- pared according to the method of Grignard (Comp.Rend., 1901, 132, 337) from ethyl magnesium bromide and ethyl formate, and boiled at 118" C. The boiling-point, quoted in Beilstein's '' Handbuch der Organischen Chemie," vol. i., p. 232, is 116.5" C. at 753.2 mm.-Secoizdary hexyl alcohol (ethylpropyl carbinol) : This alcohol was prepared from propyl magnesium iodide and propylic aldehyde, the latter of which was obtained from propyl alcohol by the Sabatier-Senderens method. The boiling- point of the ethylpropyl carbinol was 130' to 135' C.; that quoted in Beilstein, vol. i., p. 234, being 135' C.-Secondary heptyl alcohol (dipropyl carbinol) : This was obtained from the action of propyl magnesium iodide on ethyl formate, and boiled at 153" C. Secondary heptyl alcohol (di-isopropyl carbinol) : Prepared from isopropyl mag- nesium iodide and ethyl formate (boiling-point, 140" to 143" C.). Poletaeff (Ber., 1891,24,1309) records that this compound boils at 140" C.--':'Secondary octyl alcohol -.ilZethylpheizyl ccwbinol : Prepared from phenyl magnesium bromide and acetalde- hyde (boiling-point, 202'). Beilstein, vol. ii., p. 1063, records a boiling-point of 202" to 204O c. TERTIARY ALcoHoLs.-*Tertiary butyl alcohol (trimethyl carbinol) : The product, which was gaseous, was passed through a little bromine water, which was im- mediately deco1orised.-*Tertiary aiizyl alcohol (djmethylethyl carbino1)--"Tertiary hexyl alcohol (methyldiethyl carbinol) : This was prepared from ethyl magnesium The boiling-point given in Beilstein, vol.i., p. 236, is 153' to 154' C.348 THE ANALYSTn bromide and ethyl acetate (boiling-point, 121O C.). Beilstein, vol. i., p. 235, gives the boiling-point 123" C.- Teytiary lzexyl alcohol (dimethylpropyl carbinol) : This was prepared from propyl magnesium iodide and acetone (boiling-point, 123' C.). Jawein (Annaleiz, 195, 254) gives boiling-point 122.5' t o 123.5" C. at 762 mm. (Beilstein, vol. i., p. 235).--:::Tertiury hexyl alcohol (dimethylisopropyl carbinol) : This was obtained from isopropyl magnesium iodide and acetone (boiling-point 110" to 120" C.). Boiling-point quoted by Beilstein, vol. i., p. 236, is 117O C. at 744 mm.-Tehary heptyl alcohol (methylethylpropyl carbinol) : This was prepared from propyl mag- nesium iodide and methylethyl ketone (boiling-point 140" C.), Boiling-point quoted by Beilstein, vol. i., p. 236, is 140.3" C.-Twtiary heptyZ nlcohol (methylethylisopropyl carbinol) : This was prepared from isopropyl magnesium iodide and methylethyl ketone.--Te?*tiary octyl uZcohoZ (methyl dipropyl carbinol) : From propyl magnesium iodide and ethyl acetate. [The alcohols marked with an asterisk were examined by Sabatier and Senderens.] DEPARTMEW O F CHEhf ISTRY, TECHXIGAL COLLEGE, GLASGOW.

ISSN:0003-2654    

DOI:10.1039/AN9093400346

出版商:RSC    

年代:1909

数据来源: RSC

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348 THE ANALYSTn EmLwuar.-Pnge 302, lines 22 and 23, f07- “eight to nine minutes,” etc., 7 w u Z “one to two minutes being allowed from the ten minutes for cooling und-er the tap.”

ISSN:0003-2654    

DOI:10.1039/AN909340348b

出版商:RSC    

年代:1909

数据来源: RSC

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THE ANALYST. 349 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Influence of Clarification with Basic Lead Acetate Solution on the Valuation of Sugar Products, and the Relation between the Amount of Lead Added and that Precipitated. L. Eynon. (Paper comnzuTzicnted to the Ssveizth Internatioizal Congress of Applied Chemistry.)-Experiments have been made to determine the influence of increasing quantities of basic lead acetate solution, of known lead-content, on (a) the direct polarisation, ( b ) the sucrose-content determined by Clerget's method, and (c) the reducing sugar-content, of samples of jaggery sugar and Cuban molasses. The lead-contents of the clarified solutions were also determined, the weights and percentages of lead precipitated being calculated therefrom .Jaggery Szqar.-52*00 grms. of the sugar were dissolved in water, treated with a known volume of basic lead acetate solution (containing 210.36 grms. of lead per litre), and 1 C.C. of alumina cream, the whole being made up to 200 C.C. and filtered; the filtrate was used for the above-mentioned determinations. Sixteen such experi- ments were made, the quantities of lead solution added ranging from 2 to 50 C.C. (8 C.C. were sufficient for ordinary analysis). It was found that with increasing quantities of the lead solution, the direct polarisation increased, the inversion polarisation decreased-ie., became less IBvo-rotatory-and the reducing sugar- content decreased. The figures for the sucrose-content showed an increase, but this was small in comparison with the other variations.The following table, giving details of some of the experiments, illustrates these results : Volume of Lead Solution added. Direct Polarisat ion. c. c. 6 8 26 50 73.2" 73.4" 74.0" 75.1" Sucrose per Cent. (Clerge t). 76.0 76.1 76.3 76.5 Weight of Lead in Precipitation from 52 Grms. of Sample. Grms. 1.1542 1.4570 3,2978 4.7364 Percentage of Lead precipitated. Reducing Sugar per Cent.* 91 87 60 45 9.7 9.6 9.1 8 *5 These results are in harmony with Prinsen-Geerligs' statement that levulose is partially precipitated (and also dextrose, but to a, much less extent) with the non- sugar by basic lead acetate. Special experiments showed that, of the increase in the * The percentage of reducing sugar as found from the nnclarified solution was 10'2,350 THE ANALYST.P~~~~ precipitated. value for sucrose-0-5"-about 0-1" to 0.2" was due to the influence of the lead left in solution on the rotation of the sucrose. Further experiment showed that the remaining increase of 0.3" to 0.4" was not due to optical alteration of the non-sugar during inversion, and it appears, therefore, that this increase was due to the i n e r e a d volume of the lead precipitate. The weight of lead is an approximate measure of the weight of the precipitate containing it. The table shows that the amount of precipitate obtained with 6 to 8 C.C. of lead solution was comparatively small, and that the precipitate obtained with, say, 8 C.C. of lead solution (the amount required for clarification in an ordinary analysis) could not cause an error of more than 0.1" to 0.2".Cuban Mo1?asses.-26-00 grms. of sugar were weighed out in each experiment, the clarified solution being made up to 200 C.C. Eleven experiments were made ; the following table gives the details of two : Reducing Sugar per Cent'* Volume of Lead Solution added, c. c. 15 60 Direct Polarisation x 2. 32.3' 35.9" 75 45 Sucrose per Cent. (Clerget). 12.5 10-5 39.25 40.00 Weight of Lead in Precipitation from 26 Grms. of Sample. Grms. 2.3746 5.7300 The Analysis of Cane Molasses. A. R. Ling and G. MacLaren. (Paper communicated to the Seventh International Congress of Applied Claenzistry.) - The authors consider that the work by L. Eynon (see preceding abstract) as to the effect of basic lead acetate defecation on sucrose estimation adds to the reliance to be placed upon the Clerget method, rendering it a valuable method of control when used in con junction with the volumetric estimation described by Ling and Rendle (ANALYST, 1905, 30, 182).The maximum difference between them would appear to be about 3 per cent., the former method usually affording the higher result, due to the volume occupied by the lead precipitate. A number of comparative determinations are given, of which the following are a few : Sucrose (Copper). Per Cent. 40.2 34.8 28.7 35.3 65.6i Sucrose (Clerget). Per Cent. 40.6 34.8 27-8 34.9 66.0 Iiivert Sugar. Per Cent. 17-9 17.1 11.7 15.3 7.2 H. F. E. H. * The percentage of reducing sugar as found from the uiiclarified solution mas 13'9. .t. A sample of so-called cane-syrup.THE ANALYST.351 0'9992 1'0034 1.9994 3'0003 4.0176 4.9977 5'9990 7.0012 7-9990 9'0015 9.9864 11-0002 11.9125 Solution Densities of Dextrose, Lmulose, and Maltose. A. R. Ling, L. Eynon, and J. H. Lane, (Pajier communicated to t7~e Seventh International Congress of AppZied C7~eiizisty.)-The authors have prepared the three sugars above named in a state of high purity, the criterion of the latter being constancy of specific rotatory power under standard conditions of temperature and concentration. The following values were obtained with the final products, expressed in each case on the anhydrous sugars : Dextrose [.ID 170 = + 52.72" (c = lo), laevulose [ u ] ~ lS'5O = - 93-83' (c=lO), maltose [ u ] ~ 17'50= +137.79" (c=5*7). The sp. grs. of solutions of these pre- parations, varying in concentrations from c = 1 to c = 24, have been determined in duplicats.The results practically confirm those of Brown, Morris, and Millar (J. Chem. SOC., 1897, 71, 77, 276), and the excuse for publishing them rests mainly on the fact that the purity of the various sugars employed is beyond all ques- tion, and that a considerably larger number of determinations have been made. Brown and Morris (loc. cit.) co-ordinated the sp. grs. of the sugar solutions and the corresponding solution densities. I n this way they expressed their results in the form of a curve. The authors point out that, although the actual law may be a curve for all practical purposes, the results may be represented graphically by a, straight line. I n the following tables containing the mean results- Column A gives the weight of dry substance taken.Column B gives the total Column C gives the sp. gr. of the solution at 1 5 5 O C., referred to Column D gives the grms. of sugar per 100 reputed Column E gives the divisor for the calculation of grms. weight of solution. water at the same temperature. C.C. (fluid grms. at 15.5" C.). of sugar per 100 reputed C.C. from the sp. gr. 48.7130 1007'97 2.0655 3.855 48.1702 1008'08 2.0999 3.845 50'4500 1015'45 4'0243 3.839 51'4025 1023.90 5.9705 3.836 51'5618 1030'72 8'0311 3.845 51.8332 1038.26 10'0105 3.822 52.5148 1045'61 11.9444 3'819 52.6845 1053'38 13-9984 3.813 52.8802 1061.13 16'0513 3.808 53.3225 1068.63 18.0398 3.804 53.6794 1076.03 20.0182 3.595 53.8410 1084.06 22.1483 3'795 53.3030 1092.42 24.4141 3'786 DEXTROSE.1'1040 2.0121 3'0125 4.0528 3.9982 5.9136 6'9985 8'2876 3.9952 -0.0312 -1.0257 .1*6614 I I I I t 51.2864 100855 2.1710 3'938 50'9296 1015'76 4.0130 3.927 51'3828 1023'54 6*0008 3'923 52.7696 1031.05 7'9186 3'921 515144 1031.36 8'0047 3.918 5.002051*9565 1039'18 109044 3.916 52.7690 1048'83 11'7202 3.910 52.6476 1054.73 14'0207 3'904 54.7342 1062.78 16'0922 3.901 53.2702 1070'43 18.0753 3.896 54.0705 1057'50 19.9949 3.890 54.3534 108557 22.0211 3'886 52.9094 1093'55 24'1021 3.881 A. I B. I C . I D. I E. I 0'9422 1.9977 3'1074 3'8939 5'0569 5'9907 7.0032 7'9710 8'0323 8.9098 8.9132 0'0734 0.9333 1.7828 50'1806 1007'46 1.8916 3'944 50.9160 1015'66 3.9550 3'930 51.3990 1024'31 6'1926 3.926 51.4710 1030'54 7.7963 3'917 52.2945 1039'34 10'0504 3.914 53.6860 1045.63 11.6680 3.911 52'8330 1054'63 13'9795 3.908 53.4580 1061'78 15'8319 3.903 52.9998 1062'87 16*10813*903 53.2972 1069.84 17.8547 3'905 53.2600 1069'91 17'9052 3'904 53-7766 1078.76 20.2073 3'898 53.5393 1086'47 22.1869 3.897 542558 1092-35 23.7227 3'893 I I I I L LZVULOSE.*RODE I I I I L MALTOSE. A, I B. I C. I D. I E. I I I I Detection of Artificial Honey by Fiehe's and Ley's Reactions. W. Bremer and F. Sponnagel. (Zcit. Uiztersuch. Nahr. Genusm., 1909, 17, 664-667. j -The test described by Fiehe (AKALYST, 1908, 33, 397) for distinguishing between artificial honey (invert sugar) and natural honey was found to be untrustworthy. I n some cases the reaction was given by pure honey, whilst artificial honeys did not352 THE ANALYST.yield a coloration. Ley’s test (ANALYST, 1907, 32, 291) yielded better results, but was not infallible. X test described by Jagerschmid, and similar to the reaction described by him for the detection of caramel in wine (ANALYST, 1909, 215), when applied to natural honeys, gave an amber-yellow coloration in every case. A violet- red coloration was obtained with honey containing invert sugar. w, P. s. Schardinger’s Methylene Blue Test for Milk. K. Schern. (Biochem. Zeit., 1909, 18, 261-284.) - The author has investigated the test described by Schardinger (ANALYST, 1903, 28, 32) far ascertaining the freshness of milk, and finds that whilst fresh milk yielded by cows at the end of their lactation period decolorises methylene blue, as stated by Schardinger, milk from cows at the commencement of their lactation period frequently fails to give the reaction.I t was observed that the former class of milks had a greator action on the methylene blue at temperatures between 65” and 70” C., and the latter class at about 4 5 O C. Should a sample of milk fail to decolorise the methylene blue at either of these temperatures, all that can be said, therefore, is that the enzyme to which the reaction is due is not present in an active state in the sample. (See also ANALYST, 1906, 31, 299.) w. P. s. Adulteration of Mustard. G. Curtel. ( A m . des FaZsz$icntioizs, 1909, 2, 215-220.)