摘要:

NOVEMBER, 1808. Vol. XXXIII,, No. 382. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE DETECTION OF SMALL QUANTITIES OF METHYL ALCOHOL IN THE PRESENCE OF ETHYL ALCOHOL.* BY L. E. TIINKEL, F.I.C. THE greater number of the many methods proposed for the detection of small quantities of methyl alcohol in the presence of ethyl alcohol depend on the oxidation of the mixed alcohols to their respective aldehydes, and then subsequently testing for formaldehyde, ethyl alcohol being supposed to form only acetaldehyde. A heated copper spiral, potassium permanganate, and potassium dichromate, have been employed as oxidising agents.-Prescott (Pharmaceutical Archives, 1901, 4, 86) ; Trillat (ANALYST, 1899, 24, 13) ; SanglB-Ferridre and Cuniasse (i%Cz., 1903, 28, 148).* T F work was carried out in accordance with the terms of the " Analytical Chemistry Investigation Scheme.418 THE ANALYST. I find that traces of formaldehyde are invariably produced by the oxidation of pure ethyl alcohol ; hence it is almost impossible to detect small quantities of methyl alcohol in ethyl alcohol by any oxidation method. When, however, more than 5 per cent. of methyl alcohol is present, a definite result may be obtained. I have tried the various tests which have been recommended for the recognition of formaldehyde in the mixture of the aldehydes, but none were found to be a s delicate as the following one : Formaldehyde and morphine in the presence of strong sulphuric acid yield an intense violet colour, whereas acetaldehyde under similar conditions gives an orange colour.The test is best performed by adding a few drops of 8 per cent. solution of morphine hydrochloride to the dilute solution of formaldehyde contained in a test-tube, and then carefully pouring some strong sulphuric acid down the side of the tube, so as to form a layer beneath the formaldehyde. A deep violet blue ring is obtained at the junction of the liquids. This test is exceedingly delicate, and capable of detecting as little as one part of formaldehyde per million. The deep orange colour produced by acetaldehyde would mask a trace of formaldehyde ; formaldehyde and acetaldehyde may, however, be readily separated from one another by distillation. When an aqueous solution of acetaldehyde and formaldehyde is gently distilled, the whole of the acetaldehyde distils over first, and the formaldehyde after.On oxidising pure ethyl alcohol, and separating by distillation all the acetaldehyde produced, traces of formaldehyde were always present, which gave a faint violet ring with the morphine test. The addition of about 5 per cent. methyl alcohol to the ethyl alcohol gave a very decided colour reaction, which could not be mistaken for the reaotion yielded by the pure ethyl alcohol. The amount of formaldehyde formed from ethyl alcohol varied considerably with the conditions of the oxidation ; the more vigorous the reaction, the greater the formation of formaldehyde. Thus, with the heated copper spiral or with excess of alkaline permanganate the amount of formaldehyde formed is marked, but with ammonium persulphate the amount is comparatively small.With dichromate and sulphuric acid, if the mixture be strong, so that oxidation takes place on the application of slight or no external heat,, then a considerable amount of formaldehyde is produced, whereas if the oxidising mixture be very dilute and not in excess, the amount produced is exceedingly small. As a result of numerous experiments I find that the following is the most satisfactory method for the detection of methyl alcohol in ethyl alcohol, remembering that a quantity corresponding with less than 5 per cent. of the ethyl alcohol present cannot be detected with certainty: 1 cubic centimetre of the mixed alcohols is placed in a small, round-bottomed distilling-flask, then the oxidising agent is added. I€ ammonium persulphate is used, 0.8 gram of the salt is added, followed by 3 C.C.of dilute sulphuric acid (1 in 5); or in the case of potassium dichromate, 1.5 grams of the salt and 1.5 grams of pure sulphuric acid, In both cases the mixture is diluted with water to 20 c.c; the flask is then connected to a small condenser, and heated quickly over the naked flame of a Bunsen burner, the distillate being collected in test-tubes in five separate portions of 2 C.C. at a time. The first two portions, which will contain all the acetaldehyde, may be rejected. To each of the remaining portions a few drops of & per cent. solution of morphine hydrochloride are added,-THE ANALYST. 41 9 and strong gulphuric acid is poured into each test-tube so as to form a layer at the bottom. In the presence of formaldehyde a, violet ring will be formed at the junction of the liquids. In conclusion, I desire to express my indebtedness to Mr. A. C. Chapman, for advice given to me in connection with this work. RING’S COLLEGE, LOSDON.

