摘要:

THE ANALYST. SEPTEMBER, 1904. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. NOTE ON THE ESTIMATION OF SUGARS AND STARCH I N VEGETABLE SUBSTANCES. BY JOHN S. FORD. (Read at the Meeting, June 1, 1904.) THE method described here, whilst more particularly applicable to malted and unmalted grains, applies also more or less directly to other vegetable substances. In the extraction of pre-existent sugars from grains, means must be taken to avoid enzymic action on the sugars themselves, or on the other bodies present. In the case of malts containing invertase and amylase (diastase), amongst other ferments, simple aqueous extraction gives rise, as is well known, to inversion of sucrose, and to production of maltose by the action of amylase on the modified starch. Kjeldahl (Compt. Rend., Carlsberg, 1881) was possibly the first who tried to avoid this, and, amongst other methods he utilized for the inhibition of enzymic action during extraction, was a preliminary treatment with absolute alcohol, the substance being moistened with alcohol, and then heated in a water-bath until dry.This process destroyed the enzymes, and the sugars could then be extracted with water unchanged. O’Sullivan (Jour. Chem. Soc., 1886), in his method of sugar estimation, employed alcohol of different strengths for the extraction of the cereals examined, and by doing so inhibited enzymic change, and also obtained solutions of workable purity. The extraction is, however, tedious, and apparently difficult to bring to corn- ple t ion. Jais (Zed. f u r gesam., Brau, 1893), Jalowetz (Chem.Zeit. Rep. 1-S), Ehrich (Chem. Zeit. Rep., 1894), and Brown and Morris (Jour. Chem. Soc., 1893), recommend destruction of the enzymes by preliminary boiling with alcohol, the first three authors using alcohol of 90 to 94 per cent., and Brown and Morris alcohol of 80 per cent. The writer has employed this method since 1892, and wishes to point out that its utility depends upon the alcoholic concentration of the mixture, and that it is necessary to make allowance for the moisture present in the grain or substance278 THE ANALYST. CuO at 100" C. Grammes per 100 C.C. treated. Boiling with too concentrated alcohol does not destroy the enzymes, and the use of too dilute alcohol is attended with risk of alteration of the starch. The following experiment; carried out with a malt containing 1 per cent.moisture, shows the influence of the alcoholic strength : Ten grammes of the malt were boiled with 100 C.C. of the alcohol for one hour, filtered and washed with alchohol of the same concentration, air-dried, then extracted with 50 C.C. water for ten hours; filtered, and 5 C.C. of the extract added to 50 C.C. soluble starch solution at 40" C . for one hour, then boiled. Five C.C. of each extract were also added to 50 C.C. of the same starch solution at 100" C. The solutions were made up to 100 c.c., and their copper-reducing power determined as usual. CuO a t 40" C. Grammes per 100 C.C. Alcohol. Specilk Gravity, 15*6"C./ i 15'6°C. .SO2 -810 *a23 -833 *848 0.43 0.41 0.39 0.35 0-34 I i 0.75 0.41 0.39 0.35 0.34 Reaction of Aqueous Extract of Residue with Iodine.No coloration. Slight brown. ,, blue. ,, blue. ,, These results indicate that the moat suitable strength of alcohol is about 95 per cent. by volume. In the case of this malt the moisture present may be disregarded, but in natural grain, and other moist vegetable substances containing little sugar, where large quantities of the substance have to be extracted, it is necessary to allow for the water present. For example, 200 grammes of barley, containing 17 per cent. moisture, were boiled with 600 C.C. absolute alcohol for half an hour ; the destruction of the amylase and invertase was complete, and after filtration and washing with alcohol of 90 per cent. or so, the residue was air-dried and extracted with water ; the alcoholic extract, which contained a proportion of the sugars, was evaporated and then added to the aqueous extract, and the sugars estimated as uaual in the combined extract. It may be stated here that the treatment with 95 per cent.alcohol destroys the invertase aa well as the amylase. In the determination of starch by O'Sullivan's method (Jour. Chem. Soc., 1884), this preliminary treatment with alcohol enables the subsequent washing out of the amglans and other bodies to be carried out without loss of starch through diastatic action, a loss inevitable with probably all starches, but more particularly notable in the case of starch from germinated grains. In the case of vegetable substances of an acid nature, the boiling with alcohol even for half an hour gives rise to some inversion of sucrose, if present, and even with malts a slight hydrolysis occurs.If the substance is distinctly acid, a very slight excess of ammonia may be added to the alcoholic mixture before boiling. The actual volume of alcohol taken does not seem to be of much moment, provided there is sufficient to cover the substance and to boil readily; of course, this operation must be carried out with an inverted condense; to keep the concentration constant.THE ANALYST. 279 The destruction of the enzymes is no doubt due to the coagulating effect of the water at the boiling-point of the 95 per cent. alcohol. Boiling with ether 35’ C., petroleum ether 50” C., acetone 56-58” C., benzol 78-80“ C., toluol 106-110” C., as might be excepted, does not destroy the amylase to any great extent. DISCUSSIOX.Dr. SCHIDROWITZ said he must express his astonishment that no mention was made in this paper of the method for preventing diastatic action which had been worked out some years previously by Mr. Ling, and which he (Dr. Schidrowitz) should have thought was well-nigh universally used-namely, to extract with an alkali. This quite effectually prevented any diastatic action, and was far simpler than these complicated boilings with alcohol, etc. Mr. A. R. LING said the alkaline extraction method which he had proposed some years ago for the extraction of the sugars of malt was far simpler than tho treatment with alcohol described by the author, and this process he had developed in a recent paper (Jozun. Inst. Brewing, 1904, x., 238).Moreover, it appeared to him from some experiments made by a German colleague, Herr Mason, with English malts, that even 95 per cent. alcohol might not completely arrest diastatic action ; and Herr Jalowetz, he believed, had proved this. Mr. BEVAN thought that probably there would be some chance of hydrolysis by the action of the boiling alcohol. In trying some years ago to prepare pure crystals of sugar by crystallization from hot alcohol, he had invariably found that some of the sugar was inverted. ADDENDUM. Mr. Ford states that the criticisms of Dr. Schidrowitz and Mr. Ling evidently arise from a misapprehension of the object of this ‘( note,” which is only to point out the necessity of using alcohol of a definite strength when employing this method for the destruction of the enzymes. The alkali method of Mr. Ling is no doubt more suitable for technical work, but for scientific purposes it is open to various objections, and the determination of starch in the extracted residue by O’Sullivan’s method becomes practically impossible. Mr. Bevan’s remarks as to slight hydrolysis of sucrose by the boiling alcohol is, as has been mentioned, a valid objection.

