98 THE ANALYST. ORGANIC ANALYSIS. The Estimation of Acetone. G. Heikel. ( C l m z . Zeit., 1908, 32, 75-76.)- llessinger’s method, in which the acetone is converted into iodoform by treatment with an excess of iodine solution, gives excellent results with pure acetone, but in the case of crcde acetone the presence of higher ketones which also yield iodoform causes the results to be too high. On the other hand, the method of DenigCs (ANALYST, 1899, 24, 92), based upon the formation of au insoluble compound of acetone with mercuric aulphate, has the dmwback that numerous bodies besides acetone in crude acetone yield a, similar precipitate. By the use of the two methods, however, approximately accurate values may be obtained. In the manufacture of acetone, three final products are obtained in addition to the pure (over 99 per cent.) acetone, viz.: (1) The so-called ketones ” (mainly methyl-ethyl-ketone), boiling at 65” to 75” C., and having a specific gravity of 0.811 to 0.815 at 15” C ; (2) light acetone oil, boiling at 75” to 130’ C., and having a specific gravity of 0.82 to 0.83; (3) heavy acetone oil, boiling at 130” to 250” C., and having a specific gravity of 0.88 to 0.89. Samples of these products examined in aqueous solution by the two methods mentioned above gave the following results : L)enig&s’ Metliod. Per Cent. Jlessinger’s JIetliod. I)enigt‘.s’ Mctliod. Jlessingcr’s Method. Per Cent. Per Cent. Per Cent. ______ __ “ Ketones ” ... ... 89.9 63.5 0-706 Light oil ... ... ... 57.2 32.6 0.570 Heavy oil ... ... ... 39.5 25.4 0-643 The mercury precipitate in DenigBs’ method, which is almost white in the case of pure acetone solutions, is yellowish-white when obtained from “ ketones,” brownish- yellow when from light oil, and nearly brown when from heavy oil. Hence it is possible to determine rapidly whether a given sample consists of pure acetone or contains the higher-boiling constituents of the crude product. The values given above for the three constituents are, as a rule, sufficiently accurate for practical purposes, as is shown by test analyses.In one instance cited a sample with specific gravity 0.813, sold as ketones,” yielded 35-5 per cent. of acetone by Messinger’s method, and 34.9 per cent. by DenigBs’ method (precipitate perfectly white) ; so that the substance producing iodoform could only have been acetone, and not a homologous ketone.C. A. Rl. Estimation of ‘‘ Crude Fibre ” and Separation of Cellulose, Lignin, and Cutin. J. Konig. (Ber. deut. Ckem. Ges., 1908, 41, 46-49.)-1n reply to the criticism by Matthes and Streitberger (ANALYST, 1908, 15) on the author’s process for the estimation of crude fibre,” the author quotes severa.1 opinions in favour of the method. Konig’s method yields a fibre which is freer from pentosans than that obtained by any other method, and the estimation can be carried out in three to four hours. But in order that different analysts may obtain concordant results, it is necessary to adhere closely to the conditions prescribed by Konig. Substances, suchTHE ANALYST. 99 as cocoa, which are rich in fat must be thoroughly extracted before the estimation of the fibre.The glycerin employed should have a specific gravity of 1.23, and contain 20 grams of concentrated sulphuric acid per litre. The product must be washed first with sufficient boiling water (generally about 400 c.C.), then with warm 90 to 95 per cent. alcohol, and lastly with a warm mixture of alcohol and ether. The washing is so carried out that the filtrate comes through perfectly colourless. In the case of very finely ground powders, including cocoa, it is advisable to largely dilute the steamed or boiled product in large beakers, allow to settle, decant off the clear liquid, and then to dilute the sediment before boiling it up and filtering. If the decanted liquid be not quite clear, it should be further diluted and filtered before.the sediment is brought on to the filter. The author points out that what agricultural chemists term '' crude fibre " or " lignin " is not an individual substance, the propor- tion of which can be expressed in absolute terms, but is a residue of mixed coin- position which varies according to the process employed for its isolation. All that can be expected is that, provided the process be carried out exactly under standard conditions, the results shall be concordant and possess a comparative value among themselves. J. F. B. Action of Ozone on Multiple Bonds. C. Harries. (Be?.. d c i i t . C l ~ i z . Ges., 1907, 40, 4905-4908.)