ISSN:0003-2654    

DOI:10.1039/AN908330417b

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 41 9 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Composition of Bananas. Niederstadt. (Chem. Zeit., 1908, 32, 936.)- The results of analyses of bananas imported into Germany are given in the following table : Fresh Green Bananas (as Imported). Ripe Yellow Bananas (from Jamaica). Water . . . . . . ... ... ... Fat.. . . . Nitrogenous matter . . . ... ... Sucrose ... ... Dextrose, etc. . . ... Starch ... . . - ... . . . Crude fibre ... . . . Free malic acid . . . ... ... ... Mineral matter ... ... ... ... . ... ... ... . . . . . . . . . ... . . . ... ... ... Per Cent. 72-16 0.11 1.35 11.68 7-26 5-22 0.94 0.27 1.01 Per Cent. 71.92 0-17 1.65 10.49 7.26 6-14 1.20 0.25 0.92 w. P. s. Determination of the Quality of Flours as regards their Suitability for Bread-making.M. Renner. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 234-238.)-The method desoribed by Liebermann (ANALYST, 1902, 27, 155), in which the quality of a flour is ascertained by measuring the volume to which the gluten expands when heated, was found to be capable of giving useful information as to the baking quality of a flour. It was noted, during the investigation here recorded, that very white, finely ground flours yielded gluten having a lower expansion value than the coarser ground flours. This value also diminishes the longer the flour is kept, and, if flour turns ‘‘ sour,” the decrease is very marked. w. P. s. Method of Estimating the Volume of Loaves, Pastry, etc. M. P. Neumann and P. Salecker. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 285-290.) --An apparatus is described by means of which the volume of a loaf of bread may420 THE ANALYST.be ascertained, the estimation being of some importance in comparing the baking qualities of various kinds of flours. It consists of a cylindrical glass vessel of sufficient capacity to hold the loaf under examination; the vessel is provided with a flange at the top, on which rests a glass cover, and this cover is secured by means of screw-clamps. A graduated burette holding 500 C.C. rises from the centre of the cover, and a tubulure in the side of the vessel, at about one-half the height of the latter, is connected by a length of flexible tubing to a pear-shaped reservoir which is provided with a tap. The whole apparatus is filled with water up to the zero mark of the burette (just above the cover of the vessel); the tap of the reservoir is then closed, and any excess of water remaining in the latter is poured away.By lowering the reservoir and opening the tap, 500 C.C. of water are withdrawn from the vessel into the reservoir, or, if a larger-sized loaf has to be measured, a larger quantity of water is removed; The cover is then unfastened, the loaf is placed in the vessel, and, after reclamping the cover, the water is allowed to flow into the vessel and burette. A simple calculation then gives the volume of the loaf. The latter should be coated previously with collodion or molten paraffin ; if the latter be used, a correction may be made for its volume, but this is scarcely necessary. A method is also described in which rape-seeds are used instead of water for determining the space occupied by the loaf, but the results obtained are not trust- worthy unless the greatest care be taken.A measure is filled with the rape-seeds, and the surface of the latter is levelled by passing a ( ( straight-edge ” over the top of the measure. The seeds are then transhrred to another vessel, the loaf is placed in the measure, which is next filled with the seeds and levelled as before. The volume of the excess of seeds is then measured, and gives the volume of the loaf. W. P. S. Detection of Benzoic Acid in Butter. G. Halphen. (Joum. Pharm. Chim., 1908, 28,201-203.)-The test proposed depends on the conversion of the henzoic acid into the ammonium salt of diamido-benzoic acid, which, in alkaline solution, has a brown-red colour.A portion of the sample of butter is melted together with sufficient lime-water to render the aqueous portion distinctly alkaline. After cooling, the aqueous layer is separated, rendered acid with phosphoric acid, and shaken out with ether, The ethereal extract is allowed to evaporate spontaneously, and the residue dried at the ordinary temperature. Two C.C. of concentrated sulphuric acid are then added, and the mixture is heated gently until the residue has dissolved; after adding 0.2 C.C. of fuming nitric acid, the solution is transferred to a dry test-tube and heated carefully over a small flame until sulphuric acid fumes appear in the tube. When cold, the mixture is diluted with 5 or 6 C.C. of water, which causes nitrous fumes to be given off; after again being cooled, the solution is treated with a saturated solution of sodium sulphite, which is added drop by drop until all the yellow vapours have disappeared.Ammonia is next allowed to flow over the surface of the solution, when an orange-red coloration is produced if benzoic acid is present in the sample, the intensity of the coloration being proportional to the quantity of benzoic acid. Unless the above procedure be adhered to, the test may fail, and in cases where a coloration is not obtained it is advisable to add a drop of ammonium sulphide to the ammoniacal eat-solution. If benzoic acid be present, a red coloration develops at the point of contact of the two liquids. w. P. s.THE ANALYST. 421 Detection of Synthetic Colours in Butter. R.W. Cornelison. (Journ. Arner. Chem. SOC., 1908, 30, 1478-1481.)-The author’s method consists in shaking thoroughly 10 grams of the melted fat with 10 to 20 grams of glacial acetic acid at about 35” C., when separation quickly takes place, and the acid layer can be drawn off, its colour noted, and portions treated with nitric acid, sulphuric acid, and other reagents. Nitric acid appears to give the best differentiation between the synthetic colouring matters and vegetable colours. The colour reaction between curcumin and sulphuric acid should be borne in mind. The following results were obtained by this method with various colouring matters, which were incorporated with a specially prepared pure butter to the extent of 1 part of dye in 100,000 of the butter : Dye. (Pure natural Soudan I.(pure) butter) Butter yellow (impure) Cerasine orange G. (Casella) Yellow 0. B. (Heller and Merz) (Heller and Merz) Annatto Yellow A. B. Curcumin Carrot ‘‘ Alderney butter colour ” (Heller and Merz) Ranson’s butter colour ( ‘‘ vegetable ”) Dandelion brand ” butter colour (‘‘ vegetable ”) Colonr of Acid Extract. Water- white Decided pink Very faint pink Strong greenish yellow Decided bright yellow Slight warm ochre-yellow Dull yellow Intense greenish- yellow Very faint greenish- yellow Brownish- yellow Yellow Yellow Concentrated Nitric Acid. Water-white Strong pink Faint pink Acid, yellow ; oil-globule, salmon-pink Acid, faint pink : oil-globule, salmon-pin k colourless Pink; fat Little change Dull ochre- yellow Faint yellow Strong pink Almost decolorised Almost decolorised Concentrated Sulphuric Acid.Faint pink on standing Strong clear pink Faint pink As with HNO, As with HNO, Brownish-pink ; oil faint pink Faint pink on standing Strong pink Faint pink on standing Strong pink As with HNO, As with HNO, Sulphuric Acid, and Ether to Clear Solution. Water- w hit e Pink Faint colour Brownish- yellow Pink Pink Very faint yellow Yellow Very faint yellowish - - -- A. R. T.433 THE ANALYST, Egg-Cognac. G. Heuser. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 290-292.)-1n the following table are given the results of analyses of four egg-liqueurs sold in Germany, the figures expressing grams per 100 C.C. : ... ... ... . . . Alcohol . , . Total solids ... .. . . . . Fat (ether extract) ... ... . . . Nitrogenous substances ... Total phosphoric acid ... Lecithin-phosphoric acid ... ... Ash ... ... ... . . . . . I ... Colouring matter ... . . . Boric acid ... ... . . . ... . . . . . . ... . . . Polarisation of 10 per . before inversion ... cent. solution ... { after inversion ... 23.00 41.00 4-93 0.29 0.033 0-022 0.078 Saffron 0 4.6' - 14O 11. Cognac. Egg- 15.11 35.56 4.43 2.34 0.144 0.085 0.400 Saffron 0.205 2-8O - 2.8' 111. Egg- Punch. 19.75 46.00 1.01 0.68 0.029 0.018 0.082 ? 0 3.5 O - 3.8" IV. ovos- Cream. 18.56 45.60 8.33 4-42 0.306 0-171 0.523 0 0 4.1" - 0.8" The ether extract contained, besides fat, flavouring substances such as spices, and in the case of No. I. some cream was present, Calculated from the amount of lecithin-phosphoric acid present (see ANALYST, 1905, 30, 245), the number of egg- yolks used in the preparation of each litre of these liqueurs was approximately: No.I., 1.5 to 2 ; No, II., 7 to 8 ; No. III., 1.5 ; and No. IV., 12 to 15. w. P. s. Detection and Estimation of Hexamethglenetetramine in Medicines. W. A. Puckner and W. S. Hilpert. (Journ. Anzer. Chenz. SOC., 1908, 30, 1471- 1474.)-The basic body hexamethylenetetramine, N = (CH, - N : CH,),, has of recent years come into use as an internal antiseptic and diuretic, and it possesses the property of decomposing, under suitable conditions, into formaldehyde and ammonia. Solutions of hexamethylenetetramine give with bromine-water an orange-coloured precipitate of the insoluble tetrabromide, which, when dried over caustic potash, gradually becomes converted to the canary-yellow dibromide, melting a t 198" to 200" C., with decom- position.Mercuric chloride forms with hexamethylenetetramine a white crystalline compound only slightly soluble in water, and which is decomposed by boiling with dilute acid, with formation of ammonia and formaldehyde. Hexamethylenetetramine is extracted from its aqueous solutions by chloroform, from which solution it separates in a crystalline form on evaporation. These tests serve for the detection of hexa- methylenetetramine when in admixture with other medicaments. For its determina- tion, a suitable quantity of the medicine (about 5 grams of a liquid preparation) is diluted with water to about 500 c.c., 10 grams of caustic potash are added, and the liquid boiled for half an hour to remove ammonia.The liquid is then rendered decidedly acid with sulphuric acid, and boiled for at least one and a half hours, inTHE ANALYST. 423 which time the hexamethylenetetramine is completely hydrolysed. The solution is next made alkaline by the addition of caustic soda, and the ammonia,, formed by the decomposition of the hexamethylenetetramine, distilled and titrated with decinormal acid, each C.C. of which represents 0.003479 gram of hexamethylenetetramine. A. R. T. The Estimation of Hydrastine. W. A. Puckner. (Chem. ZentrbZ., 1908, 2, 266-267.)-The following method of estimating hydrststine in the fluid extract and rhizome of hydrastis is recommended as giving better results than that of the United States Pharmacopceia : FZuid Extract.-Five C.C.are mixed with 5 C.C. of potassium iodide solution (20 per cent.) and 25 C.C. ot water, the mixture thoroughly shaken and filtered, and the precipitate washed twice in the beaker, and subsequently twice upon the filter, with portions of 5 C.C. each of a mixture of 1 C.C. of the potassium iodide solution and 19 C.C. of water. The united filtrate and washings are then shaken with three successive portions of 20 C.C. of ether, and once with 5 C.C. of ether, the united ethereal extraots filtered through cotton-wool and evaporated, and the residue dried at 95" to 98" C., and weighed. Rhizome.-Five grams of the powdered sample are mixed with 50 C.C. of ether, and the mixture treated, after ten minutes, with 2 C.C. of ammonia solution, and shaken at intervals for thirty minutes, The liquid is then filtered, the residue again extracted with 50 C.C.of ether, and the extract added to the first one and shaken successively with-(1) 2 C.C. of dilute hydrochloric acid* and 18 C.C. of water ; (2) 5 drops of dilute hydrochloric acid* and 10 C.C. of water ; and (3) 10 C.C. of water, The aqueous solution is now treated with ammonia, until alkaline to litmus, and extracted with three portions of 20 C.C. each of ether, the combined extracts evaporated at the ordinary temperature, and the residue dried at 98" to 100" C. C. A. M. Characteristics of the Fatty Oils from the Seeds of Certain Fruits. J. Kochs. (Chem. Bev. Fett- u. Harz-Id., 1908, 15, 256-257.)-The oils examined were obtained by extraction of the dried and crushed seeds with ether.The air-dried seeds of the red currant (Ribes rubrum) contained 16.9 per cent. of a yellowish-brown oil, which dried in seven hours at 50" C., forming a, hard almost colourless elastic film. The seeds of the berries commonly known as ( I hips" contained 9.63 per cent. of 8 thin drying oil of a yellow to orange-yellow colour. Tomato-seeds yielded 17.3 per cent, of a thin brownish-red oil, which had slight drying properties, and might be used as a food-oil. Raspberry-seeds contained 13.5 per cent. of a greenish- yellow oil, which had good drying properties, and might be used as a, substitute for linseed-oil. Strawberry-seeds contained 16.35 per cent. of a thick yellow oil, which had good drying properties; its high Reichert-Neissl value is noteworthy, but its low iodine value is to be attributed to oxidation of the oil brought about by the heat in crushing the seeds.Euonymus europsus yielded a reddish-brown, fairly thin, non-drying oil, with a, characteristic sharp odour. As the seeds yielded 35.2 per cent. of oil, the latter could probably be utilised with advantage in the manufacture of soap. The following table gives the analytical values of these oils : * Strength of acid not stated.424 THE ANALYST, Values. Specific gravity a t 15" C . . . Sa onificatioii value .. IoIine value ... .. Reichert-Meissl value . . Butyro-refractometer read - Solidification point, "C ,. ing a t 40" C. Fatty Acids .- Melting-poiiit, "C. . . Iodine value ... .. Mean molecular weight..Unaaponifiable matter, per cent. Currant-Seed Oil. 0'9120 171.3 1525 0.77 62" - 17.5 (semi-solid) 20 1695 266.2 2.31 Hip Oil. 0.9161 172.8 152-8 0.44 67" - 17.5 (viscous) 31 174.3 276.8 2 62 Tomato-Seed Oil. ~ 0-9200 183 '6 117'8 0.22 63" -9 (viscous) - 12 (semi-solid) 26-29 129-6 281.5 2.68 Rsspberry- Seed Oil. 0-9151 180'3 162.2 0.11 65" - 17.5 (semi-solid) 30 170.3 281.5 1.86 Strawberry- Seed Oil. 0,974 184.6 72.8 13'12 82" - 21 66 -3 241 2 -42 Oil of Ezcony- mus euiopams. 0,939 230'1 - 35.31 52" - 10 3s (1)egiiining) 70 105.3 251 2 (complcte) 5 *3:3 Characteristics of Japanese Tea Oil. M. Tsujimoto. C. A. M. (Chem. Rev. Fett- u. Harz-Ind., 1908, 15, 224.)-Two specimens of the seeds from the Japanese tea-plant (Thea sinensis) yielded respectively 23.90 and 26-23 per cent.of an orange-coloured oil with a somewhat unpleasant odour and bitter taste. The oil expressed from Tokyo seed gave the following analytical values : Specific gravity at 15" C., 0.9178 ; acid value, 0.74 ; saponification value, 191.91 ; iodine value (Hubl), 9042 ; Hehner value, 95.6 ; Reichert-Meissl value, 0.66 ; and refractometer reading at 20" C., 1.4707. Fatty Acids.-Specific gravity a t 98' C., 0.8445 ; melting-point, 33.5" C. ; neutralisation value, 197.60 ; mean molecular weight, 283.91 ; and iodine value, 92-86. The oil was readily soluble in the ordinary solvents for fats. I t solidified at - 10" C. In the elaidin test it became viscid after two hours, and solidified to a butter-like mass after twenty-four hours. It could be used for the same purposes as tsubaki and sasmqua, oils (ANALYST, 1908, 238), which it closely resemble sin many respects; but it would require careful refining to remove saponine-like substances before being suitable for food.So far it has not become a coinrnercial product. C. A. &I. Separation and Determination of Salicylic Acid and Methyl Salicylate in Foods, ete. H. D. Gibbs. (Jozmz. Amer. Chem. Soc., 1908, 30, 1465-1470.)