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DOI:10.1039/AN9042900277

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年代:1904

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THE ANALYST. 279 ROASTED BEETROOT, BY E. G. CLAYTON. (Read at the Meeting, June 1, 1904.) IN a former communication (ANALYST, xx., 12) it was shown that chicory sometimes contains added sugar. Another substitute for, or additiop to, chicory is alleged to be roasted beetroot; and having had recently to decide whether certain chicory was admixed with this substance, the writer submitted to analysis some samples of beet-280 THE ANALYST. root which previously had been roasted and ground in the laboratory. The results are here stated : 0-17 4 9 5 2 - - - 59.1 6 1.37 1.93 0'99 - 7-89 8.39 6-18 0.97 .d i 8 a u 0.08 - - On an examination L these figures, it will be seen that roasted beetroot contains a larger proportion of total mineral matter than is usually present in genuine torrefied chicory, and that the soluble ash is about twice as high.I n roasted chicory the total ash would appear from the writer's own and many other published analyses to range, as a rule, between 4.5 and 6 per cent., the soluble salts constituting rather more than one-half. In beetroot the total mineral matter ranges from 6 to over 8 per cent., about five-sixths to three-fourths being soluble in water. Roasted beetroot yields to boiling water more soluble matter than is generally given by roasted chicory-it contains decidedly more sugar-and the specific gravity of its 10 per cent. inEusion is considerably higher, amounting to over 1030, as against 1023 or thereabouts. [The present writer's results do not accord with the specific gravity (1022.1) given by Bell (" Foods," 1881) for '' red beet."] The acidities of the aqueous extracts are nearly equal; so are the percentages of combined phosphoric acid ; but the proportion of chlorine appears to be higher in the ash of roasted beet- root than in that of roasted chicory.DISCUSSION. The PRESIDENT said it struck him that the composition of the ash of the roots must vary, according to the soil in which they were grown and the manures applied to the soil. Mr. HEHNER inquired whether the author had observed any difference in the microscopical structures of the tissues of beetroot and chicory. Mr. CLAYTON said that he had over and over again carefully examined samples of beetroot against samples of chicory, and the microscopical appearances were so closely similar that he should not like to attempt to differentiate between the two by micro- scopical examination. The well-marked spiral vessels observable in chicory were also to be seen in beetroot, and the dimensions were similar. That, at all events, was the case with some other roots.

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DOI:10.1039/AN9042900279

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年代:1904

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THE ANALYST. 281 IMPROVED CONTINUOUS-OBSERVATION POLARIMETER TUBE. BY JOHN SIMPSON FORD, F.R.S.E. IN the ‘( Principles and Practice of Agricultural Analysis,’’ 1897, vol. iii., p. 253, Wiley illustrates a continuous-observation tube devised by Pellet and modified by Spencer, and in (‘ Les Nouveautbs Chimiques pour 1901,” p. 215, Poulenc gives an account of the tube as described by Pellet in his L t Titres et Travaux Scientifiques,” 1900, p. 71. The writer of this note, without knowledge of these publications, made and used the form of tube illustrated below in 1899. The object of this communica- tion, however, is in no way to claim priority, but simply to call attention to the advantages of the use of this form of tube when many solutions have to be examined for optical activity, as, so far as the writer can gather, it is not well known in this country.The general construction is fairly obvious from the accompanying diagrammatic illustration of a 2-decimetre tube. The tube used by the writer is entirely con- structed of metal. The funnel (brass) has a capacity of about 65 c.c., and the tube proper (which is of “tinned copper”) of 7 to 8 C.C. The overflow pipe may empty iDto an open draining pipe, or be con- nected by means of rubber tubing to a table drain or waste jar. I n the latter case the overflow pipe has a small hole on the upper part of the bend, so arranged as to prevent siphoning action. The upper portion of the interior of the tube at the overflow end is cut away, as shown, so that air bubbles carried along find a ready exit. The openings at each end of the tube proper are slits cut at right-angles to the axis of the tube, and extending about one-third round.They are slightly wider than the corresponding annular openings of the funnel and exit tube. This arrangement allows a certain latitude in screwing the caps on, so as to bring the openings into apposition, and give at the same time a tight joint. On the outside of the tube, about the middle, two short arms (not shown in the figure) are soldered on. These rest on the edges of the lower segment of the tube case of the polarimeter, and prevent the tube from slipping round. It is obvious that, when necessary, a circulating jacket can be added to the arrangement. I n the examination of sugars or worts, the writer generally secures a volume of 80 to 90 C.C.of filtrate, of, approximately, 10 per cent strength. The specific gravities are then determined accurately, and, the solutions being at the correct temperature, the optical activities of a dozen or so can be ascertained in about five minutes, one solution being poured into the funnel after another as soon as the reading of the previous one is recorded.282 THE ANALYST. It might be thought that there would be some risk of imperfect washing out of the one solction by the other, but even when the solutions are of very varying density accurate readings are obtained. This is shown well by a series of results with sucrose solutions given below. The solutions were examined one after the other in the order given. Specific gravity '5.526.50, 1015 *80 1024.88 1034.52 1043.00 1056.48 1024.08 1055.56 1041 -50 1031.76 1022-78 1014.98 Gramm es Sucrose per 100 C .C . 4.075 6.425 8.916 11.113 14.610 6.218 14.370 10.725 8.203 5.881 3.866 Rotation in 2 dcm. tube. 5.43 8.56 11.87 14-50 19.43 8.28 19.14 14.30 10-93 7.85 5-15 66.61 66.60 66.55 66.59 66.50 66.61 66.60 ti6.67 66-64 66.75 66.61 The differences are very slight, and are only apparent when we try to displace a solution by one less dense. Wifh the first five solutions, of increasing density, the results (allowing for the influence of concentration on the specific rotation) are perfect, but where the displacement is by solutions of decreasing density, there are slight irregularities ; but these, even in the experiments above, where the variation of concentration is greatly exaggerated, are practically negligible.* Moreover, it is necessary to have the sugar solutions of approximately constant specific gravity, in order to eliminate the influence of concentration on the rotatory power, so that in practice this irregularity becomes even less probable. I n pouring the fresh solution into the tube, it is advisable to do so in portions, allowing each addition to run through before adding the next, the rotation being read before and after the addition of the last portion of the solution. AS a matter of fact, it is hardly possible to obtain errors of any magnitude through incomplete displacement of the preceding solution, because, though of approximately equal strength, the solutions are seldom of exactly the same density, and as a very slight difference in density is sufficient to give rise to diffusion stris which interfere with the passage of the polarized ray, it follows that until the one solution is displaced by the other, and the tube contents are of uniform density, the field of view is obscured. This can easily be observed on looking through the tube as a fresh solution is poured in. The field is at first dimmed, then gradually clears'up, becoming distinct and constant, and a short experience enables one to judge with certainty that the observation is reliable. The principal advantage of this form of tube over the ordinary type is the ease and rapidity with which observations can be made, there being no tedious screwing off and on of caps, with the attendant risk of refraction errors through straining the glass end plates.