-1t was decided at ihe Geneva Congress that only the seeds of Brassica nigra, B. juncea, and Simpis alba should be used in the manufacture of mustard, whilst an association of manufacturers agreed in 1907 that Dijon mustard should be prepared solely from the seeds of B.izigra. The authors have examined various ‘‘ mustard” seeds offered to the manufacturers, and found them to contain the following amounts of essential oil: B. nzgra, 0.9 to 1.3; B. juizcea (Indian and Russian), 0.85 ; Sirzapis gZaucn (Indian yellow colza), 0.62 ; Sinupis dichotoma (Indian brown colza), 0.38 ; B. rapa, 0.54; B. napus, 0.23 ; Sinupis c~rve~zsis, 0-11 ; and Evuca sativu, 0.56 per cent. Dijon mustard is prepared by mixing the crushed seeds with aromatic and salted vinegar and acetic acid, or with white wine and dilute vinegar, or with the juice of unripe grapes, and passing the product through a sieve. The following results were obtained in the analysis of three commercial samples : Total solids (dried at 100’ C.) ... Tartaric acid (total) ...... ... ... Fat ... ... ... ... Acetic acid ... ... ... ... Sodium chloride ... ... ... ... Ash ... ... ... ... ... Mustard oil ... ... ... ... A. Per Cent. 34.04 10.52 1.12 0.84 8.66 10.45 0-35 B. Per Cent. 34.0 14.23 0.85 1-06 8.14 10-39 0.36 C . Per Cent. 25.50 11.50 0.16 0.69 5-52 7.76 0.40THE ANALYST+ 353 The proportion of acetic acid in eight other samples of first and second quality ranged from 0.156 to 1.548 per cent. The mustard oil in these same samples varied from 0.24 to 0.43 per cent. Prior to the law of 1905 the addition of starch was frequent, but is now more rare, and usually does not exceed 5 per cent. in amount. Even the purest mustards frequently contain starch derived from unripe seeds, but the granules are easily distinguished from the rice or maize starch used for adulteration.The genuine seeds of B. nigm, as sold, seldom contain more than 0.3 per cent. of starch, but the proportion may ibe greater in certain cheap kinds of seeds. Among substances used at the present time for the adulteration of mustard, mention may be made of mustard-seed oil-cake of Russian and American origin (chiefly from S. alba and B. juncea), and of Indian colza-seed oil-cake, which may still contain up to 0.6 per cent. of essential oil. A wheat paste (pd@e d e bZ.4) is also sold by a Marseilles firm for use in the manufac- ture of mustard. G. A. M. As a rule it is less than 0.8 per cent. On the Analysis of Flours, with Reference to their Baking Properties.T. Kosutany. (Paper comnzzinicated to the Seventh International Coitgi-ess of Applied Chemistry.)-Bakers require a, flour which will absorb a large proportion of water in order to form a dough of the correct consistency to retain the carbonic acid gas produced by the yeast. Both water-absorbing capacity and power of retaining gas, in the author’s opinion, depend mainly on the gluten present and chiefly on the gliadin component. H e recommends the determination of the gluten by washing out, and of the gliadin by extracting the flour with 70 per cent. alcohol, evaporating, .and weighing the residue. For practical determinations of the water-absorbing capacity, it is suggested -that a dough has the correct consistency when a ball of it 3.5 cm.in diameter, made up to 100 grms. with small shot, undergoes an increase in diameter of 30 to 32 mm. in twelve to fifteen seconds, when allowed to spread on a level surface. Better results may be obtained by the perforation apparatus made by Rejto. H. F. E. H. The Relationship of Composition to Bread-making Value of Flours. F. T. Shutt. (Paper co?mzzuzicatecl to the Seventh Internatioizal Congress of Applied Clze~nistry.)-Six series of flours (eighty-one samples) were examined during the last four years. In the earlier series the usual cereal determinations were made, with special attention to the nitrogen compounds. I n the later series the theories of T. B. Wood (ANALYST, 190‘7, 32, 119, 293) have received consideration, The &‘ strength ” factors comprised water added, water retained, volume of loaf, shape of loaf, form of crust and texture. The following conclusions were drawn : (1) There is a relationship, but not a definit,e ratio, traceable between the nitrogen compounds and ‘‘ baking strength.” ( 9 ) Although the best single measure of strength for normally ripened wheats is the protein content, yet gluten chamcter is important, especially when dis- criminating between members of a series containing wheats of different varieties, immature, or frosted samples.(3) The “gliadin ratio” is erratic and of little diagnostic value ; but inore importanh is the percentage of gliadin which appears to354 THE ANALYST. be correlated vrith maturity of grain, and is highest in the best matured samples.(4) The sugar content of the flour shows no relationship to the volume of loaf. (5) The nitrogen and ash-free extract, as a rule, varies inversely as the volume of the loaf. H. F. E. H. Gas-making Capacity as a Factor in the Estimation of Strength in Wheaten Flour. A. E. Humphries and A. G. Simpson. (Paper communicated to the Seventh International Congress of Applied Chemistry.)-The principal point brought out by the authors is that, since a very large proportion of the gas evolved during fermentation is lost, the total quantity of gas evolved is not the important factor, the factors really influencing the results being the gas evolved in the latest stages of fermentation and the gas-retaining power of the dough. H. F. E. HI. The Changes produeed in Flour by Age.F. Marion. (Pajler communicated t o the Seventh Intemational Congress of Applied Chemistry.)-The author has studied five high-grade flours which had been kept in his laboratory for two years. I n some samples a rancid taste was perceptible after one year, due to the alteration of the fatty matter. The flours were analysed every month, their moisture, gluten a i d its constituents, fatty matter, and acidity determined, and the results referred back to the dry flour. Curves for the mean of these analyses are given. The gluten is practically constant for the first five months, and varies little till the nineteenth, after which decomposition is very marked. The gliadii curve shows a maximum in three months, followed by a minimum in seven; a second maximum is reached in fifteen months, and a second minimum in eighteen months, a point at; which it subsequently remains-thus, maxima and minima appear to reoccur at intervals of- twelve months.The maximum at three months corresponds to an age at which, inl practical bread-making, the flour is considered to be at its best, and the minimum at seven months to the time after which, in practice, flour is not considered suitable for this purpose. The acidity curve increases for a year and then steadily declines. The activity of the ferments of the flour appears to cease after a year, and to be checked by an alkaline substance resulting from the ammoniacal decomposition of the gluten. H. F. E. H. On the Composition of the Ash of Wheats and Flours. L. M. Vuaflart. (Papel’ coiimmicc~ted to the Seventh Internatioiaal Congress of Applied Chenaistry.)- Variations in the phosphoric acid and nitrogen contents of wheats follow each other more closely than has yet been admitted.The usual estimation of phosphoric acid n the ash gives inesact and variable results, and better results are obtainable in the wet way. Figures are given for sixteen different wheats, calculated on a basis of 15 per cent. of moisture, and may be summarised as follows : Phosphoric Acid per Yotassiuin per 100 Parts of N. 100 Parts of N. Minimum ... ... ... 49.8 ... ... 26.7 Maximum ... ... ... 59.8 ... ... 37.5 Mean ... ... ... ... 54.6 ... ... 33.8THE ANALYST. 355 It is evident that the ratio of phosphoric acid to nitrogen is fairly constant, and The ratio of The author then gives analogous analytical figures for the flours from these amounts to rather more than 50 per cent.of the nitrogen figure. potassium to nitrogen is less constant ; the average proportion is as 1 : 3. wheats : Phosphoric Acid per Potassium per 100 Parts of N. 100 Parts of N. Minimum ... ... ... 1-4.1 ... ... 10.4 Maximum ... ... ... 18.1 ... ... 14.3 Mean ... ... ... ... 15.3 ... ... 12.9 Although flour contains much less P,O, than the whole wheat, the new ratio of 15 : 100 of nitrogen is constant for the samples examined. The ratio between potassium and nitrogen is also uniform. I t is noticeable that relatively much more P,O, than potassium is removed in the bran. The distribution of phosphorus was studied in the flour from a 1908 Saumur wheat. The starch was separated from the washingfi and dried at 25’ C.The phosphorus was determined in the wet way in the starch, the washing water, the gluten, and in the extract obtained by extracting the gluten with ether and then absolute alcohol. In 100 parts of total phosphorus there were found : The gluten from 150 grams was extracted and dried iiz vacuo. 2.4 parts in the ether-alcohol extract. 13.8 ,, gluten. 66.0 ,, st arch. 17.8 ,, washing water. H. F. E. H. On Laboratory Methods for the Estimation of the Milling and Baking Properties of Wheats from Various Sources. P. Holdefleiss. (Paper conz- muizicated to the Seventh Iizterizatioiaal Congress of Appliecl Clzeinistry.)-Af ter a consideration of the causes of the variability of wheats as regards the flavour and nutritive value of their milling and baking products, the author asserts that the market prices of different kinds of wheat are very unreliable as an indication of such value.A true determination can only be made by using chemical and physical tests. The recent advances in protein analysis are of great value, but practical methods of testing the milling and baking properties have not proved so successful. He suggests that standard methods be adopted, based on the results obtained by R. Vessling.* These results showed that milling behaviour, adaptations of grinding, and the effect of damping, can be studied in a small mill (made by Seck, Dresden). Baking experiments can be carried out in the small ovens supplied by Christ of Berlin. The loaves are best judged when baked without supports, and a comparison of the behaviour of doughs made with milk with those made with water is of value.Good pressed yeast, at the rate of 2 grms. to 50 grms. of flour, should be used. The volume of the loaf obtained is best est.imated by the method of Reisch, and note * “ Ein Laborat,oriuinversuch niit verschiedenen Weizensorten zur Ergriindung ihres Mahl- und Backwertes.” 1iiau:runal-Dissert~tioii von K. TVessling. Halle a/S. 1906.356 THE ANALYST. should be made of its form, together with the colour and appearance of the crumb. Tables are appended showing the results obtained with various wheats. H. F. E. H. The Presence of Fluorine in Wine. L. Vandam. (dizn. des FaZs@catio?zs, 1909, 2, 160-169.)-From the results of experiments upon 192 samples of wine of different origin, the author concludes, contrary to the assertions of certain chemists, that fluorine is not invariably present as a natural constituent of wine, but that its presence is confined to the wines from certain localities. A large proportion of the samples examined contained no trace of fluorine. This confirms the experience of Leperre (BzdZ.SOC. Chinz. BeZg., 1909, 23,29), who found that the amount of fluorine in the ash of grapes from Malaga and Asia Minor was infinitesimal, and in some cases nil. The statement of Blarez (1908), that wines contain 1 to 2 (and up to 10) mgms. of fluorine per litre, is therefore called in question ; and it is suggested that treatment of the vines with fluoride washes may have had something to do with these high proportions. To detect an addition of fluorine, reliance may be placed upon the method in which glass is etched by the liberated hydrofluoric acid, provided that 100 C.C. of the wine be used for the test. Attempts to make this method quantitative, as proposed by Blarez and by Uaurel, have been found by the author to yield results far too high. C. A. M. Reaction of Saccharin in Beer, etc. J. Wauters. (Paper conzmunicated to the Seventh Interizutioizal Congress of Applied C7zemisti-y.)-When saccharin is heated with sulphuric acid and diresorcinol, it yields a product which, when treated with water and filtered, gives an intensely violet liquid. Purification of the residue left by the ethereal extract of beer, wine, etc., by means of potassium permanganate, yields a product which is sufficiently pure, after extraction with ether, to give this reaction.

