摘要:

AUGUST, 1912, Vol. XXXVII., NO. 437. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. ON THE APPLICATION OF ADSORPTION TO THE DETECTION AND SEPARATION OF CERTAIN DYES. BY A. CHASTON CHAPNAN AND ALFRED SIEBOLD. (Read a t the Meeting, June 5, 1912.) DURING recent years a very considerable amount of attention has been devoted to the study of certain phenomena to which the general term ‘( adsorption ” has been applied.Whatever may be the precise explanation of these phenomena, the facts are comparatively simple, and many instances-e.g., the decolorisation of solutions by means of animal charcoal-have been known and utilised for a very long time. Among adsorbent substances, kaolin occupies an important position, and a number of references to its power of removing dyestuffs from solution are to be found in chemical literature.These, as a rule, occur in communications dealing with the theory or practice of dyeing, and, with the exception of the valuable work of Gop- pelsroeder on the separation and identification of certain colouring matters by capillary methods, no systematic study of this property, from the analytical stand- point, has, so far as we are aware, been made.It is true that H. Wislicenus (Zeitsch. Chem. Id. KoZZoide., 1908, 2, Supt., II., 11-20) has suggested the application of the so-called (( fibre-alumina ” to the examination of various kinds of extracts, including dyes, and that LaWall has employed kaolin as one of the reagents in a scheme for the detection of certain natural colouring matters (“ Select Methods of Food Analysis,” Leffmann and Beam, 2nd Edition, pp.74-75), but no very definite results appear to have been obtained, and no mention is made of the separation and identification of artificial dyes. Among the more important papers dealing with the question of adsorption of coal-tar dyestuffs, attention may be specially directed to a paper by Suida (lkfonatsh. Chem., 1904, 25, 1107), in which the adsorbing properties of kaolin and other silicates and silicious materials have been studied.Few problems are more difficult than the identification of the dyes used in the colouring of foodstuffs, particularly when two or more are present together, and no apology is needed for bringing to the notice of analysts any method which is capable of facilitating such investigation, even if only to a small extent.The experiments described below had their origin in some observations made in the laboratory of one340 CHAPMAN AND SIEBOLD : APPLICATION OF ADSORPTIOK of US, that certain artificial dyestuffs could be readily separated by the use of kaolin, and that this property could in some cases be usefully applied to the examina- tion of artificially coloured food-products.The method of experimenting was very simple, and consisted in stirring in R small glass mortar the solution of the dye with a weighed quantity of kaolin, pre- viously ground with a little water. Alternatively the dry kaolin was added to the dye solution, and the mixture thoroughly stirred, or in some cases the solution of the dye was merely filtered through B layer of kaolin.The dye solutions contained in all cases 1 grm. of the dyestuff per litre. For the purposes of the experiments, 10 C.C. of the dye solution were stirred for several minutes with 5 grms. of kaolin, previously mixed with 10 C.C. of water, and the mixture filtered through a Buchner funnel with the aid of a, pump.The above amount of kaolin was always employed, but in the case of those colours which are very rapidly adsorbed, it was found that the kaolin was capable of taking up in some cases more than 1 per cent. of its weight of the dye. When tested in this manner, it was found that the various dyes experi- mented with could be divided into three classes: (a) those which are entirely adsorbed under the above-mentioned conditions ; ( b ) those which are partially adsorbed, giving coloured kaolin from which the bulk of the dye can be extracted by washing with water ; and ( c ) those which are not appreciably adsorbed.The following table contains a list of the dyes experimented with, and shows their behwiour when treated in the manner above described : TABLE I.Adsorbed. Congo red. Safranine. Magenta. Neutral red, Malachite green. Brilliant green. Methylene blue. Bismarck brown. Crystal violet. Methyl violet B extra. Auramine. Partiall Adsorbed, but Adsorbed CIo%nw partly extracted by Washing with Water. Acid green. Patent blue. Soluble blue. Acid green. (Practically all extracted by boiling water.) Not Adsorbed. Acid magenta. Eosin.Erythrosin. Fluorescein. Methyl orange. Tr opaoli n. Orange IV. Ponceau 4R. Bordeaux R. Sudan red. Tartrazin. Naphthol yellow. Picric acid. Naphthol green. Indigo carmine. Cochineal (1 per cent. solution).TO THE DETECTION AND SEPARATION OF CERTAIN DYES 341 Although three entirely different lots of kaolin which were experimented with behaved very similarly so far as their powers of adsorption were concerned, yet slight differences were observed, particularly in the case of certain of the partially adsorbable dyes.A convenient method of ascertaining whether any particular sample of kaolin is suitable for the examination of dyes by this method, is to mix 10 C.C. of a 0.1 per cent. aqueous solution of naphthol yellow, and 5 C.C. of a 0.1 per cent. aqueous solution of soluble blue.I n the case of a really good kaolin, 5 grms. should be sufficient for the coqplete separation of these two colours-that is to say, the filtrate should be yellow and not tinged with blue. Satisfactory separations of the following dyes were effected : Methyl violet B extra and naphthol yellow, crystal violet and naphthol yellow, crystal violet and eosin, auramine and naphthol green, auramine and indigo carmine, auramine and acid magenta, magenta and tropaeolin, methylene blue and cochineal (1 per cent.), malachite green and tropaeolin, brilliant green and tropaeolin, methylene blue and tartrazin, crystal violet and methyl orange, soluble blue (5 C.C.only) and naphthol yellow. I n some cases it happens that, although a dye is itself readily soluble in alcohol, if is yet incapable of being dissolved from the coloured kaolin by means of that solvent.It is clear, therefore, that this property might in some instances be made use of in order to effect the approximate separation of three dyes when present together. Thus, the 5 grms. of kaolin, having been shaken or stirred with the dye solution in the manner indicated above, and filtered, the coloured kaolin remaining on the filter might, after one or two washings with hot water, be treated with hot alcohol.The following are examples of separations effected in this manner : TABLE 11. Ponceau 4 R : Aqueous filtrate. Red. Crystal violet : Alcoholic filtrate. Purple. Safranine : Kaolin. Pink. Naphthol yellow : Aqueous filtrate. Yellow.Magenta : Alcoholic filtrate. Red. Methylene blue : Kaolin. Purplish-blue. Fluorescein : Aqueous filtrate. Dirty pink and fluorescent. Brilliant green : Alcoholic filtrate. Green. Congo red : Kaolin. Pink. That the coloration of the kaolin in the above cases was, in fact, due to the safranine, methylene blue, and congo red respectively, was proved by the application of well- known tests.Experiments were next made for the purpose of ascertaining to what extent the adsorption results given above apply to saccharine solutions. I n the case of magenta, methyl violet, safranine, Bismarck brown, brilliant green, auramine, and soluble blue, the results were substantially the same as when sugar was absent. The above results apply entirely to the removal of dyes from aqueous soZutions by means of the kaolin, but in many cases the removal of the dye from alcoholic solutions can heTABLE 111.Kaolin Dyed by Adsorption of- Congo red. Safranine. Magenta. Neutral red. Methyl violet B extra. Crystal violet. Malac hit e green. Brilliant green. Meth ylene blue. Bismarck brown, or Vesuvin. Auramine. H,SO,. Deep blue. Green, changing to dull violet on dilution.Brownish- yellow. Green. Yellowish- brown. Brownish- yellow: Yellow. Orange. Yellowish- green, becoming blue on dilution. Puce. Fawn. H2S04, 10 per :ent. by weight, Slate blue. Purple. Brownish. Violet-blue. Fawn. Greenish. Fawn. Yellowish- brown. No change. Darker. Much lighter HCI. Deep blue. Greenish- blue. Yellow. Blue. Brownish- yellow. Orange- yellow. Bright yellow.Yellow. No change. Puce. Deoolorisod. HNO,. Bluish-sla te. Bluish-green Yellowish- brown. Bluish-slate. Greenish. Dull orange. Yellow -red. Yellowish- red. Bluish-green becoming blue on dilution. Puce. Decolorised. NaOH, 10 per cent. No change. 9 9 1, Yellow- brown. Lighter and duller. No change. Nearly decolorised. $ 9 No change. Browner. Decolorised, NH4OH. ~ No change.?9 Slowly becomes lighter. Yellow- brown. No change. $ 9 D ecolor ise d . 9 9 No change. Yellower. Lighter. Alcohol. Alcohol, tinted light pink. ilcohol, coloured light pink. Deep pink solution. Little change ; reddish- yellow filtrate. Violet solution. Greenish solu- tion; partly extracted. Deep green solu- tion; easily extrac tea. No action. Yellow on boiling. Yellow solution.TO THE DETECTION AND SEPARATION OF CERTAIN DYES 343 effected by the same method, although not in the same degree.Thus, working under the above conditions, safranine which is completely removed from water, was only partly adsorbed from a solution in 90 per cent, alcohol. The kaolin containing the adsorbed dyes can be tested by the application of reagents similar to those which have been employed for the detection of dyes on wool and other fibres.As we have verified these reactions in the case of the colours experimented with, it may be useful to give the table (p. 342), although the reactions are in many cases to be found in various textbooks dealing with the subject : The coloured kaolins were, in all cases, dried before the application of the above-mentioned reagents.The dilute sulphuric acid referred to was prepared by mixing one part by weight of the acid with nine parts of water ; the sulphuric acid, hydrochloric acid, and nitric acid were the ordinary pure laboratory reagents. The caustic soda solution was a 10 per cent. solution, and the ammonia was prepared by mixing one volume of the strong ammonia solution with two volumes of water. The alcohol referred to in the last column was 90 per cent.strength. I t will be seen that we have only dealt with a few of the more commonly occurring dyestuffs, but doubtless the method would prove applicable in the case of a great many other colouring matters with which we have not experimented. I t may be said that no difference could be observed in the adsorbing properties of kaolin when this was extracted with dilute hydrochloric acid and thoroughly washed. On the other hand, the ignition of the kaolin seemed to weaken its adsorbing properties to some extent.Precipitated aluminium hydroxide ground up with water (the so-called alumina, cream) was found to be very inferior to kaolin as an adsorbent. DISCUSSION. Mr. BEVAN asked whether the respective proportions in which the dyes were present would make any difference in the accuracy of the test, and also whether there appeared to be any connection between the chemical composition of the various dyes and their degree of adsorption.Mr. RAYMOND Ross asked whether kaolin had any action upon natural vegetable colouring matters, such as occurred in fruits and in jam.Mr. J. CONNAH asked whether this method had been applied to the identification of vegetable colours (e.g., fruit juices) as well as to the coal-tar colours, and remarked that the method would doubtless be useful for the detection of artificial colouring matters in wines. Mr. E. R. BOLTON asked whether the method could be used to separate colours from oils, and also whether the authors had tried the use of Fuller’s earth. He suggested that possibly the use of kaolin and Fuller’s earth consecutively might be found advantageous.Fuller’s earth, of course, varied a good deal in its action on oils, some samples being capable of bleaching oils that would not be affected by other samples. Mr. H. E. BURGESS said that he had recently found that when a solution con- taining three or four of these dyes was applied to ordinary blotting-paper the colours were separated, and could be fairly accurately identified by cutting up the blotting-344 THE DETECTION AND SEPARATION OF CERTAIN DYES paper and dissolving out the separate colours.The colours in that case were dis- solved in glycerol before being applied to the blotting-paper ; when water was used, the same effect was not obtained.Mr. EVERSHED said that those colours which were adsorbed by kaolin were all, or nearly all, basic colours, whereas those which were not adsorbed were “acid ” dyes. The action of the kaolin was therefore analogous to that of animal fibres. A skein of wool would take up the basic colours from a neutral bath, while the acid colours would only dye wool in the presence of a little mineral acid.He should like to ask whether the authors had tried the effect of mineral acids upon the adsorption of any of these dyes by kaolin. Had any quantitative tests been made with mixtures of acid and basic colours to see whether the former passed through the kaolin com- pletely? It was well known that if fairly strong solutions of acid and basic colours were mixed, a precipitate was generally formed. If this precipitation occurred with weak solutions in passing through the kaolin, the separation must be incomplete.Had the kaolin method any superiority over the well-known methods of testing by means of wool and cotton? Mr. L. M. NASR asked whether this method applied to spirit-soluble colours. Mr. RICHMOND said that a good many years ago a method was published for detecting artificial colours in butter and margarine by shaking up with ‘‘ Spanish earth,” which, while not affecting the natural colouring matters, removed a good many artificial colours.The PRESIDENT remarked that the fact that it was possible, when two out of a mixture of three dyes had been adsorbed by kaolin, to remove one of these by treat- ment with alcohol, showed how great an influence was exercised by the liquid in which the colours were dissolved.No doubt, if alcohol had been used in the first instance, different effects as regards adsorption would have been produced, and it might perhaps be possible, by varying the solvent, to extend the application of the method. Mr. CHAPMAN, in reply, said that the classification of the various dyes into those which were adsorbable by kaolin and those which were non-adsorbable was not, of course, an absolutely sharp one, but the method was at least capable of permitting of the separation of a number of dyes from one another, and of rendering their identifica- tion possible.It was true that, generally speaking, the dyes which were adsorbable by the kaolin were those which had a basic character, whilst those of an acid character remained, as a rule, unadsorbed.This had been pointed out some years ago by Suida and others. I t was, of course, also true that some of the dye stuffs, to which he had referred, interacted and produced some precipitation. One advantage of the kaolin method over the ordinary one of dyeing wool, and also over such capillary methods as those mentioned by Mr. Burgess, was that larger quantities of the dyes could be separated, and that the dyed kaolin could be tested by means of various reagents, which could not well be applied to wool or paper. He and Mr. Siebold had not devoted much attention to natural colouring matters, but a good deal of work had already been done on that part of the subject, and had been referred to at the begin- ning of the paper. They had had no experience of the application of this method to the testing of wine, but it seemed quite possible that it would enable certain artificialDETECTION AND ESTIMATION OF SMALL QUANTITIES OF NITROUS AClD 345 dyes to be separated from the natural colouring matters of the wine. I n the case of alcoholic solutions, separation c-ould in many cases be quite readily effected, although they were of a different character from those which had been described in the case of aqueous solutions. They had not made any experiments with oils, and could not say what results would be obtained.

ISSN:0003-2654    

DOI:10.1039/AN9123700339

出版商:RSC    

年代:1912

数据来源: RSC

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DETECTION AND ESTIMATION OF SMALL QUANTITIES OF NITROUS AClD 345 A NEW METHOD FOR THE DETECTION AND ESTIMATION OF SMALL QUANTITIES OF NITROUS ACID. BY E. ROLL MILLER. (Read at the Meeting, June 5, 1912.) THIS method is a colorimetric one, and depends on the formation of paranitrosodi- methylaniline, when a solution of dimethylaniline hydrochloride is added to an acidulated solution containing nitrous acid.A yellow colour is developed immediately, unless the nitrous acid solution is very weak, in which case the colour develops on standing. The following process is recommended for carrying out the estimation : A solution of dimethylaniline hydrochloride is required, containing 8 grms. of dimethylaniline and 4 grms. of hydrochloric acid per 100 c.c., and a standard solution of sodium nitrite containing 1 part of nitrous acid per 100,000.The estimation is performed in Nessler cylinders, or a colorirneter. Fifty C.C. of the solution under examination are introduced into a cylinder, and acidulated with 1 drop of concentrated hydrochloric acid, and 3 drops of the dimethylaniline solution added, and allowed to stand fifteen minutes. If the solution is very weak, it may be necessary to allow it to stand for thirty minutes, or longer, for the complete development of the colour.The colour is then matched in the usual manner against the standard solution, which is acidulated with 1 drop of concentrated hydrochloric acid, and 3 drops of the dimethylaniline solution added. The method is very sensitive, and will detect with ease 1 part of nitrous acid per 1,000,000. The presence of nitrates does not interfere with the estimation. The great advantages of the method are its sensitiveness and simplicity.

ISSN:0003-2654    

DOI:10.1039/AN9123700345

出版商:RSC    

年代:1912

数据来源: RSC

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346 REVIS: NOTE ON THE DETECTION OF BENZOIC ACID IN MILK NOTE ON THE DETECTION OF BENZOIC ACID IN MILK. BY CECIL REVIS. THE use of benzoates for the preservation of milk has shown a considerable and wide-spread increase this year, though they seem to be seldom detected. This is undoubtedly due to the fact that benzoic acid is not usually looked for in a routine manner, and also, that the quantity of milk taken for official purposes is, as a rule, too small to allow of the examination when other tests have been made.As a further difficulty arises from the unreliability of some of the methods employed, it may be of interest to note that the following method gives certain results. While not entirely original, it embodies the most necessary procedure in the detection of benzoic acid, vie., that the removal of fat, protein, etc.: shall be done in an alkaline medium, other- wise there is much lisbility of the benzoic acid being removed with the precipitate or coagulum.The method is as follows : One hundred C.C. (not less) of milk are diluted with an equal volume of water, and, after the addition of 5 C.C. of 10 per cent. sodium carbonate solution, heated in boiling- water for two to three minutes ; 10 C.C.of 20 per cent. calcium chloride solution are then added, and the heating continued, until coagulation of the casein, etc., is complete. The liquid is then cooled and filtered, and the filtrate, neutralised with hydrochloric acid to litmus-paper. Ten C.C. of Fehling copper sulphate solution (not mixed with the tartrate solution), followed by 10 C.C.of a solution of potassium hydrate (containing 31-18 grms. per litre) are now added, and the liquid again filtered. The filtrate is poured into a separating-funnel, acidified with hydrochloric acid, and extracted with about 50 C.C. of ether. The ether is then washed three times with a, little distilled water. About 10 C.C. of water are now added to the ether in the funnel, together with 1 drop of phenolphthalein solution, and then a saturated solution of barium hydrate added gradually, until, on violent shaking, the aqueous layer remains pink.This is then filtered off into a porcelain basin and evaporated to about 5 C.C. The contents of the basin are filtered into a test-tube and dilute (1 in 100) acetic acid dropped in until the pink colour is discharged, after which two more drops are added.The liquid is then tested with 1 drop of 10 per cent. neutral, freshly-prepared solution of ferric chloride, when, in the presence of benzoic acid, the usual characteristic precipitate is obtained. This method will detect 0.02 per cent. of benzoic acid. The test with ferric chloride is the most reliable and characteristic, but it ie necessary that everything else shall, as far as possible, have been removed, which the above method ensures. When examining cream, 50 C.C. should be diluted to 200 C.C. with water and the same treatment applied.