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DOI:10.1039/AN9042900281

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年代:1904

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THE ANALYST. 283 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Determination of Cane-Sugar, Lactose, etc., in Milks, etc. F. W. Richard- son and Adolf Jaff6. (Journ. SOC. Chenz. I?zd., 1'304, xxiii., 309-311.)-The following polarimetric method is described : If the temperature of a solution of invert sugar be raised from 20" C. to 86" C., the polarimetric reading becomes nZZ, or the minus reading of the lzvulose becomes at 86" C. equal to the plus reading of the dextrose. For the analysis of a solution containing sucrose and invert sugar readings of the solution are taken at 20" C. and at 86" C., and a reading of the inverted solution at 20" C. Sucrose has [.ID = 63.05 a t 86" C., instead of 66.5, as at 20°C. ; therefore any pZus reading of the original solution at 86' C.divided by 0.6305 gives the amount of sucrose. Moreover, a 10 per cent. solution of invert sugar has a rotatory power of -20 at 20' C. One gramme of sucrose furnishes 1.053 gramme of invert sugar, with a reading of - 0.20 x 1.053 = - 0.2106. The 1 gramme of sucrose disappears on inversion, and284 THE ANALYST. with it a plus reading of 0.665; therefore every gramme of sucrose when inverted causes a reduction in the rotatory power of -0*2106+(-0-665)= -0,8756. Any diminution of the plus reading effected by Herzfeld's process divided by 0,8756 gives the sucrose. Knowing this and the rotatory value of the original solution, it is easy to calculate the invert sugar. The same process may be applied to solutions con- taining sucrose and lactose. I n the case of condensed milk, the acid mercury nitrate solution added to pre- cipitate the proteids completely inverts the sucrose when heated to 86" C.Readings of the filtrate, therefore, at 20" C. and 86' C. give the amount of lactose and sucrose. The authors are also investigating a method for mixtures of sucrose, lactose, and dextrose, depending on the very different changes which these three sugars undergo when heated in solutions containing 10 per cent. of hydrochloric acid. w. P. s. On the Solubility of Glycerides in Acetic Acid. I;. Hoton. (Bzdl. XOC- Chim. BeZg., 1904, xviii., 147-165.)-0n cooling a solution of acetic acid in a fat, two distinct layers are formed, the amounts of which vary with the nature of the fat. The glycerides with low critical temperature of solution, low refractive index, and low rnelting-points are the most soluble in the case of butter, whilst in the case of other fats arid oils the glycerides that dissolve first have high refractive indices.The following method of analysing butter is based on these facts : Five grammes of the melted and filtered butter and 10 C.C. of acetic acid (specific gravity 1.057) are heated to 60" C., with occasional shaking, in a tube 16 millimetres wide graduaked in millimetres. The liquid is then cooled to 40" C., and the amount of the upper layer measured. The cooling is continued, and at 35" C. the lower layer is decanted into a, flat dish, and evaporated at about 70" C. until the residue becomes constant in weight (extract A). The portion left in the tube is treated in the same way with 10 C.C.of acetic acid, yielding extract B and a residue C, each of which is dried and weighed and used for a determination of the critical temperature of solution, Valenta figure, and refractive index. The following are typical results thus obtained : 1 BUTTER. ARACHIS OIL. SESAME OIL. Mixtures of the above butter with margarine gave the following results :THE ANALYST. 285 Fraction. A ... ... B ... ... c ... .,. BUTTER + 10 PER CENT. MARGARINE. 40 45 65 f 20 PER CENT. MARGARINE. -l--i- 1 MARGARINE. +50 PER CENT. MARGARINE. -1- -I - 56 35 62 57 83 1 413 l The butter-fat had the following constants : Reichert-Meissl value, 25.3 ; critical temperature (neutralized butter), 51 ; Valenta figure, 47 ; Burstyn degree, 2 ; and refraction at 40" C., 42-8.The solubility of butter does not depend on the amount of volatile acids it contains. When a mixture of butter and margarine is treated in this way, there is a concentration of the latter in the fractions separating, the amounts dissolved by the acetic acid not being proportional to the respective coefficients of solubility of the butter and other fats. The author regards a figure obtained by subtracting the critical temperature of solution of fraction A from that of fraction C as the most important factor. This figure was 11-5 on the average in the case of eleven samples of pure butter, while butters containing 10 to 15 per cent. gave an average figure of 15.5. Similarly, the mean differences for the Valenta figures C - A were 22 for pure butters and 27 for the adulterated samples.Although in some cases pure butters gave results as high as those containing 10 to 15 per cent. of margarine, the author considers the method may still be of service in the case of butter with a Reichert value of 23 to 27; for in his opinion such samples, giving a value of less than 11 for the critical temperature C - A, are to be regarded as pure. C. A. M. The Amount of Cocoa Butter contained in the Cocoa Bean. S. H. Davies and B. G. McLellan. (Jozim. SOC. Chenz. Incl., xxiii., 480.)-The cells of the cocoa nib are not permeable to fat solvents, and must therefore be broken down mechanically before the fat is extracted. Neglect of this precaution is the probable cause of the low results obtained by earlier investigators.The determinations were made by breaking up the fully roasted cocoa beans, and removing the husks by winnowing. The nibs were next finely ground on stones in a small mill. The pasty mass was cooled quickly to prevent separation of " butter," and the mass of cocoa sampled. Two grammes of this sample were then extracted in a Soxhlet apparatus with the fraction of petroleum ether boiling between 40" and 50" C. The extraction was allowed to proceed for several hours, the solvent standing on the cocoa overnight. The extracted fat was dried at 95' C. for four hours and then weighed. The following results were obtained :286 THE ANALYST. Origin of Bean, Ecuador ... ... ... Venezuela ... ... ... Dutch Guiana ... ... Brazil ... ... ... Africa ...... ... Ceylon ... ... ... Mean Percentage of Fat. 53.76 52.19 56.36 54 a 6 5 54.18 53.36 Origin of Bean. Mean Percentage of Fat. I Trinidad ... ... ... Grenada ... ... ... Dominica .. I ... ... Santo Doming0 ... Unfermented ... Highly fermented Jamaica ... 54.57 55-30 55.03 55.38 54.68 58-23 General mean, 54.44 per cent. fat. Prolonged fermentation of the cocoa bean causes a loss of carbohydrate and albuminous material, yielding a product richer in fat. The variation in the amount of fat in cocoa beans of different origin is not great, and the determination yields no clue as to the geographical source of the bean. A. R. T. The Chemical Composition of the Inner Shell of the Coffee Fruit. Bela von Bit& (Jounz. Landw., 1904, hi., 93 ; through Chem. Zeit. Rep., 1904, xiii., 158.) -The following is the composition of the inner shell of the fruit of the coffee-tree (Cafea Arabica) : Calculated on On the the Dry Sample.Per Cent. Per Cent. Moisture ... ... .. - . 11.18 ... Ash ... ... ... 2.63 ... 2 *96 Soluble in ether ... ... ... 1.15 ... 1-29 Nitrogenous matter ... ... ... 5-50 ... 6.19 Extractives free from nitrogen ... 20.66 ... 23.26 Fibrin ... ... ... ... 58.87 ... 66-28 99.99 ... 99.98 Proteids (Stutzer) ... ... ... 3-94 ... 4.43 -- -- The fat is of a greenish colour, and has the following constants : Koettstorfer number, 141.2 ; acid number, 82.7 ; ester number, 58.5 ; free fatty acids (as palmitic), 37.84 per cent. ; glycerides (as tripalmitin), 28.03 per cent. The shell contained 0,022 per cent. phosphorus (on the dry sample), equal to 0.58 per cent.lecithin ; and caffeine, 0.35 per cent. The extractives contain appreciable quantities of pentosan ( C5H,0,), Chalmot and Flint's method giving 21.50 per cent. (on dry sample). 48.59 per cent. of the ash is soluble in water at ordinary temperatures. H. A. T. The Detection of Alkali Fluorides in Flesh Products. J. Froideveaux. (Journ. Pharm. Chim., 1904, xx., 11, 12.)-The following method is used in the Paris Municipal Laboratory : About 30 grammes of the finely-divided substance are mixed with 1 to 2 C.C. of a 50 per cent. solution of sodium carbonate and incinerated at a dull red heat in a platinum crucible. The charred mass is powdered, and boiled forTHE ANALYST. 287 some minutes with 5 to 6 C.C. of water, and the extract filtered, cooled, and mixed with an excess (2 to 3 c.c.) of hydrochloric acid and a few drops of helianthin solu- tion.A saturated solution of ammonium acetate is now added until the colour changes to yellow, and the liquid tested for fluorides by adding 1 to 2 C.C. of a 20 per cent. solution of calcium chloride. If a turbidity or precipitate be obtained, the presence of a fluoride is confirmed by the usual test with sand and sulphuric acid applied to the washed and dried precipitate. The method is capable of detecting 0.5 gramme of an alkali fluoride in a kilogramme of meat, The presence of acetic acid prevents the precipitation of phosphates by the calcium chloride, while it pro- motes the precipitation of fluorides. C. A. M. The Essential Oil of Artemisia Herba Alba. E. Grimal. (Bull. Xoc. Chim., 1904, xxxi., 694-697.)-This plant is very abundant in Algeria, where it is greatly esteemed for its medicinal qualities, By distillation of the fresh plant with water, the author obtained a yield of 0.3 per cent. of a greenish-yellow oil, with a strong aromatic odour, and a somewhat bitter taste resembling that of camphor. I t was soluble in 25 parts of 60 per cent. alcohol, in 2 to 2-5 parts of 70 per cent. alcohol, and was very soluble in 80 per cent. alcohol and the ordinary solvents for essential oils. I t gave the following analytical values: Specific gravity at 15" C., 0.9456; refractive index at 20" C., n, = 1.47274 ; [a]L, = - 15" 30 ; acid value, 6.46 ; saponifica- tion value, 89.23. The esters, calculated as CH,.COOCloH17, amounted to 31.15 per cent., and the free alcohols (as C,,H1,O) to 12.65 per cent. There were also identified among the constituents-Z-camphene, cineol, and esters of caprylic and capric acids. C. A. M.

