摘要:

THE ANALYST. JANUARY 1903. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. THE monthly meeting of the Society was held on Wednesday evening December 3, in the Chemical Society’s Rooms Burliagton House. The President Dr. J. Augustus Voelcker M.A. B.Sc. occupied the chair. The minutes of the previous meeting were read and confirmed. Certificates of proposal for ,election to membership in favour of Messrs. A. H. Bennett J. C. McWalter and W. Partridge were read for the second time; and certificates in favour of Messrs. Albert Edward Bell F.I.C. 59 Trinity Square, Southwark S.E. District Agricultural Analyst for the County of Dorset ; Basil Radcliffe Coysh A.I.C. 23 Woodville Gardens Ealing assistant to Mr. William Chattaway F.I.C. ; Ernest Mostyn Hawkins Watling Chambers Canterbury, assistant to Mr.Sidney Harvey F.I.C.; and Francis W. F. Arnaud A.I.C. 136, Shaftesbury Avenue W.C. assistant to Mr. Cecil H. Cribb B.Sc. F.I.C. were read for the first time. Mr. P. Macdonald was elected a member of the Society. Dr. Lewkowitsch and Rlr. John Hughes were appointed auditors of the Society’s The President announced the nominations of Officers and Council for 1903, President. -Thomas Fairley. Past-Pmside?tts (limited by the Society’s Constitution to ten in number).-M. A. Adams F.R.C.S. Alfred H. Allen A. Duprit Ph.D. F.R.S. Bernard Dyer D.Sc., W. W. Fisher M.A. Otto Hehner Alfred Hill M.D. J. Muter Ph.D. Thomas Stevenson M.D. F.R.C.P. J. Bugustus Voelcker M.A. B.Sc. ~ice-Presidents.-Bertram Blount Sidney Harvey F. Wallis Stoddart. Hon. Treasurer.-E. W. Voelcker A.R.S.M. Hon. Secretaries.-Edward J. Bevan Alfred C. Chapman. Other Members of CozmciI.-L. Archbutt Horatio Ballantyne Lawrence Briant, W. T. Burgess James Hendrick B.Sc. J. Lewkowitsch Ph.D. Frederick J. Lloyd, W. F. Lowe A.R.S.M. Raymond Ross Philip Schidrowitz Ph.D. D. A. Sutherland, W. Collingwood Williams E.Sc. The following papers were read ‘‘ The Estimation of Available Phosphoric Acid in Manures,” by W. F. Sutherst Ph.D. ; “The Estimation of Sulphur in Pig-accounts for 1902. which had been made by the existing Council. The list is as follows 2 THE ANALYST. iron,” by Clarence A. Seyler B.Sc. ; ‘‘ An Improvement in the Method of Separating Zinc from Nickel by means of Hydrogen Sulphide,” by Ernest A. Lewis; and a, (‘ Note on Pure and Commercial Civet,” by Herbert E. Burgess

ISSN:0003-2654    

DOI:10.1039/AN9032800001

出版商:RSC    

年代:1903

数据来源: RSC

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2 THE ANALYST. NOTES ON THE ESTIMATION O F SALICYLIC ACID. BY SIDNEY HARVEY, F.I.C. (Read at the Meeting, Novembw 5 , 1902.) THE following notes are a record of some years’ laboratory experience, no claim being made for any original matter. The accurate estimation of salicylic acid in wines and other organic fluids and articles of food is attended with such difficulty and uncertainty that, after testing every published process, I have felt compelled to fall back upon the well-known colorimetric process based upon the characteristic tint struck by persalts of iron in solutions of the acid. This reaction is so delicate that, quoting Allen’s ‘‘ Commercial Organic Analysis,” I part in 100,000 of water is easily detected by the tint imparted by a trace of ferric chloride. I find, however, that in actual practice the use of this iron salt is attended with some difficulties, due probably to ferric chloride in weak solution having a tendency to dissociate, and in so doing affecting the purity of the characteristic violet tint sought, and I have for some time been in the habit of adopting a 1 per cent.solution of iron alum as an improvement. I n my hands I have found the following advantages from an iron-alum solution : The colour struck is purer and deeper. It is much more stable, often retaining its depth of tint for twenty-four hours. I t is much more delicate-solut’ions of salicylic acid in pure water, 1 per 1,000,000, in the ordinary Nessler glasses treated by the iron-alum test giving a very distinct colour which can be imitated, while 1 part in 3,000,000 gives a distinctly visible coloration.Several precautions are, however, necessary. The salicylic acid must be isolated as perfectly as possible, no great amount of saline matter must be present, and the slightest inclination to alkalinity is fatal to success; on the other hand, the slight acidity communicated by the iron- alum solution is an advantage. Test experiments conducted in pure solutions of salicylic acid have yielded very encouraging results, using ordinary Nessler tubes. The iron-alum solution is preferably 1 per cent. in strength, and with a drop or two of dilute sulphuric acid per 100 C.C. will keep very well. The salicylic acid solutions should be two in number, one to contain 1 milli- gramme of acid per c.c., and this solution may be diluted to one-tenth for the purpose of making comparative estimations by “ Nesslerizing. ” These solutions are not permanent, and should therefore be freshly made when wanted.Bearing in mind the fact that the above-named solutions of salicylic acid will not keep well, it will probably be admitted that the amount of ‘‘ preservative ” found in organic liquids does not correctly represent that origizally introduced, and this I One or two C.C. should be used for each test.THE ANALYST. 3 have proved to my own satisfaction. IhIoreover, the heating of solutions of the acid (whether acid or alkaline) tends to loss, and I have therefore arrived at the conclusion that the simpler the process of isolation adopted and the less ‘( cooking ” practised the better for success, and two methods suggest themselves, viz., distillation from an acid aqueous solution and extraction by ether.With regard to the distillation method, after very numerous experiments and much work of apparent promise, I have been compelled to abandon it, the behaviour of salicylic acid mixed with organic liquids being most erratic; the frothing and intumescence is quite unmanageable at times, and even when the device of blowing steam through a hot solution is adopted the amount of steam required is very large, the consequence being that the bulk of this distillate is unwieldy, in addition to which certain volatile matters pass over and interfere. I have never succeeded in exhausting a solution by this means, and the only use I can see in the process is as a means of qualitatively testing, for which when adopting the iron-alum reaction it is valuable. I find two successive shakings out quite sufficient, and‘ the ether has but little colour imparted in the process.The ether in its turn is shaken out with two successive volumes of water containing a known amount of deci- or semi-normal alkali, the mixture obtained is carefully neutralized, and is made up to 250 c.c., or 500 C.C. with water. The liquid is very slightly coloured, if at all. As salicylic acid in a pure state can be successfully titrated with caustic alkali, I at first hoped that this process could be adopted with the alkaline extract, but the results were wildly wide of the mark, as other volatile and organic acids were found to be present, having been absorbed by the ether, and success was hopeless.The colour process had therefore to be adopted-a measured portion withdrawn, diluted to 100 C.C. if necessary, 1 or 2 C.C. of iron-alurn solution added, and the colour matched in the same way, using the weaker solution of salicylic acid mentioned above for the purpose. The maximum amount of salicylic acid capable of being judged by the iron-alum test is a solution of the strength of 1 milligramme per 100 c.c., less than this being preferable; and as regards the addition of the iron-alum solution, while 1 C.C. may occasionally be sufficient to strike a full tint, 2 C.C. is never too much. Of course, the same procedure must be adopted both in the trial and comparison liquids. In comparing the tints I have hitherto had no difficulty whatever, but Allen’s advice ( ( to add a definite amount; of salicylic acid to a liquid of the Same kind as that in which the acid is to be determined” should be kept in view.However, the very rich tint struck by iron-alum solution appears to supersede any such precaution. For acidulating the solution previous to extraction with ether I use dilute sulphuric acid. Hydrochloric acid seems to interfere with the colour struck. Concentration is not to be recommended, and in the case of syrupy and highly alcoholic liquids dilution may be permitted, so delicate is the colour-test described above. In conclusion, while small amounts of neutral alkaline salts do not appreciably I n all cases the rate of distillation is apparently very irregular.The ether method in my hands works well in an acid solution.4 THE ANALYST. affect the violet tint, the salts of the alkaline earths are very prejudicial, and hence the use of distilled water in all the dilutions is most imperative. I have pleasure in acknowledging the help rendered in the above work by my assistant, Mr. Ernest M. Hawkins, F.I.C. DISCUSSIOK. Mr. ALLEN said that it had been found by Continental chemists that in the examination of wine for salicylic acid, ethylic ether was apt to extract some other body which more or less simulated salicylic acid in its reaction with ferric chloride ; and it had been recommended that petroleum ether, or a mixture of that solvent with ordinary ether, should be substituted for ethylic ether alone, and that not inore than 50 C.C.of the wine should be employed for the test. Mr. CHAPMAN said that in the application of ferric chloride to the colorimetric estimation of very small quantities of salicylic acid he had always found considerable difficulty to be caused by the extraction of traces of tannins, which seriously interfered with the colour produced with ferric chloride. Some years ago he had made a number of experiments to ascertain whether it was possible to determine accurately small quantities of salicylic acid in beer, and the main difficulty had been to obtain colours that were comparable. Of course, in the case of pure solutions the matter was quite simple, but when sinall quantities of tannin and similar substances were present he, personally, had found it very difficult indeed to get a satisfactory result with any degree of certainty.For large quantities there was probably no better method than the ordinary bromine precipitation process, but that was hardly applicable to the estimation of small quantities in foods or beverages. To a question put by Mr. Allen, Xfr. CHAPxAN replied that in applying the bromine precipitation process it was his custom not to weigh the bromine compound, but to estimate it volumetrically. Mr. ALLEN said that his reason for asking was that there was some disagreement among investigators as to whether the compound in question was dibromo-salicylic acid or tribromo-phenol. Mr. HEHNER said that if any large quantity of wine which had not been salicylated were extracted with ether a reaction would be obtained which was identical with that of salicylic acid. I t was, indeed, a debateable question whether or not it was actually salicylic acid that was extracted. The German Government had accordingly laid down that a certain bulk-namely, 50 c.c.-and no more should be worked upon in testing wine for salicylic acid. Mr. HARVEY, in reply, said that the process he had described adapted itself conveniently to very small quantities, so that, even in the case of beer, any error due to the presence of tannin would be reduced almost to nothing. The latter, however, if in quantity, could be eliminated previously. Mr. CHAPMAN inquired whether the use of iron alum made any difference. Mr. HARVEY said that the colour was so characteristic that he did not think it would be interfered with even by tannin-at any rate, with the quantities upon which he worked.