- Methyl salicylate is added as a flavouring agent to various beverages, foods, and medicinal preparations, the synthetic product and the oils of gaultheria and sweet birch being employed for this purpose. These frequently contain a small quantity of free salicylic acid, the author having found quantities up to 0.025 per cent., while the free acid itself may also be simultaneously added to the food, and so a method for the separation of the acid and ester is desirable.The problem is complicated by the fact that methyl salicylate hydrolyses to a varying extent when added to certain substances, particularly in presence of alkalies and in a warm atmosphere. TheTHE ANALYST. 425 author has devised the following methods for the examination of the ester, and for the determination of salicylic acid and its methyl ester when present together in foods, etc. : Dctcriitination of Salicylic Acid in Methyl Salicy1ate.-This is best carried out by direct titration with standard sodium bicarbonate solution, using congo-red as the indicator. Five to twenty cc. of the ester are shaken with an equal volume of neutral distilled water in a stoppered flask, and sodium bicarbonate (free from normal carbonate) run in until the end-point of the titration with congo-red is permanent on shaking.This method gives results agreeing closely with those obtained by thoroughly extracting 10 C.C. of the natural oil or synthetic ester with Tc sodium bicarbonate solution, removing any traces of ester from the alkaline extract by shaking three times with chloroform, and then acidifying the alkaline solution, extracting the salicylic acid with chloroform, evaporating off the solvent, and determining the salicylic acid in the residue colorimetrically, as described in the 77. S. Dcpt. Agric. Bull. 107 (1907), p. 180. Sepa,ration and Estimatio.12 of Salicylic Acid and Methyl Salicylate i i z Foods, Beverages, etc.-The substance is made strongly alkaline to congo-red with approxi- mately normal sodium bicarbonate, and if the mixture is not homogeneous the aqueous solution is separated, and the extraction with alkali repeated until complete.All the salicylic acid and small amounts of methyl salicylate are now in the alkaline solution, which is shaken three times with chloroform to remove the methyl salicylate, and then acidified with diluted sulphuric acid, the salicylic acid removed by solution in chloroform, and estimated colorimetrically. The extraction of the material with the alkaline liquid should be carried out at a temperature not much above 30" C., and preferably lower, to avoid hydrolysis of the methyl salicylate. The methyl salicylate present in the material is extracted from it, after removing salicylic acid as above, by shaking several times with chloroform, and to the mixed chloroform extracts the small quantity of methyl salicylate, already extracted in the first part of the process, is added.The chloroform is next heated for half an hour under a reflux condenser with excess of 25 per cent. caustic soda solution to saponify the ester, the chloroform removed by evaporation, the residual solution then suitably diluted, and the colorimetric estimation of salicylic acid carried out on an aliquot portion. The above method has been successfully applied to the examination of such preparations as cod-liver oil emulsion, in which case the alkaline solution is separated from the emulsion by rapid centrifugalisation of the mixture.After thus removing the free salicylic acid, the methyl salicylate in these and certain other .mixtures is best separated by steam-distillation of the material acidified with sulphuric acid. Since a partial hydrolysis of the ester takes place in this acid solution, the steam- distillation must be continued until no more salicylic acid passes over into the distillate. The author shows that methyl salicylate undergoes rapid hydrolysis in presence of sodium hydroxide, and that this decomposition is also considerable in presence of sodium carbonate, though sodium bicarbonate free from the normal carbonate is practically without action. The hydrolysis in all cases increases greatly with theTHE ANALYST. temperature. For the above reasons it is necessary to employ sodium bicarbonate solutions for the extractions in carrying out the foregoing methods, and to keep the solutions as cool as practicable.A. R. T. Malt Analysis : Determination of Extract.-11. A. Hunicke. ( J o ~ m . Amer. Ghern. SOC., 1908, 30, 1431-1443.)-1n diluting and filtering a malt mash for the determination of the density of the wort, phenomena of mechanical absorption and colloidal adsorption come into play, particularly with the coarser forms of grist, so that the various fractions of the filtrate contain different amounts of dissolved matters. When, in the ordinary way, the cooled mash is diluted to 450 grains, stirred thoroughly and filtered, the concentration of the first, fraction of 75 C.C. is well below the average concentration.If the mash be stirred and allowed to stand for twenty-four hours before filtration, the extract is considerably higher than if it be filtered a short time after making; but if, after twenty-four hours, a quantity of the wort be pipetted off without filtering, it contains several per cent. less solids than the filtered wort, showing an adsorption of the solute by the fibrous colloids of the mash. In the case of coarse grists, the extraction of the viscous dextrins from the residual grains is very slow, the difficulty being chiefly a mechanical one. Of course, the very object in working a coarse griat in the laboratory is to endeavour to estimate this retardation, the coarse grist analysis being a technical and not an absolute deter- mination. The author describes the procedure he adopts in malt analysis in the following terms : Weigh off 50 grams of malt, and grind either to finest powder or in a, Seck mill at 25" C., according to requirements, avoiding all loss in the process.Add f o the malt in a copper beaker 200 C.C. of water at such a temperature that the mixture shows 45" C. Place in water-bath, stirring uniformly at regular intervals, preferably by a rotary motion of the thermometer, six rotations every five minutes. After thirty minutes at 45" C., the temperature is raised 1' C. per minute until 70" C. is reached, and the whole is kept at 70°C. for one hour. Ten C.C. of mercuric chloride of such concentration that the whole wort will contain 0.002 per cent. are added, and 200 grams of water at 70" C. The whole is stirred during the addition of the water (ten minutes), and for five minutes after.It is then cooled and made up to 450 grams. After stirring vigorously, the wort is filtered off, the first 150 C.C. are returned to the filter, and 300 C.C. are taken for the determination of the density. This method gives good results, provided the itirring and the heating up of the mash be carefully controlled. The dilution of the mash, at a temperature of 70" C., instead of after cooling, facilitates the diffusion of the dissolved matters, and gives rather higher results in consequence. By this method of mashing, the first fraction of 75 C.C. is of higher concentration than the second, the subsequent fractions increasing as in the ordinary method. This is attributed to the fact that the first fraction filters so rapidly that adsorption by the fibres of the paper has not time to take effect. J.F. B. Preliminary Tests for Maple Products. A. P. Sy. (Jouriz. Amer. Chent. Soc., 1908, 30, 1429-1431.)-Three new tests are described for the preliminary examination of maple products : (1) Golour.-Maple products contain besidesTHE ANALYST, 427 caramel, which ia insoluble in amyl alcohol, other colouring matters which are soluble in that medium and also in water. The test is carried out in the following manner: 15 C.C. of syrup, or 15 grams of sugar and sufficient water to make 15 c.c., are placed in a test-tube, 3 C.C. of pure amyl alcohol are added, and 1 C.C. of a 20 per cent. solution of phosphoric acid; the latter reagent decreases the solubility of the coloured substances in the water.Pure maple products colour the amyl alcohol layer a decided brown ; adulterated samples give fainter colours according to the quantity of maple present ; cane-sugar products, coloured with caramel, do not react. (2) Foam Test.-When heated and ignited for the ash determination, maple products form a considerable amount of foam, whereas cane products do not. The foam test is carried out by placing 5 C.C. of a syrup in a narrow cylinder graduated in 0.1 c.c., 10 C.C. of water are added, and the mixture is shaken vigorously for half a minute, allowed to stand for ten minutes, and the volume of the foam is read off. Maple syrups give from 3 to 6 C.C. of foam, average of sixty tests, was 4-1 c.c., although the two abnormal samples with a peculiar odour gave much less. (3) Volzme of Led Bnsic Acetate Precipitate.-The following procedure gives fairly concordant results : 5 C.C.of syrup, or 5 grams of sugar made up to 5 c.c., are placed in a 25 C.C. measuring cylinder ; 10 C.C. of water and 2 C.C. of basic lead acetate are added ; the liquid is mixed and then allowed to stand for twenty-four hours. For pure maple products the volume of the precipitate at the end of this time should be over 3 c.c., and is generally over 5 C.C. ; the average of twenty-three pure samples was 8-5 C.C. for syrups and 7.9 C.C. for sugars. J. F. B. Estimation of Dry Substance by the Refractorneter in Liquid Saccharine Food Products. H. Bryan. (Jown. Anter. Chern. SOC., 1908, 30, 1443-1451.)-The Abbe high-temperature prism refractometer has come into use for the estimation of dry substance in sugar-house products.Main (Intern. Sugar Jozwn., 1907,9,481) and Geerligs (ibid., 1908, 10, 68) have prepared tables showing the relations between the dissolved solids and the refractive indices, and the latter gives the corrections to be applied for temperature. The chief source of error is in the non-sugar constituents and the saline matters, so that the results with molasses are not so accurate as with purer products, but still they are quite available. The author has carried out a large number of determinations of dry substance, by direct drying on sand and by the refractometer, in samples of maple and cane syrups, honeys, cane and beet molasses, and glucose syrups, using Geerligs’ tables and the temperature corrections.He finds that in most cases the refractometer results are slightly lower than the results obtained by the direct method, but only in the case of honeys are the differences at all considerable. The refractometer results agree more closely with the direct results than the values obtained by the specific gravity method from Brix’s tables, which are always too high. The method of direct drying is so inconvenient, and the results of duplicate determinations are so variable, that there can be no question as to the great utility and substantial accuracy of the refractometer method. J. F. B.428 THE ANALYST. Determination of Sugar in Meats. A. Lowenstein and W. P. Dunne. (Jozmz. Amer. ClLeiu. Soc., 1908, 30, 1461-1465.)-The authors describe a method for the estimation of sugar in meat, which is simpler and more accurate than the official American method, and which allows of the estimation of the nitrates in the same extract.Three hundred grams of finely-divided meat are placed in an enamelled iron casserole of about 1 litre capacity, 200 to 300 C.C. of water are added, and boiled for thirty minutes. The mass is cooled, the liquid is strained through muslin, and the residue is squeezed and boiled up again with 200 C.C. of water for fifteen minutes. The second extract is added to the first and evaporated in an iron casserole over a free flame. When saltpetre is to be determined, the extraction of the meat is repeated until the liquid fails to respond to the diphenylamine test; two extractions are generally sufficient.The meat and cloth are thoroughly washed with hot water, and the united extract is concentrated to 300 to 400 C.C. The liquid is transferred to a separating funnel, and the fat is separated, the aqueous solution being returned to the casserole. The fat is washed several times with 50 C.C. of hot water each time until the washings fail to respond to the diphenylamine test. Evaporation is continued down to about 150 C.C. The extract is then transferred to a 200 C.C. graduated flask. Aliquot portions may then be taken for the determination of reducing sugars before and after inversion and of the nitrates. The sugar is preferably determined volumetrically by Pavy’s solution. J. F. B. Detection and Estimation of Free Mineral Acids in Red Wines.C. Astre. (Bzdl. SOC, Clzim., 1908 [iv.], 3, 928.)-If a red wine be dialysed into distilled water, the colouring matter does not pass through the membrane for a long time (about one and a half hours), while at the end of that period the outside liquid contains a large proportion of the salts and free acids in the wine. By working with the same dialyser under the same conditions, it is possible both to detect and to estimate free mineral acids in wine. For this purpose, 80 C.C. of the wine are placed in the dialyser, which is immersed in a vessel containing 50 C.C. of distilled water at the same level as the liquid within the membrane. After one and a, half hours the acidity of the exterior liquid is estimated by adding to 10 C.C. of it 10 drops of glacial acetic acid, and titrating the mixture with ;G potassium hydroxide solution, with tropEolin 00 as indicator.Natural wines, even when containing an addition o€ tartaric acid, and plastered wines, only require 1 or 2 drops of the alkali solution, whereas wines containing a few decigrams of mineral acids require an appreciable- quantity of the reagent before becoming yellow. By making comparative tests with wines containing a known quantity of a mineral acid, approximately quantitative results may be obtained. After each test the dialyser is washed successively with a 10 per cent. solution of sodium bisulphite, with a 1 per cent. solution of potassium hydroxide, dilute acetic acid, and water. C. A. M. The Indirect Estimation of Benzoic Acid in Wine.G. Favrel. ( A m . dc Chivz. ilnul. AppZ., 1908, 13, 343-345.)-The method is based upon the fact that benzoic acid may be extracted by means of ether from its solution in dilute (10 to 12 per cent.) alcohol. If then a wine be treated with a known quantity of --$ sodiumTHE ANALYST 429 hydroxide solution in excess of that required to neutralise its acidity, and then with the quantity of benzoic acid exactly equivalent to the added alkali, the acidity of the solution of extracted benzoic acid should be the same as that of the original wine. A standardised solution of benzoic acid ,is prepared by treating a known weight of that acid with 25 C.C. of 90 per cent. alcohol, and titrating the liquid with & sodium hydroxide solution with phenolphthalein as indicator. In estimating the acidity of a wine 10 C.C. of the sample, previously freed from carbon dioxide, are treated with 20 C.C. of zc sodium hydroxide solution, and then with the quantity of benzoic acid exactly equivalent t o the alkali. The liquid is then shaken in a stoppered cylinder with two successive portions of 40 C.C. of neutral ether, and the extracts united and evaporated on a water-bath at 70" C. in such a way that the ether distils without ebullition. As soon as the ethereal solution has been reduced to a fourth of its original volume, the distillation is stopped and the evaporation completed at a low temperature in a basin 12 em. in diameter. The distillation flask is rinsed first with 10 C.C. and then with 5 C.C. of 90 per cent. alcohol, and the washings added to the liquid in the basin, the contents of which are finally titrated with ZG sodium hydroxide solution after the addition of two drops of phenolphthalein solution as indicator. The number of C.C. required multiplied by 0.00245 gives the acidity in the 10 C.C. of the original wine. The method gives results in close agreement with those obtained by direct titration of colourless wines, and will be of use in determining the acidity of dark-coloured wines. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9083300419