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DOI:10.1039/AN904290283b

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年代:1904

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THE ANALYST. 287 TOXl COLOGl CAL ANALYSIS. The Detection of Phenokol in Cases of Poisoning. Dr. Andrea Archetti- Nova. (Chem. Zeit., 1904, l., 597.)-Phenokol ) ( Amidoace top-phenetidine, C,H,,N'$c,CR / O C H is a white powder (M.P. = 105*5'), soluble in alcohol, less so in water, benzene, and chloroform, The aqueous solution gives a reddish-yellow precipitate with bromine water, but no reaction with ferric chloride. I t dissolves in warm H,S04 to a colour- less solution, which on addition of potassium chromate becomes first brown and then green. If evaporated with a few drops of KOH solution, and then exactly neutralized with HCI, it gives a strong violet colour with ferric chloride. Ether does not extract the hydrochloride from an aqueous solution unless the base is first liberated by the addition of alkali; extraction is then very complete. In the animal organism it splits up according to the following equation : /OH CH2NH2 C 6 H 4\NHC0.CH,NH2+2H20 /0.C2H,5 = *\NH, +&OH + CBHSOH, pamidophenol. glycocol.288 THE ANALYST. and is so eliminated. The urine gives with ferric chloride a fine violet colour, characteristic of p-amidophenol, and the % presence of this is confirmed by other reactions. The second product-glycocol-can be recognised by (1) red colour with ferric chloride ; (2) a blue solution with copper sulphate and excess of KOH. It gives no reaction with Br water, or with H,SO, and K,Cr,07. Similar decomposition takes place on boiling the hydrochloride with dilute HCI for two hours. In acute cases of poisoning only a small quantity of p-amidophenol is eliminated, much remaining in the organs. H. A. T.

