ORGANIC ANALYSIS 97 ORGANIC ANALYSIS. Colorimetric Estimation of Acetylene. E. K. Weaver. (J. hmr. Chem. SOC., 1916, 38, 352-361.)-The gas containing the acetylene is first freed from hydrogen sulphide and from large amounts of oxygen and carbon dioxide, if present, and then passed through one or more fine orifices (0.2 mm. in diameter) into an absorbing solution, prepared as follows : About a quarter of a grm.of gelatine is dissolved in 500 C.C. water, the solution diluted with 500 C.C. alcohol, and 135 grm. hydroxylamine hydrochloride added. Of this stock solution, 20 C.C. are mixed with 10 C.C. of concentrated ammonium hydroxide solution, and one or two cgrms. of cuprous chloride are added, This serves to absorb the acetylene, the gelatine acting as a protective colloid with the result that a clear colloidal sol of copper acetylide of an intense red colour is obtained.After the absorption, the solution is diluted to 100 C.C. and compared in a. colorirneter with a standard which has been chosen. The standard used by the author contained 0.21 mgrm. Chromanilbraun R, 0.04 mgrm, Carmoisine B, and 2.5 grms. gum arabic in 100 C.C. If 10 C.C.of this solution be used as standard, the amount of acetylene in 100 C.C. of colloidal sol may be calculated from the equation x= 0,143 y + 0.03, where x = number of mgrms. of acetylene and y=the reciprocal of the number of C.C. of colloidal solution re- quired to match the standard. A more convenient but less accurate standard is a fixed depth of a solution of azolitmin. Amounts of acetylene as small as 0.03 mgrm.may be detected and amounts up to 2 mgrms. may be estimated within 0.05 mgrm. G. C. J. Modification of Mohler’s Reaction for Benzoic Acid. J. Grossfeld. (Zeitsch. Ufitersuch. Nahr. Genussm., 1915, 30, 271-273 ; through C h m . Zentralbl., 1915, ii., 1313-1314.)-Whilst the method described by Von der Heide and Jacob98 ABSTRACTS OF CHEMICAL PAPERS for the detection of benzoic acid (ANALYST, 1910, 35, 166) is trustworthy, the reduc- tion of the dinitrobenzoic acid with ammonium sulphide, as recommended by Mohler (cf.Halphen, ANALYST, 1908, 33, 420), is not satisfactory. The following modification of the test is therefore proposed, the reduction being brought about by means of hydroxylamine : The dry alkali benzoate residue is heated on a water-bath for twenty minutes with a mixture of 0.1 grm.of potassium nitrate and 1 C.C. of con- centrated sulphuric acid, then cooled, diluted with 2 C.C. of water, again cooled, and treated with 10 C.C. of 15 per cent. ammonia and 2 C.C. of 2 per cent. hydroxylamine hydrochloride solution. A red coloration develops more or less rapidly according to the quantity of benxoic acid present; if the mixture is heated, the reaction is accelerated, and the coloration reaches its maximum intensity when the solution is again cooled.w. P. s. Simultaneous Estimation of Carbon, Hydrogen, and Mercury in Organo- Mercuric Compounds. Grignard and A. Abelmann. (BziZZ. SOC. Chim., 1916, 19, 25-27.)-1n the combustion analysis of organic compounds containing mercury no satisfactory method was previously available for the complete condensation of the m'ercury vapours separately from the water.The authors have devised a form of combustion-tube, in which gold is employed for absorbing the mercury, while the water vapours pass on to the absorption vessels. The combustion-tube, A (see Fig.), of the usual open type, is constricted (as at e ) a short distance before the point at which it emerges from the furnace.The tube is continued for about 20 cm. beyond the constriction, and a narrower tube, B, is inserted from the open end, being held in position by a cork. The tube B is drawn out to a point, which penetrates the constriction, e, and is packed therein by a conical sleeve of calcined asbestos. This sleeve is composed of strips of thin asbestos paper about 15 inm. wide, moistened and moulded to the correct form on the point of the tube B, then dried and ignited in a crucible.The mercury vapours passing forward during the combustion enter the tube B through the constricted orifice, and are absorbed therein by gold leaf, or preferably by a helix of gold wire 0.2 mm. thick, 12-15 cm.long, and a few mni. in diameter. If the asbestos joint were perfectly gas-tight, there would be no difficulty in collecting the whole of the mercury in the tube B, but in practice there is a slight tendency for the mercury and water vapours to leak through into the space between the two tubes. This trouble is avoided by fusing a sinall tubulure, t, into the further end of