ISSN:0003-2654    

DOI:10.1039/AN9093400349

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

356 THE ANALYST. BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. The Absence of Purin Bases in Caviare. K. Linnert. (Biocheriz. Zeit., 1909, 18, 209-210.)-The question whether purin bases are present in caviare being of some interest and of practical importance to certain invalids who partake of this food, the author has examined samples of caviare with the object of ascertaining the absence or presence of these bases. He finds that it is free from purin bases, and therefore from actual nucleic acid. The method employed consisted in boiling 50 grams of the caviare with 500 C.C. of 0.5 per cent. sulphuric acid for twelve hours, filtering the solution, and removing the sulphuric acid as barium sulphate. The solution was then evaporated, the excess of barium was removed by the addition of a mixture of sodium hydroxide and carbonate, and, after the addition of hydrochloric acid, the solution was rendered strongly ammoniacal, and treated with an ammoniacal silver solution.No trace of precipitate (silver-purin compound) was obtained. w. P. s.THE ANALYST 357 Chemical Control of Disinfectants. M. W. Blyth. (Paper ~oiitnzuizicated to the Seventh Intematioizal Conggl-css of Applied Chemistry ; through J. SOC. Chent. Ind., 1909, 28, 742.)-The author shows that the Rideal-Walker test may give entirely different results when carried out by diflerent observers ; moreover, the action of disinfectants on organisms contained in faeces may be quite different from their action on naked organisms. Chemical examination of the disinfectant must therefore always be coupled with the bacteriological tests.Analysis is rendered difficult when emulsifying agents are present. The author recommends acetone as a de-emulsifying agent. For disinfectants containing soaps the procedure is as follows : To 200 C.C. of disinfectant 200 C.C. of pure acetone and 200 C.C. of petroleum ether (boiling below 70' C.) are added; the mixture is extracted with 200 C.C. of water, and then with 200 C.C. at a time of a mixture of equal parts of acetone and water, until the aqueous extracts measure 800 to 900 C.C. The washings are then extracted with 100 C.C. of petroleum ether, which is added to the main petroleum ether solution. The aqueous extract is next made up to 1,000 c.c., of which portions are taken for the determinations of emulsifying agent-i.e., free and combined alkali, resin, fatty acid, etc.A portion may be steam-distilled to see whether tar acids or hydrocarbons are still present ; this should not be necessary with the practically neutral disinfectants at present on the market. The petroleum ether solution is distilled from a large flask until the petroleum ethor and water are volatilised. The residual oil in the flask is measured (allowing for that clingiug to the flask) and represents total oil and free resin. The oil is then returned to the flask, distilled and again measured. The distillate is mixed with half its volume of petroleum ether, and extracted three times with sodium hydroxide solution (specific gravity 1*2), the washings being extracted once with half their volume of petroleum ether.The two petroleum ether solutions are mixed, evaporated, and the residual hydrocarbons measured. The alkaline solution is acidified with sulphuric acid (1 : 3), extracted with petroleum ether, the latter well washed with distilled water and transferred to a distilling flask; the solvent and water are distilled off, and the phenols remaining behind measured and fractionated as usual. Water in the disinfectant is taken by difference, but should be checked by distilling the sample and measuring the water ; the result so obtained is always about 1 per cent. too low. For disinfectants containing albumin, 200 C.C. of the sample are boiled under a reflux condenser with 200 C.C. of acetone until a homogeneous solution is obtained ; 200 C.C. of petroleum ether are then added, and the analysis carried out as above.Chemistry of Animal Faxes : A Comparison of the Analysis of Fresh and Air-dried Faxes. A, D. Emmett and H. S. Grindley. (J. Amer. C7%e??z. SOC., 1909, 31, 569-579.)-From comparisons made between the analysis of air-dried and the fresh undried faeces from man, swine, and cattle, the awthors conclude : (1) That the fresh undried faxes of swine and cattle can be satisfactorily analysed directly for the usual constituents-viz., protein, fat, moisture, ash, carbohydrates, and phosphorus. In order to keep undried faeces unaltered for some days they are kept in a thymolised jar having an air-tight lid, and a little powdered thyrnol is sprinkled over them and thoroughly mixed in, when the whole is kept at about358 THE ANALYST.2" C. during the collecting period-ie., until the faxes from the whole experimental period are collected ready for mixing and analysis, (2) That, in the case of swine, the losses on air-drying seem to be in part due to mechanical errors, and not to a loss of any one particular constituent. (3) That, in cases where there is any danger of loss of nitrogen or the products of fermentation, the analysis of the fresh faxes is recommended in preference to either the air-drying process or Konig's nitrogen method, but only in cases where the feeds consumed have been ground or chopped to a medium fineness. An appreciable loss (sometimes amounting to 2 to 3 per cent. or more of the nitrogen present) is generally suffered in the air-drying of faxes, this loss being due to volatilisation of ammonium salts, produced from fermen- tation of carbohydrates, or to actual breaking down of protein and non-protein substances, when not properly preserved. Konig's method consists in adding a definite quantity of the sample to some strong sulphuric acid, and stirring the mixture until disintegrated, when portions are taken for the nitrogen determination.The authors consider that in analysing the fresh undried dung there are corn- paratively unlimited opportunities for studying the nature of the metabolic and undigested products, which cannot be done satisfactorily upon the air-dried material. A. R. T. Estimation of Fatty Matter in Animal Faxes by Ether and Carbon Tetrachloride. A. D. Emmett. ( J . Anzer. Cheoiz. Soc., 1909, 31, 693-695.)-The author has compared the solvent action of anhydrous ether and carbon tetrachloride on the dried excreta obtained from two pigs fed on maize and on maize and middlings in two sets of experiments respectively.The length of the time of extraction was twelve hours for the carbon tetrachloride and twenty-four hours for the ether. The results obtained show that ether extracted considerably less substance from the faxes than did the carbon tetrachloride; the differences amounted to as much as 2.52 and 5.32 per cent. respectively in the two experiments, Calculated on the total amounts extracted by each solvent, it was found that carbon tetrachloride removed from 17.9 t o 33.8 per cent. more than the ether ; and, further, that ether extracted from 21.8 to 51.0 per cent.less substance than did the carbon tetrachloride. The matter which was soluble in carbon tetrachloride but insoluble in ether contained 0.185 per cent. of nitrogen, 10*11 per cent. of mineral matter, and 9.12 per cent. of calcium oxide ; tests for proteins and bile salts gave negative results. Practically the same amounts of phosphorus compounds were present in the two extracts, showing that the difference was not due to the greater solubility of lecithin in carbon t e t Pachloride. w. P. s. Estimation of Iodine in Protein Compounds (Thyroid Glands). L. W. Riggs. ( J . Amel.. Chem. Soc., 1909, 31, 710-717.)-The recent progress in thyroid therapy, and the apparent relation between the amount of iodine in thyroid prepara- tions and their physiological action, has made the accuracy of the estimation of iodine in such preparations of some importance.The method generally employed for this purpose is that proposed by Baumann (Zeit. ~3hysiol. Chem., 1898, 22, I), and, although modifications of this method tending to greater accuracy have beenTHE ANALYST. 359 suggested by other workers, the author finds that further improvements are necessary. The process now described, and based on the Baumann method, consists in igniting the dry substance with sodium hydroxide, adding sodium nitrate to the fused mass, extracting the melt with water, and shaking the acidified solution with carbon tetra- chloride, the colour of the latter solvent being then compared with standard solutions of iodine in carbon tetrachloride.As a portion of the iodine is converted into iodate during the fusion, an important part of the process consists in reducing this iodate, in order to obtain the total amount of iodine present. About 1 grm. of the dried tissue or protein is fused with twice its weight of solid sodium hydroxide ; after carbonisation, about 0.5 grm. of sodium hydroxide is added, and powdered sodium nitrate is introduced, in small quantities at a time, while the contents of the crucible are kept at a barely perceptible red heat. The fused mass is then cooled, extracted with water, the solution is filtered, the residue washed, and the filtrate and washings are diluted to a volume of 100 C.C. An aliquot portion of this solution, usually 10 c.c., is placed in a separating funnel, 10 C.C.of carbon tetrachloride are added, and the mixture is cautiously acidified with 25 per cent. sulphuric acid. After shaking (care must be taken to avoid loss due to the escape of carbon dioxide), the carbon tetrachloride layer is filtered into a small Nessler tube, and the coloration compared with that produced by known quantities of iodine in similar solution. As the coloration in the case of iodine from fused protein is not of exactly the same tint as iodine dissolved directly in carbon tetrachloride, it is necessary to prepare the standard solutions by igniting 100 grams of beef heart-tissue with sodium hydroxide and sodium nitrate, extracting the melt with water, filtering the solution, adding definite quantities of potassium iodide to portions of the latter, and shaking out the iodine from the acidified solution, as in the case of the sample itself.During the fusion a portion of the iodide is oxidised to iodate, and to estimate this portion of the iodine the acid aqueous liquid remaining after the carbon tetra- chloride has been drawn off is transferred to a flask, 0.5 grm. of Devada’s alloy (Cu 39, A1 59, Zn 2 per cent.) is added, the solution is rendered strongly alkaline, heated gently, and allowed to stand overnight, The solution is then filtered, acidified, and extracted with carbon tetrachloride as before. The following quantities of iodine per grm. of fresh gland were found by the author in various glands: Beef thyroid (fourteen samples), 0.03 to 1.47 mgm. ; pig thyroid (eight samples), 0-08 to 1-54 mgm.; sheep thyroid (six samples), 0.13 to 0.41 mgm.It was found that, as a rule, the smaller the quantity of iodine present, the greater the proportion which was oxidised to iodate ; in one case as much ah 77 per cent. of the iodine was present as iodate. Nitrous acid cannot be used to reduce the iodate, as it fails to effect the reduction quantitatively. w. P. 8. Fuchsine-S as a Permanent Standard for the Determination of Nitrites in Sanitary Water Analysis. J. H. Kastle and E. Elvove. (Paper co?nnzzmzcated to the Seventh Internationul Congress of Applied Chamistry; through J. SOC. Chem. Incl., 1909, 28, 742.)-The pink colour produced by a nitrite and Griess’ sulphanilic acid-a-naphthylamine reagent can be exactly matched by a, solution of Acid Magenta360 THE ANALYST.(Fuchsine-S : Acid Fuchsine according to Weigert), which has been acidified with hydrochloric acid. A solution of the dyestuff is prepared by dissolving 0.2 grm. in 50 C.C. of 2N-hydrochloric acid, and making up to 2000 C.C. with distilled water. Of this solution 100 C.C. are mixed with 50 C.C. of 2N-hydrochloric acid and diluted to 2000 C.C. with distilled water. From the latter solution (No. a), standard solutions are prepared containing varying quantities which are mixed with 5.0 C.C. of 2N-hydro- chloric acid and made up to 200 C.C. with distilled water. The number of C.C. of solution (No. 2), and the equivalent of ‘‘ nitrite ” nitrogen in parts per million are as follows : C.C. of Solution No. 2 ... .., 1.5 2.4 3 - 9 5.6 7.1 8.7 12.6 16.5 Eqnivalent of “nitrite ” nitrogen .., 0.0005 0.001 0.002 0.003 0*004 0.005 0‘0075 0.01 The standard solutions are made up fresh about once a month and kept in a cool place away from direct sunlight; the stock Solution No.2 is renewed about once in six months. Use of Nitron for the Estimation of Nitric Acid. H. Franzen and E. Lohmann. ( J . prak. Chem., 1909, 79, 330 ; Che??Z. Zeit. Rep, 1909, 33, 321.)- The nitron method is the only one suitable for the estimation of nitric and nitrous acids in a bacterial culture liquid. In one portion of the liquid the nitrous acid is oxidised to nitric acid by the addition of hydrogen peroxide, aud the total nitric acid is estimated as nitron nitrate. I n a second portion of the liquid the nitrous acid is destroyed by means of hydrazine sulphate, and the nitric acid is estimated alone.This method gives just as good results in the case of a bouillon solution as in aqueous solution, provided 2 to 2.5 C.C. of concentrated sulphuric acid be added per 200 C.C. of solution. J. F. B. The Absence of Laevulose in Diabetic Urine. L. Borehardt. (geit. physiol. Chem., 1909,60,411-414.)-The author states that there is no ground for the assumption that diabetic urine contains levulose. The agreement of the results when the sugar is estimated polarimetrically and by titration, as well as the negative results of direct tests for lzvulose, points to the fact that, as a rule, no sugar other than dextrose is present in such urine. w. P. s. Estimation of Phosphoric Acid in Urine and Alkali Phosphate Solutions.P. v. Liebermann. (Biochem. Zeit., 1909, 18, 44-57.)-The method proposed consists in precipitating the phosphoric acid as ammonium magnesium phosphate, dissolving the latter in nitric acid, and reprecipitating the phosphoric acid as silver phosphate by means of an excess of silver nitrate; the excess of silver is then titrated with thiocyanate solution. Twenty C.C. of the urine under examination are treated with 2 C.C. of 10 per cent. ammonium carbonate solution, about 8 C.C. of magnesia solution, and about 10 C.C. of ammonia of sp. gr. 0-96. After the lapse of twelve hours the precipitate is collected on a filter and washed with 2.5 per cent. ammonia; it is then dissolved in 50 C.C. of 15 per cent. nitric acid, and to the solution are added 5 C.C. of silver nitrate solution.Ammonia is added cautiouslyTHE ANALYST. 361 until the reaction of the solution is amphoteric, using litmus-paper as the indicator, and the whole is then transferred to a 200 C.C. flask, diluted with water to the mark, and filtered. One hundred C.C. of the filtrate me acidified with nitric acid, 2 C.C. of ammonium ferric sulphate are added, and the solution is titrated with & potassium thiocyanate solution. If CL be the number of C.C. of thiocyanate solution used, then 2.367(50 - a ) is the quantity of phosphoric acid (P20,) present, expressed in mgms. The method gives accurate results when the quantity of phosphoric acid present lies between 30 and 80 mgms.; with larger quantities the results are slightly low. Concentrated urines should, therefore, be diluted before the estimation is commenced. For the estimation of phosphoric acid in alkali phosphate solutions, the precipitation as ammonium magnesium phosphate may be omitted. A portion of the solution is acidified with 12.5 C.C. of nitric acid of sp. gr. 1.310, diluted with water to a volume of 50 c.c., an excess of silver nitrate solution is added, and the estimation is carried out as described above. When from 30 to 80 mgms. of phos- phoric acid are present in the portion of the solution taken for the estimation, the method yields within 0-5 per cent. of the quantity found by the ordinary gravimetric process. w, P. s.