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DOI:10.1039/AN9042900287

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年代:1904

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288 THE ANALYST. ORGANIC ANALYSIS. The Determination OP Formaldehyde and its Polymers. A. Seyewetz and Gibello. (Bull. Soc. Chim., 1904, xxxi., 691-694.)-Lumi&e and Seyewetz showed (Mon. Scieiztzj'., February, 1903) that on adding standard sulphuric acid to a solution of trioxymethylene in sodium sulphite solution containing phenolphthalein the amount of acid required for decolorization was proportional to the amount of trioxy- methylene present. Their results were confirmed by Lemme, who based on them a method of determining formaldehyde in aqueous solutions (ANALYST, xxviii., 363). The authors have found that there is apparently no reaction between the formalde- hyde and sodium sulphite in the cold, but that the addition of sulphuric acid decomposes the sulphite into bisulphite and sulphate, the former combining instantly with the aldehydic substance, forming a compound neutral to phenolphthalein.The reaction may be expressed by the equation : 6Na2S0, + IL;(H.COH), + 3H2S0, = 2[(NaHSO,), + (HCHO),] + 3Na2S0,. I n using this method for the rapid determination of the polymers of formalde- hyde, a eolution containing about 20 per cent. of anhydrous sodium sulphite is standardized by titration with acid, phenolphthalein being used as indicator. From 0.5 to 0.7 gramme of, e.g., trioxyinethylene is dissolved in 20 C.C. of the sulphite solution containing a drop of 0.2 per cent. phenolphthalein solution, and the liquid titratcd with standard acid. This method is stated to give more accurate results with very dilute solutions of formaldehyde than other methods.Thus, a solution containing 0.037 gramme per litre gave (1) 0.0375 and (2) 0.0373 gramme on titration. C. A. M. The Differentiation of Primary, Secondary, and- Tertiary Alcohols of the Fatty Series. (BzdZ. Soc. Chim., 1904, xxxi., 783-787.)- The method is based on the different degrees of resistance offered by the alcohols to the action of heat. Thus, tertiary alcohols are decomposed into two molecules at the boiling temperature of naphthalene (218" C.), while primary and secondary alcohols remain intact. But on raising the temperature to 360" C., the boiling-point of anthracene, only primary alcohols remain unattacked. If, then, the density of an alcohol be determined by Meyer's method in naphtha- lene vapour and then in anthracene vapour, a rapid conclusion can be drawn as to A.Kling and M. Viard.THE ANALYST. 289 the class of alcohol to which it belongs. I n the following typical examples K represents a coefficient equal to the ratio of the theoretical density to the density found (in naphthalene), and K1 the coefficient in anthracene vapour. Alcohol. Primary : Ethylic ... Propylic ... Isobutylic . . . Secondarv : IsopropyliYc . . . Diet hvl- carhnol Tertiary : Trimethyl- carbinol Di e thylhexy- Formula. CH3 - CH2 - OH C2H5 - CH2 - OH (CH3)2 = CH - CH9OH (CH,), Z C - OH Specific Sravity Theo- retical (D). 1.59 2.0’7 2-56 2.07 3.04 2-56 5.95 Specific Gravity in Naph- thalene (Dl). 1.58 2-02 2-46 2.00 2.97 1.64 3.62 1.006 1.024 1.040 1.035 1.023 1.564 1.643 Specific Gravity in hthra- cene (D2).1 5 9 2.05 2.43 1.29 1-51 1.42 3 -04 __- D K1= D2 1.000 1.009 1.057 1.604 2.013 1.802 1.957 The authors have estabiished that the method is applicable to alcohols up to C, for primary alcohols, to C, for secondary alcohols, and to C,, for tertiary alcohols. C. A. M. A Colorimetric Method for the Determination of Wood Fibre in Paper. E. Valenta. (Chem. Zeit., 1904, xlii., 503.)-The author reviews Herzberg’s method for the determination of lignin in paper, and considers that, owing to the difficulty of obtaining proper standards, it is unsatisfactory. In this process the paper is dyed in Wiesner’s reagent (50 C.C. alcohol, 1 gr. phloroglucine, 25 C.C. conc. HCl), which is only absorbed by wood fibre, and is directly compared with a set of standards pre- pared from paper containing known amounts of the fibre.In Valenta’s method a colorimeter having two 100-c.c. tubes is used, graduated to 1 C.C. One is filled with water, and under it is placed a piece of dyed paper consisting entirely of wood fibre (100 per cent.). The other tube, under which is a piece of plain wetted paper, contains a solution of the dye used, of such strength that when filled to the 100 C.C. mark the colour is exactly equal to the water tube and standard paper. The standard paper is then removed and replaced by a strip of the paper to be examined, which has been immersed for ten minutes in the colouring solution, The dye solution in the second tube is then gradually removed until the colours again exactly coincide, when the amount of solution remaining in the tube will indicate the percentage of wood fibre present in the paper (1 C.C.= 1 per cent. of wood fibre). As dye a 10 per cent. solution of aniline sulphate is used; and should the paper be heavily sized, it290 THE ANALYST. must be washed in alcohol just acid with acetic acid, then in pure alcohol, before staining. The results obtained were satisfactory, and as the method is easily and quickly applied without special chemical knowledge, it should prove of value to practical paper-makers. H. A. T. A Volumetric Chew,. , 1904, xliii., sugars are oxidized the alkali present. Method of Determining Sugar. L. Rosenthaler. (Zeit. anal. 282-285.)-This method is based upon the fact that reducing by alkaline coppr solution into acids, which partially neutralize If, then, portions of the copper solution be titrated with standard acid before and after reduction of the sugar, the difference in the acid found will stand in a definite relationship towards the amount of sugar under conditions experimentally determined.Thus, under the conditions of the author’s experiments, one molecule of dextrose or l~vulose yielded eight equivalents of acid, and 1 C.C. of ‘ I acid difference ” corresponded to 0.0225 gramme of either sugar. The alkaline copper solution used by the author contains 17.5 grammes of crystalline copper sulphate, 75 grammes of glycerin, 125 grammes of sodium citrate, and 100 grammes of 15 per cent. sodium hydroxide solution, with sufficient water to make a litre. The small amount of cuprous oxide that invariably separates from this solution must be filtered off through asbestos after the liquid has stood for three or four days, or has been heated for a few hours on the water-bath.The solution is standardized by filtering 30 to 40 C.C. through a Gooch crucible containing asbestos (to remove any particles of cuprous oxide), washing the filter with 150 C.C. of water, adding a slight excess of normal acid to the filtrate and washings, together with a drop of phenolphthalein solution, boiling the liquid for ten minutes, then adding normal alkali until a pink colour appears, and then a drop of normal acid to render the liquid colour- less. For the determination of dextrose or laevulose, 5 C.C. of the sugar solution, of about 1 per cent. strength, are mixed with 20 C.C.of water and an excess (30 c.c.) of the copper solution, and boiled for five minutes. The reduced cuprous oxide is filtered off through a Gooch crucible, which is subsequentIy washed with 150 C.C. of water. The filtrate and washings are then titrated as described above. When the sugar solution contains less than 1 per cent., enough should be taken to give about 0.05 gramme of sugar for the determination. The asbestos layer in the Gooch’s crucible can be used for many determinations without requiring renewal. C. A. M. Behsviour of Sesame Oil with HC1 and Various Sugars. A. Cawalowsky. (Zeits. Oest. Apotlz. Ver., 1904, xliii., 453 ; through Chem. Zeit. Rep., 1904, xiii., 157.) -In connection with the usual Baudouin test for sesame oil, the author finds that (a) saccharose and laevulose can be used for this test, but not dextrose, maltose lactose, or galactose ; (b) Baudouin’s sesame-oil hydrochloric acid test can be used for the identification of laevulose in glucose ; therefore ( c ) also for the examination of honey.H. A. T.THE ANALYST. 291 Saponification Value. 1 6:. I/ ''sin. Mango-Tree Gum. P. Lemeland. (Jourrz. Pharm. Chim., 1904, xix., 584-593.) -The gum of the mango-tree (Mungifera Indica) is commonly sold in the bazaars throughout India, where it is valued by the natives as an astringent. The commercial product is translucent, amber to reddish-yellow in colour, and varies greatly in the size of the lumps. The specimen examined by the author contained 16.57 per cent. of water, and of the dried substance 39.36 per cent.was soluble in water, whilst it was completely insoluble in alcohol. The portion soluble in water had an optical rotation of U, = - 25-33'. It yielded 3.36 per cent. of ash, whilst the organic matter amounted to 80.07 per cent. When treated with sulphuric acid of 3 per cent, strength, the original gum yielded 71-42 per cent. of reducing sugars (calculated as invert sugar), of which 25.33 per cent. (calculated on the original gum) consisted of galactose, and 35-1 per cent. of pentoses. That portion of the gum insoluble in water gave the following results : Moisture, 10.51 ; reducing sugars, 86.28 per cent. ; and optical rotation, UD = + 64-89, The gum was found to contain an oxidizing enzyme. Arabinose was identified. C. A. &I. Saponification Value.Identification of Guttapercha and Allied Gums by Means of their Resins. Wilton G. Berry. (Journ. Soc. Chem. Ind., xxii., 529.)-The author has obtained the following results by the examination of the mixture of resins extracted by boiling absolute alcohol from the dried samples : AVERAGE Resin. Guttapercha . . . .., From Albane .., Gut tapemha{ Fluavil. . , Chicle ... ... ... From Resin A::: ... Chicle {Resin Bj- .., SAPONIFICATION AND ACID VALUES OF RESINS. I -. ~ I- II 78.5 83.5 71.5 103.0 129-0 101.0 Tuno ... ... Jelutong ... Almeidina . . . Balata ... Payena species 77.0 77.5 50.5 69-0 103.5 Acid Value. 5.5 trace trace trace - ~~~~~ ~~ ~ ~ The composition of the gums, and the physical characters of their resins and hydrocarbons, are also described.It is pointed out that whilst the saponification values of guttapercha, tuno, and jelutong (Pontianac) are alike, the characters of the accompanying hydrocarbons are quite different. The separation of the constituent resins of Tuno and Jelutong, as in guttapercha, will probably provide a means of distinguishing one species from the other. A sample of old oxidized guttapercha, containing 0.25 per cent. of gutta and 96-75 per cent. of resins having a saponification value of 166.7, is interesting as affording evidence of the probability that the oxidation of gutta (hydrocarbon) pro- ceeds further than the formation of albane and fluavil. Further results are promised. A. R. T. * Insoluble in cold absolute alcohol. t Soluble in cold absolute alcohol.292 THE ANALYST.The Iodine Absorption of Spirits of Turpent,ine. R. A. Worstall. (Jourfz. XOC. Chem. Ind. , 1904, xxiii., 302, 3O3.)-Various grades of wood-turpentine (products of yellow-pine distillation) have recently appeared on the market, and have been employed as adulterants of spirits of turpentine. As wood-turpentine is inferior in all respects to genuine turpentine, thg author has particularly studied methods for its detection, and finds a determination of the iodine value (Hiibl) affords good evidence of the presence or absence of this adulterant in a sample. The average iodine value of 55 samples of spirits of turpentine of undoubted purity was 384. Three times the quantity of iodine necessary for complete saturation was added, and the absorption allowed to proceed for eighteen hours, Refined wood-turpentine had an iodine value of 212, and another grade of the same-water-white-a value of 328.Spirits of tur- pentine adulterated with either of these would therefore show a decreased iodine value. w. P. s. Determination of Acetic Acid in Acetate of Lime, A. G. Stillwell. ( J o w ~ . SOC. Chem. Ind., 1904, xxiii., 305,306.)-1n the hope that a uniform method of analysis inay be adopted for the valuation of this substance, the following distillation process is described : The sample on reaching the laboratory is rapidly passed through a $-inch sieve. The moisture is determined in the sample so obtained, and constitutes the original moisture. About 6 ounces of the sample are now passed through a 14-mesh sieve. This is the working sample, and the moisture should be again determined in it.Two grammes are then accurately weighed out into a round-bottomed flask of 300 C.C. capacity and having a neck 4 inches long; 15 C.C. of syrupy phosphoric acid are now added, and all drops carefully washed down from the neck with about 25 C.C. of water. The distillation is proceeded with, the distillate being collected in a l2-ounce Erlenmeyer flask containing 30 C.C. of standard sodium hydroxide solution. After one and a quarter hours this flask is removed and a small beaker substituted. The distillate in the flask is neutralized by the addition of standard sodium hydroxide solution, as is also any further quantity of acid collected in the beaker, Phenolphtha- lein being used as indicator. The distillation is usually complete in one and a half hours.During the distillation the volume of liquid in the round-bottomed flask is kept as near 40 C.C. as possible by the addition of water through a tap. The sodium hydroxide solution employed is of such strength that 1 C.C. is equal to 0.0175 gramme of acetic acid. w. P. s. Report on the Determination of Nitrogen. F. W. Morse. (Chef% Nezos, lxxxix. , 282.)-The author has carried out an investigation on the utility of methods for the determination of available nitrogen in fertilizers. Four artificially prepared fertilizers were used, consisting of superphosphate mixed with blood, with cotton- seed meal, and with blood and cotton-seed meal mixed in two different proportions. The mixtures were analysed by twelve different analysts.Two methods were used- the neutral ,permanganate method, and the alkaline perinanganate method of Jones. The first was carried out by weighing a quantity of the material containing about 0.075 gramme of nitrogen into a 400 C.C. beaker. Samples containing material treatedTHE ANALYST. 293 with acid (such as superphosphate) are first washed on a filter until the washings amount to 200 c.c., and then transferred, together with the filter: to the beaker. The material is digested with 2 grammes potassium permanganate, previously dissolved in 125 C.C. of water for thirty minutes in a steam or water bath, stirring at intervals of ten minutes, and keeping the beaker covered. After adding 100 C.C. of cold water, the liquid is filtered through a heavy 13centimetre filter-paper, which is washed with small quantities of cold water until the total filtrate amounts to 400 G.C. After drying, the insoluble nitrogen is determined in the residue by the Kjeldahl method. For the alkaline permanganate method, a quantity of material, containing about 0.045 gramme of nitrogen, is weighed out into a 600 C.C. distilling flask connected to a condenser and receiver containing standard acid, and digested with 100 C.C. of a solution containing 16 grammes potassium permanganate solution and 150 grammes sodium hydrate, dissolved in 1,000 C.C. of water for thirty minutes below the boiling- point. From the results obtained, it appears that both methods need further study. The alkaline method, which is the more rapid, seems to give better results than is generally believed. I t would probably be advantageous to increase the amount of solution used so as to give a greater amount for distillation, and to regulate the quantity of distillate collected. In the neutral method, the filtration appears to be very tedious, but can generally be hastened by using a Witt plate or Hirsch funnel. Neither method really gives the amount of available nitrogen, but only comparative results, A. G. L. The whole is then boiled slowly until the distillation is completed.