ISSN:0003-2654    

DOI:10.1039/AN9032800002

出版商:RSC    

年代:1903

数据来源: RSC

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THE ANALYST 5 APPARATUS FOR MAKING ANAEROBIC CULTIVATIONS I N FLUID MEDIA. BY WALTER H. JOLLYMAN, A.I.C. THIS is a modification of the apparatus described by Pakes and Jollyman in connec- tion with some experiments on the gas production of bacteria (Journal Chemical Society, vol. lxxix., p. 33). The apparatus consists of a round-bottomed flask or stout bottle (A) fitted with a single-bored::: stopper, through which passes a right-angled bend of manometer tube (B). This is-connected by means of a piece of thick-walled rubber tubing with another bend of glass tube (C), which passes through a cotton-wool plug into a test-tube or small flask (D) ; the rubber con- nection carries a screw or spring clip. The apparatus having been steri- lized by moist heat, the bottle is nearly filled with the medium, about 15 C.C.of which are placed in the ,cur I I tube D ; the whole is then sterilized for half an hour on two successive days in the steamer, the clip being left open, and the tube C being drawn up above the fluid in D. On the third day the bottle is placed in a calcium chloride bath (immersed up to its neck), which is maintained at a temperature of about 120" C., until all the air is driven out (five minutes will suffice to displace 50 C.C. of air); the tube C is then lowered into the medium, and the clip fastened. To inoculate the medium in the bottle a fluid culture or broth emulsion must be used ; the tube C is removed from the test-tube and dipped into the culture; on opening the clip the infected fluid in the tube will be sucked into the bottle, and when a sufficient amount has been transferred the clip is again shut. The condition in the bottle is one of complete anaerobiosis, and the partial vacuum does not exercise any ill-effect upon the growth of the bacteria. Considerable quantities of fluid cultivations of obligatory anaerobes may easily be obtained by this method, and the apparatus is specially suited to the examination of water for the B. coli, B. enteritidis sporogeizes of Klein (using milk as the medium), streptococci, etc. For the examination of water it is convenient to have the bottle graduated, so that a measured quantity of the water can be introduced. * It may a t times be advantageous to replace the single-bored stopper by one carrying two tubes, so that steam may be blown through the bottle to expel the air.