ISSN:0003-2654    

DOI:10.1039/AN9093400356

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 361 ORGANIC ANALYSIS. A Characteristie Reaction of Adrenaline. S. Frankel and R. Allers. (Biochem. Zeit., 1909, 18, 40-43.) - A bright-red coloration is produced when adrenaline solution is heated just to boiling with an equal volume of & potassium periodate solution and a few drops of dilute phosphoric acid. The coloration is stated to be characteristic of adrenaline, and to be capable of detecting 1 part of the substance in 300,000 parts. Pyrocatechol and guaiacol give a yellow or brownish colour with the test, whilst tyrosin, oxyphenylethylamine, albumin, peptone, sugar, urea, uric acid, oxalic acid, leucine, and creatine do not yield any coloration. w. P. s. Decolorising Action of Various Forms of Charcoal. E. Knecht. (Paper conanazmicated to the Seventh International Congress of Appliecl Chenhtry.)--The author has already shown (ANALYST, 1907,32, 365) that by decreasing the percentage of nitrogen in an animal charcoal, its afinity for acid dyestuffs like crystal scarlet is proportionately diminished.I n continuation of this work, he now shows that by decreasing the percentage of nitrogen, the affinity of the charcoal for a basic colour like methylene blue is not materially altered. If, on the other hand, purified animal charcoal be heated with aluminium powder or zinc dust, and then treated succes- sively with hydrochloric and hydrofluoric acids to remove impurities, its affinity for methylene blue is greatly diminished. The affinity for crystal scarlet is also diminished by this treatment (probably owing to unavoidable loss of nitrogen), but not in proportion to the decrease in the affinity for methylene blue.The opinion expressed by Paterson and by Glassner and Suida, that animal charcoal owes its decolorising action to the presence of organic compounds which are stable at a red362 THE ANALYST. heat, is upheld by the author. The decolorising action of other forms of charcoal, such as cocoanut charcoal, lamp-black, acetylene black, and naphthalene black, is also discussed, and it is shown that the more closely the substance approaches in composition to pure carbon, the less is its decolorising power. I t is highly probable that absolutely pure amorphous carbon, however fine its state of division, would be found to be devoid of any decolorising power on either aeid or basic dyestuffs.The absorption of iodine from its solution in potassium iodide by animal charcoal was found to depend, like that of crystal scarlet, on the amount of fixed nitrogen contained in the charcoal. The absorption of oolouring matters by animal charcoal cannot, therefore, be adduced as evidence that dyeing is a mechanical process. The fact that, under similar conditions, animal charcoal takes up acid colours belonging to a, homologous series in the proportion of their molecular weights, shows that here also chemical action is at work. The Examination of Chinese-wood Oil. E, W. Boughton. (Paper coyn- nazmicnteci! to the Seventh Iiztenaatioizal Congress of Applied Claemistry:)--The results of the examination of seven samples of tung oil are given.Six of the samples were received directly from China, the seventh being pressed from the imported nuts. The constants obtained agreed with those published by other observers, with the exception of the iodine value. This was found to vary greatly if H a n d or Wijs' solution was used, the temperature, time of contact, and ratio of iodide solution to oil affecting the result. With Hub1 solution, however, the variations were small, and the values thus obtained fell within the limits of those published by other observers. The oxygen absorption of the oil (Livache test) mas found to be less than that of linseed oil in forty-eight and ninety-six hours. On heating tung oil in tho steam oven for one hour, the gain in weight is greater than in the case of linseed oil.Ten per cent. of tung oil may be detected in a mixture of tung and linseed oils by either of the following tests : (1) Ten C.C. of the oil and 10 C.C. of a saturated solution of iodine in chloroform are placed in a test-tube and heated on a water-bath until the chloroform has been evaporated. The contents of the test-tube are then heated for one hour in an oil-bath at 200" C. Pure linseed oil remains liquid, whilst the presence of 10 per cent. of tung oil will cause solidification. (2) Ten C.C. of the oil are well shaken with an equal volume of concentrated nitric acid, and the mixture is cooled to 0" C. for one hour ; the oily layer becomes semi-solid if as much as 10 per cent. of tung oil be present. w. P. s. The Unsaponifiable Swbstanees contained in Cotton-seed Oil.H. Matthes and W. Heintz. (Arch. Pharm., 1909, 247, 161-175.)-The authors show that the unssponifiable matters contained in cotton-seed oil may be separated into various substances. The crude unsaponifiable matter obtained from the oil readily separates into two portions, one solid and the other liquid; the latter by distillation may be split up into a number of fractions consisting of unsaturated compounds. The solid, crystalline portion consists o f , (a) phytosterol, xhich melts at 139" C., is IEVO- rotatory, and contains one double bond ; ( b ) a saturated compound melting at 81" to 8 2 O C.; ( c ) a dextro-rotatory, unsaturated substance melting stt about 172" C.THE ANALYST. 363 The characteristic odour of the unsaponifiable matter of cotton-seed oil is due, wholly or in part, to the decomposition of the phytosterol by the alcoholic potassium hydroxide employed in the saponification.The unsaponifiable matter does not contain sulphur, and does not give a reaction with Becchi's test. w. P. s. The Occurrence of Mixed Glycerides in Natural Fats. J. Klimont and E. Meisels. (iMomtsh. fur Chem., 1909, 30, 341-346.)-The fats of the common goose and duck resemble those of other domestic animals in containing mixed glycerides. The goose-fat examined had the following analytical values : Sp. gr. at 15" C., 0.9270 : saponification value, 193.3 ; and iodine value, 70-1. By repeated recrystallisation from acetone containing a little chloroform, it yielded a crystal- line powder melting at 59" C., and agreeing in its analytical values with edipalmitostearin.The duck-fat had the following values : Sp. gr. at 15" C., 0.912 ; melting- ipoint, 27"-28* C. ; saponification value, 193.6 ; and iodine value, 71.7. It contained an oil agreeing with triolein in analytical characteristics, and yielded, on crystallisa- tion, a compound which the authors also regarded as dipalmitostearin. I n experiments with tristearin and tripalmitin, it was found that the crystals with the highest melting-point (66" C.) had a composition corresponding to that of a, mixture of 70 per cent. of tristearin and 30 per cent. of tripalmitin. These results proved that the glycerides obtained from the goose- and duck-fat were not (mixtures of tristearin and tripalmitin, and incidentally confirmed the commonly- accepted statement that pure tristearin cannot be isolated by crystallisation from fat 9 containing t ris tearin and tripalmi t in.C. A. M. Determination of the Amount of Volatile Matter in Solid Fuels. %. J. Constam. (Paper communicated to the Seventh Interizntioiznl Congress of Applied Chemistry.)-The amount of coke yielded by, and the moisture and ash contained in average samples of coals (or solid fuels), form data from which the amount of volatile matter (" gaseous content ") is calculated. Different methods of determining the yield of coke are used in different countries ; and from one and the same sample different values are thus obtained for the pro- portion of volatile mattor. Consequently, in districts where coal from different places of origin is used, the need of B uniform method of determining the yield of coke is strongly felt.The author and his collaborators have therefore investigated the various methods extant with the different crucible methods, and the Belgian, American, and Bochum methods of determining the quantity, chemical composition, and calorific power of the coke produced. The yields of coke found by these methods, and the chemical and calorific properties of the coke formed in the crucible, were compared with the coke formed from the same fuels by distillation at 830" C. in a small gas-retort. The composition and the calorific power of the combustible substance in these retort cokes proved to be very similar to those of the cokes produced in gasworks and in coke-ovens, after making allowance for ash and moisture.Pyrometric determinations showed that different temperatures prevailed in the different coking methods in which the crucible364 THE ANALYST, was used. Further, it was established that no portion of the coke was burnt in coking by either the Bochum or the American method. When, however, the younger fossil substances, such as lignite and peat, and wood, are coked, the samples should be previously air-dried, pressed into tablets, and then carbonised and cooled to room temperature in a current of hydrogen, carbonic acid, or nitrogen. The experimental results obtained lead to the conclusion that the differences in the yield of coke by the various methods are primarily due to more or less thorough car- bonisation of the fuels. The chemical coinposition of the coke produced in a crucible from coals is not affected by the composition of the original coal, but depends only on the temperature and the duration of the heating.The crucible coke produced according to Finkener's method at 700' C. resembles coal more closely than the cokes obtained at 900" to 910' C., according to the Bochum or the American method. The latter approach nearest in composition and calorific power to the cokes formed on the large scale in gasworks and in coke-ovens. The slower rise of, and the lower final temperature in dull platinum crucibles, cause the yield of coke to be greater in them than in polished crucibles. Notwithstanding the contentions of Hinrichsen and Taczak (ANALYST, 1908, 33, 431), and of Geipert, to the contrary, the author is of opinion that it is not possible to find a crucible coking method which will afford the same yield of coke as different working methods, which, indeed, dieer among themselves.On the other hand, the author would prescribe as a standard method one which gives a coke most closely resembling in composition a,nd calorific power the gas and oven coke. Such a method is the American one, which is con- venient to carry out: is applicable to all solid fuels (including those which carbonise without luminous flames), and affords very closely concordant results in parallel tests. As this method is already in general use in those countries-viz., the United States of America and Great Britain-which produce the most coal, it appears to the author that its general adoption is desirable in all conclusive analyses of fuels.The results of the examination are only comparable for different coals if they are referred to the coal or coke free from moisture and ash. The author therefore proposes in general to take for the volatile matter in a fuel-referred to the dry and ash-free substance-the figure obtained by subtracting from 100 the yield of coke as deter- mined by coking 1 grm. of the fuel in a polished platinum crucible according to the directions of the American Committee on Coal Analysis. The method is as follows: 4' One grm. of the fresh, undried powdered coal is heated for seven minutes over the full flame of a Bunsen burner in a platinum crucible weighing 20 to 30 grams, and provided with a tightly-fitting cover.The bottom of the crucible, which is supported on a platinum triangle, should be from 6 to 8 em. above the top of the burner. The flame, when burning free, should be 20 cm. high; and care should be taken to protect it from draughts during the determination. The under surface of the cover should remain coated with carbon; but the upper surface should always keep free from it." Analyses for arbitration purposes made in different places by this method on the same sample show differences for the most part of less than 1 per cent. in the yield of coke, and only rarely of as much as 2 per cent.THE ANALYST, 365 Estimation of Vermillion and Antimony Sulphide in Caoutchouc Articles. J. Rothe. (Chem. Zed., 1909, 33, 679.)-The author describes a method for the destruction of organic matter prior to the estimation of metallic compounds when the latter are volatilised by incineration.This method is of general application, even in the case of paraffin hydrocarbons and caoutchouc. If the substance is a liquid, it must first be evaporated to dryness; the coarsely powdered dry substance is placed in a, round-bottomed flask of Jena glass, together with 10 to 20 C.C. of nitric acid (sp. gr., 1.48) and 2 C.C. of concentrated sulphuric acid for every 1 grm. of dry substance taken. In the case of organic matters which are readily oxidised, it is best to moisten them with four times their weight of a more dilute nitric acid (sp. gr., 1.40) before adding the strong acid, in order to avoid danger of ignition. The mixture is then heated on the sand-bath to a degree just sufficient to maintain a steady evolution of gases.After one or two hours the heat is increased so as to drive off all the nitric acid, and subsequently to boil the sulphuric acid. After cooliug, 5 to 10 C.C. more of strong nitric acid are added to the brown-coloured residue, and the liquid is maintained in gentle ebullition until it becomes pale in colour. The flask is again heated until the sulphuric acid boils, and if the liquid remains colourless the oxidation is complete. If harmful to the subsequent determinations, the excess of sulphuric acid is then fumed off over a naked flame, and the solution containing the metals is diluted and boiled. The author has followed this procedure with a large variety of commercial organic products, using in some cases up to 20 grms.of the substance. For the estimation of mercury and antimony in caoutchouc articles it is considerably more convenient and accurate than the process of oxidation with nitric acid and potassium chlorate. J. F. B. Estimation of Caoutchouc in Hot-Vulcanised Soft Rubber, and Other Investigations on Vulcanised Rubber. G. Hubener. (Chenz. Zeit., 1909, 33, 648-649, 662-663.)-1n a previous paper (ANALYST, 1909, 170) the author described a method for the analysis of ebonite, depending on the presence of two double bonds in the raw caoutchouc molecule. Any hot-vulcanised rubber may be expressed in terms of fully-vulcanised, half-vulcanised, and unvulcanised caoutchouc, together with free sulphur. The first is saturated and does not combine with bromine, the second combines with two atoms of bromine, and the raw rubber combines with four.Caoutchouc tetrabromide is soluble in carbon disulphide, and the analysis consists of determinations of bromine and sulphur in the various fractions. The difficulty of reducing a soft rubber to a sufficiently fine powder for the action of the bromine is the main impediment to the application of this method to both soft and hard rubbers. The difficulty is best met by rubbing the soft rubber on a sharp, coarse file, allowing a longer time for the action of the bromine water, and frequently breaking up the particles of caoutchouc bromide as it is formed. About 0.1 grm. of the rubber filings is treated with 200 C.C. of water and 10 C.C. of bromine, and the mixture stood on a sand-bath for three hours at a temperature of 70" to 80" C., care being taken that excess of bromine is present all the time.The other operations have been described before (Zoc. cit.). If, however, the rubber mixture contain substances which yield bromides insoluble in water, the caoutchouc value calculated from the bromine366 THE ANALYST. absorbed will be too high. Budde has shown that the bromides of most of the substitutes present in rubber mixtures are soluble in a mixture of alcohol and carbon tetrachloride. If the brominated product be filtered off, washed and dehydrated with alcohol, and then digested with a mixture of equal parts of’ alcohol and tetra- chloride at a moderate heat, the analysis of the extracted product by the above method will generally lead to a satisfactory result.But in view of the great variety of the substances used in rubber mixtures, it is not surprising that this method some- times gives results which are too low. It is difficult to prescribe a method of universal application, but the following procedure i3 suitable for most cases : 2.5 grms. of the rasped rubber are wrapped in filter-paper and extracted for a sufficient time (four to six hours generally) with acetone in a Soxhlet’s apparatus. If resins which are insoluble in acetone be present, which is frequently the case with ebonites, this extraction must be followed by one with dichlorkydrin. The residue is dried at 60” C., and weighed. Of this residue, 0.2 grm. is weighed out and digested with 100 C.C. of water and 5 to 10 C.C.of bromine at a moderate heat until the rubber is completely disintegrated. The bromine is volatilised the product is collected on a filter and washed with hot water. The filter, together with the precipitate, is placed in a conical flask, treated with 20 C.C. of silver nitrate solution and 20 C.C. of strong nitric acid, and the liquid is boiled down to a volume of about 15 C.C. The excess of silver is then titrated back after dilution by means of standard thiocyanate in presence of iron alum, and the quantity of bromine combined with the caoutchouc is thus determined. From this value, the quantity of caoutchouc capable of reacting with bromine may be calculated in the original substance. The rest of the caoutchouc is calculated from the difference between the total sulphur (alkaline fusion) and the free sulphur (sulphuric acid in the filtrate from bromiuation).An investigation of the ash for metals which yield sparingly soluble sulphates may indicate ths necessity of correcting this latter value. J. F. B. On the Nature of the Cutin which is contained in “Crude Fibre.” W. Sutthoff. (Zeit. Untersuch. Nahy. Geizussin., 1909, 17, 662-664.) - The substance known as cutin, which remains insoluble when the “ cellulose I ’ obtained from ‘‘ crude fibre ” by the method described by Konig (ANALYST, 1906, 31, 406) is further treated with ammoniacal copper solution, consists of a wax-like substance containing a large proportion of ash and carbon. The ash, which amounts t o from 15.02 to 30.96 per cent. (in one case a specimen of cutin was obtained coctaining only 1.95 per cent.of ash), consists of almost pure silica. The dry, ash-free substance contains from 64.72 to 69.97 per cent. of carbon, and from 9.65 to 12-40 per cent. of hydrogen, and on saponification yields an alcohol, or mixture of alcohols, melting at 55” to 56” C., and containing 17 atoms of carbon in its molecule. The fatty acid portion of the substance melts at about 30” C., and is, apparently, a mixture of fatty acids, the mean molecule of which contains 11 atoms of carbon. w. P. s. Analysis of ‘‘ Sodium Cyanamide ” and ‘‘ Nitrolim.” F. E. Weston and H. R. Ellis. (Paper communicated to the Seventh International Congress of Applied Chemistry.) - The only known method of estimating sodium cyanamide is oneTHE ANALYST.367 proposed by R. Perotti ( J . Chein. SOC., Abst., 1905, ii., 870), in which the cyanamide is precipitated in ammoniacal solution by means of standard silver nitrate solution, the excess of silver being titrated after the precipitate has been removed by filtration ; this method is also given as a means of estimating calcium cyanamide in ‘‘ nitrolim.” The method does not, however, yield correct results, as any sulphide, cyanide, or chloride present may be precipitated with the cyanamide, or these silver salts may dissolve in the ammonia used and interfere with the titration of the excess of silver nitrate. An estimation of the total nitrogen in a sample by Kjeldahl’s method does riot show how much cyanamide is present, as the nitrogen occurring as cyanide, nitride, ammonia, and complex nitrogen compounds is included.The authors therefore propose the following method, which has been found to yield very concordant results : Estimation of Cyanamide and Cyawide in Sodium Cyanamide.