ISSN:0003-2654    

DOI:10.1039/AN9042900288

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年代:1904

数据来源: RSC

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THE ANALYST. 293 INORGANIC ANALYSIS. Determination of Minute Quantities of Bismuth in Copper and Copper Ores. T. C. Cloud. (Journ. SOC. Chenz. I z d . , xxiii., 524.) - The method is based upon the fact, recorded by Abel and Field (Jourrz. Cfzem. SOC., 1862), that when lead iodide is precipitated in the presence of even minute traces of bismuth the colour of the precipitate is changed to a more or less dark orange or red tint, the intensity of the colour change increasing with the quantity of bismuth present. For qualitative purposes the lead iodide first precipitated by the addition of just a sufficient amount of potassium iodide is redissolved in the requisite quantity of boiling dilute hydrochloric acid, the liquid allowed to cool, and the colour of the resulting crystals examined.The presence of 0.001 milligramme of bismuth may thus be detected. Owing to the fact that the crystalline precipitates vary in lustre and also in the size of the crystals, according to the rate of cooling, the author finds it neces- sary, for quantitative purposes, to examine the colour of the original precipitate of lead and bismuth iodides in comparison with a standard. The method is said to be capable of accurately determining 0.01 milligramme of bismuth. The following solutions are required : 1. Bismuth Nitrate.-Dissolve pure bismuth oxide in nitric acid, and dilute so that 1 C.C. contains 0.0001 gramrne bismuth. Sufficient nitric acid must be present to prevent precipitation of basic bismuth salt on dilution.294 THE ANALYST. 2. Lead ATitmte.-Dissolve 6 grammes of pure lead in nitric acid, evaporate until the excess of nitric acid is removed and the lead nitrate begins to crystallize out, then dissolve in water, making the solution up to 1 litre.3. Potassium Iodide.-Dissolve 35 grammes of the salt in water, and dilute to 4 litres. A suitable quantity of the metallic copper under examination is dissolved in nitric acid, and a solution of sodium carbonate carefully added to the cold liquid, until a small permanent precipitate is produced. The liquid is allowed to stand for some hours with frequent stirring. On filtration, the unwashed precipitate i s dissolved in dilute hydrochloric acid, and hydrogen sulphide passed through the solution. In the case of copper ores, the sample is dissolved in a mixture of nitric and sulphuric acids, and the liquid evaporated until the sulphuric acid fumes. The cold residue is treated with water and a very little hydrochloric acid, and hydrogen sulphide passed through the filtered solution.(This treatment with sulphuric acid is also followed in the case of " copper " containing appreciable quantities of lead.) The washed sulphide precipitate is dissolved in nitric acid, and,the solution made u p to 250 c c. Half of this solution is well shaken with 5 C.C. of the lead nitrate reagent, neutralized with ammonia, and a slight excess of ammonium carbonate solution added with shaking, followed by sufficient ammonia to keep the copper in solution. The liquid is filtered after being digested on the water-bath, and the small precipitate is washed with ammonium carbonate until all the copper is removed.The solution obtained by dissolving this precipitate in dilute nitric acid is evaporated until it crystallizes, when the residue is dissolved in hot water and a little nitric acid and made up to 25 C.C. in a Nessler tube. Twenty-five C.C. of the potassium iodide reagent are next added, and the precipitate produced compared with a standard made by adding a known quantity of bismuth solution to a mixture of 1 C.C. of dilute nitric acid, 5 C.C. of lead reagent, and 25 C.C. of potassium iodide. solution, the mixture being diluted with water to 50 C.C. as before. The contents of both Nessler tubes should be well stirred, and the tints of the precipitates finally compared after standing about fifteen to twenty minutes.A. R. T. The Bismuthate Method for the Determination of Manganese. Andrew A. Blair. (Journ. Anzer. Chcm. Soc., xxvi., 793.)-The author strongly recommends this method as being accurate and convenient. He emphasizes the necessity of removing every trace of hydrochloric acid before adding bismuthate. Whenever possible he prefers to dissolve in mixtures of acids free from hydrochloric acid. Chromium steels can be analysed by this method, as chromium is not oxidized in the cold; tungsten is best filtered off. To filter the solution after the addition ofl bismuthate, the author uses the pump, the funnel being placed in the neck of anl exhausted bell-jar, beneath which is placed a conical flask to receive the filtrate.. The same filter will serve for fifty or more determinations. A.G. L.THE ANALYST. 295 The Action of Sodium Picrate on Solutions of Sodium Carbonate. C. Reichard. (Zeit. anal. Clzem., 1904, xliii., 269-275.)-Details of experiments are given, from which the following conclusions have been drawn : (1) The only sodium salt capable of precipitating sodium picrate is the normal sodium carbonate. (2) The precipitation takes place whether the solution of sodium carbonate be added to the solutions of sodium picrate or vice versd. (3) Dilute solutions of sodium picrate (1 per cent.) are rendered turbid, while strong solutions (10 per cent.) solidify to a gelatinous mass. (4) The precipitation, which is gradual, takes place in solutions containing other sodium salts, including the bicarbonate and hydroxide.(5) The reaction may be employed as a teat for sodium carbonate, and conversely as a means of identifying sodium picrate. C. A. M. The Action of Sodium mtroprusside on Carbonates, Bicarbonates, Caustic Alkalies, and Ammonia. (Zeit. anal. Chem., 1904, xliii., 275-279.)- A solution of sodium or potassium hydroxide treated with a drop of a 20 per cent. solution of sodium nitroprusside becomes yellow after a few moments, the colour gradually increasing in intensity on standing. A dilute solution of ammonia, on the other hand, gives no coloration at all, or at most an extremely faint one, whilst strong solutions of sodium carbonate or bicarbonate also remain colourless. If a strong solution of sodium carbonate be treated with a few drops of sodium hydroxide solution, and then with one drop of a, 20 per cent.solution of sodium nitroprusside, no colour appears. And if to a dilute solution of sodium hydroxide, in which the yellow colour has been produced, there is added some powdered sodium carbonate, and the tube shaken, the colour gradually disappears, though it may be restored again by the addition of a relative excess of strong sodium hydroxide. Sodium nitro- prusside thus behaves in an analogous manner to litmus or phenolphthalein with regard to sodium hydroxide, though not in its behaviour towards carbonates and bicarbonates. Thus, if a strong solution of sodium carbonate containing a few drops of concentrated sodium hydroxide solution and one drop of sodium nitroprusside solution (colourless liquid) be exactly neutralized with hydrochloric acid, there is still no coloration.In the case of ammonia, experiments are described to show that when the amount of ammonia falls within certain limits (about 1.5 to 2 per cent.), it is possible to detect as little as 0-02 gramme of sodium hydroxide simultaneously present. C. A. M. C. Reichard. The Analysis of Sodium Nitrite. G. Lunge. (Chem. Zeit., 1904, xlii., 501.) -In this very detailed paper the author compares the various methods for the analysis of sodium nitrite, and gives the following results for the permanganate and sulphanilic acid methods. For the permanganate process a solution of nitrite containing 23 gr. per litre was run from a burette into semi-normal permanganate solution, and five experiments gave the following figures : I., 96.79; II., 97.02; III., 96.87; IV., 96.82; V., 96.96 per cent.NaNO,. Mean : 96.89 per cent. NaNO,.296 THE ANALYST. In the sulphanilic acid method sodium sulphanilate was used which had been dried-A, for two hours between blotting-paper ; B, subsequently kept for eighteen hours over concentrated H,SO,; C, left for further two days over H,SO,. A gave : 96-25 per cent. NaNO, (at ordinary temperatures). 96.39 ,) 9 , 7 , 96.30 ,, , f ,, 96.32 ,, 11 J , 96.44 ,, ,, , I 96.41 ), ,, (ice cold). 