ISSN:0003-2654    

DOI:10.1039/AN9032800005

出版商:RSC    

年代:1903

数据来源: RSC

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6 THE ANALYST, ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. (Chem. Zeit., xxvi., 944.)- The author has found that the albuminoid bodies left in normal milk after the removal of the casein yield a fairly constant amount of nitrogen-namely, 3.22 to 3-85 milligrammes, or 2.6 to 3.1 C.C. per 5 C.C. milk-when treated by his method of estimating albumin (see abstract, p. 13), and believes that this fact may aid in forming an opinion whether a given sample of milk is adulterated or not. For the determina- tion, 25 C.C. of the milk are diluted to 75 C.C. with water, and casein precipitated with 8 C.C. alum solution at 40’ C. After diluting the whole to 100 c.c., 20 C.C. are filtered off and used for the estimation of the albumin in solution. A Contribution to Milk Analysis.Adolf Jolles. A. G. L. Examination of Honey. J. Langer. (Zeits. f. aizgew. Chem., 1902, xv., 1041. j -Natural honey may be distinguished from artificial by means of the inverting ferment originating in the salivary glands of the bees. This substance can be precipitated with alcohol, and its effect on cane-sugar observed by means of the polariscope. Afher being boiled, honey no longer contains this active ferment. A. M. On a Simple Method of determining Starch in Yeast. Neumann-Wender. (Chem. Zed., xxvi., 944.)-To effect this determination, the author has devised a simple apparatus, a so-called amylometer,” consisting of a small hand centrifugal machine capable of carrying two small tubes, calibrated in such SL way that the amount of starch (potato starch containing 20 per cent.moisture) can be directly read off. For the determination, 1 or 2 grainmes of yeast are weighed out into a tube provided with the apparatus, graduated at 10 and 11 c.c., 10 C.C. of water and 1 C.C. iodine solution are added, the whole mixed, and rinsed with the aid of 5 C.C. water into the amylometer-tube, which is then whirled in the centrifugal machine for three minutes, after which the height of the dark starch iodide solution is read off. The determination is stated to be exact to about 1 per cent. Lenoir and Forster, Vienna, supply the apparatus. A. G. L. The Valuation of Pepsins, P. Macquaire. (Jozwn. Pharm. ChZirn., 1902, xvi., 289-292.)-The author’s method consists of digesting 2.5 grammes of pork blood-fibrin (dried at 40° C.) with 60 grammes of a 1 per cent.hydrochloric acid and a definite quantity of the pepsin for six hours at 50’ C., filtering the liquid, and testing the filtrate with nitric acid of specific gravity 1.39. By making a series of tests in an analogous manner to the estimation of diastatic activity it is possible to find the exact strength of he pepsin. Thus, assuming a given pepsin to have the enzymic value 50, as given in the table below, five tests are made, covering theTHE ANALYST. 7 1 2 3 5 8 values 30 to 70. I n each case 10 grammes of fresh fibrin, or 2.5 grammes of dried fibrin, are niixed with the acid as described above, and the quantities of pepsin corre- sponding with the values 30, 40, 50, 60, and 70 added to the respective tubes. After six hours at 50" C., with frequent agitation, the liquids are filtered, and the nitric acid added drop by drop, up to 20 drops, to each filtrate.If 20 drops do not produce a precipitate in any of the liquids, the pepsin has a value higher than 70; whilst if there is a persistent precipitate in each tube its value is lower than 30. Similarly, if there is no precipitate in tubes 1 and 2, but a pronounced one in tubes 3, 4,. and 5, the value of the pepsin is higher than 40, but lower than 50, and by making ten new tests the exact value between 40 and 50 can be obtained. The following table gives in an abridged form the enzymic values of pepsin, corresponding with the definite quantities required to digest the fibrin under the con- ditions given above : Grammes 10 5 3.3 2 1.25 Value.j Pepsin. Value 40 45 50 55 60 65 70 75 80 85 90 95 - _- - Pepsin. Grammes. 0.25 0.22 0.20 0.182 0.166 0-153 0.142 0.133 0.125 0.1175 0.111 0.105 ___- Value. 100 120 140 160 180 200 250 300 350 400 450 ______ _. Pepsin. Grammes. 0.100 0.083 0.071 0.062 0.055 0.050 0.040 0.033 0.028 0-025 0.0222 -- Value. 500 550 600 650 700 750 800 850 900 1,000 Pepsin. Gramm es. -- 0*0200 0.0182 0.0166 0.0153 0.0142 0.0133 0.0125 0*011'75 0.0111 0.010 C. A. M. The Determination of Caffeine in Tea. Andre. (BUZZ. de Pharm. de Lyon, June, 1902; Ann. de Chim. anal., 1902, vii. 427.)-Ten grammes of the finely powdered tea are triturated in a mortar with a milk of 10 grammes of magnesia and 10 C.C. of water, and the mass treated with I00 C.C. of 85 per cent. alcohol, and transferred to a flask, which is heated on the water-bath.After some minutes' boiling the liquid is decanted, and the extraction thrice repeaked with 50 C.C. of boiling 85 per cent. alcohol. The united extracts are concentrated to 60 C.C. and filtered, and the filtrate evaporated to a syrup and treated with dilute hydrobromic acid (1 in l), and again filtered. The new filtrate is treated with 50 C.C. of a solution containing bromine, 50 grammes ; potassium bromide, 100 grammes ; and water, 850 C.C. The orange-yellow precipitate of tribrom-caffeine hydrobroniide (C8HloBr3N40yHBr) is redissolved in water, and the solution diluted to 500 C.C. The amount of free bromine is determined in 50 C.C. of this solution, and is repre- sented by u. The amount of free bromine in 50 C.C.of the reagent, diluted with 50 C.C. of water, is also determined and represented by V. Then 1OV - 1Ov gives the8 THE ANALYST. amount of bromine combined with the caffeine, and the result, multiplied by the factor 0.8083, gives the proportion of caffeine. This method is stated to give results slightly higher than those yielded by Keller’s gravimetric method. C. A. M. TOXl CO LOG I CAL AN A LY S IS. The Hydrogen Peroxide Test for Blood. J. Ville and J. Moitassier. (BUZZ. SOC. Chim., 1902, xxvii., 1003-1008.)-The authors confirm the statement of Cotton (ANALYST, xxvi., 162) that the energy with which blood decomposes hydrogen peroxide varies with the different species of animals. He shows, however, that the acidity of the reagent must also be taken into account, and recommends the use of a solution containing 11 parts by volume of hydrogen peroxide and 0.35 gramme of sulphuric acid per litre.Thus’ox blood, which liberated 1,085 C.C. of oxygen from a neutral solution of hydrogen peroxide, only liberated 905 C.C. from a solution con- taining 0-25 gramme of sulphuric acid per litre, and 150 C.C. from a solution containing 1 gramme of acid per litre. The proportion of hydrogen peroxide has also an influence upon the results. Thus when 1 C.C. of the blood of a given species of animal is allowed to act upon gradually increasing quantities of hydrogen peroxide, the amount of oxygen liberated at first increases and then diminishes, The pro- portion of hydrogen peroxide giving the rnaximum amount of oxygen varies with the different kinds of animals.For example, the maximum yields of oxygen from 1 C.C. of the blood were as follows: Human blood, 960 C.C. of oxygen with 100 C.C. of hydrogen peroxide (11 per cent. by volume, 0.35 gramme H.,SO, per litre) ; horse’s blood, 830 C.C. with 100 C.C. ; ox blood, 450 C.C. with 50 C.C. ; and sheep’s blood, 240 C.C. with 25 C.C. The blood of the dog and the goat gave results approaching those given by sheep’s blood. As regards the influence of the dilution of the blood, it was found that the addition of 2 to 10 parts of water to 1 C.C. of blood considerably diminishes the amount of oxygen liberated, but that on still further diluting the blood the quantity of oxygen increases, and may eventually exceed that given by the pure blood. I n like manner dilution of the hydrogen peroxide solution has a pronounced inflxence, the amount of oxygen liberated increasing with the dilution. The authors assert that, in addition to haemoglobin and fibrinogen, blood contains other substances having an action upori hydrogen peroxide, and that they have succeeded in isolating these substances. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9032800006