-A solution of the substance of about strength is prepared, and 20 C.C. of this solution are added to a mixture of 40 C.C. of silver nitrate solution and 10 C.C. of nitric acid. The precipitate of silver cyanide obtained is collected on a filter, well washed, and the filtrate and washings are run into 20 C.C. of ammonia. The solution is warmed, and the precipitate of silver cyanamide which forms is collected on a filter and well washed. The silver cyanide is washed into a flask containing nitric acid, boiled until all the cyanide is dissolved, and the silver in the solution is titrated with .& ammonium thiocyanste solution. The precipitate of silver cyanamide is treated with dilute nitric acid (1 : 5), the acid being poured through the filter ; the residue is washed, and the silver in the filtrate and washings is titrated.Estimntioiz of Calcium Cyalza?lzide in 6 L Nitro1im.”-From 1 to 2 grms. of the finely powdered substance are shaken with water and filtered into a 500 C.C. flask, the residue being washed with water until a drop of the filtrate no longer gives a precipitate with ammoniacal silver nitrate solution. The solution is then made up to bulk, and 20 C.C. are added to a mixture of 30 C.C. (an excess) of & silver nitrate solution and 20 C.C. of The precipitate produced is collected on zt filter and washed thoroughly with warm water.Dilute nitric acid (1 : 5 ) is now poured over the precipitate, and the residue is washed until all the silver cyanamide is obtained in solution in the filtrate. The silver in the latter is then estimated by titration with thiocyanate solution. Any silver sulphide or chloride remains on the filter-paper. This method has been used by the authors with satisfactory results in studying the rate of decomposition of cyanamide under various conditions, especially ammonia. in soils which contain nitrogen, chlorides, and sulphides. w. P. s. Estimation of Iodine in Iodoform and Thymol Iodide. E. H. Gane and W. H. Webster. (Zeit. angezo. Chem., 1909, 22, 1059-1061, 1190-1191.)-For the complete saponification of iodoform, it is necessary to use a solution of potassium hydroxide in absolute alcohol, and to continue the heating for two hours.Utz’s method, however, is more rapid and convenient : The iodoform (0.5 grm.) is dissolved in 10 C.C. of a mixture of 1 part of ether and 3 parts of alcohol, and the solution treated with 50 C.C. of & silver nitrate solution and 1 C.C. of red fuming nitric acid (sp. gr., 1.42), and heated on the water-bath until the odour of nitrous acid has disappeared. It is next diluted with 100 C.C. of water, and, after the addition of368 THE ANALYSTe Iodine combined with Thymol. 1 C.C. of a saturated solution of iron ammonium sulphate, the excess of silver nitrate is titrated with potassium thiocyanate. Each C.C. of silver nitrate solution used by the iodoform solution corresponds to 0.0130 grm.of iodoform. ThymoZ Iodide.-Although the U. 5. Pharmacopceia describes this as dithymol iodide (C,H,CH,C,H701),, containing 45 per cent. of iodine, the commercial product is not a definite chemical compound. The only method giving reliable results in the estimation of the total halogens was found to be that of fusion with an alkali carbonate: One grm. of the thymol iodide is intimately mixed with 1 grm. of potassium sodium tartrate and 5 grms. of anhydrous sodium carbonate, and the mixture covered with the same quantity of the fusion mixture, and heated for forty-five minutes in a covered porcelain crucible. The fused mass is taken up with water and filtered, and the filtrate made up to a definite weight and divided into three parts.The first of these is very slightly acidified with nitric acid, and titrated with & silver nitrate solution. The result, expressed in terms of iodine, gives the “apparent iodine” in the liquid. The second part of the solution is treated with 15 C.C. of glacial acetic acid and 2 grms. of lead peroxide, and heated until the vapours no longer affect starch-paper. The chlorine is then estimated gravimetrically. The third portion of the solution is neutralised with hydrochloric acid, and trans- ferred to a separating-funnel containing 25 c. c. of carbon bisulphide. Sulphuric acid (sp. gr., 1-80> containing a little sodium nitrite is added drop by drop, the funnel being vigorously shaken after each addition, until the whole of the iodine has been liberated.The carbon bisulphide layer is now washed three times with water (20 C.C. each time), and the aqueous layer once more shaken with a fresh portion of carbon bisulphide, which is added to the former extract. The extracted iodine is then titrated with sodium thiosulphate. For the estimation of inorganic iodine, 2 grms. of the sample, 20 C.C. of carbon bisulphide, and 100 C.C. of water are shaken vigorously at intervals for thirty minutes, after which 75 C.C. of the aqueous layer is filtered, and shaken in a separating-funnel with two successive portions of 15 C.C. each of carbon bisulphide to remove the final traces of iodine, thymol, etc. Finally, the liquid is treated with 20 C.C. of the same solvent, and the iodine liberated and titrated as described above.Substances insoluble in ether are estimated by treating 2 grms. of the sample in a tared beaker with four successive portions of 10 C.C. each of ether, and decanting the liquids after fifteen minutes’ standing. The following results were obtained with samples of the commercial drug : Thymol Iodide. 1, a. 3. 4. Ash. Per Cent. 2.4 2.8 0.4 1.7 Metallic Impurities. K, Ca, Fe K, Al, Fe Fe Ca, Al, Fe ’Apparent Iodine. ” Per Cent. 44.6 45.9 54.0 44.6 Chlorine. Per Cent. 4.6 1.8 8-01 - Actual Iodine. Per Cent. 28.14 39.44 25.36 44.6 Inorganic Iodine. Per Cent. 0.67 1.50 0.92 1-85 I I C. A. M.THE ANALYST. 369 Sensitive Reactions for Lactic and Glycolic Acids. G. Denigks. (Bull. SOC. C~Z~WZ., 1909 iiv.], 5, 647-649.)-Lactic acid, when heated in the presence of sulphuric acid, is decomposed with the formation of aldehyde, which may be identified by the colour reactions which it gives with phenols and alkaloids.In applying the test, 0.2 C.C. of the solution (which ought not to contain more than 2 per cent. of lactic acid) is mixed with 2 C.C. of sulphuric acid (sp. gr., 1*84), and heated for two minutes on the water-bath, When cold, the contents of the tube are shaken with 1 or 2 drops of a 6 per cent. alcoholic solution of guaiacol or of codeine. In the former case a magenta coloration is obtained when the original solution contained as much as 0.01 mgm. of lactic acid, whilst with the codeine an orange-red colour (yellow in more dilute solutions) is produced. A rapid colorimetric method of estimating lactic acid may be based on this reaction.Glycolic acid treated in the same Fay, but at a somewhat higher temperature than that of a boiling water-bath, is decomposed into formaldehyde, carbon monoxide, and water. As soon as small bubbles of gas are seen the liquid is cooled and tested with 1 drop of the codeine solution, a yellow coloration changing to intense violet being obtained. Or, before heating the mixture of glycolic and sulphuric acids, 1 or 2 drops of a 5 per cent. alcoholic solution of guaiacol or OF p-cresol and 1 C.C. of glacial acetic acid are added, and the tube heated and shaken. With p-cresol a green or greenish-brown coloration, becoming bright green on dilution with alcohol or acetic or sulphuric acids, is obtained, whilst with guaiacol there is produced a violet tint, which changes to brown on dilution with alcohol, and remains violet on dilution with acetic or sulphuric acid.C. A. M. Use of Methylglyoxal as a General Colour Reagent. G. Deniges. (Bull. SOC. Chiin., 1909 [iv.], 5, 649-651.)-A solution of methylglyoxal may be used as a reagent for many cyclic compounds, and particularly for phenols and certain alkaloids of the morphine group. The reagent is prepared by shaking together in a stoppered flask 20 C.C. of a 5 per cent. (by weight) solution of glycerol, 100 C.C. of water, and 0.6 C.C. of bromine until the-latter has dissolved, after which the solution is heated on the water-bath for twenty minutes. I t is then boiled for five or six minutes to expel all traces of bromine, and diluted to about 100 C.C.When cold, it is mixed with 20 C.C. of pure sulphuric acid and distilled, and 50 C.C. of the distillate used as the reagent. When employed in the absence of bromine, 0.4 C.C. of the reagent is mixed with 2 C.C. of sulphuric acid (sp. gr., 1-84), a, few mgms. or a few drops of the substance under examination introduced, and the tube shaken. The following colorations are produced in the presence of the substances named : Pyrogallol, intense brown ; yesorcznol, orange ; pyrocatechol, red ; a-naphthol, intense bluish-violet ; and P-izapht7zol, yellow, changing to green. Of the alkaloids of opiuni, apomorphine gives a reddish-violet tint, changing to intense violet after contact for two minutes with 2 to 4 C.C. of glacial acetic acid; oxymorphine gives a yellowish-green tint after treatment with the acetic acid ; morphine, a yellow coloration, changing to brown ; and codeine, a bright yellow, becoming grttenish or bluish-green. On adding 1 C.C.of glacial acetic acid and boiling the liquid after it has stood for two minutes, the colour becomes violet in the case of morphine and blue in the case of codeine.870 THE ANALYST. In certain cases a trace of the substance is dissolved in 2 C.C. of glacial acetic acid, and the solution mixed with 1 C.C. of sulphuric acid, and then treated with 1 C.C. of the reagent. Under these conditions ZizdoZ girss a raspberry-red coloration ; scatol, an orange coloration ; and pyrroZ, B brown coloration. For this purpose 0.1 c.c, of a 4 per cent. solutioii of potassiuni bromide, 0.4 C.C.of the reagent, and 2 C.C. of sulphuric acid (sp. gr., 1-84), are shaken together, a few mgms. or 1 to 2 drops of the substance to be tested introduced, and the tube shaken. PhenoZ gives a carmine-red coloration, changing to blood-red and then to orange ; sclZicyZic acid and its salts and esters, a green colour; and gaZlic acid, a blue colour, changing to violet. I n other cases the condensation only occurs when the sulphuric acid is more concentrated. Thus, in testing cyclic hydrocarbons 0.2 C.C. of the reagent is used with 2 C.C. of sulphuric acid and 0.1 C.C. of potassium bromide solution, and the mixture heated. Under these conditions hornologues of benxeue give a red coloration, whilst mphthnlene gives a green coloration, changing to greenish-blue on dilution with acetic acid. Saiztoniize, when gently heated, gives a, reddish-violet colour, changing to blue and finally to green.Thiopheize, of which not more than 1 mgm. should be used, gives in the cold a red coloration, changing to violer; and then to blue, and. even to green if the ainount reaches 1 mgm. The reaction affords a very sensitive test for traces of thiophene in benzene. From 0.5 to 1 C.C. of the latter is shaken with 2 C.C. of sulphuric acid, 0.2 C.C. of the reagent, and 0.1 C.C. solution. Pure benzene gives no coloration in the cold when thus examined. The reagent may also be used in the presence of bromine. C. A. h1. The Decomposition of Nitroglycerine. R. Robertson. (Chent. News, 1909, 99, 389.)-This paper deals with the decomposition of nitroglycerine in the absence of the catalytic acceleration due to volatile decomposition products.A special apparatus was constructed arranged to condense any nitroglycerine volatilised unchanged, and on rotation about an oblique axis, return it to the inain portion to be again heated. The nitroglycerine, from 0.3 to 5 grrus., dissolved in acetone (the solvent being subsequently driven off), was absorbed by glass-wool i n the horse- shoe-shaped decomposition tube of the apparatus, which was heated in an oil-bath. A stream of carbon dioxide was passed through the apparatus at the rate of 1,000 C.C. per hour, the products of decomposition being carried off to an observation-tube, in which the concentration of nitrogen peroxide was determined by the method of Robertson and Napper, and thence over red-hot copper and copper oxide asbestos to a gas-burette containing caustic potash solution. For a temperature range of from 90' C.to 135" C., it was found that nitro- glycerine deconiposes as uniformly as a stable gun-cotton from which the volatile decomposition products are continuously removed ; that the nitrogen is evolved wholly as nitrogen peroxide, in which respect nitroglycerine differs from nitrocellulose ; that the rate of decomposition is a function of the temperature, being doubled for every 5 O of rise; and that nitroglycerine has a higher rate of decomposition than nitro- cellulose under similar conditions. 0. E. M.THE ANALYSTo 371 Stability of Smokeless Powders. (Zeit. ges. Schiess- 24. Spnmqstofiir., 1909, 4, 254.)-The stability of a smokeless powder under the Abel test is measured by the time of heating required to cau8e a colour-change in a test-paper.This time, T, consists of t,, the time necessary for the formation of the acid decomposition products, and t,, the time required for the evolution of gas and its action on the test-paper. The true stability is given by t,, and approaches T, the apparent stability, more closely for a loose gun-cotton than for a gelatinised powder. Thus T affords no satisfactory Iiasis for comparing two powders, because t, may be much greater for one than for the other. The property which prevents the ready escape of gaseous decomposition products does not serve a useful purpose by protecting the powdsr against external influences, such as humidity, because decomposition is due to internal reactions.The addition of substances which absorb decomposition products is useless, because it is only by increasing t, that they increase T. The apparent stability may be so great that the decline of true stability to a point approaching the danger limit is relatively very small. During the life of a powder the apparent stability sinks slowly until the critical age is reached, at which point the decomposition products are so rapidly evolved that they break down the structure of the powder and escape freely. The apparent stability falls suddenly to 0. Thus, a test carried out; a short time before the critical age niay show satisfactory result, although the period of rapid decomposition is close at hand.The utility of substances intended to increase the stability of powders by protecting them from outside influence is not proved. Those which also bet,ray incipient decomposition by a change of colour appear to be the most promising. Two methods of obtaining better tests are suggested : (1) By comparing the test on the powder with a test on the gun-cotton freed from solvent, the apparent and real stabilities would be obtained ; (2) by a suitable choice of solvent the curve connecting age and apparent stability might be made to show a regular decline, instead of continuing almost horizontal to the critical age and then falling off suddenly. A test would then not only show the actual condition of a powder, but also its probable length of life. 0. E. hl. The Action of Iodine on Phenols, with Special Reference to a Rapid Method for the Estimation of Tannin Materials.W. M. Gardner and H. H. Hodgson. (Paper communicated to the Seventh Intemational Congyess of Applied Chenzistq.)-The work of Bottinger (Anncdeit, 1890, 258, 238 &ad 252) and Guignet (Compt. Tend., 1891, 113 and 200) has indicated a possibility of estimating tannic and gallic acids by means of reducing agents, and attempts were made by the authors to obtain a quantitative yield of benzoic acid by the action of reducing agents under varying conditions. Guignet’s work was repeated, and further experi- ments were made, using zinc, sodium, magnesium, aluminium, sodium h ydrosulphite, and hydriodic acid, each in neutral, acid, and alkaline solution. In no case was the desired result obtained, but the observation was made that tannic and gallic acids were readily attacked by alkaline reducing agents, and the following method for the estimation of tannic acid was eventually developed: To an aqueous solution of372 THE ANALYST.tannic acid standard iodine solution is added in excess, and, after the addition of a few drops of starch solution, sodium hydroxide solution is added until the blue coloration disappears; an excess of sodium hydroxide is to be avoided. Dilute hydrochloric acid is then added in sufficient amount to liberate the unabsorbed iodine, the amount of which is estimated by titration with standard sodium thio- sulphate solution. Working with widely differing quantities of tannic acid, the method was found to be strictly quantitative, and, further, the process was found to be applicable to the estimation of many phenols ; for example, phenol, catechol, hydroquinone, salicylic acid, pyrogallic acid, and gallic acid.I n these substances each hydroxyl group requires 1 molecule of iodine, but with other phenols the reaction, though quantitative, appears to be empirical. The method was then applied to ordinary tannin-containing materials-viz., gall-nuts, sumach, valonia, divi-divi, and quebracho-the results being compared with those obtained by using the Lowenthal process. The difference in the results obtained by the two methods was usually less than 1 per cent. The iodine method was applied both before and after precipitating the tannic acid by means of gelatine, as in the Lowenthal process.w. P. s. Estimation of the Tannin of Hops-Part 11. A. C. Chapman. (J. Inst. Brew., 1909, 15, 360-374.)-1n a previous paper (ANALYST, '1908, 33, 95) the author described his method of estimating tannin in hops by weighing as an insoluble cinchonine compound containing 4 per cent. of nitrogen and 60 per cent. tannin. Owing to difficulties of complete oxidation by the Kjeldahl method, the nitrogen value of this compound on further investigation is now found to be higher, and 4.3 per cent. is nearer the truth; the factor for conversion of cinchonine lupulo- tannate into tannin thus becomes 0.55. The table given in the original paper is reproduced with corrected values. Contrary t o the usual statement, the author finds no evidence of reduction in hop tannin during storage, the error probably having arisen through the use of Lowenthal's method. Foreign hops contain higher percentages of both tannin and resins than English hops, but choice Bavarians with 3.13, and Alsace with 2.64 per cent. of tannin show that the com- parative value of these hops is not a function of the tannin percentage. Eight samples of Mid-Kent hops were placed in the order of their value to the brewer, due regard being paid to colour, aroma, condition, freedom from disease, etc., and the resins and tannin then determined in them. Sample. A. B. C. D. E. F. G. H. Soft Resins. Per Cent. ... ... 6.02 ... .. 5'37 ... ... 5.20 . .. ... 5.28 ... ... 5.90 ... ... 4.51 ... ... 4.55 ... _... 4.70 Hard Resins. Per Cent. 7.80 8.10 7.70 7-60 7.60 9.50 8.27 7-20 Total Re s i 11 s . Per Cent. 14.00 13.47 12.90 12.88 13.50 14.01 12.82 11.90 Tannin. Per Cent. 2.28 3.30 2.56 2.16 2.00 2.62 2.09 2-40THE ANALYST. 373 Sample A was worth 30 per cent. more than D, E, or G, though the tannin percentage in samples A and D are nearly alike, while A and B are hops o€ very nearly the same quality, although the tannin in them is very different. I n short, the proportion of tannin furnishes no criterion of the value of hops, a result arrived at by Briant and Meacham (J. Fed. h t . Brew., 1897, 3, 482). The addition of hop infusion to a boiled wort only removes about 4 per cent. of the total soluble noiz-coagulable nitrogen. Gallo-tannic acid, however, is able to precipitate a con- siderable amount of nitrogenous matter from malt wort to which a hop infusion has been added. There is very little doubt that the nitrogenous matter precipitated from malt wort by hop tannin belongs to the class of albumoses. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9093400361