96.53 ,, 9 , 9 1 96.29 ,, ,, (at ordinary temperatures). 96.44 l l 9 , 1, 96.34 ,, ? t 1 , -- Mean 96.37 per cent. NaNO,. B gave : 96.71, 96-94, 96.85, 96.65 per cent. C gave : 96.47, 96.67, 96.77 per cent. The use of sodium sulphanilate dried over H2S0, gives, therefore, results only 0.1 to 0.2 per cent.below the permanganate method. When immediate blueing of the starch iodide paper is taken as the end point of the reaction, the latter method gives results comparable with those of the perman- ganate titration ; but as the preparation or purifying of the sodium sulphanilate is attended with considerable loss and trouble, while the permanganate method is very simple in application, he recommends that this be taken as the standard process. It is only unreliable when formic acid salts are present, which very rarely occurs. Mean : 96.74 per cent. NaN02. Mean : 96.67 per cent. NaNO,. H. A. T. The Determination of Nitrogen. L. Ddbourdeaux. (Bull. Soc. C ? L ~ ? L . , 1904, =xi., 578-580.)-The author has established that in the methods of Will and of Kjeldahl the ammonia is often accompanied by various amines.Thus, in the case of pyridine the conversion into ammonia is only partial, whilst caffeine yields a mixture of ammonia and monomethylamine. He has also found that the method in which sodium hypobromite is employed does not liberate the whole of the nitrogen in the amines, even in the case of urines. The method recommended is not capable of general application, but is stated to yield the whole of nitrogen in the form of ammonia without amines in the case of the following compounds : (1) Oxygenated compounds ; (2) hydroxylamine ; (3) nitro derivatives, in which the nitro group has a phenolic function; (4) nitrites, cyanides, and double cyanides ; (5) cyanates and thiocyanates ; (6) certain amides and imides ; (7) amines, in which the radicle has an acid function.This method, which is based on the action of alkali monosulphides on nitrogenous bodies in the presence of certain salts-notably, alkali thiosulphates-consists of two successive distillations in an iron flask connected with a modified Schloesing's apparatus constructed entirely of glass. The substance is first distilled to dryness with 50 grammes of crystalline potassium thiosulphate and 200 C.C. of a solution of potassium monosulphide, prepared by saturating a solution of potassium hydroxideTHE ANALYST. 297 solution of 36' B6. (specific gravity 1.33) with hydrogen sulphide, and adding an equal volume of the same hydroxide solution. In the second distillation, to remove the last traces 0: ammonia, 25 C.C.of potassium hydroxide solution and 250 C.C. of water are added to the residue in the flask, and about 150 C.C. of distillate collected. The ammonia is received in an excess of pure hydrochloric acid, and then determined. C. A. M. The Estimation of Argon in Atmospheric Air. H. Moissan. (Bull. Soc. Chim., 1904, xxxi., 729-735.)-The method was based on the absorption of the oxygen and nitrogen in a known quantity of air and measurement of the residual argon. The apparatus consisted of a graduated measuring vessel, holding about a litre of air, and connected by means of a pump with two tubes kept at a red heat, the first of which contained a mixture of quicklime and magnesium, and the second about 1 gramme of calcium in very small crystals. The air, after being dried over metaphosphoric acid, was introduced into the measuring vessel, where it was left all iiight at a constant temperature, and was then made to circulate through the absorption-tubes for three hours, until the height of the barometer connected with the pump became constant, showing that there was no more absorption of gas.A graduated tube was then attached to the pump, and the residual gas (argon) drawn into it and measured over mercury. Preliminary experiments proved that the first absorption-tube retained the whole of the oxygen and most of the nitrogen, and that the second retained the remainder of the nitrogen, also the hydrogen resulting from the decomposition of traces of moisture in the first tube, and also all gaseous im- purities in the air.The following results were thus obtained with samples of air of different origin : Atlantic Ocean, 0-9492 ; Paris, 0-9337 ; summit of Mont Blanc, 0.9352 ; London, 0.9325 ; Berlin, 0.9323 per cent., etc. In general, air from the interior of continents at heights from 0 to 4,800 metres contained from 0,932 to 0.935 per cent., whilst samples of air from over the sea were usually somewhat higher. C. A. M. Comparison of Methods for the Estimation of Soil Acidity. F. P. Veitch. (Journ. Anzer. Chem. SOC., xxvi., 637.)-The author proceeds as follows to determine the reaction of a soil : About 10 grammes of the soil are allowed to stand overnight with 100 C.C. of distilled water in a Jena glass flask. Fifty C.C. of the supernatant liquid are drawn off and boiled in a covered Jena beaker, after adding a few drops of phenolphthalein, until a pink colour is developed or until the volume has been reduced to 5 C.C.without the appearance of a colour. The pink colour shows the soil to be alkaline, while no colour shows it to be acid or neutral. The degree of acidity is determined by means of lime-water as follows : To three portions of soil, each consisting of as many grammes as the standard lime- water contains milligrammes of CaO per c.c., are added 50 to 60 C.C. of distilled water, and different amounts-e.g., 10 c.c., 20 c.c., and 30 c.c.-of lime-water. All three portions are at once evaporated to dryness on a steam-bath, the residues298 THE ANALYST. transferred to stoppered Jena flasks with 100 c,c.of distilled water, and allowed to stand overnight. Fifty C.C. are then drawn off from each portion and boiled, after adding a few drops of phenolphthalein, until a pink colour is produced, or until the volume is 5 C.C. The test is then repeated on three more portions of the soil, the amounts of lime-water added in this case differing from each other only by 1 or 2 C.C. The quantity of lime-water necessary to produce an alkaline reaction is taken as a measure of the acidity of the soil. The results will serve as a guide to the acidity of the soil. A. G. L. Standard Substances for Alkalimetry and Iodometry. F. Ra schig. (Zeit f. angezu. Chem., 1904, xviii., 577-584.)-1n the preparation of the standard hydro- chloric acid solutions, hydrogen chloride is passed into a flask containing water ; this is weighed before and afterwards, and then made up to a known volume.Standard solutions of sulphur dioxide may be prepared in a similar manner. The strength, however, should not be allowed to exceed &, as there is a great tendency for the gas to escape. Iodine solution is standardized against the sulphurous acid solution, and the same quantity of acid solution may lhen be used to ascertain the titre of an alkali solution. After the colour of the iodine has been exactly discharged methyl orange is added and alkali solution run in to neutralize the acid formed, in accordance with the equation- The results of the iodometric titration are liable to be rendered inaccurate by oxidation of the sulphurous to sulphuric acid. The solution of sulphur dioxide must therefore be freshly prepared, and be delivered into the iodine solution froin a pipette dipping below the surface of the liquid. In a subsequent issue of the Zeitschrif't fiir angezunndte Chenzie (1904, xxii., 716) W. A. Roth claims priority of the method for preparing standard solutions for hydro- chloric acid, on the ground that he recommended it at the Fifth Congress of Applied Chemistry in 1903. I t was, however, fully described by Dr. G. L. Moody in 1898 SO, + 21 + 2H20 = H2S0, + ,HI. (Tmizs. Chem. SOC., lxxiii., 658). A. M. The Filtration and Incineration of Precipitates. M. Dittrich. (Berzchte, 1904, xxxvii., 1840; through Chem. Z e d . Rep., 1904, xiii., 156.)-For the latter filtration, washing, and ignition of gelatinous precipitates, the author recommends the addition, to the liquid to be filtered, of finely pulped filter-paper. Washing is much more thorough, and instead of forming a hard thick mass, the ash is pulverulent. This method is of especial advantage when the precipitate has to be dissolved and reprecipitated, and when iron and alumina are to be separated by fusion with caustic alkali. H. A. T.