ISSN:0003-2654    

DOI:10.1039/AN9123700346

出版商:RSC    

年代:1912

数据来源: RSC

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FOOD AND DRUGS ANALYSIS 347 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. ANALYSIS OF FOOD AND DRUGS. Examination of Copaiba Oil. E. Deussen and B. Eger. (Chem. Zeit., 1912, 36, 561-562.)-0n treating 6-caryophyllene with nitrogen peroxide, a com- pound, CI,H,,N,O,, which may be termed P-nitro-caryophyllene (m.-pt. 159.5" to 160° C.), is obtained. This reaction may be used in the examination of copaiba oil in the following manner: Three grms.of the sample are dissolved in 27 C.C. of anhydrous ether, and the solution treated with nitrogen peroxide until the precipitated P-nitro-caryophyllene begins to agglomerate. The precipitate is then separated, washed with ether, dried on porous porcelain, and weighed (cj. Annalen, 1912, 388, 138). The following yields of P-nitro-caryophyllene were thus obtained : Caryophyllene (from clove oils) 50 to 52; Para copaiba oil (a), 9-5 to 10; (b, c, d,) 15 to 16; Maracaibo copaiba oils, 3 to 6; Maranham copaiba oil, 8 to 9; Para copaiba oil (d) adulterated with 10 per cent.of gurjun oil, 13.3 to 14.3; with 20 per cent, of gurjun oil, 11.7 to 12.7 ; with 30per cent., 10.7 to 11-7 ; and with 50 per cent., 7.7 to 8.3 per cent.For the detection of 10 per cent. of African copaiba oil in Para oil, the optical rotation may be determined. The melting-point of the dihydrochloride also rises with the increase in the proportion of African copaiba oil. Thus, on passing hydrochioric acid gas into pure Para oil, a mixture of P-caryophyllene dihydro- chloride (m.-pt. 69' to 70" C.) and of Z-cadinene hydrochloride (m.-pt.117' to 118" C.) is obtained, melting at about 75" C., whilst in the presence of African copaiba oil, which is rich in cadinene, the m.-pt. of the mixed hydrochlorides is raised to about 85" C. by 5 per cent.; about 111' C. by 10 per cent.; and about 114' to 115" C. by 20 per cent. I n testing Para copaiba oil for gurjun oil by Turner's reaction 3 drops of the sample are dissolved in 3 C.C.of glacial acetic acid, and the solution treated with 2 drops of freshly prepared 10 per cent. sodium nitrite solution, and then cautiously with concentrated sulphuric acid. In the presence of gurjun oil the acetic acid solution becomes dark violet within thirty minutes. Since certain pure copaiba balsams give a faint positive reaction in this test, the author modifies the method by using 1 drop of the sample and 1 per cent.sodium nitrite solution, and only taking note of colorations produced within five minutes. When a positive result is obtained by this method, 170 grms. of the sample are separated by distillation into three fractions of 50 grms. each up to 145" C. Each of these fractions is dissolved in 300 grms.of acetone (containing water), and the solution oxidised by adding, with constant shaking, 160 grms. of powdered potassium permanganate in portions of about 3 grms. every fifteen minutes. After oxidation is complete, the acetone solution is decanted, and the manganese residue shaken, first with 200 grms. of acetone, and then with 200 grms. of ether. The solvent is evaporated, and the residual oil dried and fractionated under a pressure of 2 to 3 mm., so as to obtain three fractions, boiling respectively below 130" C., 140° C., and 165" C.The second and, especially, the third fractions are then subjected to the semi-carbasone test as follows :348 ABSTRACTS OF CHEMICAL PAPERS Two grms. of the fraction are added, drop by drop, to a concentrated aqueous solution of 1.1 grm.of semi-carbazide hydrochloride, to which has been added 1 grm. of potassium acetate dissolved in 3 grms. of alcohol and 1 drop of acetic acid, and the final mixture is cleared by the addition of sufficient alcohol. The semi-carbazone is collected after two days, washed with water, dried on porcelain, and weighed. Its m.-pt. ranges from 215" to 228" C., rising to 234" C.after recrystallisation from boiling alcohol. The high specific rotation ( + 317') in concentrated aqueous chloral hydrate solution is characteristic of the semi-carbazone from gurjun oil. C. A. M. Estimation of Hydrocarbons in Beeswax and Carnauba Wax. A. Leys. (J. Pharm. Chim., 1912,5,577-591.)-A method of estimating hydrocarbons in waxes is based upon the fact that the higher alcohols in beeswax, etc., are soluble in a mixture in equal parts of amyl alcohol and concentrated hydrochloric acid, whilst hydrocarbons may be separated as a solid cake from the solvent.Ten grms. of the wax are saponified with 25 C.C. of alcoholic potassium hydroxide (45 grms. per litre of absolute alcohol) and 50 C.C. of crystallisable benzene in a flask, with a tubulus and tap at the side, so that it may also serve as a separating funnel. After heating the mixture for twenty minutes, 50 C.C.of hot water are added, the boiling continued under a reflux condenser for another ten minutes, and the flame then withdrawn. The liquid soon separates into two layers, and the lower soap solution is then drawn off without cooling. The residual benzene is heated again for ten minutes with 50 C.C.of water, which is subsequently drawn off as before, and the benzene is then evaporated, leaving a residue of alcohols and hydrocarbons. This is treated little by little with 100 C.C. of hot &my1 alcohol, and the whole afterwards mixed with 100 C.C. of concentrated hydrochloric acid, and gently heated, with continual stirring, until the mixture has become completely fluid.The flask is now slowly cooled, and the cake of hydrocarbons at the top is separated from the semi-crystalline mass below, redissolved in the 50 C.C. of the mixture of amyl alcohol and hydrochloric acid, separated as before, pressed between filter-paper, heated on the water-bath in a tared basin, and weighed. The wax alcohols in the solvent are separated by heating the liquid with an excess of water, cooling the mixture, drawing off the lower layer of diluted hydrochloric acid, evaporating the amyl alcohol, taking up the residue with benzene, and evaporating the solution in a tared basin. As a further test the liquid fatty acids of the wax may be estimated by treating the lead salts with benzene.Two samples of pure beeswax thus examined gave the following results : Alcohols, 39.21 and 39.60 (melting at 77" C.) ; hydrocarbons, 10.44 and 13-03 ; and liquid fatty acids, 8-40 and 8.52 per cent. respectively.I n the presence of ceresin or other foreign hydrocarbons, the amount of beeswax is calculated from the ester value, and the corresponding quantity of hydrocarbons deducted from the total hydrocarbons separated.Carnauba wax thus examined yielded 49.22 per cent. of alcohols (m.-pt. 81° C.), but no hydrocarbons. C. A. M. Refractive Index of Beeswax. L. Feldstein. (Chem. Engineer, 1912, 15, 211-212.)-To obtain data as to the refractive index of pure beeswax at temperaturesFOOD AND DRUGS ANALYSIS 349 above the m.-pt., twenty-seven samples of known purity were examined.These gave results falling within the limits of 1.4398 and 1.4451 at 7 5 O C., whilst samples known to contain small quantities of foreign substances gave values outside these limits. Since all pure waxes give a sharp reading at 7 5 O C., it is recommended that that temperature should be adopted for the estimation, and that the calculation of results to the corresponding values at 40" C.should be abandoned. C. A. M. Detection of Benzoic Acid in Foods. 0. Biernath. (Ver5fentZ. a. d . Gebiete d. Militarsanitlitswesens, 1912, Heft 25 ; through Chem. Zentralbl., 1912, I,, 1929.)-The reaction of A. Jonescu (J. Pharm. Chim., 1909, 29, 523) with 1 drop of 1 per cent. ferric chloride solution and 3 or more drops of 1 per cent. hydrogen peroxide solution is very sensitive ; it renders possible the detection of 0.001 grm.benzoic acid in foods, by distillation, in fifteen minutes. Mineral acids, volatile fatty acids, and other volatile acids hinder the reaction. If the first distillate from material containing benzoic acid does not yield a reaction within fifteen minutes, four subsequent distillates from the residue will each give the reaction within fifteen minutes.Salicylic acid, accompanying the benzoic acid, may be destroyed by means of alkaline permanganate in the liquid obtained by distilling the sample with 20 C.C. of water and 0-5 C.C. of sulphuric acid. The benzoic acid is then distilled off, and its presence determined as before. 0. E. M. Analytical Constants of Some Vegetable Fats. H. Sprinkmeyer and A.Diedrichs. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 23, 581-596.)-The following results were obtained with samples of different vegetable fats which are now being used for edible and other purposes : Mowrah butter- Crude, 23 samples : Lowest ... ... Highest.. . . . . Refined, 9 samples : Lowest ... ... Highest.. . Sh ea butter- 13 samples : Lowest ... ... Highest.. . .. . Adjab fat- Stillingia tailow- Crude, 1 sample : Refined, 3 samples : Lowest ... ... Highest.. . . . . Borneo tallow- Tulucuna fat- Dika fat- Malukang butter- Befined, 1 saniple Refined, 1 saniple 1 saniple ... ... 1 sample ... ... "ID 40" C. 50.7 53.2 52.8 54 -2 58.2 60.7 52.4 46'7 47'1 46 *7 51.7 3 6 5 44.2 Iodine Value. 61.2 64.2 60.2 63.8 54'4 60-0 59.0 39 5 40.5 29-7 64.9 2'9 19.4 3sponifi- cation Value.190 '4 192.7 190'0 192.0 177.0 188-0 182-8 200.9 202-4 196.6 194'8 242-0 253'0 Acid Value. 15.0 58.1 1.3 3 -5 9.0 66.6 29.0 0.6 0.9 1 -0 -_ 4-0 11.4 Melting- Point 0 c. 24.5 28'4 26-4 28'4 43 *4 45'2 42.5 41.3 42 5 28 -7 37 '5 33.0 - Solidify- ing Point O c. 16.6 22.2 18 -7 19.6 21.0 25 '2 39-3 26 *7 27 -5 22.6 32.3 - - Reichert- Meissl Value. 1 -70 - - - 1-40 2.50 - 0 -20 0 -80 - 2.30 0.22 15-50 ?olenske Value.0 '40 - -- - 0 '45 - 0.50 0.50 0.60 - 0'50 5-50 0.60 LJnnsaponi- fiable Matter. Per Cent. 1'82 -- - - 3.60 10.01 7 '40 0 -30 0'49 0.50 - - -350 ABSTXACTS OF CHEMICAL PAPERS Mowrah butter is obtained from the seeds of Bassia longifolia, adjab fat from the seeds of Mimusops djave, shea butter from the seed kernels of Bassia Parkii, tulucuna fat from the seeds of Carapa procera, dika fat from the seeds of Irvingia gabonensis, and malukang butter from the seeds of Polygctla bulyracea. With the exception of tulucuna fat, and possibly stillingia tallow, all the above-mentioned fats are suitable for edible purposes.Tulucuna fat possesses a bitter taste. W. P. S. Behaviour of Milk when treated with Ammonium Sulphate, and a New Method for the Estimation of Laetose.E. Salkowski. (Zeitsch. physiol. Chem., 1912, 87, 89-95.)-When milk is saturated, or nearly so, with ammonium sul- phate, the proteins are precipitated completely together with the fat, and a clear solution is obtained in which the lactose may be estimated polarimetrically. Fifty C.C. of the milk are shaken with 17.5 grms.of ammonium sulphate, and, when the salt has dissolved, the mixture is diluted to 100 C.C. with saturated ammonium sulphate solution. The whole is shaken and passed through a dry filter, the filtrate being examined polarimetrically. w. P. s. Detection of Saponin in Beverages and Foods by Haemolysis. C. Sor- mani. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 23, 661-566.)-A rhsumh is given of the papers published by A.Rusconi (Boll. SOC. Med. Chir., Pavia, 1910, 1911,1912) on the detection of saponin by hemolysis-that is, the property possessed by certain substances of dissolving the red colouring matter from blood-corpuscles when the latter are suspended in a suitable medium. The blood-corpuscles are obtained by submitting defibrinated blood to centrifugal action with 1 per cent.sodium chloride solution, separating the corpuscles, and suspending them in physiological salt solution. The liquid or substance to be tested must not contain alcohol or carbon dioxide, and must be neutral in reaction ; before being added to the corpuscle liquid it is rendered isotonic or slightly hypertonic by the addition of 2 per cent. of sodium citrate.The test may be used for the detection of Agrostemma githago in flour, the injurious properties of these seeds being due to the presence of saponin. I n this case the flour is made into a dough with 2 per cent. citrate solution, and the dough is then kneaded with a further quantity of the citrate solution, the extract obtained being filtered, and B portion of the filtrate used for the test.The mixture of corpuscle liquid and the solution to be tested is placed in a thermostat for three hours, at the end of which time the red colouring matter will have been dissolved, and the super- natant liquid will appear coloured, should haemolysis due to the presence of saponin have taken place. Red wine contains a substance which inhibits hemolysis by saponin, but which may be removed by precipitation with albumin. The test will detect the presence of 1 part of saponin in 10,000 parts of beer, or in 40,000 parts of aerated water.w. P. s. Detection of Saponin. J. Ruhle. (Zeitsch. Untersuch. Nahr. Genussm., 1912 23, 566-577.)-The author has investigated various tests for the detection of saponin, and finds that Vamvakas’ reaction, and colour reactions with sulphuric acid, with Frohde’s reagent, and with naphthol, thymol, and ox-gall, are all unreliable, chieflyFOOD AND DRUGS ANALYSIS 351 owing to the presence of interfering substances in the articles under examination (cf.ANALYST, 1912, 22). Saponin may, however, be readily detected, even in the presence of glycyrrhizin, by means of its haemolytic properties.The action of the saponin is dependent on the amount of cholesterol contained in the corpuscles, those containing the largest quantity being most resistant to the haemolytic action of the saponin. If cholesterol be added to the corpuscle liquid, a point is reached finally at which saponin has no action, and in this way saponin may be differentiated from other haemolytic substances. In carrying out the test, 1 C.C.of a dorpuscle liquid (obtained by mixing 1 C.C. of defibrinated blood with 99 C.C. of a 0.9 per cent. sodium chloride solution, submitting the mixture to centrifugal action, pouring off the super- natant liquid, and diluting the residue to 100 C.C. with the sodium chloride solution) is mixed in a test-tube with from 1 to 3 C.C. of the solution to be tested.If, after the lapse of some length of time, the corpuscles have dissolved, a further quantity of the liquid under examination is mixed with cholesterol and the test repeated; the absence of hemolytic action in this test indicates definitely that saponin is present. About 4 parts of cholesterol will inhibit the action of 20 parts of saponin. The cholesterol is most conveniently added to the saponin solution in the form of an ethereal solution, the mixture being then heated to 36" C.for some hours in order to expel the ether. When only very small quantities of saponin are being dealt with, the test may be carried out on a microscope elide, the haemolytic action of the saponin being observed under the microscope. w. P. s. Polarimetric Estimation of Starch.C. J. Lintner. (Zeitsch. angew. Chem., 1912, 25, 1177.)-Wenglein's method of hydrolysing the starch with sulphuric acid of sp. gr. 1.7 is liable to give irregular results in hot weather owing to the hydrolysis pro- ceeding too far. The substitution of hydrochloric acid for sulphuric acid is not practi- cable, since, even without heating, the stage of gelatinisation followed by colloidal solution may be rapidly passed.Under the conditions found most suitable for obtaining constant results, barley starch gave [.ID = 198" either with sulphuric acid of sp. gr. 1-7 kept cool, or with acid of sp. gr. 1.4 at 22" C., the latter being found the more reliable. The method finally based on these experiments wag as follows : 28 grms. of the finely- ground barley are thoroughly mixed with 5 C.C.of 96 per cent. (by vol.) alcohol in a 100 c.c.-flask with a wide neck, and 50 C.C. of sulphuric acid of sp. gr. 1.4 (= 50 per cent. of sulphuric acid) introduced with continual shaking. The flask is then left for an hour, with frequent shaking, at 22" C., after which 10 C.C. of a 2 per cent. phospho- tungstic acid solution are added, and the contents made up to 100 C.C.with sulphuric acid of sp. gr. 1.3 ( = 40 per cent. acid). After thorough shaking, the mixture is filtered, and examined polarimetrically, using sodium light. The rotation multiplied by 10-1 gives the amount of starch in the air-dried barley. C. A. M. New Method for the Estimation of Glycerol in Wines. C. Beis. (Bull. SOC. Chim., 1912, 11, [iv.], 618.)-Existing methods for the estimation of glycerol in wines usually involve removal of the sugar by means of barium or calcium hydroxide, variations in the quantities of which lead to inconsistent results : too little allows sugar to pass into the glycerol, while too much causes the retention of glycerol, To352 ABSTRACTS OF CHEMICAL PAPERS meet this difficulty the following method was devised: 100 C.C.of ordinary wine, 50 C.C. of sweet wine, or 25 C.C. of wine over 1.035 sp. gr., are neutralised in a porcelain basin with barium hydroxide and concentrated at 70' C. to a syrup, mixed with sand, and extracted by warming with acetone below its boiling-point. The first portion of acetone is sufficient in quantity to prevent its dilution by the water in the residue below 95 per cent.of acetone ; succeeding portions are smaller. (40 to 50 c.c.) Each portion is cooled and filtered ; the process is carried on until the volume of the filtrate reaches 200 C.C. Two aliquot parts of the filtrate are evaporated without ebullition. TO the other is added five times its volume of water, and powdered barium hydroxide; a few milligrams in excess of the weight of sugar, if this is not more than 0.050 grm. : a weight equal to that of the sugar if this is between 0.050 and 0.300 grm.; and four-fifths of the weight of tbe sugar if between 0.300 and 0.500 grm. Sand is added, and the mixture extracted wit.h 40 C.C.of acetone, followed by several portions of 25 C.C. Each extract is filtered, and the united filtrate evaporated in a suitable vessel and the residual glycerol weighed.The sugar is estimated by Fehling's solution in one of them. 0. E. M. Analyses of Wines from Eastern France, G. Filaudeau. (Ann. FaZsi@., 1912, 5, 296-303.)-The wines examined comprised samples from the departments of Meurthe-et-Moselle (10 samples), Meuse (9), Vosges (8), Haute-Sa6ne and Doubs (lo), and Jura (10). The results obtained were normal as compared with those found in other years for these wines. w. P. s. Analyses of Wines from the Department of Gironde. E. Dubourg. (Ann. Falsific., 1912, 5, 281-296.)-Results of analyses of 206 samples of red wines and 71 samples of white wines from different districts in the department of Gironde (France) are recorded, the wines all being of the 1911 vintage. The average percentage results for all the red wines were: Alcohol, 9.8; total solids, 23-58; ash, 2 4 2 ; reducing sugars, 3-75 ; volatile acid, 0-85 ; non-volatile acid, 2.70 ; potassium hydrogen tartrate (from the total potassium), 4.60; (from the tartaric acid), 1-95. In the case of the white wines (excluding the sauternes) the average results were : alcohol, 10.1 ; total solids, 28-47 ; ash, 1.74 ; reducing sugars, 7-74 ; volatile acid, 0.55 ; non-volatile acid, 3-19 ; potassium hydrogen tartrate (from the total potassium), 2.69 ; (from the tartaric acid), 2-20, As compared with other years, the red wines contained less non- volatile acid and a correspondingly larger amount of potassium. These irregularities were less accentuated in the case of the white wines. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700347