-The author denies the statement of Molinari (ANALYST, 1908, 22) that compounds containing triple bonds of the acetylene type may be distin- guished from those containing double bonds by means of ozone.The means pre- scribed by Molinari for ascertaining whether ozone is fixed or noi are stated to be quite inadequate, and the conclusions founded on the test (toe. cit.) are therefore unsound. As a matter of fact, compounds containing acetylenic bonds form perfectly definite ozonides, several of which have been isolated. The use of ozone for deter- mining the structure of the nucleus in aromatic compounds is likewise unjustified by the experimental facts. J. F. B. Melting-Points of Phenylhydrazine and Certain Osazones. E. Fischer. (BET. cleut. Chem. GES., 1908, 41, 73- 77.)-The author has re-determined the melting- point of phenylhydrazine, which has been previously recorded by himself as 2 3 O to 23-5" C., and by Berthelot as 17.5" C.Working on a particularly pure specimen with the thermometer immersed in the semi-fused mass, he has now found 19.6' C. to be the true melting-point. The true melting-points of the osazones are very uncertain and difficult to determine, since they depend on the rapidity of heating. Tutin (ANALYST, 1908,25) has recently stated that phenylglucosazone melts at 217' C., but the author cannot confirm this. Heated in a capillary tube, at the rate of lo C. per 2-3 seconds, the glucosazone begins to melt at about 205' C. (208' C. corr.), and complete fusion will take place at this temperature if the flame be extinguished ; but if heating be continued at the same rate the fusion, which takes place with decom- positition, is not complete until the thermometer indicates 209' C.(213' C. corr.). When the osazone is heated so slowly that the temperature rises from 195O to 200' C. in one minute, fusion begins at the latter temperature with decomposition and softening. Phenylgalactosazone melts, according to the rapidity of heating, at100 THE ANALYST. temperatures ranging between 180" and 193' C. When heated at the rate of lo C. per 2--3 seconds, the melting-point is about, 1 8 6 O C. (188OC. corr.), but slight differences are unavoidable in different determinations. Maltosazone, under the same con- ditions, melts at about 205' C. (208" C. corr.). Lactosaxone begins to melt at about 200' C., but fusion is not complete until 210' to 212' C. (213' to 215' C.corr.). I t i8 not advisable to prepare osazones by means of phenylhydrazine base and acetic acid unless the base be freshly purified. The original prescription of 2 parts of phenylhydrazine hydrochloride and 3 parts of sodium acetate is preferable. The hydrochloride should be recrystallised from alcohol until it is quite colourless. J. F. 13. The Detection of Sesame Oil. H. Sprinkmeyer. (&it. UntersucIi. Nrihi-. G~Ic~Lss?~L., 1908, 15, 20-21.)-The author finds that rancid cottonseed oil containing sesame oil gives no red coloration when shaken with hydrochloric acid and furfural, unless at least 17 per cent. of sesame oil is present. This fact is of Borne importance, as, according to German law, margarine must contain so much sesame oil that a distinct red coloration is produced when 0.5 C.C.of the clear melted fat is mixed with 9.5 C.C. of cottonseed oil and the mixture is shaken with an equal volume of hydrochloric acid and a few drops of 2 per cent. alcoholic furfural solution. Rancid cottonseed oil also interferes with Soltsien's reaction for sesame oil. H. Kreis (Chew. Zeit., 1908, 23, 87-88) states that rancid sesame oil gives a less intense coloration with furfural and hydrochloric acid than does fresh sesame oil. The addition of cottonseed oil appears to influence the delicacy of the test to a certain extent; the coloration obtained is more permanent than that given by mixtures of sesame oil with olive oil. w. P. s. Estimation of Starch. E. Parow and F. Neumann. (Zeit. Spiritzuiitd., 1907, 30, 561-562.)-1n the common method of estimation, in which the starch is djssolved by means of malt extract, the hydrolysis completed by hydrochloric acid, and the dextrose estimated by means of Fehling's solution, the authors have obtained too low results when they have used the theoretical factor, 0.9, for calculating the dextrose into starch, and therefore employ an empirical factor, 0%.For the rapid valuation of commercial products they have devised the following simple modification of Gschwendner's polarimetric method : Ten grams of the sample are mixed with 50 C.C. of acid brine (prepared by dissolving 200 grams of salt in 800 C.C. of water, adding 220 C.C. of hydrochloric acid of specific gravity 1.125, and filtering the liquid), and heated in a boiling water-bath under a reflux condenser.The 100 C.C. flask is shaken at intervals, and kept immersed in the boiling water for exactly one hour, after which 10 C.C. of basic lead acetate solution are introduced, and the liquid cooled and made up to the mark. It is then treated with a little purified bone charcoal, filtered, and polarised in the 200 mm. tube. As the con- version of the starch into dextrose is incomplete, three parallel estimations should be made and concordant results obtained. The following factors for convertingTHE ANALYST. polarimetric values into starch were obtained from a large number results by this method and by the ordinary diastase-acid method : Polarisation Factor for Dry Starch. 