出版商:RSC    

年代:1908

数据来源: RSC

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THE ANALYST 429 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Estimation of the Formaldehyde evolved by the Disinfectant “ Autan.” G. Fendler and W. Stuber. (Zcits. aizpzo. C l ~ m . , 1908, 21, 2018-2027.)- Autan ” is a disinfectant sold by the Bayer Company, consisting of paraformaldehyde and barium peroxide, together with a little alkali carbonate to control the action. The two main ingredients are packed separately in quantities calculated for the disinfection of rooms of different cubical contents. When required for use, the two powders are mixed together and treated with a definite proportion of water (80 per cent.), which is measured out in the tin can in which the ‘‘ autan” was packed. The room is then sealed, and in a few minutes a violent evolution of formaldehyde and water vapour ensues; the fumes are allowed to remain in the room for five hours. For the valuation of the formaldehyde contents of ‘( autan ” the conditions of the experiment must be adapted so as to imitate thoBe of practical use.A carboy of 75 litres capacity is selected to represent the room, and a waterproof wood-pulp tumbler serves as the reaction vessel. A frame is made of zinc strips to hold the tumbler, and this is attached to a stout wire which passes through the cork of the carboy so that it may be suspended in the closed vessel. The contents of the two packages are weighed separately, sampled, and the samples are mixed in the same proportions as the original weights. For a carboy of the above size about 5 grams of the mixed sample are required. The substance is placed in the tared tumbler, and the aliquot proportion of water required is calculated after determining the volume of the tin measuring can.Three litres of water are placed in the carboy, the necessary430 THE ANALYST, quantity of water is mixed with the ‘‘ autan ” in the tumbler, the latter is inserted in the frame, and this is suspended in the closed carboy at a distance of about 10 cm. above the surface of the water. After remaining for five hours, the wire is pulled up through the cork as far as it will go, the contents of the carboy are swirled round in such a manner that nothing comes in contact with the tumbler, the stopper is with- drawn and quickly replaced by a plain stopper. The tumbler is weighed in order to determine the loss of water plus formaldehyde which has taken place in the course of the reaction, and the contents of the carboy are shaken vigorously.In order to determine the formaldehyde, 150 C.C. of the liquid in the carboy are treated with 30 C.C. of f! sodium hydroxide solution and 30 C.C. of & iodine solution, acidified after five minutes, shaken in a closed flask for half an hour, and titrated back with thiosulphate. The quantity of formaldehyde found is then calculated in terms of the number of grams evolved per cubic metre of nominal disinfection capacity of the package; this should be about 2.1 grams per cubic metre; the quantity of water evaporated ia about 13-15 grams per cubic metre. J. F. B. Quantitative Estimation of Albumin in Urine. A. Jolles. (Chem. Zeit., 1908, 21, 917.)-For the estimation of albumin in urine the gravimetric method of Scherer gives the most accurate results, but in the case of urines containing mucus or pus the filtration is very difficult, and often impossible.Esbach’s clinical method is e v p more difficult in such cases, and frequently no precipitate is formed at all. The author has found that by the use of suitable quantities of a mixture of 50 C.C. of 1 per cent. acetic acid, 50 C.C. of commercial formol, and 15 grams of common salt, the precipitation of albumin is complete, and the estimation may be made even in the most difficult cases. In carrying out this estimation, 100 C.C. of the liquid are placed in a beaker of about 200 C.C. capacity, and neutralised, if necessary, by means of dilute acetic acid, Five C.C.of the formol reagent are added, and the mixture is heated in the boiling water-bath for about thirty minutes, until the albumin separates end the supernatant liquid becomes clear. The precipitate is collected on a tared filter and treated in the usual manner. J. F. B. New Reaction for Bile Acids and their Detection in Urine. A. Jolles. (Chem. Zeit., 1908, 21, 917.)--The author has discovered a new test for the bile acids which is superior to Pettenkofer’s reaction, and is not influenced by the presence of albumin, urea, carbohydrates, etc. Two to three C.C. of a 0.1 per cent. solution of the bile acid are treated with one or two drops of a 5 per cent. solution of rhamnose and 2 to 3 C.C. of strong hydrochloric acid, the mixture is boiled for a short time, and after the production of a transitory red coloration it ultimately acquires an intense green fluorescence. The reaction is due to the methylfurfural derived from the rhamnose, and is sufficiently sensitive to show the presence of 0.0001 gram of cholic acid in 1 C.C.of solution. For the detection of bile acids in urine, 50 C.C. of the urine are treated with 15 C.C. of a 3 per cent, casein solution, and 10 per cent. sulphuric acid is then added drop by drop until the casein is completely precipitated, for which purpose 0.6 to 0.8 C.C. is generally sufficient. The liquid is filtered off, and the precipitateTHE ANALYST. 432 is treated in a beaker with 10 C.C. of absolute alcohol, at the ordinary temperature for about an hour. The alcohoI is filtered off, 4 to 5 C.C.of the filtrate are mixed with one drop of a 5 per cent. solution of rhamnose and 4 to 5 C.C. of hydro- chloric acid, and boiled for a minute. After cooling, the contents of the tube are shaken with 2 C.C. of ether. In ordinary cases, the green fluorescence is then distinctly visible if the urine contains 0.05 per cent. of sodium taurocholate, but in the case of highly concentrated urines, and in urines rich in indican and aromatic hydroxy-acids, the reaction is less delicate, owing to the strong coloration of the filtrate. In these cases the fluorescence may be increased by concentrating the rays of light through a lens. J. F. B. Quantitative Estimation of Urea. A. Jolles. (Chem. Zeit., 1908, 21, 915.) -A new method for the estimation of urea is based on the determination of the carbonic acid produced by its oxidation by means of alkaline hypobromite. About 0.25 gram of urea is treated with 100 C.C. of a solution of 30 grams of bromine in 10 per cent. sodium hydroxide in a flask of about 750 C.C. capacity. The contents of the flask are protected from the air by a Bunsen valve, and are shaken for about five minutes to complete the oxidation. The excess of hypobromite is reduced by the addition of 3 grams of Devarda’s alloy. The carbonic acid is determined in the usual way, and the result is corrected by a blank experiment carried out with the omission of the urea. The errors of the method amount to 0.2 to 0.4 per cent. Unfortunately, the method is not applicable in presence of organic matters or carbonates. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9083300429