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

352 ABSTRACTS OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Estimation of Small Quantities of Bilirubin. E. Herzfeld. (Zeitsch. physiol. Chem., 1912, 77, 280-284.) - When an alcoholic solution of bilirubin is treated with a few drops of a solution of p-dimethylaminobenzaldehyde (prepared by dissolving 20 grms. of this substance in 500 C.C. of hydrochloric acid and adding 500 C.C. of water) a green coloration is produced, the intensity of which is propor- tional to the amount of bilirubin present, and this amount may be estimated byBACTERIOLOGICAL, PHYSIOLOGICAL, ETC.353 examining the mixture with the spectrophotometer. For the estimation of bilirubin in blood, 20 C.C. of the latter are mixed in a mortar with absolute alcohol, then transferred to a 100 C.C.flask, diluted to about 75 C.C. with alcohol, and 2 C.C. of the reagent are added. The mixture is heated on a water-bath until the green coloration has developed, then cooled, and diluted with alcohol to the mark. The solution is now examined with the spectrophotometer. The quantity of bilirubin, x, is calculated from the extinction coefficient, e, observed, according to the formulae : x = 0.00132.e e w. P. s. Mechanism of Coagulation. J. Duclaux. (Comptes rend., 1912, 154,1426- 1429.)-A theory of coagulation by osmotic action is based upon the following hypotheses : (1) The osmotic pressure of a solution of several substances is the sum of the partial osmotic pressures ; and (2) in a state of equilibrium the relative propor- tions of different substances that a membrane will allow to pass will be the same on each side of the membrane, the only differences being in the proportions of substances that cannot pass through the membrane.If, for example, to alcohol containing one substance in solution a second soluble substance be added, the alteration in the osmotic pressure will depend upon the size of the molecule of the added substance.If the molecules are very small, the increase of volume caused by their addition will be negligible ; whereas, if they are large, there will be considerable increase in volume and a corresponding decrease in the pressure. If, further, two vessels, A and B, are charged with the same alcoholic solution, and separated by a membrane porous to water and alcohol, and a substance capable of reducing the osmotic pressure in B and of not traversing the membrane, be added, water will pass from B into A.But since, according to the second hypothesis, the relative proportions of water and alcohol must always be the same in A and B to obfain equilibrium, alcohol must also pass from B into A in such quantity that the composition of the liquid in A remains constant in so far as concerns the relative proportions of water and alcohol.But under such conditions the osmotic pressure in B muet remain lower than in A , and consequently the osmosis will only cease when the whole of the original liquid in B has passed through the membrane into A. The added substance will separate spon- taneously. If the original solution contained one grm.-molecule per litre, it is necessary that the grm.-molecule of the added substance should occupy in solution a volume greater than 1 litre before such conditions of osmosis are brought about ; and this is usually the case with colloidal substances.In colloidal solutions the place of the porous membrane is assumed to be taken by the free space between the particles of the colloidal substance, and this space will be indefinitely enlarged by the force of osmotic action, until separation of the colloid occurs spontaneously. C.A. M. Studies on Enzyme Action. 11. Hydrolytic Action of Some Amino-Acids and Polypeptides on Certain Esters. K. G. Falk and J. M. Nelson. (J. Amer. Chein. SOL, 1912, 34, 828-845.)-The authors suggest as a tentative hypothesis that354 ABSTRACTS OF CHEMICAL PAPERS the hydrolytic action of lipase is due to an optically active substance of protein character, readily hydrolysed in aqueous solution to form lipolytically inactive Substances.The characteristic groups of protein substances are the amino and carboxyl groups, free or combined. The possible hydrolytic actions of some simple amino-acids and polypeptides were therefore studied by observing the quantity of acid produced at 38" C., when methyl acetate, ethyl butyrate, and olive oil were dissolved or suspended in aqueous solutions containing glycin, alanin, phenylalanin, leucin, glycylgl ycin, leucylglycin, glycylleucin, diglycylgl ycin, aspartic acid, and glutamic acid.Three sets of measurements were necessary for each experiment : with solutions containing amino-acid or polypeptide alone, ester alone, and with a mixture containing botb.Sorensen's formol method (ANALYST, 1908, 33, 19) was used for the estimation of amino-acids and polypeptides, except that Tc soda was used for the titrations in place of p; phenolphthalein was used as indicator through- out, most of the end-points being a distinct pink colour, and not the definite red recommended by Sorensen.Many hundreds of determinations are tabulated, and there was found to be a satisfactory agreement between the results obtained and those already published by Sorensen, in so far as the work covered the same ground. Glycin and alanin showed the greatest amount of action with ethyl butyrate, and least with methyl acetate. Phenylalanin showed a markedly greater action with methyl acetate, less with ethyl butyrate, and least with olive oil.Leucin gave practically no action with the three esters. Glycylglycin gave the same slight action with methyl acetate and ethyl butyrate, but none with olive oil. With leucylglycin, glycylleucin, and diglycylglycin, maximum, though small, actions were obtained with ethyl butyrate, very slight but distinct with olive oil, while with glycylleucin and diglycylglycin and methyl acetate, negative values were obtained.With aspartic and glutamic acids the order of magnitude of action was methyl acetate, methyl butyrate, olive oil, considerably greater action being caused by the former, as was to be expected from the greater ionisation constant of the former.The selective action with different esters is strongly suggestive of the selective action of lipases from different sources with different esters. I t seems probable that many of these selective actions of the lipases may be reproduced with amino-acids and polypeptides of varying structure or in the presence of other substances. There is no evidence, however, that the hydrolytic action of lipase is to be attributed to amino- acids or polypeptides.The specific groupings present in the amino-acids or polypeptides which show this activity may be present in more complex substances, such as the proteins, and from this point of view the stirdy of the hydrolytic actions of the decomposition products, such as the amino-acids from preparations possessing lipolytic activity, and of the more complex polypeptides or other substances synthesised from them, may throw light upon the substances capable of causing such lipolytic act ion.H. F. E. H. Kumagawa-Suto Method of Estimating Fat in Animal Substances. R. Watanabe. (Biochem. Zeitsch., 1912,41,71-77.)-As the result of a, critical exami- nation of this method (ANALYST, 1908, 33, 362), the author finds that it is quite reliable for the direct estimation of fat in the following animal substances withoutBACTERIOLOGICAL, PHYSIOLOGICAL, ETC.355 drying the latter before saponification : Flesh, heart, liver, pancreas, kidneys, intestines, bones, skin, ascitic and pleural fluids, and frogs. In the case of blood, defibrinated blood, blood-plasma, blood-serum, and brains, better results are obtained when the substances are extracted with alcohol, and the extract used for the estimation of the fat (cf.ANALYST, 1910, 35, 527). Suprarenal glands yielded, after saponification, 27 per cent. of matter soluble in petroleum spirit, but more than one-half of this consisted of unsaponifiable substances. w. P. s. Loss of Fat during the Drying of Animal Tissues.M. Tamura. (Biochem. Zeitsch., 1912, 41, 78-lOl.)-Shimidzu has already drawn attention to the fact that an apparent loss of fat takes place when animal tissues are dried before the fat is estimated by the Kumagawa-Suto process (cf. ANALYST, 1910, 35, 527), and this is confirmed by the result of an extended investigation carried out by the author. If, however, the substance be dried as quickly as possible in quantities of from 100 to 200 grms., with the addition of an equal quantity of alcohol, the loss of fat due to oxidation does not usually exceed 0.5 per cent.of the total quantity of fat present. w. P. s. Blue Colour-Reaction of Phosphotungstic Acid with Uric Acid and Other Substances. 0. Folin and B. Macallum. (J. Biol. Chem. 1912,11, 265; through Chenz.Zentralb., 1912, I, 1928.)-Phosphotungstic acid in presence of saturated sodium carbonate solution gives a blue coloration not only with uric acid, but also with phenol, tyrosin, tannic acid, thymol, orcinol, resorcinol, vanillin, and phloro- glucinol. The reaction appears to be characteristic of aromatic compounds containing a hydroxyl-group in thep-position. Moreover, it appears to be due to an impurity in the phosphotungstic acid, and not to the acid itself.0. E. M. Refractive Indices of Solutions of Certain Proteins. VI. The Proteins of Ox Serum: a New Optical Method for the Estimation of the Various Proteins in Ox Serum. T. B. Robertson. (J. Biol. Chem. 1912, 11, 179; through Chem. Zeiztmlbl. 1912, I, 1929.)-The alteration a in the refractive index of a solvent produced by dissolving in it 1 grm.of protein was the same, whether the proteins were dissolved in the native serum, or whether they were precipitated with alcohol, washed with alcohol and ether, dried, and dissolved in & potassium hydroxide solution. The value of a was also independent of the dilution, and was not altered when the serum was made acid.For the proteins of ox serum the value of a is 0.00195. The refractive power of the mixed proteins in ox serum represents the sum of the refractive powers of tho individual proteins. For refractometric purposes the non-proteins of the serum may be regarded as a &-grm. molecular sodium chloride solution. The value of a for the albumins of ox serum dissolved in Q saturated or weaker ammonium sulphate solution is identical with the value for solutions in distilled water : it is 0.00177.The discovery of the additive character of the refractive indices rendered it possible to modify the method of Reiss so that the individual proteins hitherto identified in blood serum could be estimated356 ABSTRACTS OF CHEMICAL PAPERS separately. insoluble globulins, and 5.4 per cent.total albumins. Ox serum was found to contain 2.34 per cent. soluble globulins, 0.76 0. E. M. Estimation of Sugar in Blood and Urine. E. Frank. (Zeitsch. phzysiol. Chem., 1912,78,165-166.)-The author replies to criticisms of his method for the estimation of sugar in blood (ANALYST, 1910, 35, 260). w. P. s. Estimation of Benzoic Acid, Hippuric Acid, and Phenaceturic Acid in Urine.H. Steenbock. ( J . Biol. Chem., 1912, 11, 201; through Chem. Zentralbl., 1912, I , 1930.)-For the estimation of hippuric acid 100 C.C. of urine are boiled for two hours with 10 grms. sodium hydroxide and 25 C.C. of hydrogen peroxide ; the hippuric acid is thus converted into benzoic acid, and the colouring matter of the urine is oxidised. The liquid is rendered acid with sulphuric acid, bromine water is added and the liquid made up to 200 C.C.and filtered; 50 C.C. of the filtrate are extracted with ether, the ether evaporated off, and the residue sublimed and weighed. To estimate the phenaceturic acid, the sublimate is titrated with & sodium hydri- oxide, and the proportion of the benzoic acid to the phenylacetic acid formed from the phenaceturic acid calculated from this titration and the weight of the dry sublimate.0. E. M. New Method for the Estimation of Hippuric Acid in Urine. 0. Folin and F. F. Flanders. (J. Biol. Chem., 1912,11, 257; through Chem. Zentralbl, 1912, I, 1930.)-A mixture of 100 C.C. urine and 10 C.C. of 5 per cent. sodium hydroxide solution is evaporated to dryness on the water-bath ; the hippuric acid in the urine is thus converted into benzoic acid.The residue is transferred by means of 25 C.C. of water and 25 C.C. of concentrated nitric acid to a flask fitted with a reflux condenser, and boiled for four and a half hours with 0-2 grm. copper nitrate to destroy colouring matter and similar substances in the urine. The contents of the flask are saturated with ammonium sulphate in a separating funnel, and extracted with chloroform, and the united chloroform extracts washed once by shaking with a solution of sodium chloride containing hydrochloric acid, and the benzoic acid in the chloroform extract titrated with TG sodium ethoxide and phenolphthalein. 0.E. M. Estimation of Phenol in Urine. M. Hensel. (Zeitsch. physioZ. Chem., 1912, 78, 371-381.)-The method proposed depends on the fact that phenol is dis- solved from its acid aqueous solution by ether, and that it can be extracted from the ethereal solution by means of sodium hydroxide, but not by sodium hydrogen carbonate.Five hundred C.C. of the urine are rendered alkaline and evaporated to 100 c.c., the solution being then acidified with phosphoric acid and distilled with frequent additions of water, until all the phenol has passed over, as is shown by the distillate ceasing to give a reaction with Millon’s reagent.The distillate is then extracted four successive times with ether, the united ethereal extracts are shaken four times with a 4 per cent. sodium hydrogen carbonate solution, and afterwards the same number of times with The sodium hydroxide extracts are united, acid added until the alkalinity of the solution is equivalent to sodium hydroxide solution.BACTERIOLOGICAL, PHYSIOLOGICAL, ETC.357 20 C.C. of & solution, and the phenol in the alkaline solution is titrated by Penny and Kossler's method. The method yields trustworthy results in the case of urines containing large quantities of carbohydrates. A method described by Mooser (Zeitsch.physiol. Chem., 1908, 63, 155), in which the distillate from the urine, acidified with phosphoric acid, is redistilled from calcium carbonate in a current of carbon dioxide, and the phenol titrated in this distillate, was found to yield accurate results. w. P. s. Estimation of Urea in Urine by Riegler's Method. A Correetion Factor.T. Ekeerantz and S. Eriekson. (Zeitsch. physzol. Chem., 1912,79,171-176.)-1n the estimation of urea in urine by Riegler's method (c.f. ANALYST, 1912, loo), substances other than urea, such as uric acid, purine bases, creatinine, neucleo-albumin, etc., are decomposed and yield carbon dioxide and nitrogen, and the results are, consequently, too high. Those substances which interfere may be removed by treating the urine with twice its volume of a solution containing 10 per cent. of phosphotungstic acid and 1 per cent.of hydrochloric acid of sp. gr. 1.12, and removing the precipitate by filtration after the lapse of four hours; the urea is then estimated in the filtrate. In most cases, however, sufficiently accurate results for all practical purposes may be obtained by treating the urine directly and multiplying the result obtained by 0.926 in order to correct for the amount of nitrogen liberated by the substances other than urea.w. P. s. Detection of Savin Oil in Toxicological Cases. J. Hamalainen. (Biochem. Zeitsch., 1912,41, 241-246.)-Savin oil contains about 50 per cent. of sabinol acetate, which constitutes the toxic principle of the oil; this acetate on hydrolysis yields sabinol, which, in the body, combines in part with glycuronic acid, and is excreted in the urine as sabinol-glycuronic acid.When the latter is boiled with a, mineral acid a cymene is formed, and the identification of the latter has been suggested as a means of detecting savin oil in urine. Other oils, however, such as turpentine, thuja oil, etc., when administered to animals, pass into the urine in the form of derivatives which yield cymene.Sabinol-glycuronic acid may be identified by means of the characteristic crystalline salts it yields with certain bases, particularly with strychnine, and the following method is described by the author for the detection of savin oil in cases of suspected poisoning by this substance : The urine is treated with neutral lead acetate in neutral or feebly acid solution, the precipitate formed is separated by filtration and washed, and, after the filtrate has.been rendered ammoniacal, basic lead acetate is added as long as a precipitate is produced. The basic lead salt is collected on a filter, washed with water, decomposed with cold 5 per cent, sulphuric acid, the lead sulphate is separated, and the solution neutralised with barium carbonate.After filtration, the filtrate is concentrated, preferably under reduced pressure, and the barium is precipitated by treating the warm solution with hot strychnine sulphate solution. The mixture is filtered while hot, and the filtrate allowed to cool. Strychnine sabinol-glycuronate separates out in the form of brilliant needles which melt a t 196" C. with decomposition.This salt has 2 molecules of water of crystallisation; it is fairly soluble in hot water, and but358 ABSTRACTS OF CHEMICAL PAPERS slightly soluble in cold water, alcohol, ether, acetone, chloroform, benzene, petroleum spirit, or ethyl acetate. On concentrating the mother-liquor, a strychnine salt with 3 molecules of water crystallises out, melting at 193" C.It is more readily soluble than the first-mentioned salt, and on cooling its solution rapidly, the salt with 2 molecules of water is obtained. Urine from rabbits, which had received a dose each of 1.5 C.C. of savin oil, yielded crystals of strychnine sabinol-glycuronate when examined by the above method. w. P. s. Microchemical Reaction of Spermatic Fluid.P. Aleixandre. (Zeitsch. anal. Chem., 1912, 51, 473-475.)-A reaction proposed by De Dominicis (Resveglio Medico, May 15, 1910) consists in treating a trace of the fluid with a drop of a saturated gold tribromide solution on a microscope slide, heating the mixture to boiling, and examining it under the microscope. At a magnification of 300 diameters rectangular or cross-shaped crystals, having a garnet colour, are observed. The crystals are soluble in alcohol and in alkali solutions, but not in acids. The author has examined this test, and finds that it is not very sensitive; the crystals are rarely obtained unless the spermatic fluid is of a concentration of more than 2 per cent.Quadratic crystals are also frequently obtained, and are due to the presence of cholin.w. P. s. Colorimetric Method for the Estimation of Uric Acid. E. Riegler. (Zeitsch. anal. Chem., 1912, 51, 466-470.)-The method depends on the blue colora- tion which is obtained when uric acid is treated with phosphomolybdic acid and disodium phosphate. The coloration is not given by albumin, psptones, albumoses, creatine, creatinine, or sugar, although these substances yield a similar colour when treated with phosphomolybdic acid and potassium or sodium hydroxides.For the estimation of uric acid in urine, 1 C.C. of the sample is placed in a test-tube, and in two similar tubes are placed, respectively, 1 C.C. of a 0.1 per cent. uric acid solution and 1.2 C.C. of the same uriue from which the uric acid has been removed by means of ammonium chloride.(This iis effected by heating 10 C.C. of the urine with 3 grms. of ammonium chloride to 40" C,, and filtering the mixture after the lapse of thirty minutes; 1.2 C.C. of the filtrate is employed, in order to allow for the increase of volume due to the ammonium chloride.) To each of the iubes are then added 2 C.C. of a 10 per cent. phosphomolybdic acid solution, and a sufficient quantity of a 5 per cent. disodium phosphate solution to make the contents of each tube up to 10 c.c.; a mark may be provided on the tubes for this purpose. After the contents of the tubes have been mixed, they are heated over a flame until small bubbles of gas are evolved, then cooled, and the colorations compared in a colorimeter. The coloration yielded by the urine is first compared with that given by the known quantity of uric acid. The apparent quantity of uric acid in the 1.2 C.C. of urine from which the uric acid has been removed is also estimated by comparison with the standard, and its quantity deducted from the amount found in the urine itself. This correction has to be made, as urine contains substances other than uric acid, which give a coloration with the reagents. Should the urine contain albumin, this must be separated by boiling the urine and filtering it before the estimation is carried out. The standardORGANIC ANALYSIS 359 solution of uric acid is prepared by boiling 0.1 grm. of uric acid and 0.1 grm. of sodium hydrogen carbonate with 50 C.C. of water, cooling the solution, and diluting it with water to a volume of 100 C.C. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700352