the tube A , and introducing through this tubulure a current of dry purified oxygen at a pressure slightly higher than that existing in the com- bustion-tube. The slight inward leakage of oxygen through the joint is sufficient to ensure that the whole of the products of combustion pass down the tube B.The heat of the furnace is so manipulated that no condensation can occur in the packing,ORGANIC ANALYSIS 99 while the projecting portion of the tube is surrounded with metal gauze and gently heated so that the water vapour passes on to the absorption apparatus.Certain organo-mercury compounds are dificult to burn, and must be mixed with powdered copper oxide ; the presence of halogens necessitates the use of lead chromate in the ordinary manner. The mercury tube is cooled in the desiccator and weighed after the combustion ; the mercury is then expelled by connecting the tube with a water aspirator and heating at 400' C. J.2'. B. Differentiation and Valuation of Erythrosin and Bengal Rose. A. Leys. (AWL Chim. anal., 1916, 21, 25-32.)-Erythrosin, the sodium salt of tetraiodo- fluorescein, usually contains only a trace of chlorine attached to the resorcinol nucleus, and shows little or no fluorescence, whereas Bengal rose (the sodium salt of tetraiododichlorfluorescein) in which the chlorine is largely present in the phthalic nucleus, shows pronounced fluorescence.I n estimating the value of these dyestuffs it is therefore necessary to determine the amount of substitution, and their relative proportions of chlorine and iodine..Moisture.-A weighed quantity is dried at 100' C. Minerat Matter.-From 2 to 3 grms. are extracted in a Soxhlet apparatus with 200 to 250 C.C. of absolute alcohol, until the oxtract is nearly colourless. The alcoholic solution is evaporated to obtain the pure colouring matter, the residue is extracted with boiling water, the extract made up to definite volume, an aliquot portion evaporated, and the saline residue ignited and weighed.Estimation of the Amount of Substitution.-From 2 to 3 grms. of the pure dyestuff separated by the extraction with alcohol are fused with 5 to 10 grms. of potassium hydroxide and 10 to 15 grms. of sodium carbonate, the melt dissolved in boiling water, and the solution made up to 200 C.C. The total halogens in 25 C.C.of the solution are then estimated by titration with & silver nitrate, and the number of C.C. required by 100 grms. of the pure dyestuff compared with those required by erythrosin and Bengal rose. The following table gives the values shown by compounds found in commercial products : Formula. C,H,O,I,Na,, Erythrosin . . . . . . . . . . . . C2,H,0,13CNa,, Chloriodo-erythrosin ...... ... C,,H,O,I,Na,, Incomplete erythrosin , . , , . . . . . C,,H70,1,C1Na2, Incomplete chloriodo-erythrosin . . . C,H80,Cl,Na,, Sodium dichlorfluorescein , . , . . . C,,H,O,Cl,INa,, Sodium dichlorrrionoiodofluorescein C,,H,O,Cl,I,Na,, Sodium dichlordi-iodofluorescein . . . C2,H50,C1,13Na2, Sodium dichlortri-iodofluorescein . . . C20H,0,C14Na,, Sodium tetrachlorfluoresceiii .. . . . C,H50,C141Na,, Sodiuni tetrachlormonoiodofluorescein C,H,0,C141,Na2, Sodium tetrachlordi-iodofluorescein C,,H,O,Cl,I,,Na,, Sodium tetraclilortri-iodofluorescein C,,H20,ClJ4Na2, Te tra-Rengal rose . . . . . . . . . Moleculai Weight. 880 788 754 663 445 571 697 823 514 640 766 892 1,018 Silver &rate re- quired per 100 Grrns. c. c. 4-54 5-07 3.97 4 -53 4'49 5.25 5 '73 6-07 7-78 7.81 7 '83 7-84 7.85 3hlorine.'er Cent. - 4.50 5.36 - 15.95 12.43 10-18 8'62 27 -62 22.18 18-53 15.91 13.94 Iodine. Per Cent. 57.7 48-35 38-36 - - 22-24 36.44 46-29 - 19.84 33.15 42.71 49.90 x 127 - 11'8 17'7 - - 71 -0 3595 17'7 - 142.0 71.0 47.3 35.5100 ABSTRACTS O F CHEMICAL PAPERS If the number of C.C. of silver nitrate approximate 4-54 or less, the product belongs to the erythrosin class, and should show only a negligible fluorescence in aqueous solution.But if the number exceeds 5.07 the dyestuff belongs to the Bengal rose class, and should show more or less pronounced fluorescence. Estimation of Iodine.-Fifty C.C. of the solution of the fused saline mass are acidified with dilute sulphuric acid, and shaken with carbon bisulphide and a little potassium nitrite.The bisulphide extract of the iodine is decanted, washed with water, treated with a few C.C. of sodium bicarbonate solution, and titrated with $D sodium thiosulphate solution. The nature of the dyestuff may then be ascertained by comparing the ratio of iodine to chlorine with the values in the table. C. A. M. Estimation of Methyl Alcohol in Ethyl Alcohol. G.Reif. (Arbeit. Kaiserl. Gesundheitsamte, 1915, 50-56 ; through Chem. Zentralbl., 1915, ii., 1056-1057.)