出版商:RSC    

年代:1903

数据来源: RSC

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8 THE ANALYST. 0 RGAN IC AN A LY S I S. A New Test for Formaldehyde. Manget and Marion. (Ann. de Chim. anaZ., 1902, vii., 407, 408.)-In the case of milk the surface of the liquid is lightly powdered with amidol or diamido-phenol. After a few seconds normal milk, or that containing carbonates or borates, assumes a salmon colour, whilst, when formaldehyde is present, a characteristic canary-yellow colour is developed. For the detection of formaldehyde in the jelly of preserved meats a few crystals of amidol are added toTHE ANALYST, 9 the melted substances. When the preservative is present, a yellow colour, changing to dirty yellow on the addition of a drop of ammonium hydroxide, is developed, Jelly free from formalin gives a rose-brown colour, changing to blue when treated in the same way.C. A. RE. The Determination of Traces of Alcohol. G. Argenson. (BUZZ. Xoc. Chim., 1902, xxvii., 1000-1003.)-A standard solution of alcohol, containing, say, 1 part in 500,000, is distilled with 5 C.C. of a saturated solution of potassium bichromate and 1 C.C. of concentrated sulphuric acid with precautions to prevent spurting. The first 5 C.C. passing over are mixed with 0-5 C.C. of decolorized fuchsin solution and left for an hour, and the colour is then matched by adding freshly-prepared & N. potassium permanganate solution drop by drop from a burette to 5 C.C. of water. The process is then repeated with the liquid under examination, which must not contain more than 1 part of alcohol in 200,000, and the coloration obtained is practically pro- portionate to the amount of permanganate required.As a rule, the proportion of aldehyde in the dilute solutions of alcohol is small enough to be neglected. But when more aldehyde is present 20 C.C. of the liquid should be subjected to a preliminary distillation without the chromic mixture, and a, deduction made for the results thus obtained. The fuchsin reagent is prepared by dissolving 0.25 gramme of fuchsin in 500 C.C. of previously boiled water, and passing a slow current of sulphur dioxide into the cold solution. Before decolorization is complete the liquid is set aside for several hours, after which, if it is still coloured, a few bubbles of gas 'are introduced so as to leave it nearly, but not quite, colourless. C. ,4. M. On the Quantitative Sepa,rntion of Maltose and Lactose.Charles I. Boyden. (Jowwz. Anzer. Clzem. Soc., xxiv., 993.)-The following method of separating lactose from maltose is based on the fact that Saccharomyces nnomohs (Hansen) hydrolyses maltose with formation of glucose, which is then readily fermented, whilst lactose is unaffected : 50 C.C. of the solution, containing about 0.5 per cent, of maltose and lactose and 1 per cent. of Pasteur's mixture, are sterilized at 100" C. on three successive days for thirty minutes. The liquid is then inoculated with a pure culture of X. ct~zonzoZzcs, and incubated at about 30" C. for two or three weeks, the culture having been grown in agar and transferred to Pasteur's fluid before use. After the incubation, the liquid is filtered through a bacterial filter and sugar (lactose) determined by Allihn's method.The difference between the sugar found before and after inoculation represents the maltose. From results given by the author, it appears that after the above treatment 0 to 5 per cent, of the maltose remains in the solution, whilst the lactose is entirely unaffected, A. G. L. The Detection of Rosin Oil in Mineral Oils. G. Halphen. (Joz~m. Pharm. Chiin., 1902, xvi., 478-483,)-4 drop of the oil is mixed with 2 C.C. of a solution of crystallized phenol in carbon tetrachloride (1 in 2), in a large porcelain crucible, and10 THE ANALYST. the mixture then treated with bromine vapour, which is introduced by placing the mouth of a flask containing a solution of bromine (1 in 4) in carbon tetrachloride within the crucible.Rosin oil gives a pronounced violet colour in five to ten seconds, whilst mineral oils give only brown colorations, with a slight violet fluorescence. By inaking comparative tests with oils of known purity, less than 10 per cent. of rosin oil may thus be detected. The substances giving the coloration are apparently the same as those giving the Liebermann reaction. They can be extracted with strong alcohol, and the residue from the alcoholic extract gives the reaction with still greater intensity. The author classifies oils in general into four groups with reference to their behaviour in this test. 1. Oils giving intense coloration : Violet-Rosin oil. Carmine, with bllzle or deep violet shade-Rosin oil, Chinese wood oil (which also gives emerald green tints).Carmine, with little or no violet tint-Marine animal oils. 2. Oils giving fainter reactions : Carmine-Animal oils, eart hnut oil (irregular), suint, cow's butter. 3. Oils forming two zones, the upper violet and the lower bright, though fainter, blue : Linseed and hempseed oils. 4. Oils giving feeble and indefinite colorations : In general, all other vege- table oils. This reagent can also be used to simplify the author's method of detecting drying and marine animal oils in mixtures containing other oils (ANALYST, xxvii., 14). C. A. M. Determination of the Specific Gravity of Wax. H. Mastbaum. (Zeits. f. aizgew. Chenz., 1902, xxxvii., 929.)-The author determines the specific gravity at the boiling-point of water, and compares it with water at 15" C.The wax is melted and poured into a pyknometer, the base of the neck of which is somewhat contracted, so that a wire may be attached to it, by which the pyknometer is hung in the beaker. Over its neck is also fitted a tube to prevent drops of water being pro- jected into the bottle. To prevent concussion a piece of wire gauze is placed over the bottom of the beaker. The pykno- meter is immersed in a bath of boiling water for quarter or half an hour; the neck is then drawn above the surface, and the capillary stopper, which has been first warmed, is rapidly inserted. The author does not determine the water- content of the pyknometer at 100" on account of the tendency to form bubbles of vapour. He weighs the vessel filled with water at 15", making a correction for the expansion of the glass.I n the case of Jena glass 16"' the tables of Fuchs may be utilized (Xeits. f. a7zgezo. Chem., 1899, 26). If the boiling-point of water differs from 100" by 0.5" C. or more, a, correction must be made for expansion. A. M.THE ANALYST. 11 The Application of Polarimetry to the Estimation of Tartaric Acid in Commercial Products. Edgar B. Kenrick and Frank B. Kenrick. (Joum. Arner. Chem. Xoc., xxiv., 928.)-A large number of experiments were made by the authors t o ascertain the effect of various substances on the rotation of tartaric acid and mixtures of tartaric acid and sugars, and they found that in ammoniacal solution cadmium, boron, aluminium, tin, lead, manganic salts, iron, nickel, cobalt, and especially arsenic, antimony, and bismuth amongst the metals, influence the rotation appreciably. Molybdic acid also increases the rotation considerably.They give tables showing the effects of these bodies on the rotation and methods of analysis for the commercial products containing tartaric acid, which they divide into the following three groups : Group 1.-Substances like Rochelle salt and cream of tartar containing tartaric acid or calcium tartrate, but no other optically active material or body influencing the rotation. Grozy 11.-Mixtures containing both tartaric acid and sugar-q., many of the effervescing compounds, Group 111.-Mixtures containing tartaric acid with one or more modifying agents or traces of optically active substances--e.g., tartar baking-powders. The following methods of analysis are given : Group I.-If the tartrates present are completely soluble in dilute ammonia, a weighed quantity of the substance containing not more than 2 grsmmes tartaric acid is moistened with 3 or 4 c c.water in a 50 C.C. measuring flask, and enough ammonia (specific gravity 0.924) added to leave not more than 2 C.C. in excess. The solution is made up to 50 C.C. with water, filtered through a dry filter, and read in a 200- millimetre tube. The amount (y) of tartaric acid (C,H,O,) in grammes is given by the formula y = 0.00519 x, x being the rotation in minutes. If insoluble calcium tartrate is present, 2 grammes of the sample are dissolved in 30 C.C. water and 1 C.C. hydrochloric acid. To the hot liquid 4 C.C. ammonia and a solution of 0.2 gramme sodium phosphate are added ; the liquid is transferred to a 50 C.C.flask, diluted to the mark, filtered, and read as before, the above formula being used for the calculation. Tartaric acid present as potassium hydrogen tartrate may be estimated by the first method, and that combined with lime found by difference. Group 11.