出版商:RSC    

年代:1912

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ORGANIC ANALYSIS 359 ORGANIC ANALYSIS. Angeli’s Reaction for Aldehydes. 0. Baudisch and J. H. Coert. (Bey., 1912, 45, 1775-1779.)-Angeli’s test for aldehydes is based on the fact that an aqueous solution of the sodium salt of nitrohydroxylaminic acid forms with various aliphatic and aromatic aldehydes hydroxamic acids which are readily detected in minute quantities by their characteristic iron reaction.The sodium salt of nitro- hydroxylaminic acid first splits up into nitrosyl-sodium and sodium nitrite : Na0.N : NO.ONa= NONa+ NaNO,. The nitrosyl-sodium, or perhaps free nitrosyl, combines with the aldehyde ; the hydroxamic acid produced may be isolated in the form of its internal complex copper salt. Form-hydroxamic acid may also be produced by the action of light on an aqueous formaldehyde or methyl alcoholic solution of potassium nitrate or nitrite, owing to the formation of nitrosyl or nitrosyl-potassium.In this reaction it appears probable that the combination of nitrosyl with formaldehyde or methyl alcohol takes place through intermediate stages, forming first nitroso-methyl alcohol, which then changes to methylene-nitronic acid, and, finally, to form-hyrdoxamic acid.If this course be actually followed, the formation of the nitroso alcoholate should be accom- panied by the temporary appearance of a blue-green coloration. I n performing Angeli’s test in the ordinary way no such coloration can be observed ; the change is too rapid. But in presence of certain substances-e.g., methyl acetate, acetone, ethyl acetate, or gelatin-Angeli’s salt shows with aldehydes the blue-green colour of the intermediate nitroso compound.Angeli’s salt is dissolved in a little water with a, large excess of methyl acetate, and the mixture is shaken; aqueous form- aldehyde is added, the liquid being rotated; the methyl acetate then acquires a blue-green colour, which lasts for several seconds. J. F. B. Precipitant for Amino-Acids.C. Neuberg and J. Kerb. (Biochem. Zeitsch., 1912, 40, 498-512.)-When a dilute solution of an amino-acid (for instance, glycin) is rendered distinctly alkaline with sodium carbonate, and then treated with a 25 per cent. mercuric acetate solution, a white precipitate is obtained, and, on the addition of from 4 to 5 volumes of alcohol, the amino-acid is precipitated almost completely.The following results were obtained with various amino-acids, the figures representing the percentage of the total nitrogen precipitated : Glycin, 95.7 ; d, I-alanin, 95-8 ; d-alanin, 97-3 : d, I-valin, 70.0 ; leucin, 96-6 ; Z-asparagin, 98-6 ; d-glutaminic acid, 97.2 ; d, I-serin, 94.9 ; I-cystin, 98.1 ; d, Z-phenylaknin, 97.9 ; I-tyrosin, 96.9 ; d, I-prolin, 75.4 ; I-histidin, 99.4 ; I-tryptophan, 97.7 ; d-glucosamine, 99.5 ; a-P-diaminopropionic acid, 99.4 ; d, I-isoserio, 97.8 ; S-amino- valeric acid, 96.1.w. P. s.360 ABSTRACTS OF CHEMICAL PAPERS Detection and Estimation of Arsenic in Organic Compounds. G. Bres- sanin. (Gazx. Chinz. Ital., 1912, 42, 451-455.)-The method of estimating arsenic by means of the insolubility of its iodide in sulphuric acid may also be used with organic compounds.Treated with potassium iodide in sulphuric acid of sp. gr. 1-45, precipitates of different kinds were obtained with commercial organic compounds. Thus atoxyl gave a maroon precipitate ; sodium cacodylate, a vinous red ; and arrhenal, a yellow precipitate. The precipitations were not complete, and E hrlich's '' 606 " (di-hydroxy-diamino-arseno-benzene hydrochloride) gave no precipitate in acid of this concentration, For the estimation of arsenic in such compounds it is necessary to decompose them completely by heating 0.2 to 0.4 grm.with 10 C.C. of sulphuric acid over a very minute flame (to prevent liberation of cacodylic oxide), after which the arsenic may be quantitatively precipitated a8 described before (Zoc.cit.). Ehrlich's '( 606 " is sold as a canary-yellow powder, de- composing at 175O C . without melting. It dissolves in sulphuric acid of sp. gr. 1-84 with decomposition, and the solution, when diluted to sp. gr. 1.45, now gives a, pre- cipitate with potassium iodide. Silver nitrate gives a yellow coloration, followed by a gelatinous precipitate ; copper salts give a blue precipitate ; picric acid a yellow precipitate ; and potassium ferrocyanide a green precipitate, emitting hydrocyanic acid on heating.A positive reaction is obtained with Gutzeit's test, and Fehling's solution is reduced on heating. C. A. M. Esterification of Monamino Acids by Means of Ethyl Iodide. Separa- tion of Pyrrolidonecarboxylic Acid from Glwtamic Acid.E. Abderhalden and K. Kautzsch. (Zeitsch. physiol. Chew,., 1912, 78, 115-127.)-The silver salt of pyrrolidonecarboxylic acid is readily esterified when boiled for two hours under a, reflux condenser with an excess of ethyl iodide. After the silver iodide has been removed by filtration, the ester may be obtained i n the form of a white crystalline mass by evaporating the solution under reduced pressure over sulphuric acid; it melts at 60" to 61.5" C.Under similar conditions, glutamic acid, aspartio acid, asparagin, and prolin remain unaltered. When a mixture of the silver salts of pyrrolidonecarboxylic acid and glutamic acid is boiled with ethyl iodide, the former is esterified, and may be separated from the insoluble silver salt of glutamic acid by means of benzene. Attempts to isolate pyrrolidonecarboxylic acid in the digestion products of casein resulted in the formation of an estex which could not be identified ; this ester yielded glutamic acid hydrochloride when hydrolysed with hydrochloric acid.w. P. s. Influence of Metallic Carbonates on the Estimation of the Volatile Sub- stances in Coal. E. Prost and M. Ubaghs. (BUZZ.Xoc. Chim. Belg., 1912,26, 216-223.)-Estimation of the volatile substances in coal may give an erroneous idea of the calorific value of the coal or its suitability for gas manufacture, unless account be taken of the amount of carbon dioxide in the volatile substances. I n the case of two samples of coal more than 2-5 per cent. of carbon dioxide was present in the volatile substances, whilst other samples gave amounts ranging from 0-5 to 2 per cent.The gas was found to originate from carbonates of iron, calcium andORGANIC ANALYSIS 361 magnesium in the coal. This was found to be the explanation why a coal yielding 15 to 16 per cent. of volatile substances was suitable for the manufacture of coke, whilst another coal from the same source, yielding more than 17 per cent.of volatile substances, was quite unsuitable for the purpose. C . A. M. Combustion of Volatile Organic Liquids. L. Clarke. (J. Amer. Chem. SOC., 1912, 34, 746-747.)-A combustion tube is drawn out at one end, and a tube bearing a female ground glass joint is sealed on. That part of the tube which is within the heating zone of the furnace is filled with copper oxide, held in place by plugs as usual, and the end remote from the ground glass joint is provided with a perforated rubber stopper for attachment to the usual sulphuric acid tube and potash bulb. The end of the tube bearing the ground glass joint protrudes about 4 inches from the end of the furnace.The liquid to be analysed is weighed out in a small stoppered U-tube of the type in which the stoppers close the limbs, and, by turning, may be made to put the side tubes in or out of connection with the U.To one side tube is sealed a male ground glass joint, which has been ground to fit the ground seat on the combustion tube. The stoppers of the U-tube and the joint between U-tube and combustion-tube are very lightly greased with vaseline for the upper third or fourth of their ground surfaces.The unlubricated space below, wherever pervious, is filled with air, forming an effective cushion to prevent absorption by the vaseline of any vapour, should this be soluble in paraffin. After weighing, the U-tube is con- nected to the hot combustion-tube, the other arm being connected to the usual apparatus for hying the air on its way to the combustion-tube.The stopcocks are turned, and the stream of air allowed to pass over the surface of the liquid, carrying forward vapour to the combustion-tube. If the liquid has a boiling-point as low as that of ether, it is well to immerse the lower end of the U-tube in cold water to prevent too rapid volatilisation. For liquids boiling at 100" to 125" C., it is best to immerse the lower part of the U-tube in water at 50" to 60' C.With acetone and similar liquids, neither heating nor cooling is necessary. G. C . J. Estimation of Caoutchouc as Tetrabromide. Utz. (Gummi Zeit., 1918, 26, 968-970 ; through Chem. Zeiztralbl., 1912, l., 1797-1798.)-1n order to avoid the loss of bromine which various authors have found to take place when caoutchouc tetrabromide, prepared by Budde's method, is heated with nitrio acid in presence of silver nitrate, the author recommends the method of Baubigny and Chavanne for the estimation of the bromine.The caoutchouc tetrabromide is decompofied by means of chromic and sulphuric acid mixture; a slight modification in the apparatus, consisting in the introduction of a stoppered dropping funnel, is advised. The author, independently of Hiibener, has devised a method of bromination in aqueous solution : 0.1 grm.of caoutchouc is treated in a Lintner's pressure-flask with 60 to 70 C.C. of water and 5 to 7 C.C. of bromine, and heated in the closed flask for some hours in the water-bath at 50' to 60" C. When the bromination is complete, the liquid is poured off through a filter, and the contents of the flask are extracted with boiling water.The residue of caoutchouc bromide is washed with alcohol and ether and digested with chloroform for six hours at the ordinary temperature. The362 ABSTRACTS OF CHEMICAL PAPERS bromide is reprecipitated by an excess of petroleum spirit, and, after settling, is collected on a filter, washed with akohol and ether, dried in wacuo at the ordinary temperature, and the bromine estimated in Baubigny and Chavanne’s apparatus. The bromine found ranged from 70.12 to 70-25 per cent.in six estimations; theoreti- cal, 70.14 per cent. for CloH,,Br,. A sample of Para rubber showed 93.96 and 93-72 per cent. of caoutchouc by this method. The author is investigating the error due to the presence of nitrogenous impurities in the raw rubber.J. F. B. Latent Heats of Vaporisation of Mixed Liquids. Part 111. : Mixtures of Associated with Non-associated Liquids, and the Detection of Solvates in Mixtures of Liquids. D. Tyrer. (J. Chem. SOC., 1912, Pol, 1104-1113.)-Resnlts are given for the boiling-points, vapour compositions, latent heats at constant pressure, and latent heats at constant composition for the following mixtures : Benzene and ethyl alcohol, chloroform and methyl alcohol, chloroform and acetone, carbon tetra- chloride and ethyl alcohol.I t was found that the mixture of chloroform and acetone gives a maximum boiling-point ; the three other mixtures give minimum boiling-points. From a study of the latent heats of such mixtures a method is established by which the existence of solvates in the mixtures can be detected.I n all four cases studied solvates are formed, Molecular association in liquids is the result of the combination of hydroxyl groups, and when two hydroxyl substances are mixed solvates are always formed. When a hydroxyl substance is mixed with one containing no such group, the latent heat affords a reliable test for the formation of solvates.In normal mixtures each constituent retains its own latent heat unaffected by the presence of the other constituent ; thus the latent heat of either constituent can be calculated from the latent heat of the mixture and the latent heat of the other constituent. Applying this rule to the case of an associated liquid in admixture with a non- associated liquid, the apparent latent heat of the associated constituent can be calculated at various concentrations.If no solvates are formed, the latent heat of the associated liquid in the mixture should gradually diminish as the concentration gradually diminishes, owing to the progressive dissociation of the associated mole- cules, until at infinite dilution it becomes constant, indicating complete dissociation.If this is not the case, then undoubtedly to some extent solvates are formed in the mixture. I n the mixtures above mentioned the diminution was not steady, but the latent heat in all cases, over a portion of the range of concentrations, increased with increase of the dilution. This means that solvates are formed, but it is not possible to determine their amount or composition.The acetone apparently functions in the above case as an hydroxyl substance. J. F. B. Estimation of Ferrocyanides. H. E. Williams. (J. SOC. Chem. Ind., 1912, 31, 468-471.)-The following process is stated to be free from most of the possible sources of error inherent in the Feld method: Half a gram of the ferrocyanide is dissolved in 100 C.C. of water, and the liquid distilled after adding 0.05 to 0.1 grm.of cuprous chloride (dissolved in a few drops of hydrochloric acid, or a little saturated sodium or potassium chloride solution) and 25 to 30 C.C. of 4N sulphuric acid. The distillate is passed from the condenser into absorption-flasks containing caustic alkaliORGANIC ANALYSIS 363 solution. The ferrocyanide is completely decomposed, and the hydrocyanic acid dis- tilled, by about half an hour's gentle boiling. The cyanide in the alkaline hydroxide solution is then titrated in the usual way with standard silver nitrate solution, in the presence of a few drops of potassium iodide solution.Much larger quantities of ferrocyanide may be taken if desired, and in such cases it is only necessary to add an amount of cuprous chloride equal to 2 to 3 per cent.of the weight of ferrocyanide. Sufficient sulphuric acid must be present to give an excess of acid over that required to form ferrous sulphate and sodium bisulphate. The cuprous chloride used should first be freed from cupric salt by washing with a little dilute sulphuric acid. The addition of cuprous chloride decomposes the ferrocyanide, forming cuprous cyanide, which is decomposed by the acid present, yielding hydrocyanic acid and cuprous chloride again, which latter then attacks a further quantity of ferrocyanide.Both soluble and insoluble ferrocyanides may be determined by the method, but if the substance be dry it should be finely powdered. Ferric ferrocyanide requires more cuprous chloride than above stated for its complete decomposition.For the estimation of the ferrocyanide content of cyanogen mud or spent oxide, a weighed quantity of the dried material, from which the sulphur has been rernovcd by extraction with carbon disulphide, is boiled with sodium hydroxide, filtered, washed to a definite volume, and a portion of the liquid distilled with cuprous chloride and sulphuric acid as before.The results on spent oxides are higher, gener- ally by about 0.2 to 0.4 per cent,, than those given by the titration method, and are more accurate. Thiocyanates are stated to have no influence on the distillation ; if present in spent oxide, a larger amount of cuprous chloride should be added to insure their precipitation before distilling (cf. Colman, ANALYST, 1910, 35, 295).A. R. T. Direct Estimation of Geraniol in Citronella Oil. J. Dupont and L. Labaune. (Ann. Chim. anal., 1912, 17, 210-213.)--The method depends upon the conversion of the citronellal into a nitrile, which is not affected by the potassium hydroxide in the estimation of the geraniol as geranyl acetate. Ten grms. of citronella oil (or of a mixture of geraniol and citronellal) are shaken for two hours at the ordi- nary temperature with an aqueous solution of hydroxylamine, prepared by dissolving 10 grms.of hydroxylamine hydrochloride in 25 C.C. of water, adding a solution of 12 grms. of potassium carbonate in 25 C.C. of water, and filtering the mixture. The oil rising to the surface'is decanted, dried over anhydrous sodium sulphate, and boiled under a reflux condenser for one and a half hours with twice its volume of acetic anhydride.Under these conditions the citronellal oxime is converted into citronello nitrile. After washing, neutralisation, and drying, 2 grms. of the acetylated oil are saponified with alcoholic potassium hydroxide solution, and the amount of geraniol calculated from the result in the usual way. The difference between the total products of acetylation in a preliminary test and the amount of geraniol thus found, gives the quantity of citronellal.Thus, a Ceylon oil containing 60.2 per cent. of acetylisable products was found to contain 43 per cent. of geraniol, whilst a Java oil contained 43 per cent. of geraniol and 40 per cent. of citronellal. The results given by test mixtures were in close agreement with theory.C. A. M.364 ABSTRACTS OF CHEMICAL PAPERS Oil of the Southern Cypress. A. F. Odell. (J. Amer. Chem. Soc., 1912,34, 824-826. )-The cones of the Southern cypress (Tuxodiwu distichurn) contain con- siderable quantities of a volatile oil, consisting of d-pinene, 85 per cent. ; d-limonene, 5 per cent. ; a pseudo terpene alcohol (? sabinol), 2 per cent.; carvone, 3 per cent.; tricyclic sesquiterpene, 3 per cent. ; the remainder being composed of substances boiling above 275" C. No aldehydes were found in the oil. H. F. E. H. Estimation of Hydrazine. G. S. Jamieson. (Chenz. News, 1912, 105, 268.) -According to r;he author, Rimini's method requires much time, while the following procedure, based on the general method of Andrews (ANALYST, l903,28,306),is stated to be rapid and accurate : Hydrazine salts, or the double salts of hydrazine and the metals, are analysed by titration with a standard solution of potassium iodate (3.567 grms.KIO, per litre) in presence of hydrochloric acid and chloroform. Suitable propor- tions are 20 C.C. water, 30 C.C. hydrochloric acid, and 6 C.C. chloroform. The solution of potassium iodate is run in gradually, the reaction proceeding according to the equation : The liquid is shaken between each addition of iodate, until the chloroform, which at first is coloured, becomes decolorised.Metallic double salts (such as zinc and hydrazine sulphate) may be examined by this method, and the published results are accurate. I n the case of the nickel double salt, which .is only sparingly soluble, the reaction proceeds very slowly.N,H,*EI,SO, + KIO, + 2HCl= N, + ICI + 3H,O + KC1 + H2S04. A. R. T. Detection and Estimation of Methyl Alcohol. F. Wirthle, (Chem. Zeit., 1912, 36, 700.)-In testing spirits for methyl alcohol, the first 50 C.C. (at most) of the alcoholic distillate from 100 C.C. are distilled and twice fractionated, so as to obtain first 15 C.C.and finally 3 C.C. as the final fraction. One C.C. of this distillate is oxidised by the official potassium perinanganate method, after the addition of 4 C.C. of dilute (1 : 2) sulphuric acid, the liquid filtered, and 1 C.C. of the colourless filtrate heated with 5 C.C. of concentrated sulphuric acid. On treating the cold mixture with 5 mgrrns. of solid morphine hydrochloride, a reddish-violet coloration is pro- duced in the presence of as little as 20 mgrms.of methyl alcohol (corresponding to about 5 per cent of the denatured alcohol in the spirit). At the same time a control test is made with a mixture of 20 mgrms. of methyl alcohol and 1 C.C. of 90 per cent. ethyl alcohol. If the preliminary test has given a strong violet coloration, and the spirit contains about 40 per cent.(by volume) of alcohol, 60 C.C. (from 100 c.c.) are taken, whilst with a higher alcoholic strength a proportionately smaller quantity of the distillate is used, The initial temperature of distillation in a fractional distilla- tion-flask affords information as to the amount of methyl alcohol present. Thus a, liquid containing 10 per cent.of methyl alcohol begins to distil at 75' C., and after five minutes the temperature will have risen to 76.8' C., whilst in the presence of 20 per cent. of methyl alcohol the initial temperature will be 71.5' C., rising, after five minutes, to 75.5' C. It is advisable to treat the residue from the first distillation with alcohol and to fractionally distil it again, the process being repeated so that from solutions containing about 10 per cent.of methyl alcohol about 80 C.C. in allORGANIC ANALYSIS 365 are obtained, from 20 per cent. solutions about 100 c.c., and from 30 per cent. soh- tions about 125 C.C. The mixture of methyl and ethyl alcohols is now converted into iodides by heating it under a reflux condenser with iodine and amorphous phosphorus ; these are eeparated by fractional distillation, and the methyl iodide identified by its saponification value (394.3). For the conversion of 10 C.C.of methyl alcohol into methyl iodide 31-7 grms. of iodine and 1-79 grm. of amorphous phos- phorus are required, whilst ethyl alcohol requires only 22 grms. of iodine and 1.79 grm. of phosphorus for the formation of the corresponding compound.The necessary amounts may thus be approximately calculated from the temperatures observed in the fractional distillation, a slight excess of iodine being taken. The iodides from a quantity of distillate corresponding to 10 C.C. of alcohol are distilled into 10 C.C. of water, decolorised by shaking with 14 to 16 C.C. of 10 per cent. potas- - sium hydroxide solution, separated from the supernatant liquid, washed twice with water, allowed to stand overnight, and then run into a tared flask, which is im- mediately closed and weighed.The small residue of iodides remaining in the burette is collected in a narrow calibrated tube, and its weight calculated from the specific gravity, Since 10 C.C. of methyl alcohol yield 31-35 grms. of methyl iodide, and 10 C.C.of ethyl alcohol yield 24.0 grms. of ethyl iodide, each 0.736 grm. of iodide in excess of 24 grms. corresponds to 1 C.C. of methyl alcohol. To obtain reliable quantitative results it is advisable to dilute the distillate from the spirit under examination with sufficient 96 per cent. ethyl alcohol to give a mixture con- taining approximately 10 per cent. of methyl alcohol, whilst at the same time a blank test is made with a mixture of methyl and ethyl alcohols containing 10 per cent.of the former. C. A. M. Activity of Organie Nitrogen as measured by the Alkaline Perman- ganate Method. C. H. Jones. (J. Ind. Eng. Chem., 1912, 4, 438-441.)