出版商:RSC    

年代:1908

数据来源: RSC

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THE ANALYST. 432 ORGANIC ANALYSIS. The Detection and Estimation of Cotton in Kapok. M. Greshoff. (Chew. Zentrbl., 1908, 2, 642.) -The fibres from the fruit of Eriodendron anfractuosum, known commercially as Kapok, are used as a material for filling cushions, life-belts, etc. They are sometimes adulterated with cotton, which is rodily detected, however, by a microscopical examination and by chemical tests. Thus, cotton treated with Schultze’s zinc chloride and iodine reagent is coloured reddish-blue, whilst kapok becomes yellow. Again, kapok is dyed bright red, while cotton remains practically colourless, after being immersed for an hour in a solution of 0.01 part of magenta in 30 parts of alcohol and 30 parts of water. The approximate proportion of cotton in an adulterated sample may be calculated from the amount of pentosans estimated by Tollen’s method of distillation with dilute hydrochloric acid and precipitation of the furfural in the distillate by means of phloroglucinol.The amount of pentosans in cotton does not exceed about 3 per cent., whereas in kapok they amount to 23 to 25 per cent. C. A. M. Estimation of the Yield of Coke from Coal. F. W. Hinrichsen and S. Taczak. (Stahl. u. Eisen, 1908, 28, 1277-1279.)-From 4 to 5 grams of the finely powdered sample contained in a 40 or 50 C.C. Ro~e’s crucible are heated in a current of hydrogen. All air is first removed by passage of the current of gas for at432 THE ANALYST, Iodine Value (Hanhs). least ten minutes, after which the crucible is heated gently for two minutes, then strongly for five minutes, and allowed to cool in the current of hydrogen.In this way all loss by oxidation is prevented, and results are obtained in close agreement with the technical yields of coke. C. A. M. Saponification Value. Effect of Heat upon the Physical and Chemical Constants of Cotton- seed Oil. E. Fulmer and T. C. Manchester. (Jounz. Anze~. Chenz. SOL, 1908, 30, 1477-1478.)-1t is well known that, if cottonseed oil be heated to 250" to 270" C., it fails to give the Halphen sulphur-reaction, and gives no reduction with Bechi's test if it has been subjected to a temperature of 245" C. The following table shows the results of the authors' investigation into the effect of similar temperatures upon the physical and chemical constants of this oil : .Specific Gravity at 1 5 . 3 C. 191.5 7'- Heated f m - 10 rnins. YO iilinb 190 9 190 s 190.7 190.2 190.3 190.6 190 6 190'1 190.7 190.9 Norniul uillieated \ oil ... ... 0.9221 Temperature (C.) : 1 SO" 220" 2-10" 250" 270" 7 Heated for- 10 mills. 3U Inins. 0.9267 09228 0.9229 0.9229 0'9229 0'9236 0'923ti 0*0210 0.9234 0'9218 1lefr;rctirc Index at W C. Frec Fatty Acids (calcukttcd a s Oleic Acid). 1 .A7509 Heated f w - 10 mills. 30 inins. 110.1 7; r-*- Iiented for- 10 inins. 30 rnins z /' 110'0 108'1 108.8 108.5 108.4 10s 5 10s-3 107 h 106'9 l o t i 3 I n general, the results show that the specific gravity, refractive index, and free acid, increase, and the iodine value decreases, as the temperature of heating rises. The saponification value remains fairly constant throughout.The changes are not very marked, and a cottonseed oil subjected to temperatures such as these will still give constants within the normal limits of variation for this oil, and the fact of such heating cannot, therefore, be detected from the above figures. A. R. T. New Constants for the Valuation of Mineral Lubricating Oils. R. Kissling. (Chem. Zeit., 1908, 32, 938-940.)-As some mineral lubricating oils become more '( tarry" and carbonised in use than do others, the author proposes a method in which these changes are determined. The oils are heated for fifty hours at tempera- tures of 150" and 250" C., and the tarry matters formed are then estimated by heating 50 grams of the oil to a temperature of about 80" C. with 50 C.C. of a mixture consisting of 50 parts by weight of alcohol and 50 parts of 7-5 per cent.sodium hydroxide solution, The mixture is well shaken, and the aqueous portion is then separated, filtered, and extracted with benzene. The residue obtained on evaporating the benzene extract is weighed, and represents the amount of tarry matter formed by heating the oil. The oily portion is next diluted with benzene, filtered through a weighed filter, and the carbonised matter thus collected is weighed. PennsylvanianTHE ANALYST. 433 oils are but little altered by the continued heating, the sum of the tarry and carbonised matters increasing by about 0.1 per cent., whilst Texan oils show an increase of about 1 per cent. w. P. s. Detection of Small Quantities of Turpentine in Lemon Oil. E. M. Chace.(Jounz. Arner. Chcm. Xoc., 1908, 30, 1475-1477.)-The methods of Schimmel and Co. and of Soldaini and Bert6 for the detection of this adulterant are stated to be open to several objections, chief of which are the variations produced owing to the differing sizes of the apparatus used by different workers, and also the variable optical rotation of the oil of turpentine added; while the adulterant itself is not actually identified in either method. The author prefers to isolate the nitrosochlorides from 50 C.C. of the suspected sample, and then to examine microscopically the crystalline compounds obtained for pinene nitrosochloride, which is of characteristic appearance, and can readily be distinguished from the limonene nitrosochloride in admixture with it. The amount of lemon oil employed is insufficient to cause the minute quantity of naturally-occurring pinene to interfere with the accuracy of the test.Ten to 15 per cent. of turpentine oil in oil of lemon can be detected without distillation, while if distilled by means of a fractionating column, less than 1 per cent. of the adulterant can be definitely identified. The method for the preparation of the nitrosochlorides is substantially that of Wallach. Fifty C.C. of the sample are distilled in a Ladenburg three-bulb flask or in an ordinary flask fitted with a Glinsky three-bead fractionating column. The first 5 C.C. of distillate are mixed with an equal volume of glacial acetic acid, cooled in a freezing-mixture, and, when cold, a similar quantity of ethyl nitrite is added; the solution is mixed thoroughly, and, while still cold, 2 C.C.of concentrated hydrochloric acid is run in drop by drop, and the mixture kept at 0” C. for fifteen minutes, when the solution is filtered under diminished pressure on a Buchner funnel. The filtrate is again placed in the freezing mixture for twenty minutes, and the second crop of crystals added to the first quantity, when the whole is washed with alcohol (95 per cent. by volume). I t is often advantageous to add alcohol or acetic acid to aid crys- tallisation. The dry crystals are dissolved in the smallest possible quantity of chloro- form, and then hot methyl alcohol is added until recrystallisation begins, when the liquid is cooled, more methyl alcohol added, the crystals filtered off and mounted in olive oil for microscopical examination.A. R, T. Examination of Turpentine Oil and ‘‘ Reduced Turpentine.” A. K. Turner. (Oil and CoZozLr Trades Jouwz., 1908, August 15, 503-506.)-Notwithstanding recent statements as to the accuracy of Armstrong’s polymerisation method for the estima- .tion of petroleum in oil of turpentine (cj. J. H. Coste, ANALYST, 1908, 219), in the author’s experience the method is unreliable and frequently gives results 20 per cent. below the truth, while the residue in the distillation-flask invariably gives a red colour with a solution of commercial picric acid in benzene, indicating the presence of non-volatile petroleum. The author, therefore, prefers to polymerise the turpentine oil with an equal volume of concentrated sulphuric acid, and then measure directly the residual petroleum without steam-distillation.The following are the details of434 THE ANALYST. the method : One hundred C.C. of turpentine oil, or of reduced turpentine” (Le., a mixture of turpentine oil with petroleum), is gradually shaken in a separator with an equal volume of strong sulphuric acid, in quantities of 5 C.C. at a time, avoiding any great rise of temperature by frequently cooling the mixture in a stream of cold water. When all the acid has been added, and the mixture thoroughly agitated, it is allowed to stand overnight to separate. If petroleum be present, it separates com- pletely, forming an upper insoluble layer, from which the dark acid layer may be drawn off, and the petroleum residue repeatedly washed with water until free from acid.As a precaution, this residue may be further shaken with an equal volume of strong sulphuric acid, and this process repeated until no rise of temperature takes place and the acid is only slightly coloured. The method appears to be capable of considerable accuracy, the results cited being within 2 to 5 per cent. of the actual proportion of adulterant in samples containing from 50 to 90 per cent. of petroleum. As a qualitative test, the author places considerable reliance on the behaviour of the samples on shaking. When vigorously agitated and then allowed to stand, the “ beads” so formed break up instantaneously in the case of turpentine oil ; while if petroleum be present (e.g., ‘‘ reduced turpentine ”), the (( beads ” last for some time.The ‘( aniline oil ’’ test is condemned as unsatisfactory, and the nitric acid polymerisation process as too dangerous for ordinary use. The amount of adulterant is then measured. A. R. T. Analysis of Oil Varnishes. P. C. McIlhiney. (Clzem. Engi?zccr, 1908, 8, 70-73.)-While the proportion of volatile oil (solvent) in varnishes may be readily determined by steam-distillation, and the distilled oil measured or weighed, the separa- tion of the “ gum ” from the resin in the varnish presents many difficulties. I t is im- possible to dissolve out, by any solvent, either ingredient after they have been heated together, as is the case in the manufacture of these varnishes. The author’s method consists in saponifying the mixture of gum ” and resin, and precipitating and separating the fatty and resin acids, thus leaving the gummy matters insoluble in petroleum-ether.The process is carried out as follows : From 2 to 10 grams of the varnish are saponified with a considerable excess of appropriately semi-normal caustic alkali (of known strength) in strong or, preferably, absolute alcohol, and the greater portion of the solvent then distilled and the residue dissolved in neutral absolute alcohol. The excess of alkali found by titretion with semi-normal acetic acid in absolute alcohol gives the Koettstorfer figure of the mixture. A further quantity of the standard acetic acid is now added in amount exactly sufficient to neutralise the total quantity of alkali originally added, which liberates the fatty and resin acids, and which remain in solution in the alcohol.A quantity of petroleum- ether is then added, followed by sufficient water to strongly dilute the alcoholic liquid, when the fatty and resin acids are obtained in solution in the pstroleum- ether, and the ‘‘ gum ” is precipitated from the aqueous solution. The two liquids are separated in the usual way, the fatty and resin acids being weighed, and the mixture examined qualitatively, and also by Twitchell’s method for the proportion of resin acids. The amount of fatty acids is equal to about 92.5 per cent. of the linseed oil present. Occasionally the nature of the fatty acids, whether from linseed oil orTHE ANALYST, 435 China-wood oil, may be ascertained. If the varnish contains non-volatile petroleum or other unsaponifiable matter, it will be found in the petroleum-ether extract, and may be separated in alkaline solution by petroleum-ether as usual.The aqueous liquid containing the (‘ gum,” which adheres largely to the sides of the vessel in which it is precipitated, is filtered on to a tared filter in such a manner that most of the precipitated ‘( gum ” remains behind, and the filtrate evaporated until free from alcohol, when any further precipitate of “gum” is added to the main quantity. If the weight of the vessel in which the precipitation is carried out be known, the “gum ” is best dried and weighed in this vessel, and the weight of ‘( gum ” on the filter-paper added. The odour, physical characters, acidity and Koettstorfer figures serve to identify the “ gum ” in Borne cases, The aqueous filtrate from the “gum” contains the glycerin, which may be estimated by means of Hehner’s bichromate method.I n the case of varnishes prepared with ( ( blown ” linseed oil, the oxidised fatty acids have a considerable lessened solubility in petroleum-ether, and they will there- fore be precipitated with the ( ( gum,” from which, however, they may be extracted by digesting the freshly precipitated gummy matters for some time with a moderate quantity of cold 85 per cent. alcohol. The matter thus dissolved out is weighed separately and further examined. The solubility of the acids of linseed oil thickened by heat only is scarcely altered, and any slight error in such cases is usually negligible. The resin in varnishes is usually combined with about 5 per cent.of its weight of lime, so that it is important to examine the mineral constituents of the varnish. These may be readily extracted by thinning the varnish somewhat with petroleum- spirit and treating the liquid with strong hydrochloric acid. A. R. T. New Method for the Examination of Leather. W. Fahrion. (Chem. Zeit., 1908, 32, 888-889.)-The author recommends the following ‘‘ hot-water test ” as a ready method for ascertaining the completeness of tanning experiments carried out in the laboratory : One gram of the finely divided sample is treated for ten hours wiGh 70 to 80 C.C. of water in a boiling water-bath ; the whole is shaken from time to time, and the water lost by evaporation replaced. The liquid is then allowed to cool to 75” to 80” C.made up to 100 C.C. with water, and filtered through a dry linen cloth iuto a dry beaker; 50 C.C. of the filtrate are at once evaporated to dryness in a tared platinum dish, the residue dried at 105” to 110’ C., weighed, ashed, and again weighed. On another portion of the sample moisture and ash are estimated, and the organic matter insoluble in hot water is calculated on the sample free from moisture and ash. For an ideal leather the matter insoluble in water would be 100 per cent. ; for com- mercial leather it varies from 31 to 90 per cent., according to the degree of tanning and the quantity of tanning material left in the leather. A. G. L. The Detection of Pentoses by Means of Orcinol and Hydrochloric Acid. J. Pieraerts. (BUZZ. Assoc. Chim. Sucr. et Dist., 1908, 26, 46-62.)-The author’s method of applying the orcinol hydrochloric acid teat for pentoses is to mix 5 C.C.of a 1 to 5per cent. solution of the sugar with three drops of a freshly prepared solution of orcinol (1 gram in 200 C.C. of 94 per cent. alcohol) and with 5 C.C. of strong436 THE ANALYST. hydrochloric acid, and to heat the mixture for thirty minutes on a boiling water-bath. I n the presence of a pentose a bluish-green coloration (with sometimes a blue deposit dissolving in amyl alcohol to form a bright blue solution) is obtained ; but if l=vulose, or a compound yielding Izvulose on hydrolysis be also present, a brown coloration is produced. Hence, for the detection of pentoses by this test it is necessary first to decompose by fermentation, sugars that interfere.Tollen's modification of the reagent (0-5 gram of orcinol in 30 C.C. of hydrochloric acid, with the subsequent addition of 30 C.C. of water) gives good results in the case of solid substances ; but in testing solutions for pentoses 5 c.C. of strong hydrochloric acid should be added to the mixture of 5 C.C. of the reagent with 5 C.C. of the sugar solution. The presence of dextrose has but little e.ft'ect upon the test, especially when an alcoholic solution of orcinol is used. Other aldose sugars of natural occurrence are practically without influence upon the reaction between orcinol and pentoses. C. A. M. This is attributed to the influence of the ketonic group. Detection and Identification of certain Reducing Sugars by Condensation with p-Brombenzyl Hydrazide.E. C. Kendall and H. C. Sherman. (Journ. A w r . Chem. SOL, 1908, 30, 1451-1455.)-The authors have developed certain observations of Kahl on the condensation of reducing sugars with p-brombenzyl hydrazide. This reagent is prepared by heating ethyl p-brombenzoate in alcoholic soIution with hydrazine hydrate, For condensing with the sugar, 30 mgm. of sugar, 60 mgm. of the hydrazide, and 10 to 15 C.C. of alcohol are evaporated to dryness in a test-tube in a boiling water-bath, Addition of alcohol and evaporation to dryness are repeated three or four times. In order to dissolve the uncombined sugar and hydrazide, 5 or G C.C. of chloroform and 4 or 5 drops of water are added to the residue in the tube, and heated with thorough agitation until the chloroform boils ; the hydrazone remains suspended in the hot liquid. Dextrose, galactose, mannose and arabinose give flakes or crusts of hydrazone ; lawdose gives only a milky turbidity ; whilst maltose and lactose give clear solutions.The non-reacting sugars interfere with the formation of the hydrazones of the sugars which do react, and reduce the delicacy of the test. When the conditions and quantities of reagents approximate fairly closely to those given above, the reacting sugars may be identified by the different solubilities of their hydrazones in alcohol, 20 C.C. being added to the evaporated residue in the tube and boiled. Galactose hydrazone is insoluble under those conditions, that of dextrose is soluble, and those of mannose and arabinose are partially soluble.The liquid is filtered, the alcohol is evaporated off, and the residue is taken up with chloroform and water. Alcohol is then added until the solvents mix and the mixture is boiled; arabinose hydrazone is insoluble, mannose hydrazone partially soluble, and dextrose hydrazone completely soluble. J. F. B. Determination of Reducing Sugars. F. Zerban and W. P. Naquin. (Joz~nz. Anter. Chem. Soc., 1908, 30, 145G-l4Gl.)-Munson and Walker have published tables for the estimation of reducing sugars by weighing the cuprous oxide after drying for half an hour at 100" C. in a Gooch crucible. The authors find that ifTHE ANALYST. 437 the precipitate be filtered off in a Munroe-Neubauer crucible (a platinum crucible with a filter-bed of spongy platinum) and converted into cupric oxide by ignition, the analysis may be made in half the time. In order to prevent contact with reducing gases the crucible may be placed in a, platinum dish during ignition. The copper calculated from the cupric oxide was constantly 0.0017 gram lower than that calculated from the cuprous oxide dried in the water-oven. This is probably due to residual moisture in the latter case, but in order to make Munson and Walker’s tables available, this quantity must be added as a correction to the weight of copper calculated as metal. In the analysis of low-grade products, the Neubauer crucible possesses no advantage over the Gooch, as the precipitate must be dissolved, owing to its contamination with mineral and organic impurities ; with such products the volumetric method is really preferable. It is always best to clarify low-grade solutions with just sufficient neutral lead acetate, in order to remove the reducing non-sugar constituents; basic lead acetate is not to be recommended. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9083300431