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 373 INORGANIC ANALYSIS. Analysis of Antimony Alloys. Nicolardo t and Krell. (Papel- coiizmunicated to the Seventh I.rzternatiom1 Congress of Applied Chemistry.) - If .the oxides of antimony, obtained by treating the alloy with nitric acid, are heated to 125" to 150° C., they are rendered quite insoluble in nitric acid. They are collected in a cylinder of porous porcelain, weighed, reduced in hydrogen, and any tin present estimated. A. G. L. The Separation of Antimony from Solutions of Thioantimonates. W. Sehulte, (Metnllzirgie, 1909, 6, 214-220.)-M.agnesium powder effects so cola- plete a precipitation (hydrogen sulphide being meanwhile evolved) that it may be used as an analytical method of separating antimony from thioantimonate solutions containing no other metals of that group.I n electrolytic estimations of antimony the author finds, contrary to the experience of Fischer, that the anode (as well as the cathode) loses slightly in weight. Thus, in twenty-five estimations, twenty of which were made at temperatures of 40' to 55" C., the amount of platinum lost ranged from 0.0168 to 0.0116 gram. Under suitable conditions, antimony may be electrolytically separated from Britannia metal and deposited in a pure condition upon the cathode. I n the author's experiments a plate of Britannia metal 2 mm. in thickness, and weighing 100 to 120 grms., was used as the anode, whilst a polished iron plate (9 x 7 cm.) formed the cathode. The electrolyte consisted of a solution of sodium thioantimonate containing in 10 C.C. 0.7826 grm. of antimony.The addition of 400 grms. of sodinn1 hydroxide per litre of electrolyte caused the dissolved tin to remain in solution. A current of 255 amperes per square metre was passed through a litre of the solution at a temperature of 65" to 70" C., from day to day until, after ten days, the Britannia plate had dissolved with the exception of a small residue. The electrolyte and anode were thsn renewed, and the electrolysis continued. I n this way a very brittle plate containing 99.66 per cent. of antimony was obtained. C. A. M. Contributions from the Laboratories of the General Chemical Co. of New York. (Papel. conznauiticatcd to the Seventh Intematioml Congress qf Applied Chemistry.) - Arsenic in Brimstone. - The sample is oxidised by a mixture of374 THE ANALYST. 3 volumes of carbon tetrachloride and 2 volumes of bromine, followed by nitric acid.A little water is added and the whole evaporated, arsenic being determined in the residue by the Narsh or Gutzeit method. I-lrseizic in Szilphziric Acid.-Arsenic, when more than 0-002 per cent. is present in concentrated sulphuric acid, is reduced by adding tartaric acid. The excess of the latter is removed by heating, and arsenious acid titrated with iodine solution, after neutralisation with ammonia and sodium bicarbonate. Sz~LTplzz~r in Pyrites Cinders.-The sample is heated with a mixture of 1 part of sodium carbonate and 4 of zinc oxide, air being allowed access. The sulphate formed is extracted with water and titrated with standard barium chloride solution in the presence of alcohol, an excess of barium chloride being added, which is titrated back with sodium carbonate solution.Marsh or Gziteeit Tests.-Suspension of the hydrogen evolution due to the presence of impurities such as lead in the zinc used, may be obviated by adding a colloid to the acid solution. Elect?.o-titrimetel’.-The concentration of acids, alkalies, and salts in solutions is estimated by comparing the electrical resistance of the solution with that of a standard solution at the same temperature by means of a device similar to a Wheat- stone bridge. A. G. L. Rapid Analysis of Babbitt Metal. P. H. Walker and H. A. Whitman. ( P a p r conLmzmicnteil to thc Seveizth Iilzterizntioual Coizgress of Applied Chemistry.) --Babbitt’s metal is analysed rapidly by taking separate portions for the different constituents : For copper the alloy is decomposed with hydrochloric acid, to which a little nitric acid is added; the solution is evaporated, the residue dissolved in alkaline tartrate solution, and invert sugar added; the cuprous oxide formed is filtered on asbestos, dissolved in nitric acid, and the estimation finished volumetric- ally.For lead, the alloy is decomposed as above, and lead estimated as chloride. Sntimony and tin are estimated by W. H. how’s volumetric method (ANALYST, 1907, 32, 101). Corrections are made for the quantities of copper and lead lost. A. G. L. Estimation of Boric Acid. R. Mandelbaum. (Zcit. cmorg. Chem., 1909, 62, 361-369.)-The author has modified the methyl-alcohol method for boric acid SO as to render itj possible to complete an estimation in two to threa hours with an accuracy of within 0.2 per cent.on the boric acid. About 0.7 to 0.8 grm. of a borate is dissolved in a 150 C.C. glass flask by adding about 4 C.C. of 40 per cent. phosphoric acid, and \Tanning very gently, if necessary ; sufficient phosphoric acid must be present to convert all bases into primary phosphates, and no escape of steam may take place. The flask is then connected by an exit tube to a condenser, and by an inlet tube reaching to the bottom of the flask with an empty flask of 300 C.C. capacity, to the bottom of which air free from carbon dioxide is supplied. When all carbon dioxide has been driven out of the apparatus, the exit end of the condenser is connected with a flask containing a measured quantity of standard sodium hydroxide solution in excess of that necessary to combine with the boric acid; an exit tube from this flaskTHE ANALYST.375 leads to a second condenser, connected to an empty flask carrying a, soda-lime tube to exclude atmospheric carbon dioxide. Abwt 30 C.C. of methyl-alcohol are then introduced into the flask containing the sample through a tap-funnel, and 120 to 140 C.C. of methyl-alcohol are similarly added to the empty flask between this flask and the air-supply. Both flasks are then heated by means of water-baths to a temperature not exceeding SO" C., and a current of air, at the rate of twd to three bubbles per second, is led through the whole apparatus. After about one to one and a half hours the whole of the methyl-alcohol has been distilled from both flasks ; without disconnecting the apparatus, the flask containing the sodium hydroxide is now heated until practically all the methyl-alcohol has been distilled off into the last flask.The first receiver containing the sodium hydroxide is now cooled rapidly, 50 per cent. of pure glycerin and a little phenolphthalein are added, aud the excess of sodium hydroxide is titrated with standard sulphuric acid. A. G. L Simplified Method for Estimating the Calorific Power of Combustible Gases. P. Lemoult. (Paper conzmuizicnted to the Seventh Iutenzational Congress of Applied Chenzistry.)-The calorific power of a gas consisting of hydrogen, carbon monoxide, and methane, is calculated from the formula P = 0*909n + 3.4188, where a is the total contraction produced by the explosion in excess of oxygen followed by treatment with a caustic alkali, and b is the quantity of oxygen consumed.The formula depends on the facts that the contraction and oxygen consumption are the same for hydrogen and carbon monoxide, and that the calorific heats per molecule are almost identical. A. G. L. Precipitation of Copper as Oxalate. F. A. Gooeh and H. L. Ward. (Zcit. ano~*g. Chem., 1909, 62, 34S-359.)--The conditions under which copper is precipitated completely as oxalate, independently of the quantity of copper present, were studied, and it was found that precipitation is complete if 3 or 4 grms. oxalic acid are added to the copper salt (sulphate or nitrate) dissolved in 50 or 100 C.C.of 50 per cent. acetic acid, the solution also containing 5 to 10 per cent. of free nitric acid. The free nitric acid is added to prevent hydrolysis of the copper oxalate, the basic salt being more soluble than the neutral salt ; the presence of acetic acid prevents supersaturation of the solution with copper oxalate which, if allowed, leads to serious errors when only small quaDtities of copper are present. The precipitated oxalate is washed with small quantities of water, dissolved in dilute sulphuric acid, and titrated with standard potassium permanganate solution. The results obtained are accurate t o a few tenths of a mgm. A. G. L. Volumetric Estimation of Copper in Sugar Analysis. E. B. Holland. ( J . Ind. and Eng. Chenz., 1909, 1, 313; Chem. Zed. Bep., 1909, 33, 321.)-The precipitate of cuprous oxide collected on the asbestos filter is dissolved in 5 C.C.of strong nitric acid, and the solution is washed into a conical flask with hot water. It is then evaporated to a small volume and treated with 20 C.C. of a saturated solution of zinc acetate and 20 C.C. of a solution of potassium iodide containing 165 grms. of the salt per litre ; the iodine liberated is then titrated with thiosulphate solution.376 THE ANALYST, The copper equivalent of the thiosulphate is determined by diluting 25 C.C. of standard copper solution with water, evaporating to a small bulk and titrating as described above. The standard copper solution is prepared by dissolving 10 grms. of pure copper in 200 C.C. of strong nitric acid and diluting to 1 litre.J . F. B. Analysis of Mixtures of Halogen Acids. W. M. Dehn. ( J . Anzer. Clwm Soc., 1909, 31, 525-529.)--The author’s method for the analysis of a mixture contain- ing, e.g., bromide, hypobromite, and bromate, is based upon the following : (1) The precipitation in alkaline solution of the bromide as AgBr ; (2) the decomposition of the hypobromite by means of ammonia (SNaBrO + 2NH, = N, + 3NaBr + 3H,O), or by hydrogen peroxide (NaBrO + H,O, = 0, + NaBr + H,O), and the precipitation of total halide as AgBr in aZkaZiize soIution ; (3) the decomposition of the hypobromite with ammonia, the reduction of the bromate by iron and dilute sulphuric acid, and the titration in acid solution of the total bromide. The methods are rapid and accurate. Method I., for Bromide.-A measured volume of the mixture is treated someahat slowly with an excess of TG silver nitrate, the liquid being meanwhile vigorously shaken.Silver oxide is precipitated in the alkaline solution after all the bromide has been precipitated, and is recognised by its dark brown colour. The original solution must be decidedly alkaline, and if not it is made so by the addition of caustic soda before the silver solution is run in. Dry acid sodium carbonate is then added to convert the caustic soda into carbonate and the silver oxide into carbonate, the colour of the precipitate changing from brown or black to yellowish. (This addition of acid carbonate is necessary only with chlorine mixtures ; it may be omitted in the case of bromide mixtures, and must be omitted with iodine mixtures.Fixed alkalies but not carbonates dissolve silver chloride.) The well-shaken precipitate is freed by decantation from the solution, a Gooch crucible being employed to coil& any pre- cipitate, washed, and the Precipitate treated with dilute nitric acid, and the silver nitrate in the filtrate titrated by the usual Volhard method. -Method II., f o r Hypobromite.-A measured volume of the mixture is treated with a slight excess of ammonia or hydrogen peroxide, and if the former is used, any excess must be got rid of by boiling, since it dissolves silver halide. The liquid is then treated with silver nitrate and sodium bicarbonate, etc., as before. The liquid may here be filtered through a paper filter. The titration gives the total of halide plus hypohalite in terms of halide.Method III., for Totcd Halogen und Bromate.--A measured volume of the mixture is treated with hydrogen peroxide or ammonia to decompose the hypohalite, freely diluted with water, and the bromate reduced by addition of finely-divided iron, very dilute sulphuric acid being added while shaking vigorously. After stand- ing in a closed flask for ten minutes to one hour, the solution is filtered, treated with excess of silver nitrate, and the nitric acid added and the solution boiled to oxidise the ferrous salt. The excess of silver is titrated in the cooled solution with thio- cyanate, the iron in solution acting as indicator. The silver nitrate used is equiva- lent to the total halide present, and the difference between the silver used in this method and in Mehhod 11.is equal to the bromate in terms of silver nitrate.THE ANALYST. 377 Chlorine and iodine mixtures are analysed similarly. Since silver iodate is insoluble in neutral, but soluble in alkaline, solution, while silver iodide is insoluble in both, a considerablequantity of sodium hydroxide must be added in Method I. to keep the iodate in solution. The precipitate must be dark-coloured, and no bicar- bonate should be used. I n Method 11. enough ammonia is added to decompose the sodium hypoiodate and to keep the silver iodate in solution. A. R. T. Estimation of Lead in Tin-plate Vessels, Alloys, etc. F. Knopfle. (Zeit. Uiztemuch. Nab-. Gsizzusm., 1909, 17, 670.)-The ordinary method of separating lead from tin by treating the alloy with nitric acid and filtering the resulting lead nitrate from the metastannic acid cannot be employed if the alloy contains much iron.The ferric nitrate formed always dissolves a portion of the metastannic acid, which is thrown down together with the lead when the latter is precipitated as suIphate in the usual way. The following process is therefore proposed for the estimation, the tin being converted from metastannic acid into stannic phosphate. From 0.5 to 1 grm. of the alloy, in the form of shavings, is treated in a porcelain basin with concentrated nitric acid (sp. gr. 1.50 to 1-52), exactly 1 C.C. of acid being added for each 0.1 grm. of metal taken. The basin is then covered, and water is added drop by drop until red vapours cease to be evolved.The mixture is next evaporated until a moist residue is obtained ; if the evaporation be continued to dryness, the residue must be moistened with nitric acid. Hot sodium phosphate solution is now added with constant stirring, and, after the addition of 50 C.C. of hot water, the crystalline precipitate of stannic phosphate is collected on a filter and washed. The lead is then estimated in the filtrate. Should the iron separate as oxide during the (-vaporation, it may be again brought into solution by warming after the addition of a few drops of nitric acid. The method is stated to yield accurate results. w* P. s. Volumetric Estimation of Lime in Presence of Dissolved Silica. K. Bal- thasar. (Chenz. Zeit., 1909, 33, 646-647.)