-1t is generally recognised that soluble organic nitrogen is readily available as plant-food, whereas nitrogen in insoluble combinations may or may not be so available.Thus, though dried blood and hoof meal contain most of their nitrogen in insoluble forms, they are known to possess high manurial value, whereas there is reason to believe that the nitrogen of peat, roasted leather, garbage tankage, and some other materials, is not immediately available as plant-food, For this reason certain States of the American Union forbid the use of these latter materials in compound fertilisers offered for sale.I n other States, agricultural chemists are called upon to report on the manurial value of mixed fertilisers which may contain nitrates, ammonia, and soluble and insoluble organic nitrogenous substances. The valuation of the insoluble nitrogen has hitherto presented a difficulty for the reasons stated, and the author now proposes to differentiate between the insoluble nitrogen which is converted into ammonia by digestion under standard conditions with alkaline permanganate and that which is not so transformed. That which is converted into ammonia under the conditions described in the paper is designated active insoluble organic nitrogen, and it is suggested that this active nitrogen should be assigned a manurial value but little inferior to the soluble nitrogen, whereas the residue of insoluble nitrogen, designated inactive, is held to have a very low value indeed.These views find support in field366 ABSTRACTS OF CHEMICAL PAPERS experiments-referred to but not described in the paper-and in the fact that in dried blood, high grade tankage, fish, hoof meal, cotton-seed meal, and many other sub- stances which give manurid results in close relation to their nitrogen contents, the proportion of inactive nitrogen, as determined by the author's method, is low, whereas the same method shows that the inactive insoluble organic form is the predominant form of nitrogen in peat, garbage tankage, charred leather, and other substances of notable nitrogen content but negligible manurial value.Active insoluble organic nitrogen is determined as follows : Total insoluble nitrogen is first determined by extracting 2 grms. of the sample on a filter-paper, with water at room temperature, until the filtrate amounts to 250 C.C. The filter- paper and its contents are subjected to the Kjeldahl process.So much of the sub- stance is now weighed out as contains 50 mgrms. of insoluble nitrogen, and, if a mixed fertiliser, is extracted with water, as in the determination of total insoluble nitrogen. Highly nitrogenous raw materials are mixed in a mortar with 2 grms. of powdered rock phosphate before extracting with water, and very oily materials should have a preliminary treatment with ether.The filter and insoluble matter are dried at a temperature not exceeding 80" C., and the insoluble matter is then transferred to a 500 to 600 C.C. round-bottomed flask, together with 20 C.C. of water, a few glass beads, and 100 C.C. of an alkaline permanganate solution containing 150 grms. of caustic soda and 25 grms. of potassium permanganate per litre.The flask is con- nected to a condenser as for an ammonia determination, the receiver being charged with a measured quantity of standard acid. The contents of the flask are digested short of boiling for at least thirty minutes, local overheating of the insoluble residue being avoided by the use of wire gauze and asbestos-paper between the flame and the flask. About 95 C.C.are now distilled, preferably at such a rate that the operation requires an hour. A tendency to froth may be overcome by prolonging the digestion until this no longer manifests itself, and then distilling at a somewhat brisker rate, so that the whole process occupies about ninety minutes as usual. The ammonia in the distillate is the measure of the active insoluble nitrogen. The method has been adopted since March, 1911, by the experiment stations of New York, New Jersey, and the New England States, as the result of laboratory and field experiments in 1910.G. C. J. Action of Permanganate on Organic Substances. J. Hetper. (Zeitsch. anal. Chem., 1912, 51, 409-429.)-111 earlier papers (ANALYST, 1911, 36, 232, 422) the author has shown that many organic substances are quantitatively oxidised to carbon dioxide and water by permanganate in acid solution, whilst the members of another large group of compounds may also be estimated by means of permanganate, the reaction being a quantitative one, with acetic acid for one of the end products.The influence of alkaline permanganate has now been studied. In the majority of cases it proves a less useful reagent than an acid solution.For example, ethyl alcohol, which can be quantitatively oxidised to acetic acid in acid solution, is oxidised partly to acetic acid and partly to carbon dioxide in alkaline solution, the former reaction predominating if the action begins in the cold, the latter if the mixture is hot from the start ; but at no temperature between 0" and 100' C.can either reaction be sup-ORGANIC ANALYSIS 367 pressed entirely. Methyl alcohol is much more quickly oxidised in alkaline than in acid solution, the products being carbon dioxide and water in either case. Caffeine, theobromine, and antipyrin, which only consume from 40 to 80 per cent. of the theoretical amount of permanganate in acid solution, are almost quantitatively oxidised to carbon dioxide, water (and ammonia) in alkaline solution.Many sub- stances which are oxidised quantitkively in acid solution behave similarly in alkaline solution, but in a much greater number of instances the results in alkaline solution correspond to no single reaction. However, the author thinks that the consumption of permanganate in alkaline solution under standard conditions may prove a useful constant, especially when compared with the corresponding number obtained in acid solution.The experimental conditions followed in the author’s laboratory are as follows : The permanganate solution is :, and contains 40 gr. of caustic soda per litre. Of this solution, 25 C.C. is placed in a 200 C.C. flask with 65 C.C. of water, and the sub- stance dissolved in 10 C.C.of water. So much of the substance is taken as may be expected to reduce about 10 C.C. of the permanganate, and, if the substance is insoluble in water, it is mixed with 1 grm. of glass powder, not omitting in such a case to add 10 C.C. of water to the contents of the flask to insure uniformity of conditions in all experiments. The fiask, with its contents, is heated on the water-bath for one and a half hours ; 25 C.C.of oxalic acid (containing 75 C.C. concentrated sulphuric acid per litre) is then added, and the solution titrated with permanganate containing 40 grms. of glacial phosphoric acid per litre. The result is calculated to C.C. of +’ permanganate per gram of substance. The amount of permanganate reduced by forty-two sub- stancesunder these and some other conditions are given in the paper.* G. C. J. Influence of Peptones on the Estimation of Reducing Sugars by Fehling’s Solution. A. Bernardi. (Biochem. Zeitsch. 1912, 41,160-164.)-Although peptones do not reduce Fehling’s solution, their presence in sugar solutions causes more cuprous oxide to be precipitated than is due to the reducing action of the sugar alone.In cases, therefore, where sugar has to be estimated in solutions containing peptones, the latter should be removed by means of phosphotungstic acid previous to the estima- tion of the sugar. w. P. s. Physico-Chemical Basis of the Seliwanoff Lamdose Reaction. A. Jolles. (Biochem. Zeitsch., 1912, 41, 331-332.)-When dextrose is placed in contact with concentrated hydrochloric acid for some months, the solution yields a reaction for laevulose with the Seliwanoff test.The author finds, however, that the polarisation of the sugar is not changed, a fact which shows that either the quantity of laevulose formed is so small that it cannot be estimated, or, which is more probable, that the substance giving the Seliwanoff reaction is not laevulose. The action of dilute alkali solutions on dextrose is much more pronounced, and the change is accompanied by the formation of appreciable quantities of an acid.For instance, 200 C.C. of a 0% per cent. dextrose solution were mixed with about 40 C.C. of -& sodium hydroxide solution ; 50 C.C. of this mixture required 9-1 C.C. of Fo- acid for neutralisation when titrated at once, but after the lapse of ninety-four hours the same quantity of the368 ABSTRACTS OF CHEMICAL PAPERS mixture used only 7.7 C.C.of the acid, phenolphthalein being used as the indicator in both cases. The author also found that the Seliwanoff test would detect the presence of as little as 0.1 per cent. of lmvulose in urine containing dextrose. w. P. s. Method for Determining the Value of Commercial Starches for Use in Cotton Mills.G. M. MacNider. (J. Ind. Eng. Chem., 1912, 4, 417-422.j-The value of starch for cotton-mill purposes depends on its property of swelling and forming a viscous solution when treated with hot water, the principal starches used being maize, potato, cassava, and, to a small extent, wheat, sago, and rice. As each of these starches has a different viscosity, to obtain the best results they must each be used in a diff'erent manner. No definite relation exists between their behaviour and the size or shape of the grains.The author determines the viscosity of each starch at a high temperature under conditions similar to those in which it is used in the mills, employing for the purpose a Scott viscosimeter in the following manner : 12 grms. of the starch are weighed intc a 600 C.C.beaker, 300 C.C. distilled water added (thus making a 4 per cent. solution), and heated over a Bunsen burner, with constant stirring, to the boiling-point and boiled for ten minutes; 200 C.C. of this solution are then poured into a viscosimeter cup, which is jacketed with boiling water, the temperature allowed to become constant, which it does with most starches, at 94' C., and 50 C.C.run out into a graduated vessel, the time being measured with a stop-watch. The number of seconds so required divided by the number of seconds required to deliver 50 C.C. of boiling water (nine seconds) gives the viscosity value. The recorded results show that not only is there a' difference between different starches, but also a considerable variation in the viscosity of different samples of the same starch, only a small part of this latter difference being due to variation in moisture content. The viscosity of maize starch increases uniformly with the length of time of boiling, and corresponds to the increase in concentration brought about by continued boiling.Potato starch reaches its maximum viscosity after being boiled five minutes ; it then decreases rapidly, the increasing concentration having no effect and after thirty minutes' boiling it has fallen below that of maize starch, which has been boiled for the same length of time.Cassava starch attains itis maximum viscosity at the boiling-point, after which it decreases uniformly with the length of time of boiling, and thus resembles potato starch, though to a less extent; the former starch, therefore, has a much wider application in sizing and finishing.Wheat starch has a much lower viscosity than any of the others examined, and shows a gradual but small increase with the time of boiling. Wheat starch foams more in boiling than any other. Rice starch, even at the end of thirty minutes' boiling, still shows a value only very slightly greater than unity.The degree to which starches go into solution on continued boiling was examined, and it was noticed that those from roots and tubers developed under ground (potato and cassava) showed a high rate of solution, while This is a valuable property of maize starch as compared with others.ORGANIC ANALYSIS 369 those from the grains developed above ground were very insoluble. An examination was made of some ‘( thin boiling starches,” which usually consist of maize starch treated in some way to reduce the viscosity.Experiments are described showing the effect of boiling maize starch with borax, alkali, and boric acid, as regards viscosity changes. A small amount of all these reagents reduces, while a slightly larger amount increases, dscosity.H. F. E. H. Estimation of Thymol, Salicylates, and Allied Compounds. A. Seidell. (Amer. Chem. J., 1912, 47, 508-526.)-The method given in the author’s previous paper on this subject (ANALYST, 1909, 34, 536) is admittedly tedious, and was only suggested as a possible improvement over the ordinary bromate titration in which tribromo-phenol bromide is formed.The control of the too vigorous action of bromine on the compounds under examination has now, in the author’s opinion, been accomplished more satisfactorily. The method is as follows: A quantity of 0.1 to 0.5 grm. of thymol or other substance to be estimated is placed in a glass- stoppered bottle, with 1 to 2 C.C. of carbon tetrachloride and 100 C.C. of water.Ehmine vapour is poured in till the mixture, after thorough shaking, shows a con- siderable excess. After half an hour, 5 C.C. of carbon disulphide, immediately followed by 5 C.C. of aqueous potassium iodide (20 per cent.), are added, and the liberated iodine titrated with Fc thiosulphate. An additional amount of potassium iodide is added, and if there is no further liberation of iodine, the burette reading is taken, 5 C.C.or an excess of aqueous potassium iodate solution (2 per cent.) added, and the titration, after thorough shaking, continued till the iodine colour is discharged. The second titration corresponds to the hydrobromic acid formed by the action of bromine on the compound used. Two molecules of hydrobromic acid are equivalent to 1 molecule of thytuol; 1 C.C.Fc thiosulphate, therefore, is equal to 0.0075 grm. thymol. The results quoted vary from 99.0 to 100.8 per cent. of the theoretical. Carbon disulphide and tetrachloride serve to remove the compound from the aqueous layer, and the reaction in the organic solvent is more under control, only dibromothymol being produced. Carbon tetrachloride, unlike carbon disulphide, is little acted on by bromine on standing, and is therefore added first ; but a satisfactory end-point in the titrations is not obtainable without the addition of the disulphide as described.Salicylic acid may be determined when in admixture with benzoic acid, the latter being unacted on. Other substances tried gave variable results. A. R. T. Tetraformal-trisazine from Formaldehyde and Hydrazine Hydrate, a New Reducing Agent for Analytical Use.K. A. Hofmann and D. Storm. (Ber., 1912, 45, 1725-1730.)-Hydrazine hydrate is employed in analytical chemistry for the precipitation of silver, gold, mercury, platinum, selenium, and tellurium, but its reducing power is too great to permit of fine differentiations among the noble metals, and it also reduces solutions of copper and bismuth. The precipitates are not easily filtered, and firm mirrors are not obtainable on glass.Hydrazine hydrate also attacks glass, and is not free from alkalis. The authors, therefore, recommend, as a reducing agent far more under control and free from alkalis and acid, the com-370 ABSTRACTS OF CHEMICAL PAPERS pound tetraformal-trisazine, C,H,,N,, formed by the combination of formaldehyde with hydrazine hydrate.This substance has the structural formula- HN.CH,.N. CH,. NH For its preparation, 50 C.C. of 35 per cent. formalin are poured slfwly into 50 C.C. of hydrazine hydrate cooled with ice, and after one hour a further 30 C.C. of formalin &re similarly added. The mixture is placed in a basin, covered with paper, and left for one or two days, when the yield of crystallised compound should amount to 27 grms.The crystals are filtered off, washed with spirit, redissolved in water, and precipitated with alcohol and ether ; they may also be recrystallised as flat, silky needles from slightly alkaline hot water. At 28O C., 100 grms. of water dissolve 14 grms. of the azine. Silver nitrate yields first a white precipitate, changing im- mediately on warming to a fine adherent metallic mirror; palladium chloride also yields a mirror.Gold chloride yields first a blue colloid, and later a dark precipitate. Copper sulphate gives a reddish-brown solution. The azine is not decomposed by alkalis, from which it crystallises unchanged. In alkaline solution, copper salts are reduced to cuprous oxide, mercury, gold, and silver salts to the metals, whilst plati- num and palladium chlorides give stable, reddish-brown solutions. I n presence of excess of potassium hydroxide, chromates, molybdates, vanadates, selenites, and tellurites remain unchanged, even at the temperature of the water-bath; but on the addition of ammonium chloride, indigo blue molybdenum oxide, red selenium, or black tellurium are precipitated.Tungstates are not reduced even in ammoniacal solution. Thus tetraformal-trisazine may be recommended as a selective reducing agent which is readily prepared in a perfectly pure form. The substance, though stable towards alkalis, is very sensitive to the action of acids, even carbonic and acetic acids, forming polymerised formalazine, (CH,N,CH,),, as an insoluble white powder.Ammonia is one of the principal products of the action of hot dilute sulphuric acid, J. F. B. HN.CH,.N.CH,. I ‘ 4 H. Examination and Valuation of Turpentine. H. Wolff. (Furbenxeitung, 1912, 17, 1492 ; through Chem. Zentralbl., 1912, I., 1930.)-The colour is more conveniently, determined by a comparison with solutions of iodine, potassium dichrornate, etc., than by means of the Lovibond colorirneter.The polymerisation with sulphuric acid, which involves oxidation, should not be omitted (cj. Marcusson, Chem. Zeit., 1910, 34, 285); otherwise, adulteration with residues from the manu- facture of turpentine may be overlooked. The distillate obtained before and after the chief fraction in the distillation of turpentine are to be found on the market and are difficult to detect when added to turpentine. The greater part of the residual oil distils earlier when mixed with turpentine than it does alone.On the other hand, with concentrated or fuming sulphuric acid, more separates from the mixture than would be anticipated from the amount of residual oil. I t is evident that sulphuric acid has less action in the presence of high-boiling constituents.A separation of more than the normal 2 to 4 per cent. is sometimes shown, when the resinification is well started, even by pure turpentines, in which there is a slight natural increase ofORGANIC ANALYSIS 371 these constituents, and, consequently (petroleum being excluded), is not a proof of adulteration with these residues.A small increase in the residue on evaporation, with a large increase in the amount separated by fuming sulphuric acid, points to an adulteration with these waste products, whereas an increase in the resinifica- tion is of no value as an indication. A residue of 1 per cent. on evaporation has a noticeably bad effect on the drying-period, whilst 2 or 3 per cent. renders a turpentine useless for many purposes in the varnish and colour industry.0. E. &I. Estimation of Petroleum in Turpentine. H. Wolff. (Farbenzeituizg, 1912, 17, 1553 ; through Chem. Zentralbl. 1912, I, 1931.)-The constituents dissolved by nitric acid are, contrary to the statement of Herzfeld (Chem. Zeit., 1910, 34, 885), cyclic hydrocarbons, since they can be reduced by the slow action of nascent hydrogen, the solution being kept warm.I t was found that xylene can be dissolved in concentrated sulphuric acid alone, but that long shaking is necessary; this explains the conflicting results obtained by Marcusson and Herzfeld with turpentines containing xylene. Consequently Herzfeld's method of determining benzene has only a qualitative value, and only then if it is positive and agrees with the other constants (boiling-point, bromine number, etc.).The separation of petroleum or paraffin hydrocarbons by concentrated fuming sulphuric acid is more valuable, especially if, by the method of Ute, the refraction of the separated residue is determined. The Marcusson method is preferable for the exact determination of petroleum and benzene hydrocarbons.In the case of a strongly resinified oil, if there is a considerable separation with concentrated sulphuric acid, even when the Marcusson test gives a negative result, it is better to examine once more the substance separated with sulphuric acid by the Marcusson method. 0. E. M Tests for Determining the Purity of Oil of Turpentine. R. Mareille. (Ann. Falsific., 1912, 5, 241-251.)-Determinations of the solubility of oil of turpentine in acetic acid, the rise in temperature when mixed with sulphuric acid, and the solubility in sulphuric acid, are stated to yield results which will afford evidence as to the genuineness of a sample of turpentine.Solubility in Acetic Acid.-The acetic acid employed should contain 98 per cent. of the acid and 2 per cent.of water; it should be capable of dissolving an equal volume of anhydrous carbon disulphide at a temperature of 39 to 40" C., at which point a mixture of equal volumes of the two liquids should just become turbid ; if the temperature at which the turbidity is observed is lower or higher than this, the strength of the acid must be adjusted accordingly. Five C.C. of the oil of turpentine are placed in a stoppered graduated tube, and shaken with successive additions of acetic acid until a clear mixture is obtained at a temperature of 15' C. The quantity of the acid required to dissolve 1 part of the oil of turpentine is then calculated. For genuine samples this quantity is usually less than 4. The oil of turpentine may also be distilled, the distillate being collected in five separate portions, which are then sub- mitted to the test. The first fractions dissolve in about 3.5 parts of acetic acid, whilst the fifth fraction may require up to 4.5 parts of acid. The presence of petroleum diminishes the solubility of the oil, the fifth fraction of a sample containing 5 per372 ABSTRACTS OF CHEMICAL PAPERS cent. of petroleum requiring from 6 to 7 volumes of acetic acid. Oil of turpentine adulterated with (( benzine ” has a greater solubility than pure oil of turpentine. Thermal Test with Xulphuric Acid.-The method of carrying out this test in the case of fatty oils has been described by Tortelli (ANALYST, 1909, 34, 168). The same procedure is adopted with oil of turpentine, but, as the latter evolves very consider- able heat when mixed with sulphuric acid, it is better to perform the test on a mixture of 5 C.C. of the sample and 15 C.C. of (‘ vaseline oil.” Genuine oil of turpen- tine gives a value of from 68 to 72, and the presence of 10 per cent. of mineral oil will diminish this value by about 7. Solubility in Xulphuric Acid.-One hundred C.C. of petroleum, 20 C.C. of oil of tur- pentine, and 50 C.C. of sulphuric acid are mixed in a Rose tube, and the increase in the volume of the sulphuric acid is ascertained after the lapse of one hour. In the case of genuine oil of turpentine, the increase will be about 19.2 C.C. (that is, 96 per cent. of the oil is soluble in the acid), whilst with an oil containing 10 per cent. of mineral oil the increase in the volume of the acid will be only 17.1 C.C. The test is useless should benzine ” be present. Care should be taken to examine the petroleum used in the test, as some specimens yield notable quantities of matter soluble in sulphuric aoid. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700359