-Since magnesium modifies the rotation of tartaric acid and sugar if both are present together, its presence must be taken into account in mixtures of this !PUP- If magnesium is absent, a quantity of the sample, containing not more than 8 grammes tartaric acid or 5 grammes sugar,is dissolved in cold water and made up to 100 C.C. (solution A). Twenty-five C.C. of this solution are placed in a 50 C.C. flask with a few drops of methyl orange; if alkaline, the solution is neutralized with hydrochloric acid, 1 C.C.ammonia added, the volume made up to the mark, and a reading (a) taken. The quantity of hydrochloric acid necessary to decompose the salts of the organic acids present is ascertained in another 25 C.C. of the solution, methyl violet, which turris pale green with mineral acids, being used as indicator. To another 25 C.C. of solution A 2 C.C. in excess of this quantity of hydrochloric acid are added, the liquid is heated to 70" for ten minutes, rapidly cooled, a few drops oi12 THE ANALYST. methyl orange and enough ammonia to leave 1 C.C. ammonia in excess are added, the volume is made up to 50 c.c., and a reading ( b ) taken at room temperature. If z is the weight of sugar in the sample, t the temperature, x the rotation, and y the weight of tartaric acid present, ; x = 2a - 79.7~ ; y = 4 x 0-00519~.x .= 2 (a - b) 1.254 142 - 0.5t If magnesium is present, solution A is prepared as before: To 10 C.C. of this 4 u t i o n , 25 C.C. water, 4 C.C. ammonia, and enough ammonium chloride ta give a clear liquid, are added, and magnesium precipitated by means of sodium phosphate (8 grammes dissolved in 10 C.C. hot water for every 5 granimes crystallized magnesium sulphate). The precipitate is filtered off and washed by means of the pump, the volume of the filtrate being made up to 100 c.c., and a reading (c) taken. The sugar is determined in 25 C.C. as before after inversion (reading d). Then, If inverted sugar is present in the sample, its quantity is determined by Fehling's solution, and due allowance made for it.Group 111.-The effect of the iron and aluminium present as impurities and of the trace of inverted starch has to be considered. The method used depends on the fact that ammonium rnolybdate not only increases the rotation of tartaric acid SO much that the rotation due to the inverted starch is rendered insignificant, but also annuls the effect of the iron and aluminium. The solution, however, must be strictly neutral and free from phosphates. A quantity of the sample containing not more than 0.2 gramme tartaric acid, 0.3 gramme alum, or 0.3 gramme acid calcium phosphate is treated with 10 C.C. of ~t 10 per cent. citric acid solution, and 10 C.C. of a solution of ammonium molybdate containing 44 grainines per 250 C.C.After shaking occasionally for fifteen minutes, 5 C.C. of a 12 per cent. magnesium sulphate solution and 10 C.C. of 20 per cent. ammonia are stirred in, After a, few minutes the liquid is filtered through a dry filter, 20 C.C. of the filtrate measured into a 50 C.C. flask, and neutralized with hydrochloric acid, using methyl orange indicator. Ten C.C. molybdate solution and enough water to make the volume UP to 50 C.C. are then added, and the solution, filtered if necessary, is polarized in a 53)O- millimetre tube. If x is rotation in minutes, the quantity (y) of tartaric acid in grammes is given by the formula- The total volume should now be exactly 35 C.C. y = 0*001212. No method of analysis for substances containing tartar emetic is given. A. G. L. The Detection and Estimation of Chestnut Extract in Oak Ext,ract.F Jean. (Ann. cle Chtim. anal., 1902, vii., 404, 405.)-According to the author extracts of oak for tanning purposes are frequently adulterated with extracts of chestnut wood. The presence of the latter may be detected by the fact that when shaken with a solution of iodic acid it liberates a certain quantity of iodine, whilst noTHE ANALYST. 13 such reaction is obtained with extracts of oak, mangrove, mimosa, sumach, lentigcus, fustic, or barberry. In making a qualitative test, the extract is shaken in a sepa- rating-funnel with a solution of iodic acid and carbon bisulphide, tetrachloride, or chloroform, and if a violet coloration is obtained the presence of chestnut extract may be regarded as certain.For a quantitative determination, 2 to 3 grammesof the extract are mixed with 50 C.C. of water, and shaken with 5 grammes of a 5 per cent. solution of iodic acid and 5 gramnies of carbon bisulphide in a stoppered flask, the operation being repeated until the bisulphide is no longer coloured violet on the addition of iodic acid. The iodine taken up by the bisulphide is then titrated with standard thiosulphate, and the amount of chestnut extract calculated from the data that each gramme of iodine liberated corresponds, on the average, to 6.25 grammes of dry chestnut extract, to 16 grammes of extract of 25" Beaumb, and to 19 grammes of extract of 20" BeaumB. C . A. M. Examination of Gutta-percha. E. Marckwald and F. Frank. (Zeits. f. angazo. Chem., 1902, xv., 1029.)-The determination of the gutta is best carried out by dissolving in chloroform and precipitating with acetone.About 2 grammes of dry gutta-percha are dissolved in 15 C.C. of chloroform, and the clear solution is slowly poured into 75 C.C. of acetone, which at the same time is stirred. The gutta forms a voluminous porous cake, which is easily pressed out and washed without loss. The resin remains in solution, and the other impurities, such as dirt, are in suspension. The gutta is washed with acetone, dried at 100' C., and weighed. The dirt may be estimated by pouring the solution and washings through a tared filter. If some finely divided gutta goes with it, this may be redissolved in toluene and added to the rest of the gutta. Dissolution in chloroform and precipitation with alcohol gives results which are too high, because part of the resinous matter is insoluble in alcohol.Good results are, however, obtained by precipitating with ether. Some 2 grammes of gutta-percha are dissolved in 10 C.C. of chloroform, then 100 C.C. of ether are added, and the solution is allowed to stand twenty-four hours. The gutta is then filtered off, dried, and weighed. Another method is to treat 1 gramme with 100 C.C. of boiling petroleum ether (boiling-point 35" to 50" C.) for one hour under an inverted condenser. The solution is allowed to stand twenty-four hours, the residue filtered off, dried, and weighed. A. MI. A Simplified Met,hod for the Quantitative Determination of Albumin. A&Af Jolles. (Monatsheftc f. Cheyn., xxiii., 589.)-The method depends on the fact, previously noticed by the author (Ber.d. k . Akacl. Wisseitschuften, cx., l l b , May, 1901), that in the oxidation of albuminoid bodies by means of permanganate in acid solution a fixed proportion of the nitrogen is converted into substances (urea and ammonia) from which it can be evolved as gaseous nitrogen on subsequent treatment with sodium hypobroiiiite. In applying this method to the determination of albumin in urine, 100 c.c., or,14 THE ANALYST. in the case of urines very rich in albumin, 25 or 50 C.C. of the urine are made slightly acid with a few drops of dilute acetic acid, and heated to boiling, with constant stirring, after the addition of a small amount of sodium chloride solution. The precipitate is rapidly filtered off, washed with hot water till free from chlorine, then washed off the filter-paper into a beaker, the contents of which are made up to a volume of 300 to 400 C.C.with water, and gently heated to boiling after the addition of 5 C.C. of sulphuric acid {specific gravity 1.4). Whilst the whole is kept boiling quietly a solution of 8 grammes potassium permanganate in 1 litre of water is added gradually, 1 C.C. at a time, until the last addition produces a brown precipitate of manganese dioxide. The solution is then concentrated until this precipitate has disappeared, and the addition of the permanganate solution continued, in portions of 0.5 ex. at a time, until the precipitate produced by each addition does not disappear even after boiling for fifteen minutes. During this process the volume of the solution should never be less than 100 c.c., water being added if necessary. After the oxida- tion is finished, the small precipitate of manganese dioxide is removed by adding a little oxalic acid; the solution is then concentrated to about 50 c.c., cooled to a temperature of 15" to ZOO, and enough of a 33 per cent. caustic soda solution added to make the liquid alkaline to litmus, after which it is transferred to a nitrometer, sodium hypobromite added, and the evolved nitrogen estimated as usual. The weight of this nitrogen multiplied by the factor 7.68 gives the quantity of albuminoid bodies present. This factor was found empirically by submitting different quantities of pure albumin to the above treatment, when it was found to vary only between the limits of 7.60 and 7-75. The quantity of nitrogen given by the above method by any one substance appears to be about 81.5 per cent. of that given by Kjeldahl's method. From the test analyses supplied it appears that the evolution method gives results accurate to within 1 per cent. on the albumin. I t requires three to three and a half hours for its execution, and is consequently quicker than Kjeldahl's as applied to the determination of albumin in urine. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9032800008