-By the following method, lime in cement, etc., may be estimated in thirty t o forty minutes : 0.7 grm.of the sample is completely decomposed with hydrochloric acid in a small porcelain dish, which is warmed if necessary. The yellow syrupy mass is then transferred to a 350 C.C. Erlenmeyer flask provided with a mark in its preferably narrow neck. After boiling the solution for two minutes to expel carbon dioxide, about 50 C.C. of a reagent are added, consisting of 25 grms. of animonium chloride, and 100 C.C. of acetic acid made up to 1 litre with ammonia solution. The liquid is again boiled, and 50 C.C. of The whole is then cooled rapidly, made up to the mark with water, stirred thoroughly for three minutes, and filtered through a dry filter. The excess of oxalic acid present is estimated by means of potassium permanganate solution, after adding sulphuric acid, in 50 C.C.of the clear filtrate. Ammonium acetate is added to the original solution with the ammonia because it has been found to favour the formation and settlement of calcium oxalate. oxalic acid solution are slowly added. A. G. L.378 THE ANALYST. New Method of Estimating Nickel in the Presence of Cobalt. J. A. Sanchez. ( B d . SOC. Chinz., 1909, [iv.], ‘5, 641-647.)-0n treating a solution of potassium cobalticyanide with silver nitrate, a precipitate of silver cobalticyanide, which is insoluble in hot water and dilute acids, is produced- K,Co2(CN),, + 6AgN03 = Ag,Co,(CN),, + 6KN0,. Under the same conditions the double cyanide of nickel and cobalt is converted, not into silver nickelocyanide, but into silver cyanide and nickel nitrate- K,Ni(CN), + 4AgN0, = 48gCN + 2KNO, + Ni(NO,),.h applying these reactions to the separation of cobalt and nickel, the mixed sulphides are dissolved in hot aqzm regin, the solution evaporated to dryness, and the residue dissolved in the smallest possible quantity of hot water. The solution is neutralised, if necessary, with potassium hydroxide, and treated with a 10 per cent. solution of potassium cyanide until the precipitate is just redissolved. The solution is next evaporated to dryness to oxidise the cobaltoso-cyanide into cobalti- cyanide, and the dry residue dissolved in 20 C.C. of hot water and treated with an excess of a 10 per cent. solution of silver nitrate, until a yellowish-white precipitate is obtained.One C.C. of the silver nitrate solution should be added for each 0.1 C.C. of potassium cyanide solution previously employed. The liquid is heated and stirred before filtration, and the precipitate washed by decantation with hot water. The filtrdte is treated with sufficient 14 per cent. potassium bromide solution to precipitate the silver, and the nickel in the filtrate and washings from the silver bromide precipitated with potassium hydroxide. The precipitate is immediately oxidised with bromine water, boiled for ten to fifteen minutes, filtered off, ignited and weighed. Volzinaetric Estimation of Nickel.-The oxidised precipitate is transferred, together with the filter-paper, to a 100 C.C. flask, and mixed with about 20 C.C. of water, and 5 C.C. of a 20 per cent.solution of potassium iodide. After the addition of 5 C.C. of 20 per cent. sulphuric acid, the amount of iodine liberated by the nickel oxide is titrated with standard thiosulphate solution- Ni,O, + 2HI = H,O + 2Ni0 + I, One C.C. of a & N solution of sodium thiosulphate is equivalent to 0*000586 grm. of nickel. As little as 0.0001 grm. of nickel may be estimated by this method. Estinzation of Cobalt.-The nickel and cobalt are estimated together as sesquioxides, and the difference between the result and the amount of nickel, estimated as described above, gives the proportion of cobalt. C. A. M. Rapid Volumetric Method for the Estimation of Niobium in Presenee of Tantalum, and its Application to the Analysis of Minerals containing Niobium. F. D. Metzger and C.E. Taylor. (Zeit. afzorg. Clzena., 1909, 62, 382- 394.)-The method depends on the fact that if succinic acid be added to a bisulphate melt of niobic and tantalic oxides, the solution obtained can be diluted and heated without depositing insoluble compounds of the two elements ; in this solutionTHE ANALYST. 379 niobium only can be reduced by means of amalgamated zinc, and titrated with potassium permanganate. In applying the method to the analysis of a mineral, the weight of mixed oxides of niobium and tantalum from 0.2 to 1 grm, of sample is obtained as usual. The oxides are then fused with 5 grms. of potassium bisulphate, 10 C.C. of concentrated sulphuric acid are added, and heating continued until a clear solution is obtained. The solution is poured into a beaker, the crucible rinsed out with 30 C.C.of sulphuric acid, and the whole allowed to cool, when the solution should be perfectly clear. Two grms. of succidic acid are stirred into the liquid, after which 20 C.C. of a saturated solution of succinic acid in water are added cautiously, followed by about 200 C.C. of water, The liquid is heated to 75" C., and sent through a Jones zinc reductor (ANALYST, 1903, 28, 254), previously warmed by running through it 200 C.C. of 5 per cent. sulphuric acid at 7 5 O C., and filled with 20 per cent. sulphuric acid, also heated to 75" C. The niobium solution is followed first by 50 C.C. of 20 per cent. sulphuric acid, and then by 200 C.C. of 5 per cent. sulphuric acid. The brown reduced solution and washings are at once titrated in an atmosphere of carbon dioxide with permanganate solution.The degree of amalgamation of the zinc in the reductor is important; as little mercury as possible should be used, and the reductor is best prepared by shaking 600 grms. of sieved zinc for several minutes with 250 C.C. of a solution containing 0.5 grm. of mercury dissolved in 25 C.C. of concentrated nitric acid; the amalgamated zinc is washed first with water, then with dilute sulphuric acid, and kept under water. After each reduction, a length of several em. is removed from the reductor and replaced by fresh zinc to prevent clogging. Under these conditions niobic oxide is reduced to an oxide approximating to the formula Nb,0,.,,7, whilst tantalic oxide is unaffected. The results obtained differ from those given by fractional crystallisation of the fluorides by several per cent.; but the reduction method always showed the presence of niobic oxide in the separated tantalic oxide, and the authors regard the volumetric results (which in one case vary from 53.52 to 54-84 per cent. of niobic oxide, as against 57.13 to 56.82 gravimetrically) as much more nearly correct than the gravinietric values. A. G. L. The Volumetric Estimation of Selenious Acid. L. Marino. (Paper corn- naziiziccLted to the Seveiath I?atornatiolznl Congress of Applied Chemistyy.)--The method is based upon the oxidation of selenious acid by means of alkaline potassium perrnanganate solution. It has the advantages of being independent of conditions of concentration and temperature, and of also being applicable to insoluble selenites.Before using the reagent (preferably in oxalic acid solution is introduced, and a deduction subsequently made for the permanganate equivalent of this. The results are stated to deviate from the theoretical amounts by not more than 0.16 to 0.20 per cent. solution) an excess of C. A. M. Determination of Traces of Silver, and the Solubility of some '' In- soluble " Silver Salts. G. s. Whitby. (Paper coiitmzmicated to the Seventh lizteritntioizul Congress of Applied Chemistry.)-Whilst investigating a method for preparing a colloidal solution of silver, it was found that solutions of silver salts380 THE ANALYST. when heated with a little sodium hydroxide and certain organic bodies develop a brown or yellow colour, even when the amount of silver present is very minute.Fifty C.C. of a solution containing one part of silver in 25,000,000 parts of solution gave a recognisable colour. I t has also been found possible to apply this method to the quantitative deterinination of traces of silver. The organic substances which have hitherto been found capable of giving this colour when heated with silver solutions containing a little sodium hydroxide, are dextrin, gum arabic, glycerol, cellulose (in the shape of filter paper), starch and sucrose, but the last of these is most suitable for the determination of small quantities of silver. To 50 C.C. of the silver solutiou, appropriately diluted, are added a few drops of a fairly concentrated solution of sucrose, and the beaker containing the liquid is immersed in a bath of boiling water for two minutes.solution of sodium hydroxide are added, and the heating is continued for not more than two minutes until the colour develops. The solution is cooled, transferred to a Nessler glass, aud the colour compared with that of a standard. The standard colours are prepared from silver nitrate solutions of known strength, and are most conveniently of such strengths that 1 C.C. equals 0*000001 grm. of silver, and 1 C.C. equals 0-0000005 grni. of silver. The standard should not be prepared more than twelve hours before the actual experiment, since the colour deepens somewhat on standing. The colour produced by these minute amounts of silver is due to the presence of colloidal silver. The solutions give the Tyndall effect, and display the other characteristics of colloidal solutions of silver.The method is being applied to the determination of the solubility of sparingly soluble silver salts, particularly with reference to the conditions that, arise in analytical work. Thus, at 2 1 O C. the amount of freshly-prepared flocculent silver chloride dissolved by a litre of water was found to be 1.55 mgm. ; a result which confirms the values obtained by Kohlrausch and Rose, and by Bijttger. About 6 drops of a Reduction of Ferric Salts by Copper in Volumetric Analysis. W. C. Birch. (Chem. Nezos, 1909, 99, 273.)-The author states that ferric salts can be reduced by copper. From twenty-five to thirty pieces of pure electrolytic copper, 2 x 2& cm. in size, are washed first with dilute nitric acid and then with dilute sulphuric acid, and the acid ferric solution then added and the liquid gently boiled in a round-bottomed flask, each piece of copper being bent in the centre at right angles to prevent buniping.Reduction is complete in five minutes. Cuprous and ferrous chlorides are produced in equall proportions, and double the amount of bichromate is required for the same amount of Fe as when sulphuric acid alone is present. A small piece of calcite is added to the flask during cooling, and during titration, to prevent oxidation of the cuprous salt, As indicator, the author used a freshly prepared saturated solution of potassium ferricyanide in dilute sulphuric acid. A drop of the solution to be tested and of this indicator are mixed on a white tile, and covered from light for thirty seconds if no immediate blue colour is produced.The reaction is complete if no blue colour is shown in this time. In the case of hydrochloric acid solutions the amount of free acid should not exceed 25 C.C. of The method can also be applied to solutions in hydrochloric acid.THE ANALYST. 381 1 : 2 HCI, and it is specially necessary to have the surface of the copper perfectly clean, for if superficially oxidised, the results will of course be above the truth. A. R. T. Estimation of Phosphorus in Iron and Steel. G. Chesneau. (Paper commzmicated to the Seventh Iuternational Congress of Applied Chemistry.)-The proportion of phosphorus in the phospho-molybdate precipitate depends on the concentrations of the salts present, and on the quantity of phosphorus itself.According to the author, it is quite impossible to obtain precipitates of constant composition by one operation only. He therefore proceeds as follows : For each grm. of metal dissolved, 50 C.C. of a reagent (containing 50 grms. of ammonium molybdate, 50 C.C. of concentrated ammonia solution and 500 C.C. of nitric acid, sp. gr. 1.2, per litre) and 5 grms. of ammonium nitrate are added, and the whole is kept at 6 5 O to 70" C. for one and a half hours. The precipitate is then filtered off, dissolved in 50 C.C. of ammonia solution (1 : 4), the solution is exactly acidified with nitric acid, mixed with 15 C.C. of the reagent, and kept at 40" C. for two hours. The precipitate now obtained is filtered off, washed with water, and dried at 105" C., or, dissolved in ammonia solution, evaporated to dryness, and ignited at 400" to 450" C.The dried precipitate contains 1.60 per cent. of phosphorus ; the ignited precipitate 1-69 per cent. A. G. L. On the Gases liberated by the Action of Cupric Salts on Steel. E. Goutal. (Paper conzinzLnicatccl to the Seventh Iuternntioiinl Coizgwss of Applied Clztmisti.y.) - Amongst the gases produced by the action of a slightly acid, concentrated potassium cupric chloride solution on steel is found a small quantity of carbon monoxide, which appears to exist as such in the steel. Its quantity, which may be estimated by its action on iodic anhydride (1205) or on oxygenated hzmoglobin, amounts to from 0-006 to 0.014 per cent. of the weight of the metal. w. P. s. Analysis of Tungsten Steel. F. W. Hinrichsen. (Paper comizuizicated to the Seventh International Coizgress of Applied Chemistry.)-In the analysis of tungsten steels, great difficulty occurs in the phosphorus determination. ,The following method is said to give satisfactory results : The nitric acid solution of the tungsten steel is evaporated to dryness, and the residue is fused with sodium peroxide. On subsequent solution in water, all the tungsten (and chromium), and the whole of the phosphorus is recovered. From one portion of this solution the three elements just mentioned are precipitated quantitatively by mercurous nitrate, and after ignition a mixture of tungstic acid, chromic oxide, and phosphorus pentoxide is obtained. In another portion of the solution the chromium is determined volumetrically, and in tt third the phosphoric acid is estimated as follows : After neutralising, and rendering alkaliue with ammonia, precipitation is effected by magnesia-mixture (Jorgensen's method). In order to remove these the magnesia-mixture precipitate is dissolved off the filter by In this way very minute quantities of tungstic acid are precipitated.382 THE ANALYST. the aid of nitric acid, and the phosphoric acid separated by Finkener's method of precipitation in presence of tartaric acid. Analysis of Wolfram and Hubnerite. P. Nicolardot. (Papel. conziituizicated to the Seventh Interizatioizal Congress of Applied Chemistry.) - Wolfram and Hiibnerite are very easily decomposed by fusion with alkalies. To separate tungstic acid from silica, the mixed oxides are heated at 400' C. in a current of air incompletely dried and saturated with chloroform vapour. Tungsten volatilises in the form of oxychlorides ; silica remains unaffected. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9093400373