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

372 ABSTRACTS OF CHEMICAL PAPERS INORGANIC ANALYSIS. Detection of Small Quantities of Alkali Bicarbonate in Presence of much Normal Carbonate. R. T. Haslam. (J. Amer. Chem. Xoc., 1912, 34, 822-823.)-The carbonate suspected to contain bicarbonate is dissolved in recently boiled water, and excess of calcium chloride is added. If alkali bicarbonate was originally present, some calcium bicarbonate will remain in solution with the calcium chloride.After standing five minutes, a portion of the solution is filtered free from calcium carbonate, and a few drops of ammonia are added to the filtrate. An immed- iate precipitate of calcium carbonate indicates a large amount of bicarbonate in the original sample. With only small amounts of bicarbonate present, the precipitate may not appear for ten minutes.The test will detect 0.1 per cent. of bicarbonate in normal sodium carbonate. The presence of ammonium salts vitiates the results because of the solubility of calcium carbonate in such solutions. G. C. J. Neutral Ammonium Citrate Solution. A. J. Patten and C. S. Robinson. (J. Ind. Eng. Chem., 1912, 4, 443-446.)-According to the official methods of analysis drawn up for the guidance of American agricultural chemists, the ammonium citrate solution for use in determining available phosphoric acid is to be prepared by dis- solving citric acid in water, adding ammonia until the solution is neutral to corallin, and then diluting it with water until the sp.gr. is 1.09. The authors point out that the determination of the end-point with corallin is very difficult, and that purified litmus, though better, is also unsatisfactory as an indicator.Solutions ‘( neutralised ” by four experienced analysts were used to extract a phosphatic manure, with the result that the manure was found to contain 2-83, 3-69, 4.17, and 4-82 per cent. of insoluble phosphoric acid. The authors think that the amount of ammonia necessary for neutralisation should be determined by the conductivity method as suggested byINORGANIC ANALYSIS 373 Hall and Bell (J.Amer. Chem. SOC., 1911, 33, 711 ; J. I d . Eng. Chem., 1911, 3, 559). The solution is nearly neutralised, and then equal measured portions are transferred to measuring-flasks, and a measured and different amount of dilute ammonia is added to the contents of each flask, so that two flasks at least contain an excess of ammonia and two an excess of acid.The contents of the flasks are then diluted to the mark, and their relative conductivities determined. It is unnecessary to determine the absolute conductivities. Provided the same apparatus is used for all the determina- tions, the Wheatstone bridge readings may be plotted against the volumes of dilute ammonia, and the break in the curve will indicate the volume of ammonia necessary to neutralise so much of the solution as was taken for the test.The error of this method, even in the hands of persons with no previous experience of conductivity measurements, is only one-tenth the error of the most careful titration with corallin or litmus. G. C. J. Separation of Beryllium from Aluminium.M. Wunder and P. Wenger. (Zeitsch. anal. Chem., 1912, 51, 470-473.)-From a mixture of beryllia and alumina, the former may be separated as follows : The mixture is fused with 5 grms. of sodium carbonate in a, crucible, which is covered at first, but subsequently uncovered, whilst the mixture is maintained in a state of fusion for two to three hours.The melt is boiled out with water, about a gram of sodium carbonate is added, and boiling con- tinued for a few minutes. Beryllia remains undissolved. It is filtered off, washed, dried, ignited, and weighed, and re-fused with sodium carbonate, and the whole process repeated to insure the solution of the last traces of alumina. In the mixed filtrates, alumina is precipitated by boiling with excess of ammonium nitrate, and is filtered, washed, dried, ignited, and weighed in the usual manner.The worst recorded results are 0-1466 grm. beryllia and 0.1385 grm. alumina found with 0.1472 and 0.1379 grm. respectively present. The results are not stated in such a way as to show what additional error, if any, might be expected to result from the omission of the second fusion.In practice, more or less iron will, as a rule, be present in the material presented for analysis, and the whole of this iron will remain as insoluble hydroxide with the beryllia, any chromium also present passing as chromate into the solution of sodium carbonate and aluminate. Precipitates of beryllia contaminated by ferric hydroxide are ignited, fused with bisulphate, and the aqueous solution of the melt is poured into a solution of 10 grms.of caustic soda in 150 C.C. of water, and the whole boiled. The precipitate consists of ferric hydroxide free from beryllia, and is washed, re-dissolved in acid, re-precipitated by ammonia, and weighed as ferric oxide as usual. The alkaline solution of beryllia is acidified, and the beryllia precipitated by means of ammonia.When chromium is present in the original material, it will exist as chromate in the filtrate from the alumina, and may be recovered by reduction with alcohol and precipitation with ammonia. G. C. J. Volumetric Estimation of Chloric Acid and Chlorates. A. Kolb. (Chem. ,%it., 1912, 36, 635.)-The high results obtained by the action of hydrochloric374 ABSTRACTS OF CHEMICAL PAPERS acid on chlorate in presence of potassium iodide at the ordinary temperature are due to the presence of atmospheric oxygen, and may be avoided by removing the air from the hydrochloric acid solution by means of a current of carbon dioxide, dissolving the chlorate in water which has been boiled and carrying out the reaction in a vessel filled with carbon dioxide.To 10 C.C. of air-free potassium chlorate solution (about &) are added 1 grm. of solid potassium iodide and 50 C.C. air-free hydrochloric acid of sp. gr. 1.125 in the order given, and the mixture allowed to stand five to ten minutes in a stoppered vessel in the dark. After addition of 200 to 300 C.C. water, the separated iodine is titrated. If the quantity of chlorate solution is more than 10 c.c., the hydrochloric acid must be increased proportionately, otherwise the reaction is slower.An increased quantity of chlorate in the 10 C.C. is without effect on the reaction-velocity, but more potassium iodide is required to keep the iodine in solution. 0. E. M. Quantitative Determination of Perchlorates. A. B. Lamb and J. W. Marden. (J. Amer. Chem.SOC., 1912, 34, 812-817.)-The minus errors which attend estimations of perchlorate by fusion with sodium carbonate or other substances, and determination of the resultant chloride as silver chloride, are shown to be due to loss of chloride by volatilisation. This may be wholly avoided as follows : The substance (0.5 grm.) is weighed into a Jena glass test-tube of about 25 to 30 C.C.capacity. An asbestos plug is pushed down into the tube within 2 inches of the bottom, and a second plug 2 inches nearer the top. The tube is clamped in a nearly horizontal position, and the perchlorate is heated gently until effervescence ceases. A somewhat stronger heat is then applied, until, in from ten to fifteen minutes, the chloride is thoroughly fused. When cool, the contents of the tube, including the plugs, are washed on a Gooch crucible with hot water, and the chloride in the filtrate deter- mined in the usual manner.A correction must be made, if necessary, for chloride in the asbestos used, and in the most exact work 0.1 mgrm. may be added to the weight of silver chloride found, as a correction for the loss with the final wash liquors. Without this last correction, the worst result of eight recorded by the authors is only 0.05 per cent.below the theoretical. G. C. J. Estimation of Chromium in Bronzes containing Tin and Antimony. H. Schilling. (Chenz. Zeit., 1910, 36, 697.)-The following rapid modification of von Knorre’s method is recommended : Two grms. of the finely-divided turnings are dissolved in 25 C.C. of hot aqua regia (lHNO, to 4HC1), and the solution mixed with 40 C.C.of sulphuric acid (l:l), and evaporated until white fumes appear. Complete removal of the aqua regia is essential. When cold, 200 C.C. of water are added, and the precipitated sulphates dissolved by boiling, with the exception of the lead sul- phate. The copper and antimony are now precipitated by means of iron wire in the metallic form, the liquid filtered after five minutes, and the precipitate washed.The filtrate and washings are made up to 500 c.c., heated to boiling, and treated first with a few drops of silver nitrate solution (1 : 20) as a catalytic agent, and then with 10 C.C. of a cold saturated solution of ammonium persulphate. By vigorous boiling the chromium is oxidised to chromic acid, whilst the bulk of persulphate is mean-INORGANIC ANALYSIS 375 while decomposed, The remainder, together with any permanganato that may have been formed, is decomposed by adding 5 C.C.of hydrochloric acid (sp. gr. 1.12) and boiling the liquid for a short time. When completely cold, the chromium is estimated by titration in the usual way. The presence -of tin does not affect the accuracy of the results, C.A. M. Iodimetric Estimation of Copper. K. Sugiura and P. A. Kober. (J. Amer. Chem. SOC., 1912, 34, 818-822.)-Though the iodimetric method for the estimation of copper is capable of yielding results of a high order of accuracy, this is only the case when the thiosulphate is standardised under conditions very closely resembling those prevailing in actual assays.I n consequence of this, many papers have been published on the influence of various amounts of acid, salts, water, etc., the most recent being that of Peters (ANALYST, 1912, 277). Instead of trying to secure uniformity in all the conditions by the methods advocated by Peters and others, the authors think it far more easy to precipitate the copper as hydroxide, to dissolve the washed precipitate in acetic acid, and to titrate the resulting solution with thiosulphate after addition of potassium iodide.One advantage of the method is the stable end-point with starch indicator (no return of the blue colour). The only point in the method requiring close attention is the precipitation as hydroxide. To the solution, containing phenolphthaleln, 33 per cent.alkali is added drop by drop until a slight precipitate of copper hydroxide remains undissolved. $ caustic soda free from carbonate (containing baryta) is then added from a burette until a change of colour is observed. Any excess of alkali containing carbonate would hold some copper in solution, whilst a large excess even of caustic alkali would prolong the operation of washing the precipitate. If the precipitation be performed as described, three or four washings suffice. The precipitate with the filter-paper is returned to the flask in which the precipitation was carried out, the precipitate is dissolved in 25 C.C.of 10 per cant. acetic acid, 3 or 4 grms. of potassium iodide are added, and the titration with thiosulphate conducted as usual.The thiosulphate is standardised by precipitating a measured volume of a standard copper solution with subsequent solution of the precipitated hydroxide and titration as described. Obviously, the concentration and nature of the acids and salts in the original solution are without influence ou the results, if the washing of the hydroxide be sufficiently prolonged. The amount of washing which the authors give the precipitate cannot remove the whole of the salts, but the test numbers given in the paper show that no sensible error is introduced from this cause.G. C . J. Estimation of Oxygen and Occluded Gases in Copper. G. L. Heath. (J. Ind. Eng. Chem., 1912, 4, 402-404.)-The loss in weight on heating copper drillings in hydrogen is not due entirely to oxygen from cuprous oxide and sulphurous acid, but also includes gases derived by tho metal from the fuel and refining in the furnace and, in addition, any trace of moisture.I n recognition of this fact it isnow customary to heat the drillings to constant weight in a current of carbon dioxide before proceeding to the determination of oxygen. The loss in weight during the preliminary heating in carbon dioxide is returned as " absorbed gases," and includes376 ABSTRACTS OF CHEMICAL PAPERS hydrogen, and traces of carbon dioxide, carbon monoxide, and nitrogen.The author finds that the subsequent loss of weight by heating in hydrogen does not express the true oxygen of the cuprous oxide present in the cast metal, for the metal may take UP SO much hydrogen during the process that the amount of oxygen may be under- estimated by more than 20 per cent.An accurate determination of oxygen may be made bypassing a current of carbon dioxide through the heated tube for twenty minutes after reduction by hydrogen is complete. In the author’s laboratory the carbon dioxide is purified by treatment success- ively with & saturated solution of permanganate, solution of silver sulphate, concen- trated sulphuric acid, anhydrous calcium chloride, dry chromous chloride, stick phosphorus, phosphoric anhydride, and anhydrous calcium chloride.The hydrogen is purified by means of a 10 per cent. solution of caustic potash saturated with permanganate, concentrated sulphuric acid, heated palladium asbestos, a 5 to 10 per cent. solution of pyrogallol in 50 per cent.caustic potash, and anhydrous calcium chloride. The clean drillings (50 grms.) are placed in a hard-glass tube, 30 em. long and 6 mm. diameter, with one long bulb or two round ones; and if the copper is very porous or of unknown origin, the sample is dried at 1000 C. while passing a current of carbon dioxide, and the tube with its contents re-weighed after cooling and replacing the carbon dioxide by air.Air is once more expelled by carbon dioxide, and this gas continuously passed while the tube is heated to full redness for twenty minutes. After cooling and replacing carbon dioxide by air, the tube is re-weighed, the loss being due to occluded gases in the copper. Hydrogen is now passed through the tube, which at its forward end is connected to a gas-washing device containing 10 C.C.of an ammoniacal solution of cadmium chloride (2 per cent.). According to the fineness of the drillings, from one to two hours at a red heat is required to reduce the cuprous oxide. Finally, hydrogen is expelled from the tube and from the copper by replacing the stream of hydrogen by one of carbon dioxide while maintaining a red heat. After twenty minutes, the tube is cooled by an air blast, the carbon dioxide replaced by air, and the final weighing of the tube made.The loss since the previous weighing represents oxygen and sulphur, and the latter is determined by iodine titra- tion of the contents of the cadmium chloride bulbs after addition of hydrochloric acid snd appropriate dilution. Proof of the accuracy of the method is given by a careful electrolytic assay of the reduced drillings.The sum of the copper (and silver) thus found, plus the percentage of arsenic and foreign metals found by complete analysis, should amount to 100 per cent. without any oxygen or occluded gases. In three sets of test numbers given, the totals are 100*0007, 99.9998, and 99.9901. Such check-work implies the use of refined electrolytic methods such as those described by the author (ANALYST, 1911, 36,172), which permit of the determination of copper with an error not exceeding 0.001 per cent.(see also ANALYST, 1900, 25, 253; 1905, 30, 385). G. C. J. Precipitation of the Copper - Arsenic Group and Separation of its Divisions. J. I. D. Hinds. (J. Amer. Chem. SOC., 1912, 34, 811-812.)-The method of precipitation described has regard to the fact that a fairly high concen- tration of acid is necessary for the complete precipitation of quinquevalent arsenic,INORGANIC ANALYSIS 377 whereas cadmium, antimony, and tin are not completely precipitated unless the acid concentration is kept low.To 50 C.C. of the solution, if approximately neutral, 5 C.C.of concentrated hydrochloric acid and 10 drops of nitric acid are added, or a less amount of hydrochloric acid if the original solution is strongly acid, The solution is concentrated to half bulk, whereby not more than one-thousandth part of the arsenic is lost. The nitric acid serves to oxidise all the tin to the stannic condition, which is desired, because stannous sulphide is not readily soluble in colourless ammonium sulphide; at the same time, some arsenic is oxidised to the quinquevalent condition. Arsenic is now precipitated by passing hydrogen sulphide for ten minutes through the hot solution, which is heated once or twice until it actually boils. About 80 C.C.of water are added, and the current of hydrogen sulphide continued until the liquid is cold, or for fifteen minutes.The precipitate, which contains the sulphides of all the metals of the group, is filtered, washed, and transferred to a beaker, where it is covered with strong ammonia. Hydrogen sulphide is passed through the mixture for two minutes, after which the other sulphides are separated by filtration from those of arsenic, antimony, and tin, which pass quantitatively into the filtrate with only a trace of copper.G. C. J. Qualitative Analysis without Hydrogen Sulphide. H. Trapp. (Zeitsch. anaZ. Chenz., 1912, 51, 475-180.)