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 437 INORGANIC ANALYSIS. Method for the Estimation of Iron, Aluminium, and Phosphoric Acid, when occurring together. T. Cooksey. (Proc. Roy. Soc., New South Wales, 1908.)-As most of the results obtained in the method depend on the estimation of the phosphoric acid left in the filtrates, a description is first given of a volumetric method for the estimation of this acid, depending on its precipitation as tricalcic phosphate ; the process is a modification of the one described previously by Emmer- ling (Laizclw. Verszuhsstat., 1886, 429), and is especially applicable to the estimation of phosphates in the ashes of such articles of food as milk, vinegar, wines, etc., which do not contain iron or aluminium. The ash is dissolved in hydrochloric acid, a drop of methyl-orange is added, and potassium hydroxide solution is run in until the solution is just slightly acid.The solution is then boiled to expel carbon dioxide, an excess of calcium chloride solution and a few drops of phenolphthalein are added, and the mixture is neutralised by the addition of ;G potassium hydroxide solution ; the point at which the methyl-orange just becomes yellow is noted, and the addition of the potassium hydroxide is continued until a slight but permanent pink coloration is obtained. The number of C.C. required between these two points corresponds with the amount of phosphate present, 1 C.C. of & solution being equivalent to 0-00355 gram of phosphoric acid (P205). Provided that there is an excess of calcium chloride present, magnesium does not interfere with the estimation.Estimation of Iron and Aluminium in the absence of Phosphoric Acid.-To a slightly acid solution containing the iron and aluminium, sodium phosphate (NaH,PO,) is added in known quantity, together with a drop of methyl-orange. Decinormal potassium hydroxide solution is then run in until a yellow coloration is obtained, the whole is warmed to promote coagulation of the precipitate, and the latter is collected on a filter, and washed. The phosphate in the filtrate is then estimated as described above, and the difference between the amount found and that added originally gives the quantity precipitated with the iron and aluminium. The former is precipitated as Fe,(PO,),, and the latter as Al,(PO,),. The iron is then438 THE ANALYST.estimated separately by the iodine method, which depends on the liberation of iodine from potassium iodide by a ferric salt. The iodine is titrated with thiosulphate solution, and one atom of iodine is equivalent to one atom of iron. Knowing the amount of iron and of the total phosphoric acid in the precipitate, the quantity of aluminium can be calculated. Estimation of Iro?a, Aluminium, and Phosphoric Acid when present together in solution.-The method is as follows: To the solution, which must be suficiently acid to produce a yellow colour and not a reddish one with the iron present, is added a, definite quantity of standard sodium phosphate solution. If the solution is too strongly acid, it may be partially neutralised. After the addition of a little methyl- orange, & potassium hydroxide solution is run in until the pink coloration has just disappeared, the mixture is diluted to a volume of about 90 c.c., and warmed on the water-bath.The precipitate is collected on a filter and washed with hot watsr until free from chlorides. The filtrate is treated with an excess of calcium chloride, then rendered slightly acid by the addition of a few drops of & hydrochloric acid, using methyl-orange as indicator, and boiled to expel carbon dioxide. The procedure is the same as that described previously. The precipitated phosphates collected on the filter are dried and ignited at a moderate temperature until constant in weight. The iron is then estimated by dissolving the phosphates in hydrochloric acid, and apply- ing the iodide method.From the weight of iron and aluminium phosphates, the amount of the iron, and the amount of phosphoric acid left in solution, the quantities of iron, aluminium, and phosphoric acid in the original solution can be calculated. The addition of the sodium hydroxide should be accompanied by constant stirring in order to avoid local action on the phosphates, the latter being readily acted on by alkaline solutions, losing a part of their phosphoric acid. The total phosphoric acid in solution need not exceed twice the quantity needed to combine with the iron and aluminium. w. P. s. Loss of Carbon Dioxide during Solution of Steel in Potassium Cupric Chloride. E. P. Moore and J. W. Bain. (Journ. SOC. Chem. Ind., 1908, 27, 845- &&)-The authors determined the carbon volatilised during the solution of 3 grams of steel in 200 C.C.of acid potassium cupric chloride solution by leading the gases evolved over red-hot cupric oxide, and measuring the carbon dioxide produced. The solution used was obtained by dissolving 300 grams of the double salt in one litre of water and adding 75 C.C. of concentrated hydrochloric acid; solution of the steel was effected at a temperature of 65" C. With a steel apparently containing 0.653 per cent. of carbon, four determinations showed that 0.03 to 0.06 per cent. of carbon had been volatilised, whilst with a steel apparently containing 1-18 per cent. of carbon 0.03 to 0.04 per cent. of carbon had been lost. A. G. L. New Method for the Analysis of Bronze, Brass, and Similar Alloys.E. Schurmann and H. Arnold. (Chem. Zeit., 1908, 32, 886-887.)-0ne gram of the alloy and 5 C.C. of a 50 per cent. solution of tartaric acid are placed in a 150-C.C. beaker; 4 C.C. of nitric acid (specific gravity, 1.4) are then gradually added, withTHE ANALYST. 439 constant shaking and cooling ; to the clear solution 7 C.C. of nitric acid and 80 to 90 C.C. of water are added, and the copper is deposited electrolytically, usicg Frary’s apparatus (QNALYST, 1908, 30), on a gauze cathode of 50 sq. cm. surface, with a current of 1.5 amperes at 4 volts; the electrolyte is kept cold by oirculating water through a test-tube around which the wire anode is wound, and which is immersed in the liquid; lead may be deposited on the anode, but dissolves again on standing.At the end of the electrolysis, which requires one hour, the liquid is made alkaline with potassium hydroxide, and lead and the trace of copper left in solution are precipitated with very dilute potassium sulphide, filtered off, and separated with sulphuric acid as usual. In the filtrate, antimony and tin are separated with oxalic acid and hydrogen sulphide. The trace of tin which may have been deposited with the copper is recovered by dissolving the latter in nitric acid. . If zinc is present, the sulphides of tin, antimony, lead, and copper are first precipitated with hydrogen sulphide in the liquid left after the electrolysis, after adding a considerable quantity of sulphuric acid. A. G. L. Separation and Estimation of Tin, Arsenic, and Antimony in Bronzes.M. Dinan. (Monit. Scicnt., 1908, 22, 600-602 ; through J o z L . ~ . SOC. Chenz. Iizd., 1908, 27, 963-964.)-Three grams of the alloy are treated with 30 C.C. of nitric acid (specific gravity, 1*4), the liquid being boiled after the action has ceased. The in- soluble residue, containing the whole of the tin, antimony, arsenic, and phosphorus, together with a little copper and lead, is washed by decantation, and then dissolved, by boiling for thirty minutes or more in a solution containing 10 grams of oxalic acid and 4 to 5 grams of ammonium oxalate; 1 C.C. of hydrochloric acid is then added, the whole diluted to 400 c.c , and a rapid stream of hydrogen sulphide passed tlirough the nearly boiling liquid for two hours. The precipitated sulphides of all the metals present, except tin, are filtered off and washed with hot water ; the filtrate is concentrated, 5 to 6 grams of oxalic acid are added, and tin is precipitated electro- lytically from the hot liquid, a current density of 1 ampdre per sq.dm. being used; in the filtrate phosphorus may be estimated as usual. From the sulphide precipitate obtained above, the sulphides of antimony and arsenic are dissolved by means of boiling potassium hydroxide solution, leaving the sulphides of copper and lead ; the filtrate is evaporated to 40 c.c., 60 C.C. of hydrochloric acid are added, and the heating is continued until hydrogen sulphide is completely expelled ; the precipitated arsenic sulphide is filtered off, washed with dilute hydrochloric acid, dissolved in potassium hydroxide solution, and converted into arsenic chloride by adding 60 C.C. of hydrochloric acid and a few grams of potassium chlorate; after boiling off the excess of chlorine, the arsenic is estimated iodometrically.I n the filtrate from the arsenic sulphide, antimony is similarly oxidised to the pentavalent state by means of hydrochloric acid and potassium chlorate, and estimated iodometrically, after boiling off chlorine and diluting to 500 to 600 C.C. Alternatively, antimony may be electro- lytically separated from arsenic by dissolving the sulphides in sodium sulphide solu- tion, adding alkali hydroxide and potassium cyanide, and electrolysing the liquid in the cold, using aslow current density. The sulphides of copper and lead obtained above are dissolved in nitric acid440 THE ANALYST.(specific gravity, 1.2); the solution is added to the filtrate from the original in- soluble, and the whole evaporated to about 15 C.C. ; 3 C.C. of a saturated solution o sodium acetate are added, and the cold solution is electrolysed, using a current of N.DlOo = 0.5 a m p h at 4 volts ; the copper is weighed on the cathode, and the lead peroxide, deposited on the anode, is dried at 180" to 200' C. and weighed. In the liquid, zinc is estimated, as usual, with sodium carbonate, after destroying ammonium salts. If iron is present in the alloy it contaminates many of the deposits, and its exact determination is complicated. A. G. L. Simple Method for the Estimation of the Halogen in Mercuric Chloride or Bromide. (ZeiLs. Anorg. Chenz., 1908, 59, 271-272.)-The mercuric chloride or bromide is dissolved in water, four times its weight of pure sodium hydroxide and an excess of hydrogen peroxide are added, and the solution is slowly heat,ed to boiling.As soon as the excess of hydrogen peroxide has been decomposed the precipitated mercury is filtered off and washed. The filtrate, which is free from mercury, is acidified with nitric acid, and the halogen estimated in the customary manner. A. G. L. M. Kohn. The Estimation of Nitrates in Bismuth Salts. W. H. Simmonds. (Chemist nizd Drzigist, 1908, 73, 108.)-Titration with a solution of indigo is recommended as a suitable method of estimating nitrates in the oxide, hydroxide, citrate, oxychloride, and phenate of bismuth. The reagent is prepared by dissolving 5 grams of indigo carmine in water, filtering, adding 50 C.C.of strong sulphuric acid to the filtrate, and making up the solution to a litre. The method cannot be used with the salicylate, tannate, or gallate of bismuth, and no satisfactory method is known for the estimation of nitrates in the last two. I n the case of the salicylate satisfactory results may be obtained by the following modification of Loof's method, which is based on the forma- tion of nitrosalicylate. From 0.2 to 0.5 gram of the salt is shaken with 5 C.C. of water, and the liquid cautiously mixed with 10 C.C. of strong sulphuric acid. The resulting crimson colour is matched with that produced under the same conditions with a definite quantity of a 0.1 per cent. solution of potassium nitrate containing 0.1 gram of sodium salicylate.Commercial samples of bismuth basic salicylate con- tained from 0 to 4 per cent. OE bismuth nitrate (BiONO,,H,O), whilst seven samples of the basic carbonate containedfrom 0 to 2.6 per cent., and three samples of citrate from 0 to 2.49 per cent. C. A. M. Electrolytic Determination of Nitric Acid. 0. L. Shinn. (Jozm. Anze~. Chenz. SOG., 1908, 30, 1378-1381.)-1n 1905 Ingham studied the electrolytic de- termination of nitric acid by reduction to ammonia, using the rotating anode and a high current density. The reduction must be performed in presence of sulphuric acid and copper sulphate, and if standard acid be employed, the ammonia formed may be estimated by back titration without the necessity of distilling. Considerable difficulty has been experienced in reproducing Ingham's results, the values generally obtained being considerably too low.The author proves that this error is due to residues of unreduced nitric acid, and that these residues escape reduction owing toTHE ANALYST, 441 the premature precipitation of the copper. This trouble may be surmounted by adding further quantities of copper sulphate during the course of the electrolysis. The rapidity of the precipitation of the copper depends on the speed of rotation of the anode, and if this be reduced to 120 revolutions per minute, complete reduction of the nitric acid may be effected with the proportions prescribed by Ingham. For obtaining good results, the voltage should be about 10 with a current of 4 to 5 amp8res.This requires that the quantity of acid present be limited to 20 to 25 C.C. of $ sulphuric acid. The only advantage to be gained by rotating the anode is that the copper comes down as an adherent deposit, in which case a second, and some- times a third quantity of copper sulphate must be added. With a stationary or slow- moving anade the copper deposit is spongy ; this does not affect the result, provided the copper deposit be not allowed to oxidise before washing out the acid solution from the dish for titration. J. F. B. Rapid Colorimetric Method for the Estimation of Small Quantities of Water-Soluble Phosphoric Acid. Pouget. (Chein. Zeit ., 1908, 32, 832.)-This method, which gives extremely accurate results for the estimation of exceedingly minute quantities of phosphoric acid depends upou the action of the molybdates of the alkaloids upon the phosphoric acid.A coloured turbidity is rapidly formed, which is stronger the greater the quantity of phosphate present. The estimation is then performed by comparison in a colorirneter with standards containing known quantities of phosphoric acid. The best reagent is strychnine molybdate, which always shows a direct proportionality between the coloration and the quantity of phosphoric acid. I n the estimations it is necessary always to maintain a, certain degree of acidity, corresponding to about 7 to 8 per cent. of nitric acid. The method is sensitive to 1 part of phosphoric acid in 12,000,000 of liquid. J. F. B. A New Method of Separating Silica and Tungstic Acid. E. Defacqz.(Bull. SOC. Chim., 1908 [iv.], 3, 892-894.)-Silica is not reduced by hydrogen at a temperature of 600" to 800" C., nor does it combine with chlorine at the same temperature. Tungstic anhydride, on the other hand, is reduced by hydrogen under the same conditions to a lower oxide, or even to the metallic state. I n the former case it readily yields oxychlorides, and in the latter case gives a hexachloride on treatment with chlorine. The mixture of silica and tungstic anhydride is heated to redness in a current of hydrogen, and when reduction is sufficiently complete the boat is introduced into a glass tube, with arrangements to condense the volatile products, and heated to redness in a current of chlorine. If the reduction with hydrogen is complete, the condensed products will consist of a mixture of tungsten hexachloride and oxytetrachloride (red needles); otherwise they will consist of a mixture of the oxytetrachloride and of yellow oxychloride. The absorption vessels containing these chlorides and oxychlorides are treated with very dilute ammonia solution, the washings united, and the tungsten estimated by one of the known methods. The boat containing the residual silica is heated in a current of air or in hydrogen to expel the chlorine, and then weighed. The silica should not darken when heated in hydrogen, and should not, after fusion with potassium bisulphate, give any of the reactions for tungsten compounds. C. A. 14.