--The method depends on the fact that methyl iodide reacts with methyl sulphide in the cold, with the formation of trimethylsulphine iodide according to the equation : CH,I + (CH,),S = (CH,),SI, whilst the corresponding ethyl compound is not formed at ordinary temperature, If, however, the proportion of methyl iodide in the mixture of methyl and ethyl iodides is very small, the ethyl compound is produced, but its formation may be prevented by the addition of ether.The trimethylsulphine iodide behaves as a salt of hydriodic acid, and can be titrated with silver nitrate solution. Wirthle’s method (ANALYST, 1912, 37, 367) is used for the preparation of the mixed alkyl iodides, and the specific gravity of the mixture will indicate approxi- mately the amount of methyl iodide present.Two C.C. of the iodide mixture are placed in a 20 C.C. flask, and, if the quantity of methyl iodide in the mixture exceeds 5 per cent., 2 C.C. of methyl sulphide are added ; if the proportion of methyl iodide is less, only 1.5 C.C. of methyl iodide is added, together with 0.5 C.C.of dry ether. The flask is closed, kept in a desiccator for twenty-four hours, the crystals of trimethyl- sulphine iodide are then rinsed on to a dry filter with dry ether and washed with the latter. The crystals are next dissolved in water and titrated with standard silver nitrate solution. One molecule of silver nitrate is equivalent to 1 molecule of methyl alcohol.I n the estimation of methyl alcohol in brandy, a preliminary test is made as described by Wirthle (loc. cit.) to ascertain whether this alcohol is actually present. One hundred C.C. of the sample are then treated with 10 C.C. of sodium hydroxide and distilled in an apparatus fitted with a Le Be1 still-head; the distillate should measure about 10 C.C. more than the quantity of alcohol in the sample.The total amount of alcohol in the distillate is now estimated, and from the result is calculated the number of C.C. of distillate corresponding with 10 C.C. of alcohol. This quantity of the distillate is used for the preparation of the mixed iodides. The boiling-point observed during the distillation of the sample will give an indication of the proportion of methyl alcohol present, and consequently of the quantities of iodine and phosphorus required, but an excess of 1 grm.of iodine per 10 C.C. of the alcohols is without influence. When large quantities of methyl alcohol are present, observation of the boiling-point of the sample will enable a distillate containing approximately 10 perORGANIC ANALYSIS 101 cent.of methyl alcohol to be obtained. The mixed iodides are then treated with methyl sulphide and the estimation completed as described. VCT. P. s. Methods of Analysing Vegetable Parchments. R. W. Sindall and w. Bacon. (Paper Mcdcers’ lWonthly J. ; through Chem. News, 1916,113,67-68.)-The usual method of disintegrating paper for microscopic examination is not applicable to parchment papers in which the fibres are firmly cemented together by colloidal cellu- lose.Methods which depend on the use of chemicals for overcoming this adhesion, e.g., with cuprarnmonium solution or sulphuric acid, are unsatisfactory, because such chemicals, while dissolving the cementing substance, may attack the fibres and introduce appreciable errors in their subsequent estimation.The authors therefore prefer a mechanical method of disintegration such as is conveniently afforded by a small vertical coffee-mill. About 0.5 grm. of the sample is crumpled up with hot water, torn into small pieces, and passed several times through the mill with a little water until the fibres are sufficiently separated. I n preparing the fibres for micro- scopic examination, the specimen should be mounted in zinc chloride-iodine reagent somewhat more dilute than is suitable for ordinary paper analysis, since tho strong reagent gives such a dense blue coloration with the parchmentised fibres as to make them practically opaque.The correct degree of dilution of the staining reagent suitable for the differentiation and estimation of mixed rag and wood cellulose fibres in vegetable parchments, is best found by trial.In highly parchrnentised specimens the wood cellulose fibres may lose some of the characteristics by which they are recognised in the microscopic examination of ordinary papers. J. F. B. Reducing Action of Phenylhydrazine on Certain Metallic Oxides. E. Puxeddu. (Gazx. Chim. Ital., 1916, 46, 71-76.)