出版商:RSC    

年代:1903

数据来源: RSC

摘要:

14 THE ANALYST. INORGANIC ANALYSIS. The Detection and Electrolytic Determination of Lead. G. Meillere. (Joz~rw. Pharm. Chim., 1902, xvi., 465-469.)-The precipitation of lead as sulphide from an acid solution, prior to its electrolytic determination, is frequently difficult when the metal is only present in traces or when certain salts are present in the ash. This difficulty is completely obviated by adding to the substance a known quantity of pure electrolytic copper-say, 2 to 5 C.C. of a solution of copper sulphate contain- ing 50 grammes in 250 C.C. The saline residue from the ignition is taken up with dilute (1 per cent.) nitric acid, and the solution treated with hydrogen sulphide and set aside for twenty-four hours. The precipitation of lead is then complete, even when only a fraction of a milligramiiie is present.The mixed sulphides are separated, washed, and treated with 10 C.C. of strong nitric acid, and the solution diluted to 50 c.c., boiled to expel nitrous vapours, filtered, and diluted to 100 C.C. It isTHE ANALYST. 15 then electrolysed in the usual manner with an anode of much greater surface than the cathode. The author has employed this device with success in the rapid detection of lead in urine, food products, and various organs of the body, the addition of the copper greatly facilitating the destruction of organic matter. C. A. M. On the Determination of Lead in Ores. Irving 0. Bull. (School of Mines Quart., xxiii., 348.)-The author has made a large number of experiments to compare the accuracy and rapidity of the different volumetric methods of determining lead, each method being tried on six samples of lead ore, the lead contents of which had been determined by means of closely agreeing gravimetric analyses in which the lead was weighed as sulphate, chromate, and peroxide.The effect of the impurities usually occurring in lead ores-namely, barium, strontium, calcium, bismuth, and antimony-was also tried on each method. All the methods tried depend initially on the conversion of lead into lead sulphate, mixed with gangue and other insoluble sulphates, obtained by treating the ore with nitric or nitro - hydrochloric acid, evaporating with sulphuric acid, and filtering off from soluble sulphates after dilution. The best results were obtained with Blexander's molybdate, Low's ferrocyanide, the dichromate, and Koenig's ammonium carbonate methods, the two first especially giving very good results, and only requiring about one hour for each determination.In the molybdate method the mixture of lead sulphate and impurities obtained as above is boiled for at least ten ininutea with ammonium acetate solution; the solution is then acidified with acetic acid, diluted to 200 c.c., again boiled, and a standard ammonium molybdate solution added until all the lead is precipitated. The end-point is ascertained by shaking the solution vigorously, allowing it to stand for a few minutes, and testing 1 drop of the clear liquid with 1 drop of a solution of 1 part tannin in 300 parts water and 1 drop of a lead solution ; the appearance of a yellow colour indicates the presence of ammonium molybdate in excess.The molyis- date solution is prepared by dissolving 9 grammes of the salt in 1 litre of water and standardizing against lead sulphate. Since the indicator is not very sensitive, requiring about 0.8 C.C. of molybdate to affect it, a blank must be made to ascertain the correction due to this. This method gave very good results when tried on the ores ; the presence of antimony, bismuth, and calcium had no effect on it ; but in the presence of barium and, to a lesser extent, strontium, it gave low results. In the ferrocyanide method, as used by the author, the mixture containing the lead sulphate is gently heated to boiling with 10 C.C. of a saturated solution of ammonium carbonate. After cooling, the precipitate is transferred to a filter, thoroughly washed, and then placed with the filter-paper in a flask containing a hot mixture of 5 C.C.glacial acetic acid and 25 C.C. water. This is boiled until tho lead carbonate has dissolved, diluted to 150 c.c., heated to 60" C., and titrated with standard 1 per cent. potassium ferrocyanide solution, drops of uranium acetate solution placed on a white tile being used as indicator. Here also the correction due to the indicator must be determined. This method also gave very good results when From 0.3 to 1 gramme ore was used for each determination.16 THE ANALYST. tried on the ores ; the presence of antimony, strontium, and calcium did not affect the results, but bismuth lowered the values found very slightly, and barium should not be present in any considerable quantity.Sutton's modification of the dichromate method was carried out as follows : The impure lead sulphate is treated with ammonium acetate solution, the acetate solution obtained diluted to 150 c.c., and a fair excess of standard potassium di.chromate solution run into the boiling liquid. After boiling for another two minutes the pre- cipitate is quickly filtered on a Gooch crucible, thoroughly washed, and the excess of dichrornate in the filtrate determined as usual with ammonium ferrous sulphate or thiosulphate solution. This method gave slightly high values for the ores, and it was found that in the presence of bismuth, antimony, barium, strontium, or calcium, in appreciable quantities, high results were obtained.I n the ammonium carbonate method the impure lead sulphate is frequently shaken during twenty minutes with 50 C.C. of a 10 per cent. ammonium carbonate solution ; the lead carbonate, etc., is filtered off, washed, placed with its filter-paper in a beaker, and digested at 50" C. for ten minutes with 50 C.C. ;& nitric acid, after which the excess of acid is titrated with caustic soda, using methyl orange as indicator. Good results were obtained when this method was tried on the ores, which were not affected by the presence of either antimony or bismuth ; but barium, calcium, and especially strontium, gave very high values. A. G. L. The Determination of Iron in Natural Waters. L. W. Winkler. (Zed awd. Chena., 1902, xli., 550-553.)-The author recommends a colorimetric method in which ammonium sulphide is used as the reagent.When a little of this is added to 100 C.C. of an aqueous solution, containing 0.1 mgm. of ferrous iron, the solution assumes a deep-brown colour, and the reaction is still perceptible with 0.01 mgm. ; with ferric iron the reaction is considerably less sensitive. A very dilute solution of either ferrous or ferric iron is coloured a bluish-green by ammonium sulphide when ammonia is also present in large quantity. The following solution is required for the comparison test : 0.7 grammes of ferrous ammonium sulphate dissolved in water, 10 drops of dilute sulphuric acid added, and the whole diluted to one litre; 1 C.C. = 0.1 ingm. iron. This solution must be rigorously preserved from contact with air.For the determination, 100 C.C. of the freshly-drawn water are placed in a glass cylinder, 5 C.C. of hydrogen sulphide water and 1 to 2 drops of ammonia added; 100 C.C. of distilled water are similarly treated, and the above ferrous iron solution added drop by drop, with agitation, until the two solutions have approximately the same depth of colour: this cannot yet be determined with certainty, since the former is brown, the latter bluish-black. To the latter solution 2 to 3 drops of dilute hydro- chloric acid are now added, and after decolorization has taken place a few drops of ammonia; sufficient ferrous solution is then dropped in until both solutions have the same depth of tint, Lastly, both solutions are decolorized with hydrochloric acid and ammonia again added; if the colour of both matches exactly the determination is finished : z C.C.of ferrous solution used = x mgm. of ferrous iron per litre in the water under examination. To obtain accurate results, the amount of ferrous iron inTHE ANALYST. 