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

382 THE ANALYST. APPARATUS, ETC. Adsorption : with Special Reference to the Rising of Saline Solutions in Filter-Paper. R. Krulla. (Zeit. physik. Chesn., 1909, 66, 307-348 ; through C7ze?12. Zeit. Rep., 1909, 33, 325.)-If fairly dilute saline solutions are adsorbed by vertical strips of filter-paper, it is found that the salt does not rise to the same extent in the paper as the water. If the percentages of a simple salt present in solution are marked off as abscism, and the heights to which the salt rises from the corresponding solutions, when the height to which the water rises is kept constant, are entered as ordinates, a curve is obtained which rises rapidly at first and then tends t o become parallel to the horizontal axis. If now the height to which the salt in the 1 per cent.solution rises is divided by the height of the salt in the 21 per cent. solution, and the quotient multiplied byp, number; are obtained which, entered as ordinates on the corresponding abscissae, give rise to a straight-line curve which is constant for all salts, and has the equation : y = 0.8353~ + 0.1670. Some consequences of this law are discussed in the paper. Further, it is found that in solutions of several salts the adsorption of the individual salts is not affected by the presence of the other salts provided that they possess no ion in common, and that no chemical reaction takes place. If the salts possess a common ion, then the adsorption of each is diminished. The adsorption of highly dissociated salts is often less than that of salts less dissociated. The author assumes from this that salts are completely dissociated at the contact surface of water and amorphous body (paper) ; the greater the concentration of the products of dissociation in the solution, the more of the salt is adsorbed.In highly concentrated solutions the quantity adsorbed diminishes with increase of concentration, as does the electrical conductivity. Under similar conditions different salts are adsorbed to a varying extent-ie., each salt has an adsorption constant. Salts may also be split up to a slight extent by adsorption, free a1kal.i or free acid being produced in the residual solution. The paper concludes with some applications of the above results to analytical work. A. G. L. The Centrifuge in Quantitative Analysis. H. G.Parker. ( J . Amer. Clzeni. SOC., 1909, 31, 549-556.)-The great majority of precipitates obtained by the usual gravimetric methods can be separated by the centrifugal method froin the solutionsTHE ANALYST. 383 containing them, and the method is rapid and the separation of the precipitate complete. The author uses for this purpose a centrifuge of substantial design, driven by an electric motor. To a cast-iron head at the top of the spindle of the machine are attached two steel arms 3 mm. thick and 20 mm. wide. The rings for supporting the jackets holding the separation flasks are screwed to these arms, and the jackets are of brass tube, silver solder being used to secure the bottom of the jacket and the flange at the top to the tube, as ordinary soft solder was found to be useless. The radius of rotation was about 20 cm., and 1,500 to 1,800 revolutions per minute for two or three minutes were the usual speed and time adopted in this work.As precipitating flask, a vessel 14 emL. long, with diameter at widest part of 3.5 cm., is used, such vessel holding about 75 C.C. This vessel at its neck (lower end) fits into a weighed platinum crucible in a firm water-tight joint made with a short section of pure rubber tubing, the latter being held between the outside of the neck of the flask and the inside of the crucible. Two sizes of crucible are employed-one 10 mm, diameter by 20 mm. long, and the other 15 mm. by 27 mm. long. The edges are nearly parallel and fairly stout. The flask and crucible thus connected are fitted into a metal container or jacket, as usual, the flask being supported on a short section of metal tubing, the crucible resting squarely on the bottom of the jacket.The space between the flask and jacket is filled with water, so that the hydrostatic pressure is the same inside and outside, and any tendency to leak when the spindle is rotated is eliminated. The solution is placed in the separating flask with its attached crucible, and the necessary reagent added. This may be done without danger to the rubber bushing on the neck of the flask by placing a ring of asbestos paper round the crucible below the rubber. The platinum is cooled by the solution, and the bushing is preserved; but care must be taken not to allow the flame to come into contact with the platinum immediately over the rubber.The heating of the solution in this flask is conveniently done by means of a small copper plate provided with a hole or socket in which the crucible rests, the plate being covered with asbestos board. The plate may be lowered away froin the crucible, the flask being held in a clamp and the boiling thus regulated, and, when precipitation is complete, the whole apparatus (flask and crucible) is rotated. The solution is drawn off by siphon, and wash-water then added to the flask contents, stirring up the precipitate with the jet of water ; three more washings with sinall quantities of water are usually sufficient. The crucible may then be removed from the flask and dried, ignited, etc., as required. I t is convenient to run duplicate determinations, so as to keep the two arms of the centrifuge equally loaded.If the amount of solution is larger than can be accommodated in the flask, it is transferred in portions uutil the whole of the precipitate is obtained in the crucible. Occasionally, with the larger crucible, the stoppage of the centrifuge carried light particles from the surface of the precipitate into the flask. This was pre- vented by hanging over the edge of the flask, during rotation, a stirring-rod with a slight pear-shaped enlargement at the lower end, which just reached inside the mouth of the crucible, and hung centrally, forming a loose stopper which prevented upward currents, but did not prevent the downward passage of the precipitate. No The solution may, if required, be boiled.384 THE ANALYST, weighable amount of precipitate was ever found in the wash-waters, though some precipitates, such as sulphur, do not separate well.The method is accurate and rapid, tedious filtration and the burning off of filter- papers being avoided. The crucible is small and quickly cooled, and there is little exposure to the air. A. R. T. Apparatus for Extracting Liquids with Ether. A. H. Fiske. (Anzer. Chewz. J., 1909, 41, 510-515.)-This apparatus, which is preferred to that of van Rijn (Ber., 1895, 28, 2387), as it is capable of extracting over 1 litre of liquid at a time, consists of a flask, A, connected with a reflux condenser, B, between the two l B i being a trap, C, from which the distillate runs to the flask D, which contains the liquid to be extracted.The trap C consists of a small bulb, connected with the mouth of the condenser tube by a piece of rubber connection tubing, and is a modification of that of Boessneck (Chenz. Zeit., 1890, 14, 870). D is a distilling flask of 500 C.C. or 1,000 C.C. capacity, with side-tube. The solvent is distilled off from A, and the vapour condensing in B drops into the well of the trap C, running into D down to the bottom of the fiask, finally rising through the liquid, and carrying with it in solution some of the substance to be estracted from the liquid in D. The solvent ultimately overflows from D back into A, whence it is again distilled, When the liquid in D is to be renewed, the siphon fitted in D, as shown in the figure, serves to draw off the liquid, and further quantities may be run in through the funnel; this should have a stem long enough to dip under the surface of the liquid to prevent the escape of vapours from the side-tube connected with the flask A.To extract solutions of high sp. gr., the vertical distance from A to C should be increased until the column of ether in the delivery tube from C is sufficiently heavy to start the circulation, forcing the solvent through the heavy liquid in D. The trap C may also be used in ordinary distillation work, a U-shaped bend being made in the delivery tube to form a liquid seal and prevent the escape of vapours. A. R. T. An Apparatus for Continuous or Intermittent Extraction. H. Vigreux. (BzdZ. SOC. Chinz., 1909 [iv.], 5, 699-'702.)-The apparatus shown in the figure consists of st cylinder, A, pierced by four symmetrical openings, a, near the base, and provided with an indented lip, B.This cylinder fits over an open tube, B, in the top of which is a notch, c, to receive the siphon C, and is kept in position by the movable corks d. The holes n in the cylinder are wrapped round with cotton cloth over which is fixed fine mire-gauze, so that the liquid is filtered before being siphoned over, and the extractor thus connected together is placed in the pear-THE ANALYST, 385 shaped vessel. The tapering extremity of this is fitted into the cork of a flask con- taining the solvent, whilst its mouth is closed by a cork through which passes the outlet tube of a reflux condenser which is so fixed that the condensed liquid drops on to the indented lip of the cylinder A.Thence it falls on to the material to be extracted, which is placed in -the pear-shaped vessel, passes through the filtering C Fig. 2. material covering the holes a, and fills the cylinder to the level of the top of the tube B, being then siphoned over into the lower flask. If the siphon be removed, the extraction becomes continuous. The height of the tube 13 in the cylinder is regulated by the position of the corks d, and the liquid may thus be siphoned off under different pressures, which may be increased or reduced according to the difficulty of filtration of the extract. C. A. M. Glass-cutting by Means of an Electric Wire. F. L. Jouard. (J. Amer. Chem. SOL, 1909, 31, 654.)-Glass tubes, bottles, etc., may be cut in two quite smoothly by passing an electric current through a length of thin resistance-wire which has been wound round the glass vessel and carefully adjusted.The current from the 110-volt lighting circuit mBy be used, and, apart from the resistance-wire, the only apparatus required is a couple of pieces of No. 18 insulated copper wire, a pair of ring-stands, and a suitable rheostat. The vessel must be quite dry, and should have a file-scratch on it to provide a starting-point for the crack. After joining the ends of the resistance-wire to the copper leads, fixing the latter at any386 THE ANALYST. desired height by means of the ring-stands, and connecting the rheostat in series, the resistance-wire is fastened in a single loop round the glass vessel so as to pass directly over the file-mark, and drawn taut by moving the ring-stands.A particle of asbestos paper is inserted between the crossed ends of the loop, and enough current is turned on to heat the wire to dull redness. The crack always follows the path of the resistance-wire, whether this path be straight round the vessel or in the form of a curve or spiral. w. P. s. An Automatic Pipette for Sodium Hydroxide Solution. F. G. Benedict. (J. Amer. Chein. SOC., 1909, 31, 65%654.)-The apparatus described is particularly intended for delivering quantities of concentrated sodium hydroxide solution as required for the neutralisation of the concentrated sulphuric acid used in the Kjeldahl method of estimating nitrogen. Owing to the viscosity of the solution the glass tubes employed in the construction of the apparatus are of large diameter ; rubber tubing is dispensed with as far as possible, and the portion of rubber tubing subjected to most wear ; i.e., the part B can be replaced without disturbing the whole apparatus.Furthermore, the V-shaped piece of rubber A minimises the wear on B. The pipette itself consists of a glass cylinder, D (an ordinary lamp-chimney may be used), with a two-hole rubber stopper, G, inserted in the base; in one of the holes is fixed the end of the tube leading from the carboy of concentrated sodium hydroxide solution, and in the other is inserted the tube F, which serves as the shut-off from the reservoir is opened simultaneously, allowing the sodium hydroxide solution to flow into the pipette. The bottle is held suspended until the level of the liquid rises to a mark fixed arbitrarily on the side of the pipette; at that moment the bottle is lowered, cutting off the supply of solution and displacing a definite volume of the solution through the overflow tube into the distillation flask or other vessel.The mark on the pipette may be so adjusted that the quantity of alkali discharged will be more than sufficient to neutralise the sulphuric acid used for the digestion. w. P. s. Acheson Graphite a Substitute for Platinum Electrodes. J. W. Turren- tine. (Paper communicated to the Seventh International Congress of Applied Claenzistry.) -Acheson graphite has been found to be a satisfactory substitute for platinum in the construction of insolubIe electrodes to be used for electrolytic work.The electrodes used are 15 x 2.5 x 0.5 cm. ; one end is electroplated with copper, and a copper wire is387 THE ANALYST* then soldered on. treated with molten paraffin wax, of the inaterial or the nature of the deposit. by turning on a lathe. in thickness, the weight being 3.5 grms. the best methods of manipulation, etc., with graphite electrodes. To render the electrodes non-absorbent, they are heated and then This treatment does not affect the conductivity A graphite dish has also been obtained The capacity of the dish is 200 C.C. ; its walls are only 1 mm. Experiments are in progress to ascertain A. G. L. A New Viseosimeter. Stormer. ( J . I d . awl Eng. Chenz., 1909, 1, 317-318.)-1n this apparatus a small paddle-wheel, driven by a constant force, ifi made to revolve in about 50 C.C.of the liquid, and the number of revolutions made in a given time is recorded on the dial of an indicator. The variation of the temperature during the test is negligible, and the results are stated to be inore concordant than those obtained with many of the types of apparatus measuring the efflux velocity of a fluid, The revo- lution of the wheel is instantly stopped by means of a brake at the desired moment. C. A. M. INSTITUTE OF CHEMISTRY. PASS LIST : JUNE-JULY EXAISINATIOKS, 1909. OF twenty-nine candidates who presented themselves for the Intermediate Examina- tion, the following seventeen passed: W. Caw, A. P. Clark, R. L. Collett, B.A. (Cantab.), W. Dickson, S. Elliott, R. H. Ellis, N. Evers, J. E. Hackford, A. D. Hey- wood, F. E. Laughton, J. R. Nicholls, W. M. Paulley, B.A. (Cantab.), G. C. Petrie, E. F. Pollock, S. Robertson, T. Schwarz, and J. A. L. Sutcliffe. One candidate presented himself for a General Examination for the Associateship, and passed . L. Knight, 9.R.S.M. Six candidates presented themselves for the Final Associateship Examination in the Branch of Mineral Chemistry, and four passed: H. L. Allen, B.Sc. (St. hndrews), R. H. Pindlater, R. Gawler, B.Sc. (Leeds), and G. A. Smiley, B.Sc. (Lond.). In the Branch of Metallurgical Chemistry, of five examined, three passed: A. Marcan, A. Marks, A.R.C.Sc. (Lond.), and A. W. Schultz, A.C.G.I. Of seven candidates who presented themselves in the Branch of Organic Chemistry, the following three passed : R. Boyd, B.Sc. (Glas.), C. S. Garland, B.Sc. (Lond.), h.R.C.Sc. (Lond.), and J. Young. I n the Examination in the Chemistry of Food and Drugs, and of Water, of nine who presented themselves, five passed: F. S. Auiuonier, W. G. Carey, R. D. Carty, A.R.C.Sc.I., T. R. Greenough, B.A. (Cantab.), and C , E. Sage. One of the candidates, C. E. Sage, was examined for the Fellowship.

ISSN:0003-2654    

DOI:10.1039/AN9093400382

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

388 THE ANALYST. NEW BOOKS. MODERS ORGANIC CHEMISTRY. (Conteinporary Science Series.) By C. A KEANE, D.Sc., Ph.D. London and Felling-on-Tyne : The Walter Scott Publishing Company, Ltd. 1909. 8vo. 488 pp. 29 illustrations. Cloth. 6s. net. The subject-matter is subdivided and classified as follows : I. Historical Development of Organic Chemistry. IT. The Structure of Organic Compounds. 111. Classification of Organic Compounds. IV. The Aliphatic Hydrocarbons. V. The Cyclic Hydrocarbons. VI. Meltingpoint and Boiling-point of Organic Compounds. VII. The Sources of the Hydrocarbons. VIII. Hydrocarbon Deriva- tives. IX. Ethereal Salts. X. Derivatives of the Hydrocarbons containing Nitrogen. XI. The Laboratory Methods of Organic Chemistry. XII. Stereo- chemistry. XIII. The Sugars. XIV.Isomeric Change and Dynamic Isomerism. XV. Heterocyclic and Polycyclic Compounds. XVI. Synthesis of Physiologically Active Organic Compounds. EXERCISES IX PHYSICAL CHEMISTRY. Translated by A. T. CAUERON. London : hrchibald Constable and Co. 1909. 8vo. 190 pages of subject-matter, with 49 illustrations and index. Cloth. Price 6s. net. 11. Determination of Density. 111. Determination of Moiecular Weights in Solution. IV. Thermo- Chemistry. V. Determination of Optical Constants. VI. The Thermostat. VII. Chemical Statics and Dynamics ; Electro-chemistry. VIII. Foundations. IX. Electrical Conductivity. X. Faraday’s Law ; Transport Numbers. XI. Measure- ment of Differences of Potential. XII. Electrostatics. Appendix. LABORATORY NETHODS OF INORGANIC CHEMISTRY.By H. and W. BILTZ. Xuthorised translation by W. D. HALL a d W. C. BLANCHARD. First edition. New York : J. Wiley and Sons. London : Chapman and Hall. 1909. 8vo. 244 pp., illustrations and index. Cloth. Price 12s. 6d. net. The material, as shown by the table of contents, is arranged according to the types of compounds. The contents comprise : Elements ; Changes of Condition ; Simple Compounds ; Compounds containing a Complex Negative Component ; Compounds containing a Complex Positive Component ; Complex Non-Electrolytes ; Preparation of Compounds of the Rare Elements from their Minerals. By W. A. ROTH, Ph.D. The subject-matter is divided as follows : I. Introductory. The work is essentially a course of inorganic chemical preparations. INTERNATIONAL FOOD CONGRESS. (Society of the White Cross of Geneva.) THE second meeting of this Congress for the Repression of Adulteration in Foods, Chemical Products, Drugs, Essential Oils, etc., will be held in Paris from October 17 to 24, under the Presidency of Professor Bordas. Section I. deals with Alimentary Technology ; President, Professor Muntz. Section 11. : Hygiene ; President, Dr. Landouzy. Section 111.: Crude Drugs, Essential Oils, etc.; President, M. D. Guignard. The Hon. Secretary in the United Kingdom is Mr. L. M. Douglas, of 3, Lauder Road, Edinburgh, to whom all inquiries should be addressed.

ISSN:0003-2654    

DOI:10.1039/AN9093400388

出版商:RSC    

年代:1909

数据来源: RSC