-Higher oxides are first reduced by passing sulphur dioxide through the solution. If insoluble sulphates separate at this stage, they are filtered off and examined separately. After boiling off excess of sulphur dioxide, hydrochloric acid is added, and any precipitate formed is filtered off and examined in the usual manner.To the solution, or filtrate from insoluble chlorides, nitric acid is added to peroxidise the iron, then ammonia until a precipitate begins to form or until the solution is no longer acid, and finally ammonium sulphide in excess. Any insoluble sulphides are filtered off, and the filtrate is acidified to throw down the sulphides of tin, antimony, and arsenic, if present.These metals, as well as the alkali metals, alkaline earth metals, and magnesium, which pass into the filtrate, are separated and identified in the usual manner. The ammonium sulphide precipitate, which may contain mercury, lead, bismuth, chromium, aluminium, zinc, iron, manganese, copper, cadmium, cobalt, and nickel is treated with nitric acid, and any undissolved mercuric sulphide is filtered off.Lead is precipitated as sulphate, and bismuth tested for by diluting a portion of the solution. If bismuth is present, it is next separated, after expelling the excess of acid in the solution. On addition of caustic soda and a little bromine and warming, all the remaining metals are precipitated as hydroxides except chromium, aluminium, and zinc, which pass into the filtrate as chromate, aluminate, and zincate, except when iron is also present, when chromium will be found in the precipitate.The filtrate is divided into three portions, in one of which aluminium is precipitated by ammonium chloride; in another, zinc is detected as sulphide, whilst the third is reduced with sulphur dioxide, and any chromium precipitated as hydroxide. The hydroxides of iron, manganese, copper, cadmium, cobalt, and nickel are digested with ammonium sulphide and washed.From the mixed sulphides iron and manganese are extracted by dilute hydrochloric acid and separated from each other378 ABSTRACTS OF CHEMICAL PAPERS by means of sodium acetate.The sulphides of copper, cadmium, cobalt, and nickel, are dissolved in hot concentrated sulphuric acid, and the solution is neutralised with ammonia. Copper and cadmium are precipitated by shaking with zinc dust, the solution of cobalt and nickel is filtered, and these metals precipitated as hydroxides by boiling with excess of caustic soda. The residue of zinc dust with any copper or cadmium is treated with hydrochloric acid, which dissolves the zinc and cadmium, and the latter may be separated from the zinc by boiling the filtrate from the undissolved copper with excess of caustic soda.An alternative method of analysis, also dispensing with the use of hydrogen sulphide, is described in the paper. G. C . J. Determination of Iodides by Direct Titration.J. W. Turrentine. ( J . Id. Eng. Chem., 1912, 4, 435-436.)-The method, an empirical one, is intended for the rapid estimation of small amounts of iodide in presence of much chloride, such as is required in a laboratory where large numbers of kelp samples have to be reported on. The solution (10 to 100 c.c.) containing the iodide to be estimated is transferred to a 250 C.C.separator, into which 15 C.C. of dilute (1 : 10) sulphuric .acid and 15 C.C. of carbon tetrachloride are also introduced. A solution of permanganate, containing about 1 grm. per litre and standardised in an exactly similar manner on known amounts of iodide, is next added from a burette with shaking after each addition. With the decrease in the concentration of iodide, the solubility of the iodine decreases until, as the end of the titration is approached, the solution appears colourless.The easiest end-point to work to, however, is the persistence for one minute of the pink tint due to excess of permanganate. From the reading, an empirically determined deduction of 0.2 C.C. is made, and the remainder is then the measure of the iodide present.In standardising the permanganate, measured volumes (10 to 100 c.c.) of an exactly 0-1 per cent. solution of potassium iodide are treated in the manner described. By taking varying volumes, not only is the iodine value of the perman- ganate determined, but also the empirical correction already referred to. A series of numbers is given showing that in tbe author's hands this correction is about 0.2 C.C.permanganate, and that with this correction the method enables the analyst to determine small quantities of potassium iodide with an error not exceeding 6 per cent. with as little as 10 mgrms. present, nor exceeding 3 per cent. with quantities of 20 to 100 mgrms. The application of the method may be extended by effecting the standardisation in presence of large quantities of any salt, in presence of which the analyst is called upon to determine traces of iodide; but where this other salt is sodium chloride, such procedure is unnecessary.The author frees his carbon tetrachloride from reducing substances by prolonged treatment with iodine, subse- quently removing the excem of iodine with thiosulphate and washing the carbon tetrachloride with water.G. C. J. Potassium Iodide and Mercurous Nitrate as Sensitive Reagents for Tungsten and Molybdenum. E. Kafka. (Zeitsch. anaZ. Chem., 1912, 51,482.)- To the neutral solution of tungstate or molybdate, 1 drop of a saturated solution of mercurous nitrate is added, and this is followed by 1 C.C. or more of concentratedINORGANIC ANALYSIS 379 hydrochloric acid and excess of potassium iodide.The mixture is shaken vigorously until the green mercurous iodide first formed redissolves. In presence of much tung- state or molybdate, the solution assumes a blue colour at once. With little tungstate or molybdate present, the colour develops more slowly. As little as 0.2 mgrm. of sodium tungstate gives a distinct reaction. To distinguish between tungsten and molybdenum, potassium thiocyanate is added to the blue solution, which will change to blood-red in presence of molybdenum.Solutions containing so little molybdenum as to develop no blue colour in the first reaction may give a distinct red with thiocyanate. The function of the mercurous nitrate in the reaction first described is to increase the reducing power of the hydrogen iodide by forming a stable complex with the liberated iodine.G. C. J. Separation of Nickel and Palladium by Means of Dimethylglyoxime. W. Wunder and V. Thuringer. (Ann. Chim. anak, 1912, 17, 201.)-The solution of the two metals is slightly acidified, preferably with hydrochloric acid, and treated with an excess of a, 1 per cent. solution of dimethylglyoxime in 2 per cent. hydro- chloric acid.After standing for thirty minutes on the hot-water bath the precipi- tated palladium is collected, washed with boiling water, ignited, and weighed in the metallic form. The filtrate is boiled and rendered slightly alkaline with ammonia, and the precipitated nickel dimethylglyoxime is collected in a Gooch crucible, washed with boiling water and then with 20 per cent.alcohol, and dried at 100' C. until constant in weight. The weight multiplied by the factor 0.2031 gives the amount of nickel. In solutions containing 0.025 grrn. of palladium and 0.0846 grm. of nickel, the amounts thus found in six estimations were 0.0248 to 0.0252, and 0-0840 to 0.0843 grm., respectively. C. A. M. Use of Oxygen under Pressure for Estimating Carbon in Ferro-Alloys.P. Mahler and E. Goutal. (Compt. rend., 1912,154, 1702-1705.)-The use of the calorimetric bomb in the estimation of carbon in steel (ANALYST, 1911, 36, 562) has been extended to the most refractory ferro-alloys. With these alloys, not only must one use litharge as a flux as in the case of very hard steels, but an auxiliary com- bustible is required. As auxiliary combustible the authors use iron of known carbon content.From 0.5 to 3 grms. of the alloy, according to its supposed carbon content, is taken for combustion, together with two or three times its weight of iron. With alloys very high in carbon, of which only 0-5 grm. can conveniently be taken, the proportion of iron must be increased, as there is some difficulty in effecting complete combustion of charges with a total weight of less than about 3 grms.Of litharge a weight equal to balf that of the combustible charge is taken. A second experiment is made under identical conditions, save for the omission of the ferro-alloy. This second experiment provides the correction for the carbon in the soft iron and for any constant errors of the method. The authors now employ caustic soda for absorbing the carbon dioxide, and estimate the amount of the latter by titration before and after combustion, using phenolphthalein as an indicator.The test numbers given in the paper show that, when the method does not give results in close agree- ment with those of the ordinary direct dry combustion method, it gives higher380 ABSTRACTS OF CHEMICAL PAPERS results. In these cases-high-grade ferro-chromes and ferro-silicons-the authors think their higher numbers must be preferred.The following numbers serve to illustrate the difference in results by the two methods. A 69 per cent. ferro-chrome showed 10.6 per cent. carbon by the bomb, and 9.7 per cent. by ordinary direct dry combustion. A 75 per cent. ferro-silicon showed 0.20 per cent. carbon by the bomb, and 0-11 per cent.by the ordinary method. Results by the two methods with ferro- vanadium and ferro-molybdenum agree very closely. G. C. J. Separation of the Rare Earths. C. James. (J. Amer. Chern. SOL, 1912, 34, 757-771.)-The paper states in a compendious form the best methods available for the separation of La, Ce, Pr, Nd, Sm, Eu, Gd, Tr, Dy, Ho, E, Tm, Yb, Lu, Ct, Yt, and Sc, in mixtures where all may occur.The methods are suited to large scale operations rather than to analytical practice, one method requiring a few thousand fractional crystallisations. But, though several of these elements can be determined with fair accuracy in minerals or mixtures of oxides in which they are the chief constituents, exact methods for the separation of others are not yet known, Where spectroscopic examination shows one or more of the rarer earths to be present in notable proportion, reference to this paper will show the analyst whether an approximate estimation of these elements is reasonably practical, and, if so, will indicate the necessary steps to be taken.G. C. J. Improvements in the Ludwig-Sipocz Method for the Estimation of Water in Silicates. M.Dittrich and W. Eitel. (Zeitsch. anorg. Chem., 1912, 75, 373-381.)-The method referred to in the title of the paper is that in which the powdered mineral is mixed with dry fusion mixture in a platinum boat, heated in a current of dry air in a combustion tube, and the water absorbed in appropriate drying tubes and weighed. The authors propose to replace fusion mixture by sodium car- bonate, chiefly because it is easily obtained anhydrous by three hours' heating below 300' C., and can be mixed with the powdered mineral without risk of the absorption of more than a few tenths of a mgrm.of moisture. They also agree with Hillebrand ( ' 6 Analysis of Silicate arid Carbonate Rocks," p. 87) that the higher melting-point of sodium carbonate makes its use preferable to that of a mixture of sodium and potassium carbonates.The other innovations of the authors relate to the apparatus employed. They use a quartz combustion tube 45 cm. long by 22 mm. diameter, and 0.5 mm. in the wall. The platin-iridium boat, which is 12 cm. long, is provided with a cover and enclosed in a cylinder of thin platin-iridium foil, just fitting the corn- bustion-tube, to protect the latter in case of frothing.The forward end of the combustion-tube is drawn out and connected by a ground joint to the first tared drying-tube. The other end of the combustion-tube is also ground to receive a quartz plug carrying a tube of small diameter, which is connected by rubber tubing to the apparatus for drying the current of air.Sulphuric acid is used for drying the air and for absorbing the moisture given up by the mineral. Heating is effected by a multiple Bunsen burner, supplemented as a rule by five to tea minutes heating with a multiple blowpipe, or an electric furnace may be used with advantage. In the latter case the temperature is raised to 850" to 900° C. in about twenty minutes,INORGANIC ANALYSIS 381 maintained at this point for fifteen minutes, and then raised to 1000" to 1050Ofor ten to fifteen minutes.One grm. of the substance with 6 grms. of sodium carbonate is a suitable charge, and the residue in the boat is immediately available for the determination of silica, alumina, etc. Duplicate determinations of moisture seldom differ by more than a few tenths of a, milligram.G. C. J. Volumetric Estimation of Sulphuric Acid, Nitric Acid, and Nitrous Acid, in Nitrating and Waste Acids. G. Finch. (Zeitsch. Schiess- a. Sprelzgstofwesen, 1912, 7, 113.)-A wad of cellulose fibre is placed in 50 C.C. of the diluted mixture of acids, excess of barium carbonate added, and stirring continued until the evolution of carbon dioxide nearly ceases, when the liquid is boiled for five minutes.The precipitate of barium carbonate and sulphate is well washed, the filtrate boiled for several minutes with a wad of cellulose and 50 C.C. of sodium carbonate, filtered, the precipitate washed until no reaction is obtained with phenolphthalein, and the excess of sodium carbonate in the filtrate titrated back with hydrochloric acid and methyl orange.The cellulose, prepared by steaming ash-free filter-paper cut into small pieces for two days, and kept for use in alcohol, ensures the precipitation of the barium sulphate in an easily filtered condition. The barium carbonate is prepared by precipitating barium chloride solution with sodium carbonate in the cold, and washing thoroughly by decantation. If & barium hydroxide solution is used instead for the neutralisation, the acids may be estimated simultaneously ; the total acidity is given by the amount of barium hydroxide used, and the nitric acid, present in the filtrate as barium nitrate, i s estimated as before.Nitrous acid, if present, is titrated with permanganate, and: deducted from the total acidity. The nitrometer may show a higher total nitrogen, than the volumetric method; this is attributed to the presence of lower nitric-acid esters of glycerol, not removed in the after-separation.The error is usually negligible. 0. E. M. Rapid Method of Purifying Sulphupic Acid. G. Bressanin. (Gum. Chim. Ital., 1912, 42, 456-458.)-The principle of the method of separating arsenic, etc. (ANALYST, 1912, 206), may be applied to the purification of sulphuric acid for toxicological work.The acid is first concentrated to sp. gr. 1.52, then cooled, and treated with 10 C.C. of a 30 per cent. solution of hydriodic acid. After standing for twelve hours it is filtered through glass-wool and purified asbestos, and the iodine eliminated from the filtrate by boiling. Acid containing as little as 0-0005 mgrm.of arsenic per C.C. gives a precipitate with the reagent after some time. The purific. ation must be carried out in vessels of Jena glass, since ordinary glass or porcelain may yield further traces of arsenic to the acid. Tin, copper, cadmium, lead, anti- mony, and selenium, are also precipitated-the last in elementary form ; whilst nitric and nitrous acids are reduced to nitrogen peroxide.Mercury and bismuth are not precipitated, and no precipitate is given by the members of the third and following groups of metals. C. A. M.382 ABSTRACTS OF CHEMICAL PAPERS New Reagent for Thorium. M. Koss. (Chem. Zeit., 1912, 36, 686.)-Tho solution to be tested is rendered strongly acid with hydrochloric acid and a few drops of a solution of sodium hydrogen hypophosphate (NaHPO,, 2H,O) added. With considerable quantities of thorium a white flocculent precipitate forms at once ; with small quantities heating or long standing is necessary. Less than 0.0001 grm. of thorium oxide in 1 C.C. of solution may thus be detected. Titanium and zirconium are simultaneously precipitated. Previous treatment with hydrogen peroxide converts the titanium into pertitanic acid, which is not precipitated by the reagent. To remove zirconium, the mixed precipitate, after washing, is oxidised with sulphuric and nitric acids, and the solution precipitated with oxalic acid ; zirconium remains in solution. 0. E. M. Quantitative Determination of Yttrium. C. F. Whitternore and C. James. (J. Amer. Chem. Soc., 1912, 34, 772-774.)-Precipitates of yttria are apt to be contaminated with salts of sodium, potassium, lithium, and magnesium, and with ferric oxide and alumina, if the corresponding elements are present in the solutions from which the yttria is precipitated. Thus yttrium may be overestimated by 5 per cent. if precipitated by caustic soda, ammonia, or oxalic acid, in presence of salts of sodium or potassium. The ammonium salts of several organic acids were tried as precipitant, with unsatisfactory results; but it is found that ammonium sebtt- cate precipitates yttria quantitatively and free from sodium even when large quan- tities of sodium are present. In presence of potassium, a, second precipitation as sebacate is necessary to obtain exact results. In presence of iron, aluminium, mag- nesium, or lithium, the whole of the yttria may be precipitated free from any trace of these elements by means of oxalic acid, provided the precipitation be made in the cold, and that excess of ammonium chloride is present. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9123700372