ISSN:0003-2654    

DOI:10.1039/AN9083300437

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 442 APPARATUS, ETC. New Apparatus for the Quantitative Distillation of Ammonia. P. A. Kober. (Journ. Amer. Chem. SOC., 1908, 30, 1131-1135.)-The author has succes8- fully applied Folin’s method (Zeits. physiol. Chem., 37, 161) to the distillation of ammonia at the end of a Kjeldahl estimation. The mass left at the end of the digestion is diluted with 40-95 C.C. of water, according to the quantity of sulphuric acid (10 to 25 c.c.) used, and the Kjeldahl flask is connected to a cylinder 45 cm. high and 5 cm. wide, by means of a tube passing to the bottom of the cylinder ; the standard acid is placed in this cylinder. An excess of pure sodium hydroxide solution is then sucked over into the Kjeldahl flask from a second cylinder through a tube widened at the bottom to a bore of at least 12.5 mm.to prevent obstruction by sodium sulphate, the flask being vigorously shaken. The second cylinder is then disconnected, and replaced by an apparatus for purifying air, and suction continued for another hour, at the end of which time all the ammonia, will have been transferred to the first cylinder, the contents of which are titrated as usual. A little toluene or petroleum may be placed in the flask to avoid frothing. A. G. L. An Automatic Siphon-Pipette. H. S. Bailey. ( J o z m . Amer. Chem. Sot., 1908,30, 1508-1509).-This pipette is a modified form of that devised by G. E. Patrick, and is useful for supplying approximately constant amounts of sulphuric acid and other reagents. The pipette has duplicate measuring-vessels to avoid loss of time in waiting for refilling.The two vessels, H, and H,, may be of any desired capacity, and are con- nected alternately with the supply and delivery outlet by means of a four-way stopcock, so that one is refilling while the other is emptying. The tube F, which forms the core of the stopcock, must be of such a length that there is no danger of the solution, which siphons in from C, running over even when the stock-bottle is full. The small capillaries, with the safety-bulbs D, D, should be longer than F, since drops of the solution froin the last charge may occasionally collect in them, and be forced upward by the outgoing air when H is refilling. C is a siphon having a, leg in F a little shorter than the one in the reservoir, so that the solution may drain back rather than into the pipette when raised to remove the stock-bottle.The apparatus is fastened to a board by leaden strips, and is secured to the shelf on which the stock-bottle stands, at such a height that the tops of the vessels H, and H2 are level with the bottom of the reservoir. With the handle K turned to the right, the siphon is started by blowing into one hole of the two-holed rubber-stopper which holds C in place in the stock-bottle,443 THE ANALYST. when H, fills until the solution is level in the capillary with the solution in the reservoir. A reversal of the handle then empties H, while H2 fills. A. R. T. Separating Funnel for the Estimation of Unsaponi- Aable Matter in Oils and Fats. Wittels and Welwart. (Chem. Zeit., 1908, 32, 941.)-The piece of apparatus shown in the illustration is intended for use in estimation of un- saponifiable matters in fats and oils.The solution con- taining the saponified fat is introduced into the funnel, and diluted with water until the surface is from 2 to 4 mm. below the point 72. Ether is then added, the mixture is shaken, and, after separation has taken place, the ethereal portion is run off by the tap c . A fresh quantity of ether is next added through the neck a, and the extraction is repeated. The use of the apparatus does away with the necessity of drawing off the aqueous portion each time in order to collect the ethereal extract. w. P. s. A Rapid Viscosimeter. F. Schultz. (Chem. Zeit., 1908, 32, 891.)--The viscosimeter consists of a tube of 0.5 cm. bore, 18 to 20 em. long, drawn out at one end to a jet of 0.1 cm. bore, and provided with a paper scale graduated in rnillimetres. If an oil is allowed to flow from the vertically held pipette, the height at which the oil stands in the pipette when the stream begins to break up into separate drops is dependent only on the viscosity, if the temperature is kept constant. The pipette is standardised on four or five oils of known viscosity, and will then give results correct to 0.5" Engler for oils having a viscosity of less than 30" Engler. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9083300442