-Yellow oxide of mercury when added to an ethereal solution of phenylhydrazine is instantly reduced to finely divided metallic mercury.Red mercuric oxide is also reduced to the metallic form, with the simultaneous formation of a small amount of a crystalline compound- probably diphenyl mercury. Of the oxides of lead, only the peroxide PbO, reacts with phenylhydrazine at the ordinary temperature, while the oxide Pb,O, reacts on heating.I n both cases the suboxide Pb,O is produced. A similar reduction of mercurous oxide is effected. C. A. M. Hopkins-Cole Reaction for Protein. H. G. D. Breidahl. (Biochem. J. 1915, 9, 36-37.)-Hopkins and Cole investigated (Proc. Roy. Soc., 1901, 68, 21) the Adamkiewicz protein reaction, and found that the test failed when pure acetic acid was used.They showed that the presence of glyoxylic acid in the acetic acid was a necessary factor, and on this account they modified the test by dispensing with the use of acetic acid, employing instead a glyoxylic acid reagent, prepared by reducing oxalic acid solution with sodium amalgam. The author now points out that the sulphuric acid has also an influence on the reaction, and that it is necessary, in the case of old sulphuric acid, to subject the same to a preliminary treatment with granulated zinc ; the concentrated acid should be well mixed with the metal and left for a few days.The test is carried out by mixing the protein solution with the102 ABSTRACTS OF CHEMICAL PAPERS glyoxylic acid reagent, and then pouring the concentrated sulphuric acid down the side of the tube; a brilliant violet coloration is produced at the junction of the two liquids.w. P. s. Action of Normal and Basic Lead Acetate on the Sugars, with Remarks on Rubner’s Test for Dextrose and Lactose. H. Rogerson. (Biochem. J., 1915, 9, 245-252.)--Rubner’s test (Zeitsch. anal. Chem., 1885, 24, 447) is carried out by adding some lead acetate to a dilute solution of dextrose, and then adding ammonia drop by drop until a permanent precipitate is formed.On standing in the cold the liquid becomes coloured gradually, first yellow, and then rose or flesh red; on heating the coloration takes place more quickly. The author finds that dextrose, laevulose, and galactose gave a flesh colour and a precipitate; mannose a yellow colour, but no precipitate ; lactose a yellow colour and precipitate ; and maltose a, yellow to buff colour and precipitate.These tests clearly indicate the futility of adopting this reaction of Rubner as specific for dextrose and lactose. Many experiments are described in which normal and basic lead acetate in the presence of different alkalis are allowed to react at varying temperatures with all the ordinary sugars and polyhydric alcohols, and it is concluded that their action is somewhat complex, and that it is impossible to correlate the effects observed with any particular sugar in order to identify it.There is little doubt that the precipitates obtained in many cases are complex derivatives of the sugar and the acetates of lead. H. F. E. H. ’Use of Nickel Hydroxide in Tannin Estimation.P. Singh and T. P. Ghose. (J. SOC. Chem. Ind., 1916, 35, 159-160.)-Nickel hydroxide powder is recommended as a substitute for hide-powder for the absorption of tannin. I n the discussion Procter pointed out that as an empirical method it offered no advantages to the tanner over the well-established hide-powder method, while nickel hydroxide appeared to be inferior to hide-powder as a reagent for distinguishing between gallic acid and tannin. He regarded most of the tannin compounds as colloidal precipitates rather than as true salts. C. A. M. Estimation of Thiophen in Benzene. 0. Paglini and B. Silbermann. (Gaxx. Chim. Ital., 1915, 45, 385-390.)-The method depends on the formation of thiophen mercuri-acetate, C,H,O,Hg. C- C.HgC,H30, I1 I1 C2H,02Hg.C - S - C.RgC2H3O2, which is insoluble in all ordinary solvents, and may be separated from glacial acetic acid, in which, when hot, it dissolves in the proportion of 1 : 5. A little more than the calculated quantity of mercuric oxide is dissolved in twice its weight of hot glacial acetic acid, and the solution cooled for the separation of the mercuric acehate. The sample of benzene under examination is then added, and the mixture boiled on the water-bath for about fifteen minutes. The precipitate of thiophen mercuri-acetateINORGANIC ANALYSIS 103 is separated from the cold solution, washed several times with ether, dried at 100°C., and weighed. The method gives accurate results in the estimation of quantities of thiophen ranging from 1 to 0.5 per cent. C. A. M.