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年代:1912

数据来源: RSC

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382 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. Estimation of the Concentration of Colloidal Solutions with the New Interferometer for Liquids. R. Marc. (Chem. Zeit., 1912, 36, 537.)-The interferometer described by F. Lowe (Phys. Zeitsch., 1910, 11, 1047) was sensitive with true solutions to 0.003 per cent., with a 4-cm. cell; it is found to be nearly as sensitive with solutions of dextrin, albumin, and other colloids.The ageing of such solutions on standing was almost without effect on the concentration 8s determined by the instrument. For small ranges the concentration was found to be nearly enough proportional to the readings to render a calibration curve unnecessary. With colloidal solutions the difficulty of matching the right pairs of lines is increased, and methods for overcoming this are given.As an example of the application of the instrument to concentration determinations in colloidal. solutions, adsorption experi- ments (albumin and dextrin by barium carbonate) are described. The method may be extended to the examination of water : at the waterworks, by examining before and after filtering ; for potable waters, before and after shaking with a substance capable of adsorbing colloids, but not affecting substances in true solution.The method is not usually applicable to dyes. 0. E. M.APPARATUS, ETC. 383 New Apparatus for the Coking Test of Coal. R. Lessing. (J. Soc. Chem. Ind., 1912, 31, 465-467.)-This apparatus is devised to show, more markedly than the usual b 6 crucible method” can, the difference in the coke produced from various coals.The apparatus is also useful for quantitative determinations of the volatile matter, in which respect it gives, generally speaking, results similar to those obtained by the old method. 1. Factors tending to Increase the b b Volatile” Valu,e.-(a) Burning of coke in the more or less oxidising atmosphere ; ( b ) 6‘ spitting ” of coal-dust due to the explosive character of gasification of some coals, or rush of currents produced by the flame. 2.Factors tending to Decrease the ( 6 Kolatile” Value.-(a) Insufficient coking of the coal ; (b) secondary catalytic decomposition of volatile products on the walls of the crucible ; ( c ) decomposition of volatile products by radiation in the waste space of the crucible ; ( d ) deposition of carbon during coking by too rapid primary decomposition of volatile coal sub- stance.These factors are at work concurrently, and may compensate each other, but their presence explains the difliculty of obtaining agreement under slightly altered working conditions. In order to avoid the drawbacks due to the waste space above the coal, and to the excessive amount of heated surface in contact with the gas and vapours in the crucible test, the author uses a cylindrical vessel, as shown in the figure.B is the heating-tube of quartz glass, round which an electric resistance coil of platinum wire is wound. A number of quartz pin-points are fused on this tube to keep the turns of the coil apart. To concentrate the heat where required, the wire is first wound to a coil about 3 mm.in diameter, and this coil is then wound round the heating-tube. The re- acting vessel B is a flanged quartz tube about 10 mm. in internal diameter, fitting loosely into the heating-tube. (Platinum tubes may be used instead of quartz tubes.) One grm. of the powdered sample of coal is placed in this tube B, and a third quartz tube C, fitting closely into the reacting chamber B, is placed on top of the coal before the commencement of the test.The pressure on the coal may be altered if desired by filling the piston-tube C with varying quantities of quartz powder. The outer tube A is permanently fixed in an insulating material, such aB kieselguhr. Suitable resistance is provided according to the voltage of the supply current, end a rheostat is combined with the furnace itself, SO that the temperature can be controlled.When the current is turned on, the different stages of carbonisation can be observed as the temperature rises; moisture goes off quickly, as a rule, some of the occluded gases follow, and, shortly after this, tarry vapours are evolved, increasing in volume according to the coal used for the test, and, finally, the heavier tars and pitchy matter make their appearance, the latter condensing on the cool parts of tube C.The teat takes from five to seven minutes, and the tubes are then allowed to cool, when the tar a t the mouth of B may be burnt off without interfering with the coke. The apparatus brings out the peculiarities of cokes from coals, although in the The sources of error of the crucible test are stated to be-384 ABSTRACTS OF CHEMICAL PAPERS crucible test little or no difference is to be seen.The same kind of coal also gives the same characteristic coke. The paper is illustrated with photographs showing the appearance of the cokes produced by coals in this apparatus, together with their analytical figures. A. R. T. Modification of the Beckmann Apparatus.E. Knecht and J. P. Batey. (J. Chem. SOC., 1912, 103, 1189-1193.)-For the determination of the boiling-points of aqueous solutions of certain sparingly soluble dyestuffs, the ordinary types of Beckmann apparatus failed to give satisfactory results owing to superheating effects caused by cohesion of the liquid on the glass walls of the vessel. The authors were therefore led to devise a method of electrical heating by means of a platinum wire in direct contact with the solution.The apparatus (see figure) consists of a tube with a platinum heating coil inside, and somewhat thicker wires fused through the glass for making the connections. When in use the apparatus is supported in an outer cylindrical glass jacket placed in a wide-mouthed bottle, packed at the bottom and round the neck with cotton-wool.With this arrangement the boiling-point of the liquid was found to remain constant to 0-001" C. In employing this method precautions must be taken to avoid any appreciable electrolytic action. The elec- trolytic effect will depend on the drop in potential across the headng-coil, and when this is reduced below a certain point no electrolysis should take place.In the above apparatus the resistance of the heating-coil at 100" C. was 0.47 ohm; the current used was 6.5 ampitres, hence the drop in potential was only 3 volts. In another apparatus the coil had a resistance of only 0.32 ohm. With a current of 7.5 ampitres, the drop in potential was 2-2 volts. With a 10 per cent. solution of potassium chloride in this apparatus, no chlorate was formed after boiling for half an hour, and the electrolysis of potassium iodide was very small.Measurements of molecular elevations of boiling-point made in this apparatus were in satisfactory agreement with published results. The authors found the molecular weight of tannic acid in aqueous solution to be between 3000 and 4000.Results have also been obtained for various dyestuffs, including benzopurpurine and indigo white. With the electrical heating constant readings are readily obtained without special precautions. J. F. B.APPARATUS, ETC. 385 Drying Oven. J. H. Coste. (J. SOC. Chem. Ind., 1912, 31, 471.)-This oven can be maintained at a constant temperature, and throughout its area a stream of hot air, or other gasof the desired temperature circulates.As shown i n the figure, a horizontal cylindri- cal copper vessel, a, contains a F suitable quantity of a pure liquid, the boiling-point of which is near that of the temperature required. This vessel is heated by a series of gas-jets, and the vapour is con- densed at by and returned. The muffle-shaped drying-chamber, cc, is surrounded by the boiling liquid, or its vapour, with the exception of about one-thirtieth of its ex- ternal surface (the door).Air which bas passed through a flattened I l C C t d d hi tube, dd, lying under, but not in contact with, the drying-chamber, enters it at the bottom of the end in the vapour, and leaves through a slit, communicating with the chimney f, in the door which is fixed tightly against the end of the chamber by m a n s of steam rubber jointing and a screwed hinging bar against the end of the oven. The area of the drying chamber is small, relative to that of the total heated surface. If desired, the air may be dried before it enters the pre-heater at h, or other gases may be used. The drying-chamber will hold six watch-glasses or flat weighing- bottles placed on 8 copper tray, allowing several determinations of water to be simultaneously carried out, and the substances to be dried rapidly attain a tempera- fure within 1" of that of the vapour. A. R. T.

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DOI:10.1039/AN9123700382

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年代:1912

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APPARATUS, ETC. 385 REVIEWS. ALLEN’S COMMERCIAL ORGANIC ANALYSIS. Vol. V.: Tannins and the Analysis of Leather. By W. P. DREAPER. 1911. London : J. and A. Charchill. Price 21s. net. Remembering the painstaking work which distinguished the first edition of this well-known book, the perusal of the sections on Tannins and Leather Analysis has been one of disappointment to the writer. The author has failed to render himself familiar with much recent work, and as a compilation, the chapters must be pro- nounced uncritical and in places unreliable, and containing much obsolete and useless matter.In several cases work is incorrectly described, and in more than one is attributed to the wrong author. Such charges are not to be made lightly ; and, at the risk of being tedious, they386 REVIEWS must be supported by detailed instances.On the very first page the tannins as a class are characterised as ‘( notably soluble in ethyl acetate.” In fact, their solubility in this reagent is very varied, and in some cases almost nil, and this peculiarity has been used by Stiasny in the separation of different members of the group. Tannins are spoken of as 6‘ powerful reducing agents,” (‘ especially in alkaline solution,” while it is only under the last condition that they show any marked affinity for oxygen.On p. 7 gallotannic acid is mentioned as a glucoside, which is contrary to the modern view. Sumach-tannin is described as “possibly identical with gallotannic acid,” while Strauss and Schwendner have shown that this is not the case.Hemlock-tannin is stated to contain phloroglucol, which is incorrect. The tannin of horse-chestnut bark is spoken of as “chestnut tannin,” which is misleading, since the very important chestnut extract of commerce is made from the wood of the true Spanish chestnut, castanea vesca, which is not even mentioned in the table. The same remark is also to some extent true of ‘( ulmo-tannic acid,” since the LLulmo” bark of South America, which is now much used in tanning extract manufacture, is probably not a, true ulmus.On p. 8 the Stiasny formaldehyde test for catechol tannins is incorrectly given, and completely misunderstood. The Seyda test with gold chloride on the following page is merely the formation of colloidal gold, and the reaction is produced by any feeble reducing agent.On p. 14 the phloroglucol test with deal-shaving is stated in a note to be given also by catechol. Procter (“ Lab, Book,” p. 152) has shown that this is an error, though a blue violet is given by resorcinol, which is often present in commercial catechol ; and this correction is quoted by the author himself on p. 54 without remark ! Schiffs reputed syntheses of digallic acid, both with phosphorous oxychloride and with arsenic acid, are now generally discredited, as it has been found impossible to free the product from the reagents without reconverting it into gallic acid.Hunt’s attempted synthesis with monobromo-proto-catechuic acid and potassium gallate (which is mentioned on p. 17 without the name of its author) has never been success- fully repeated, though tried by Schiff, and is now assumed to have been an error.The formula for ellagic acid, which on pp. 19 and 23 is attributed to Nierenstein, was proposed long ago by Graebe, and proved by Kostanecky, Perkin, Herzig, and others. On pp. 29 and 30 all the information as to the chemistry of catechins is more or less obsolete ; the work of A“. G. Perkin is not quoted, and the constitution according to Kostanecky is not given, though this is one of the few formula in the chemistry of the tannins which deserves credit.On p. 31 chestnut wood extract is said to contain 14 to 20 per cent. of tannin, though 30 per cent. is nearer the modern standard, and this criticism applies to nearly all the tabular information given on the strength of tanning materials, the analyses quoted being mostly by obsolete methods giving far too low results.In fact, the information on tanning materials, occupying pp. 31 to 55, is very sketchy and incomplete; for instance, oak-wood extract, which is now one of the most important materials, is mentioned only in a table of 1883 attributed to Simand, which gives the total tannin as 14.47, and the part of this soluble in cold water ae 15-09 I On pp. 42 and 43 qualitative tables attributed to Procter are really due toREVIEWS 387 Andreasch, and no mention is made of the fact that they are only applicable to alcoholic solutions, though the original source is referred to on p.55 with apparently no idea that the tables are identical with those given. No mention is made of the frequent use of extract of mangrove bark as adulterant of quebracho, nor of methods for its detection.The modern quantitative methods are correctly given, mostly in the words of the official prescriptions of the I.A.L.T.C. and the A.L.C.A., but are not critically discussed; and a good deal of space is occupied by the description of antiquated processes, most of which are known to give incorrect or unreliable results.In the section on the analysis of leather the von Schroeder method of glucose estimation is very briefly described, but the necessary glucose table is omitted both there and in the section on glucose estimation in tanning materials, and in place of it a single factor is given. No mention is made of the ordinary volumetric method, which, if carried out with proper precautions, gives results of considerable accuracy, and is very useful as a rapid process of preliminary investigation, and will usually decide whether or not artificial loading has taken place.Sucrose is now sometimes used in place of glucose, and, of course, is not estimated by either process without previous inversion. No mention is made of Fahrion’s method of deter- mining a tannage value by boiling with water, and in the formula for calculating hide-substance from the Kjeldahl determination of nitrogen, + is written instead of x , Further remarks seem unnecessary.HENRY R. PROCTER. DYES AND COLOURING MATTERS, DYESTUFFS OF GROUPS 6 TO 12, COLOURINU MATTERS By J. T. A very valuable feature of this fourth edition of Allen’s well-known treatise is that the analytical examination of the various organic products under consideration is pre- ceded by thoroughly upto-date descriptions of the systematic chemistry of these materials, each section being dealt with by competent experts.In the chapter on dyes and colouring matters a brief r6sum6 is given of the modern development of artificial colouring matters and of the relations of dyes to the textile fibres.A con- sideration of the nitro-, nitroso-, and isonitroso-colouring matters is included in this section, which also deals very fully with the important azo-dyes. Very comprehensive tables are given, showing the mode of formation and the specificreactions of the azo- dyes. In some instances, however, the abbreviations employed have almost ceased to be intelligible.For example, Fast Acid Scarlet (4)SO,Na.CI,H,. N2(6). C,,H,.OH is said to be obtained from beta-acid, and Acid Ponceau from a and y naphthylamines (sic). There are also a few orthographical errors, such as ‘ I unsoluble,” phenatidine,” and ‘( dinitrosoresorcnol.” The remaining synthetic dyes are arranged in seven groups (groups 6 to 12 inclusive), a separate section being devoted to indigo.The prevailing views on the constitution of the di- and tri-phenylmethane colouring matters are critically examined and the properties of the principal commercial dyes of these series are arranged in tabular form. The azine, azonium, quinoline, and acridine dyes are similarly treated. OF NATURAL ORIUIN AND ANALYSIS OF COLOURINU MATERIALS.HEWITT.388 REVIEWS Indigo is classified under colouring matters of natural origin, and, possibly on this account, very little space is devoted to the important subject of synthetic indigo. The estimation of indigotin is, however, dealt with in greater detail, especially as regards the oxidation and reduction tests, reference being made to such modern developments as the production of indigotintetrasulphonic acid and the reduction of sulphonated indigotin with titanous chloride.A survey of such natural dyestuffs as logwood, fustic, turmeric, cochineal and the red woods is followed by a, chapter on the analysis of colouring materials, giving methods for the examination of commercial colouring matters and their detection of the dyed fibres.The detailed information contained in a very concise form in this section of the treatise should prove of the greatest service to analysts called upon to examine fabrics dyed with the colouring matters employed in modern practice. G. T. MORGAN. FOODS : THEIR ORIGIN, COMPOSITION, AND MANUFACTURE. By WILLIAM TIBBLES, M.D., LL.D., etc. London : Baillidre, Tindall and Cox.1912, Price 18s. net. This work is a veritable encylopzedia of foods, and of substances used in the preparation of food. I t would, indeed, be difficult to mention any food material, from the most important and necessary to the most trivial condiment or colouring matter, which does not here find a place and adequate description. The hard-worked scientific man must always feel a sense of gratitude towards his more leisured confrere, when that leisure is employed in the collection and compila- tion of the widespread information which to-day forms so important an adjunct to the analytical armoury.I n order that such a work should fulfil a really helpful and useful purpose, it is necessary that the author should possess sufficient scientific insight to enable him to judge of the value of the different sources of information at his disposal and sufficient diserimination to sift them adequately.When these dicta are applied to the work under review, one is compelled to admit that they are fulfilled. The selection of authorities is excellent, and the “drawing from opposing authorities the pith of their knowledge,” described in the preface by the author as It is almost unnecessary to say that no man can be an authority on all branches of the widely diverse subjects here presented, nor does it seem that the author makes any special claim to have any special knowledge of any one of them. It is, therefore, inevitable that the expert in any of these subjects may have cause to find fault with Borne of the statements, etc., made, particularly if his pet theories happen to be omitted, or inadequately mentioned.I n actual fact there are numerous errors, but these do not militate against the intrinsic value of the work. The author is happiest in those sections which deal with processes which are not closely interwoven with trade secrets and methods, for which one wili look in vain in this, as in any other book ; but in the general composition of the final products, and in trade descriptions of these products, there is much sure ground.One notes with pleasure the great use which has been made of the invaluable bulletins of the U.S. Department of Agriculture, and the large collection of these will be useful to many. I t would be quite impossible to deal with the various chapters source of delight,” has, in nearly all cases, been happily carried out.REVIEWS 389 one by one, as the before-mentioned diversity of subject-matter precludes personal criticism as much as it precludes comprehensive expert treatment in its composition.Part I. deals with the (6 chemical constitution of foods and the classification and character of their proximate principles.” The matter dealing with this intricate subject is well put together, and displays knowledge of the latest work, though some references to the conclusions of older investigators might well have been omitted in view of more reeent findings.The chemical presentation is somewhat crude in expression in many cases and this is true of the work as a whole, though there is never any real doubt as to the meaning intended.There are some curious and oft repeated errors which are difficult to understand, such as the description of ‘‘ cholesterin ” as a nitrogenous fat, though in its proper place it is correctly described. “Protagon ” is also spoken of as a separate entity, The carbohydrates are fully dealt with, and the section has been compiled from reliable sources.In the chapters on the Mammalia, Pisces, and Aves, the author is probably at his best, as the scientific descriptions and classification are from excellent authorities, and are presented in a concise and thorough manner, with full details as to distribu- tion on the earth’s surface, and to the use made of them as food. There is also EL useful chapter on meat inspection and regulations, and on the composition of meat as eaten and its digestibility. The properties of meat extracts, soups, etc., are given, and from the remarks appended there is evidently considerable personal knowledge of these aliments.The care which the author has expended in the sifting of available data is nowhere better seen than in the sections dealing with such debatable matters as milk and milk products.In addition to the general consideration of the subject, he has succeeded in disentangling from the masses of conflicting evidence which have gathered round such points as the influences which affect the composition of milk, the effect of feeding, period of lactation, etc., the more vital and probably correct, conclusions. One notices, however, with a slight feeling of amusement, the list of constituents of milk which is given, and which, if all had to be determined, would render the analysis a rather titanic task, very different from the usual (( total solids and fat ” beyond which few analysts appear to venture.The bacteriology of milk-souring is, on the other hand, very inadequately de- scribed, and the latest work is not mentioned. Under milk preparations, cheese, both in its aspects of manufacture and subse- quent ripening, is adequately dealt with, and nearly every milk preparation known finds notice, and, in general, correctly, except in the case of condensed milk, for which only one or two quite out-of-date methods are referred to. The chapters on Cereals, Vegetables, and Fruits are excellent and most complete, the botanical descriptions being quite reliable.Full details are given of the preser- vation of fruit, and it is to be wished that the description of ‘(jam ” manufacture was applicable to more of our jams than it can possibly be. The Public Analyst will be fully in accord with the author in his remarks under ((What is jam?” A compre- hensive list of colouring matters is appended, and it is noticeable that some common errors in regard to these are avoided.Even in such a difficult subject as that of oils, the information is reliable and390 REVIEWS trustworthy, though some of the processes stated to be used are somewhat obsolete. A few of the trade descriptions in this section are not quite correct, such as the information that ‘( nucoline ” is palm-kernel oil. The other chapters which deal with tea, coffee, chocolate, spices, condiments, sugar, honey, confectionery, wines, spirits, and malt liquors may be passed over without comment.The only serious mistake that the author has made is the inclusion of analytical methods, as in nearly all cases these are hopelessly impossible or badly described. As they are quite out of place, it would have been much better if they had been omitted.In spite of the condensed nature of the book, the matter is always in most readable form, and the proof-reading, with a few exceptions, carefully done. There is not the least doubt that this work would be of much assistance to the general analyst as a concise book of reference. C. REVIS. VOLUMETRIC ANALYSIS FOR STUDENTS OF PHARMACEUTICAL AND GENERAL CHEMISTRY.By C. H. HAMPSHIRE, B.Sc., A.I.C. Pp. vi + 104. London : J. and A, Churchill. 1912. Price 3s. 6d. net. As its title indicates, this book is not intended for the use of analysts, but for the instruction of students, particularly pharmaceutical students, and it must be judged accordingly. For example, anyone who attempted to use this book as a book of reference, and followed the directions given on p.98 for the analysis of a mixture of boric acid and borax, would soon find himself in difficulties, unless he already knew all that this book has to teach. But the student who has steadily worked through the book up to this point would be in no difficulty, for in earlier pages the principles underlying mixed titration are clearly explained; The whole book is a model of lucidity, and one can only regret that the author did not suppress some redundant paragraphs, such as the titration of sodium bicarbonate after that of potassium carbonate had been described, and so have found room for a short description of methods of standardising apparatus. Criticism on many points which a t first sight seem to invite criticism, is silenced by the reflection that the author’s students are mainly concerned to determine whether certain drugs comply with the requirements of a Pharmacopoeia which, in addition to other demerits, is fourteen years old. There are very few misprints, but presumably the direction on p. 23 to determine the strength of limewater by titrating 25 C.C. with I ( normal ” acid must be reckoned as one, and one would like to believe that the word 6‘ better ” on p. 6, line 4, was a misprint for ‘‘ necessary.” The former is scarcely a strong enough word with which to back a recommendation to make use of a desiccator for cooling ignited sodium carbonate, which is to be the ultimate standard in all the acidimetric and alkalimetric work which is to follow. G. CECIL JONES.

ISSN:0003-2654    

DOI:10.1039/AN9123700385

出版商:RSC    

年代:1912

数据来源: RSC