17 the water should be within the limits of 0.3 and 1.5 mgm. per litre; if less than 0-3 mgm., 500 C.C. of the water should be taken; if more than 1.5 mgm., a small measured quantity, and correspondingly dilated. Iron in the ferric condition is deter- mined in the same way, after reduction to the ferrous condition by means of hydrogen sulphide. For the determination of both the ferrous and ferric iron, a few C.C. of hydrochloric acid are added to 10 to 100 C.C. of the water, and the whole evaporated to dryness.The residue is taken LIP with a little water and hydrochloric acid, the solution treated with hydrogen sulphide solution, heated for a few ininutes on the water-bath, and filtered, the filtrate diluted to 100 c.c., and the iron determined as above. The advantages claimed for ammonium sulphide over potassium ferrocyanide or ammonium thiocyanate are that it is more sensitive, and that it obviates the con- version of ferrous into ferric iron. C. A. 11. The Iodometric Estimation of Bismuth as Chromate. E. Rupp and G . Schaumann. (Zeits. a/rzorg. Chem., xxxii., 362.)-The method consists in pre- cipitating the bismuth solution, which should be as free as possible from mineral acids, with a fairly large excess of a standard potassium chromate solution, and diluting the whole to it known volume.After the lapse of ten minutes, during which the solution is occasionally shaken, the solution is filtered from the precipitated bismuthyl dichromate, and after ascertaining that precipitation was complete by adding ammonia to a portion of the filtrate, the residual chromate is determined in another aliquot part by adding potassium iodide and sulphuric acid and titrating after a few minutes with thiosulphEte solution, One atom Bi corresponds to 1 molecule K2Cr04, or to 3 atoms iodine. Potassium chromate is used for the precipitation instead of the dichromate in order to completely neutralize the free acid formed during the reaction, which would otherwise exert a solvent action on the precipitate. dccording to the authors, neither sodium acetate, ammonia, nor caustic soda may be used to effect this neutralization, and the solution must not be heated, otherwise the results are much too low.A. G. L. The Retention of Armnic by Iron in the Marsh-Berzelius Apparatus. Charles Lathrop Parsons and Morris A. Stewart. (Journ. Amer. Chem. soc., xxiv., 1005.)-The authors have found that the lack of sensitiveness shown by many samples of pure zinc is due to the presence of small quantities of iron, which apparently is able to retain arsenic. Even so low a percentage of iron as 0.0011 will cauge a retention of arsenic (0.0002 gramme out of 0.0050 gramme). On boiling down the solution left in the generator with strong nitric acid, and dissolving the zinc salt out of the residue with hot water, a red deposit is left, which contains all the iron, some water, and all the arsenic left in the generator. The authors insist on the necessity of taking precautions to insure the absence of iron, and state that even in the presence of iron qualitative indications may be obtained from a8 little as 0.01 inilligramme arsenic.A. G. L.18 TEE ANALYST. The Separation of Manganese from Cobalt and Nickel. E. Pozzi-Escot. (Ann. de Chim. arrzak, 1902, vii., 376.)-When manganese is precipitated by ammonium hydroxide in excess in the presence of ammonium salts, and hydrogen peroxide or ammonium persulphate is added, the precipitate consists of a brown hydroxide yielding the definite oxide (Mn,O,) on ignition. Nickel and cobalt, on the other hand, remain in solution, and when the latter predominates the filtrate has a more or less pronounced reddish tint, due to the formation of a per-coboltic salt, C.A. M. A New Separation of Thorium from Cerium, Lanthanum, and Didymium, and its Application t o the Analysis of Monazite. Floyd J. Metzger. (Journ. Amw. Chem. SOL, xxiv., 901.)-The author has found that fumaric acid precipitates thorium almost completely from neutral aqueous solutions, and quantitatively, on boiling, from neutral solutions containing at least 40 per cent. of alcohol, whilst cerium, lanthanum, and didymium are not precipitated from aqueous solutions, and only cerium to a very small extent from alcoholic solutions. However, if a mixture of thorium with cerium, lanthanum, and didymium is precipitated with fumaric acid in a 40 per cent.alcohol solution, the precipitated thorium fumarate will contain small quantities of the other earths ; but one reprecipitation is perfectly sufficient to give pure thoria. Acetates must be absent in this separation, since a solution of cerium, lanthanum, or didymium fumarate in 40 per cent. alcohol is completely pre- cipitated by even EL few drops of ammonium or sodium acetate solution. This precipitate is completely soluble in excew of acetate, whereas thorium fumarate is only partially soluble in ammonium acetate. Fumaric acid precipitates none of the other metals except zirconium (quantitatively), silver, mercury, and erbium (to a very slight extent). The author's method of separating thorium as applied to the analysis of monazite sand is as follows : One gramme of the finely powdered mineral is evaporated several times with 15 C.C.of concentrated sulphuric acid until decomposition is com- plete. The sulphates are then gradually dissolved in 700 C.C. water kept at 0" C., and the solution, after being allowed to stand for several hours with frequent stirring, is filtered off from the quartz, the filtrate nearly neutralized with dilute ammonia, and precipitated with 50 C.C. of a cold saturated solution of oxalic acid. The oxalates are filtered off after some time, washed, and converted to hydroxides by heating with 25 C.C. strong potassium hydroxide solution. The hydroxides are filtered off, and dissolved in dilute nitric acid. The solution is evaporated to dryness on a water- bath, the residue taken up in 50 C.C.water, 80 C.C. alcohol and enough water to make the volume up to 200 C.C. are added, and the solution heated to boiling after adding 25 C.C. fumaric acid solution (0.1 gramme per 10 C.C. 40 per cent. alcohol). The precipitate is filtered off whilst hot, and washed with 40 per cent. alcohol ; precipitate and paper are then placed in the original beaker, treated with 25 to 30 C.C. boiling hydrochloric acid (1 : l), and, after diluting a little, the solution is filtered off, evaporated on a water-bath without allowing a crust to form on the sides of the vessel, dissolved with stirring in water, and the solution made up to 150 C.C. with alcohol and water, any carbonaceous residue being neglected. The solution is pre-THE ANALYST. 