ISSN:0003-2654    

DOI:10.1039/AN9042900293

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

THE ANALYST. 299 APPARATUS. The " Thermophor " Water-bath. Norrenberg. (Chem. &?it., 1904. xliii., 481.)-The '' Deutsche Thermophor A.G." (Andernach a/R) has produced a new water-bath, mainly intended for heating or distilling ether and other highly inflam- mable liquids. I t consists of a thick-walled vessel, which is filled with and immersed in boiling water for ten minutes. The temperature of the water remains at 65" to 70" for several hmrs, and this apparatus should prove useful when a fairly constant temperature of 603 to 70" is required for prolonged periods. H. A. T. Improved Absorption Apparatus. Otto Scheueri (Chem. Zeit., 1904, I., 598.)-This apparatus consists in a form of spiral so constructed that the gases passing come in contact with a very large surface of the absorbing liquid.Each convolution of the r r spiral " can be filled inde- pendently (from a pipette?), and contains a fine jet causing the gas to break up into minute bubbles, pass- ing through the whole quantity of the absorbent. Figures are given showing that the efficiency of this absorber is materially higher than 18 rrn that of other types. H. A. T. The '' Dalite " (Daylight) Lamp for Colour Matching. Walter M. Gardner and A. Dufton. (Joz~rn. Soc. Chem. Id., xxiii., 598.)-The authors claim to have invented a lamp which gives a light of precisely the same character as that of good daylight. The invention consists of an electric arc-lamp of the ordinary type, enclosed in a jacket of specially prepared glass which absorbs the excess of yellow and other rays emitted by the arc-lamp.The new lamp should prove useful in the accurate matching of colours required in the dyeing and printing industries, and in chemical laboratories for various purposes, such as titrations, where hitherto the employment of artificial light has been unsatisfactory. The lamp has the additional advantage over daylight in yielding a light of uniform character. Particulars may be obtained from E. Hickson, 38, Well Street, Bradford. ABSTRACTOR'S NoTE.-The usefulness of this lamp would be increased if a smaller, and therefore cheaper, size were manufactured. A. R. T.300 THE ANALYST. Fi8.I. A New Fractionator. Dr. J. Houben. (Clzem. Zeit., 1904, xliv., 525.)- Winssinger’s fractionating apparatus, in which a glaes tube, cooled by a current of water, is inserted in the neck of the fractionating flask, is unsatisfactory, as the temperature, or rate of fractionation, cannot be easily regulated.I n the author’s improved apparatus an aluminium cylinder, open at the top, reaches to the bottom of the neck of the flask. In this a second cylinder, cooled by a current of water or air, is inserted, and the temperature of the outer cylinder can be maintained at any desired point by raising or lowering the cooler to the requisite extent. r Fig. I. illustrates the device in action. A is the outer jacket, the top of which is expanded and, by means of springs, grips the inner, cooled cylinder (B). This exactly fits the outer cylinder ; and as it can be raised to any desired position, con- siderable variation of temperature is possible. neck,” to be connected to any flask by rnehps of a bored cork (Fig. 11.). Increased effect is obtained by com- bining two or more systems, as in Fig. 111. The author finds that a very high degree of efficiency is obtainable with this apparatus. H. A. T. The complete apparatus can also be fitted in a glass

ISSN:0003-2654    

DOI:10.1039/AN9042900299

出版商:RSC    

年代:1904

数据来源: RSC