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 443 PARLIAMENTARY REPORTS. METHODS OF TREATING AND DISPOSING OF SEWAGE. FIFTH REPORT OF THE ROYAL COMNISSION ON SEWAGE TREATMENT. (Cd. 4278.) THE Commission wag appointed to inquire and report (la) what method or methods of treating and disposing of sewage (including any liquids from any factory or manu- facturing process) may properly be adopted, consistently with due regard for the requirements of the existing law, for the protection of public health, and for the economical and efficient discharge of the duties of local authorities ; ( I b ) if more than one method may be so adopted, by what rules, in relation to the nature or volume of the sewage, or the population to be served, or other varying circumstances or require- ments, the particular method of treatment or disposal to be adopted be determined;444 THE ANALYST.(2) to make any recommendations which may be deemed advisable with reference to the treatment and disposal of sewage. The first Report issued (1901) by the Commission was of an interim character, and dealt with the suitability of different lands or soils for the purification of sewage ; the second Report (1902) was a formal document covering certain scientific papers which were presented as an Appendix to that Report; in the third Report (1903) the Commission dealt with the relations between local authorities and manufacturers in regard to the disposal of manufacturing effluents. The Commissioners found that the present state of the law was most unsatisfactory, that the attitude of local authorities towards manufacturers had differed widely, and that many manufacturers were seriously handicapped ; purification of the effluents by the local authorities is in the great majority of cases practicable, and could be done more cheaply than by the manufacturers themselves.Recommendations covering these points are then made. The fourth Report (1904) deals with the pollution of tidal waters, with special reference to the contamination of shell-fish, The present Report deals chiefly with the relative merits of the various methods which are available for the purification of the sewage of towns. The Commissioners are satisfied that it is practicable to purify the sewage of towns to any degree required, either by land treatment or by artificial filters, and that there is no essential difference between the two processes; the choice of a scheme must depend on a number of considerations which are discussed helow.I t is generally desirable to remove from the sewage, by a preliminary process, a considerable proportion of the grit and suspended matters, before attempting to purify it on land or by means of filters ; two or three hours’ quiescence is usually sufficient to produce a tank-liquor fairly free from suspended solids, whilst, in the case of continuous flow sedimentation, the period of flow should generally be from ten to fifteen hours. Only about 25 per cent. of the organic solids present in domestic sewage are digested in the septic tank, when the tanks are worked at a twenty-four hours’ rate; the liquor issuing is bacteriologically almost as impure as the sewage entering the tanks, and is not more easily oxidised in its passage through filters than is domestic sewage which has been subjected to chemical precipitation or simple sedimentation.NO definite rules can be laid down as to how long a septic tank should be run with- out cleaning, and the rate of flow through the tank is a matter which requires special consideration for each place. At but few places should the sewage be allowed to take longer than twenty-four hours or less than twelve hours to flow through the tank, and at least two tanks should be provided, so that, if necessary, one tank can be used a k m . There is less risk of nuisance if the tank and the feed channels to the filters are covered in. The addition of from 2 to 3 grains of lime per gallon considerably reduces the amount of suspended solids in the liquor, enables a larger quantity of the liquor to be treated per cubic yard of filter, and the offensive character of the liquor is largely destroyed.I n the case of sewages which contain certain trade wastes, and strong sewages from water-closet towns, it is generally desirable to subject the sewage to some form of chemical treatment before attempting to oxidise the organic matter contained in it. This treatment aids the deposition of the suspended solids and facilitates the aubse-THE ANALYST. 445 quent filtration. With continuous flow, an eight hours’ rate is usually sufficient to produce a fairly good tank liquor from domestic sewage of average strength ; if the sewage is allowed to remain quiescent in the tank two hours’ settlement would usually sufice.Unless special circumstances favour a particular plan, it would appear that there is very little difference in annual cost between the various methods of tank treatment when taken in conjunction with the cost of subsequent filtration. Within ordinary limits, the depth of a contact bed makes practically no diEer- ence to its efficiency per cubic yard, but it is generally inadvisable to construct a contact bed of a greater depth than 6 feet or of a less depth than 2 feet 6 inches. For practical purposes, a given quantity of coarse material will give the same amount of purification whether it is arranged in the form of a deep or a shallow percolating filter, provided that the supply of liquor per square yard is the same.In the case of fine material, it appears that shallow filters have a greater efficiency than deep filters. The amount of sewage which can be purified per square yard of contact bed or of percolating filter varies nearly inversely as the strength of the liquor treated. Taking into account the gradual loss of capacity of contact beds, a cubic yard of material arranged in the form of a percolating filter will generally treat about twice as much tank liquor as a cubic yard of material in a contact bed. Percolating filters are better adapted to variations in flow, yield more aerated effluents, and give less risk of nuisance from smell than do contact beds. There is no essential difference between effluents from land and effluents from artificially constructed filters.Soils which are particularly well adapted for the purification of sewage yield effluents containing only a very small quantity of unoxidised organic matter, and of a higher class than effluents from artificial filters ; unsuitable soils, however, may give very impure effluents. All trade effluents of which the Commission have had experience interfere with or retard processes of purification to some extent, but in no case does the admixture of trade refuse make it impracticable to purify the sewage, although in some cases preliminary treatment may be necessary. As regards the choice of a method of sewage treatment, it is considered that this should depend primarily on local conditions. If a sufficient quantity of good land, to which the sewage can gravitate, can be purchased for about 3100 per acre, land treatment would usually be the cheapest method to adopt.Where only clay land is available, it would be cheaper and more satisfactory to provide artificial filters. Or, if the case were one in which it was necessary to obtain a high-class effluent, it might be cheaper to pay a somewhat higher price per acre than $100, rather than to adopt artificial treatment, or the latter, as usually carried out, yields distinctly inferior effluents. On good land the sewage can be treated at the rate of 30,000 gallons per acre per day; filters with a top layer of very fine material, such as sand, can be made to give good results with a rate of filtration of 400, or even 500, gallons per cubic yard per day, if the sewage be weak and well clarified.No general rule can be laid down as to the increase in flow, due to storms, which should occur in branch sewers before sewage is allowed to pass away by the overflow untreated; the general principle should be to prevent such an amount of unpurified sewage from passing over the overflow as would cause a nuisance. Under446 THE ANALYST. the arrangements recommended by the Commission (stand-by tanks, sufficient filter area, etc.), no storm sewage arriving at the outfall works would be discharged without some preliminary method of settlement, The Commission further recommend that a Central Authority should determine the nature of tests which are to be applied for the purpose of standards, and that it should be made the duty of the Rivers Board or of the County Council to determine from time to time, subject to appeal to the Central Authority, what standards should be adopted.In the first instance, it would be convenient that the Central Authority should prescribe one standard for all non-tidal waters; in place of the existing statutory provisions, and that the Rivers Board or County Council should fix a higher or lower standard where required. If an effluent, complying with the standard fixed for the water into which it is discharged, gives rise to a complaint, no action should be allowed to be brought in respect of alleged damage; but the Central Authority, on ascertaining that the complaint is well founded, should be empowered to fix a different standard.Should an effluent not comply with the statutory standard, actions for damages should be brought in the ordinary Courts. Power should be conferred on the Central Authority to suspend the operation of any standard to allow time for the construction of works, etc. For the guidance of local authorities, it is provisionally stated that an effluent would generally be satisfactory if it complied with the following conditions : 1. That it should not contain more than 3 parts per 100,000 of suspended matter; and 2. That, after being filtered through filter-paper, it should not absorb more than : (a) 0.5 part by weight per 100,000 of dissolved or atmospheric oxygen in twenty- four hours. ( b ) 1.0 part by weight per 100,000 of dissolved or atmospheric oxygen in forty- eight hours; or (c) 1.5 parts by weight per 100,000 of dissolved or atmospheric oxygen in five days.Apart from the question of drinking-waters, there is no evidence that the mere presence of organisms of a noxious character in a river constitutes a danger to public health or destroys the amenities of the river. Generally speaking, therefore, there is no justification for demanding that a, local authority shall so treat its sewage as to render it bacteriologically pure ; the cost would be practically prohibitive. Storm- water as well as sewage would have to be treated, and the water of rivers would still require to be treated before it could be distributed for drinking purposes. The Central Administrative Authority would be empowered to secure the economical and efficient discharge of the duties of local authorities and others, in regard to pollution, and to protect public health, as the conditions of different cases vary to such an extent that the necessary control cannot be provided by any direct enactment which could be enforced by the ordinary Courts.The Central Authority would also deal with (1) disputes between local authorities and manufacturers as to the terms and conditions on which the trade effluents shall be admitted to the sewers ; (2) the control of shell-fish layings ; (3) the protection of water-supplies from pollution ; (4) the collection of information as to the available water-supplies of the country;THE ANALYST. 447 ( 5 ) the collection of information as to the need of water in various parts of the country ; (6) the settlement of standards for different reaches of water ; (7) conferring powers on local authorities to provide separate sewers for surface water and to enforce the provision of separate drains; and (8) the settlement of questions as to the extra, amount of sewage which a local authority should be required to treat during storms.The Report also gives the results of a number of experiments carried out with the object of ascertaining the manurial value of sewage sludges. A record of these investigations is published as an Appendix (No. 8) to the Report. Dr. W. Somerville, as the general result of his experiments, concludes that the nitrogen and phosphoric acid of sludge are in a much less available form than the same substances in sulphate of ammonia, superphosphate, and fish-meal.None of the sludges experimented with produced any considient manurial effect on the growth of turnips, swedes, or mangolds. Professor T. H. Middleton states that the figures obtained do not permit of any conclusions as to the relative values of sludge and artificial manures. The only definite conclusion is that, in the case of root crops and grass, the action of the nitrogenous and phosphatic constituents of sludge is very slow as compared with the effect pro- duced by nitrogen and phosphates supplied by ordinary artificial manures. Dr. J. A. Voelcker concludes that further experiments are necessary before the effect of sludge on grass-land can be determined; the only clear benefit wag to be traced to the more quickly acting material sulphate of ammonia, and it is by no means certain that permanent improvement of the pasture resulted.I n the case of wheat, the experiments showed that the different sewage sludges used, when employed in sufficient quantity to supply 40 pounds of nitrogen per acre, were capable of increasing the yield of both corn and straw by 10 to 12 per cent. above the unmanured produce. The ‘‘ artificial equivalents ” of the different sludges produced an increase in corn and straw of 16 to 17 per cent. above the unmanured produce. The tendency of the use of sewage sludges is to produce a greater length of straw. From a practical point of view, none of the sludges used would be worth 10s. a ton on the farm for wheat- growing purposes. These investigations show that, on the whole, the manurial constituents of sewage sludge act much more slowly than those of ordinary artificial manures.w. P. s. THIRTY-SECOND ANNUAL REPORT OF H.M. INSPECTORS OF EXPLOSIVES, 1907, 17-18. Tests for Mercury in Explosives. F. H. AND P. V. DUPR~. For the detection of mercury, different classes of explosives require different treatment, and in some cases very delicate methods are necessary to detect the minute quantities present. I n all cases a special form of spectrum-tube has been employed by the authors. This consists of two stoppered tubes of about 20 C.C. capacity joined by a capillary tube. One of the stoppers carries a, tube fitted with a tap; all grinding must be very carefully performed, in order to hold a vacuum for448 THE ANALYST.several hours. About the centre of each tube, the electrodes, contained in tubulures slanted up so as to prevent the entrance of the explosive, are attached. The parts of the tubes below these tubulures are filled with the substance to be examined, the stoppers are replaced, and the apparatus is exhausted by a vacuum pump (not a mercury pump). The parts of the tube containing the explosive are immersed in water at 90" C., and a discharge from a 6-inch induction coil is passed through. The capillary tube is then examined, end on, preferably with the aid of a condenser to increase the brilliancy of the spectrum. If traces of mercury be present its spectrum will be seen, together with those of any other gases, such as oxygen, hydrogen, nitrogen. The spectrum of nitrogen may be eliminated by passing a current of hydrogen through the cold tube before exhaustion.The lines which are relied on for proving the presence of mercury are : yellow, 5,790 and 5,769 ; green, 5,461 ; violet, 4,359. Ungelatinised guncotton may be tested directly ; gelatinised explosives may be prepared by grinding with French chalk. In the case of cordite and hard gelatinised explosives, the mercury salt is extracted by ether and separated by electrolysis under conditions fully described in the Report. Minute traces of metallic mercury are detected by concentrating its vapours on silver-foil by heating the explosive with the foil in a closed bottle. Small traces of mercury may enter an explosive in the form of contamination by means of machinery previously used with mercury salts.Cases are on record where traces of mercury persisted in the products for six months after the use of mercury salts had been discontinued. The authors have ascertained that -001 mgm. of mercury is sufficient to retard the heat test of an explosive by five minutes. The use of a strip of silver-foil in carrying out the heat test counteracts the effect of the mercury, but itself has a masking action on the test owing to the absorption of the acid vapours by the silver. Gold is less objectionable than silver, but is quite inadmissible with nitroglycerin explosives. Heat Test Papers for Explosives.-Several batches of paper tried by the authors, though otherwise satisfactory for the heat test of explosives, have been found to contain Home substance, insoluble in water, which is capable of liberating iodine from potassium iodide in the presence of acetic acid. I n future all papers prepared for this test should be washed twice, for half an hour each time, in a 10 per cent. solution of acetic acid, and subsequently washed for at least twelve hours in a running stream of tap-water. After two rinsea in distilled water and drying, the paper is ready for dipping. The authors point out the necessity of adhering most closely to the specified details in carrying out the heat test, as small variations may cause great discrepancies. Papers may be checked against approved papers prepared by the authors. Amongst variations in carrying out this test the authors have encountered : variations in the method of heating the bath, interference with the convection currents, insuflicient grinding, excessive moistening of the papers, e tic. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9083300443

出版商:RSC    

年代:1908

数据来源: RSC