101 of concordant Soleil-Veatzke c i r c 21 a r .cltal.Ch. Scalp. Degrees. Potato ...... ... 2.872 ... ... 8.28 Maize ... ... ... 2.938 ... ... 8.47 Rice ... ... ... 2.944 ... ... 8.49 Wheat ... ... ... 2.918 ... ... 8.42 C. A. M. Polarimetric Estimation of Starch. E. Ewers. (Zeds. oflent. C~CWL., 1908, 14, 8-19.)-Further investigation of the process devised by the author (ANALYST, 1906, 31, 25) showed that in the polarimetric estimation of starch the influence of optically active bodies other than starch is by no means negligible. Corrections have had to be applied, ranging in the case of wheat flour up to 3.7 per cent., and in the case of maixe to 9 per cent. In the case of dry samples, the material is finely ground and sifted; potatoes are rasped to a pulp and carefully sampled, The estimation consists of a main determination and a blank. For the former, 25 C.C.of glacial acetic acid are placed in a 200 C.C. flask without wetting the neck ; 10 grams of the substance are then introduced, the flask is closed and shaken vigorously until. the mixture is uniform. The stopper and neck of the flaek are then washed down with a further 25 C.C. of glacial acetic acid. I n the case of potato pulp, 10 to 13 grams of pulp are weighed out and introduced into the flask with 50 C.C. of acetic acid. The flask is placed in a boiling water-bath, and kept there for ten minutes. Then 10 C.C. of dilute hydrochloric acid (10 C.C. of the 25 per cent. acid per 100 c.c.) are added, and the flask is left in the water-bath for exactly six minutes, being shaken round every minute. Hot water is next added to bring the volume up to about 180 c.c., and the flask is kept for fifteen minutes longer in the boiling water-bath.It is then cooled to 20' C., 2 to 3 C.C. of a saturated solution of potassium ferrocyanide are added, and the contents are diluted to the mark, filtered, and polarised. Should the filtrate not be clear, a few crystals of zinc sulphate may be added to assist clarification. The blank experiment is performed as follows: Five grams of the substance are placed in a 100 C.C. flask with 70 C.C. of water at 50" C. (in the case of potato starch 35" C , ) , and mixed by shaking. I n the case of potato pulp, 10 grams are digested with 70 C.C. of water at the ordinary temperature for one hour. Potato starch is digested for half an hour at the ordinary tempera- ture; the grists, flours, and starches of cereals are digested at 48' to 50" C.for half an hour in the case of starches, an,[ one hour for the other products. Then 25 C.C. of glacial acetic acid are added, and digestion is continued at the same temperature for half an hour (starches only fifteen minutes). The temperature is finally adjusted to 20" C., ferrocyanide is added, and the liquid is diluted to 100 C.C. before filtering and polarising. The specific rotatory power of starch under the conditions prescribed varies according to its origin. The following values for [ a ] ~ , at 20" C., at a, con- centration of 5 per cent. are given : Wheat, 183.62" ; rice, 186.07" ; maize, 184.19' ;102 THE ANALYST, potato, 186.46". The values are practically constant for different concentrations. The moisture is determined by drying 10 grams of material for one hour at 40" to $0' C., and then for four hours a t 120" C. J. F. B. The Specific Gravity of Different Kinds of Starch. E. Parow. (Zeit. Spirit?tsind., 1907, 30, 432 ; Chem. Zeit. ,z2ep., 1908, 32, 17.)--The values given below were for the most part the mean results obtained in several determinations by means of the picnometer at 17.5' C. (water at 17.5" C. = 1) : Starch from Potato ... Wheat ... Xaize ... Rice ... Spccitic Gravity of Anhydrous Starch in Water. 1 -648 1.629 1.625 1.620 Specific Gravity of An hy drons Starch in Toluene. 1.513 1.502 1.499 1.504 Specific Gravity of Starch containing Water, in Water. Water per Cent. 18-72 19-35 20.14 13.38 13-80 14-60 11.06 12.88 14.36 11.92 13.10 14.14 Specific Gravity. 1.463 1.436 1-453 1.515 1.496 1.492 1:522 1 -504 1.490 1.514 1.500 1 -501 Specific Gravity of Starch containing Water, in Toluene. Water per Cent. 15.03 13-90 12.60 14.03 Specific. Gravity. 1.361 1-365 1.378 1.360 C. A. 31.