19 cipitated with 10 C.C. fumaric acid solution, the precipitate filtered off, ignited, and weighed as thorium dioxide.The above method was shown to be exact when compared with methods in which the thorium is separated with thiosulphate, ammonium oxalate, or both, and is much more rapid, only requiring about one-third of the time necessary with the older methods. A peculiar and, as yet, unexplained property of the fumarate is to leave a thorium dioxide after combustion in oxygen, which, on heating over the blast-lamp, gives off white vapours with the loss of a few milligrammes in weight. This occurs even if the thoria used for the precipitation has been previously thrown down by fumaric acid and ignited over the blast-lamp. A. G. L. Rapid Estimation of Potash. B. Sjollema. (C'hem. Zed., 1902, xxvi., 1014.) --This process has been worked out for the analysis of fertilizers, and avoids the usual tedious operation of removing the sulphuric acid from the solution before precipitation with platinum. The method is as follows : To the sulphate solution is added some barium carbonate, which produces potassium carbonate and barium sulphate ; some magnesium chloride is then introduced, which decomposes the potassium carbonate and yields the desired solution of potassium chloride.The barium carbonate is prepared by precipitation and kept as a cream under water, not being allowed to become dry. I n the analysis of kainit, 5 grammes are boiled for fifteen minutes with 200 or 300 C.C. of water, a quantity of the cream containing 5 grammes of barium carbonate is added, and the boiling continued for half an hour.As the material already contains magnesium chloride, a further addition in this case is not necessary ; the liquid is, therefore, simply diluted, and an aliquot portion after filtration is evaporated with platinum as usual. Substances which are essentially sulphates of potassium and magnesium are t.reated as above, but for every 1 part by weight of the sample taken 2 parts of barium carbonate and 1 part of magnesium chloride are added. Fertilizers containing soluble phosphoric acid require too much bariuni carbonate for the process to be convenient ; but a mixed material, consisting of Thomas meal, Chile saltpetre, and a potassium salt, gave correct results on boiling with water and barium carbonate, adding a few drops of hydrochloric acid before precipitating with platinic chloride.F. H. L. A Rapid Method of Estimating Lime. F. B. Guthrie and C. R. Barker. (PYOC. Royal SOC. New South Wales; through Chem. News, lxxxvi., 208.)-The method consists in mixing calcium oxalate, precipitated as usual, with dried and powdered ammonium nitrate. A few minutes' ignition over a Bunsen burner then suffices to convert the calcium completely into oxide, the weight of which is stated not to be altered by prolonged ignition over the blow-pipe. A. G. L.20 THE ANALYST. The Deterninafion of Free Anhydrous or Hydrated Lime in Cements. Maynard. (BzdZ. SOC. Chim., 1902, xxvii., 858-862.) - The author states that glycerin is capable of extracting calcium oxide or hydroxide from cement (either freshly ground or when set) without acting upon the other constituents. About 0.5 gramme of the powdered sample, previously dried at 120" C., is mixed with an exactly measured quantity (50 c.c.) of glycerin at 60" C., and the flask closed and kept for five days in an oven at not less than 40" C., its contents being well shaken each day.On the sixth day the liquid is diluted with absolute alcohol and filtered, and the lime which has dissolved determined and taken as free lime. C. A. M. The Proposed Standardization of Cement Analysis. W. Harry Stanger and Bertram Blount. (Jown. Soc. Chem. Ivzd., xxi., No. 19.)-The authors oppose the recommendation of t,he Committee of the New York Section of the Society of Chemical Industry for the formulation of standard methods of analysis for cements and cement materials on the ground that, since no method of analysis is perfect, each chemist must be left free to choose that which he thinks the best, and offer some criticisms on the method proposed by the Committee (Joum.SOC. Chenz. Ind., xxi., 30), especially as regards the non-estimation of the insoluble residue, which constitutes a valuable criterion concerning the mixing and burning of the cement. They also give a description of the method of analysis used by themselves, the out- lines of which follow : For silica and chief bases, 0.5 gramme of the cement is thoroughly mixed in a 6-inch evaporating basin with a few C.C. of water ; about 20 C.C. of hydrochloric acid (specific gravity 1-15) are then added, the whole is again well mixed until the cement has dissolved almost completely, evaporated to dryness on a hot plate, and baked for one hour, the temperature being at least 200" C.This operation com- pletely dehydrates the silica, one evaporation being sufficient, since only very small quantities (0.0009 gramme) are left in solution. The dry residue is digested with 30 C.C. hydrochloric acid, the solution diluted with water, and silica and insoluble residue filtered off. The filtrate is precipitated with a slight excess of ammonia, heated until only just alkaline, and the precipitate of ferric hydroxide and alumina filtered off. The filtrate from this is heated to boiling after the addition of about 12 C.C. strong ammonia, and the lime precipitated by adding 25 C.C. of a hot 4 per cent.ammonium oxalate solution. The whole is kept boiling for two or three minutes, allowed to stand for one hour, and filtered. The filtrate from the calcium oxalate is rapidly boiled down in a dish to a pasty stage, the dish covered, and the boiling continued to dryness after the addition of 40 C.C. concentrated nitric acid to destroy ammonium salts. The residue obtained, consisting chiefly of magnesia and alkalies, is treated with a little water and hydrochloric acid, excess of ammonia and a few drops of ammonium oxalate solution are added, and the small precipitate formed on heating is filtered off. I t consists of the small quantity of lime left in solution, together with silica, iron, and alumina derived from the various vessels used. Its weight is usually about 0*0015 gramme after ignition, and in ordinary work it may be neglected.TO the filtrate from this 10 C.C. of strong ammonia andTHE ANALYST. 21 2 C.C. of a 10 per cent. sodium phosphate solution are added, the ammonium mag- nesium phosphate filtered off after standing, with occasional shaking, for two hours, and ignited at the mouth of the muffle. The precipitates of silica and insoluble residue, iron and alumina, and lime are gently burnt off with their filter-papers, and then ignited for one hour at the highest temperature of the muse. For insoluble residue and sulphuric anhydride 0.5 gramme of the cement is dissolved as above, the whole evaporated to dryness, the residue taken up in 10 C.C. hydrochloric acid, and the solution filtered off after diluting.I n the filtrate SO, is precipitated with barium chloride, the precipitate filtered off and ignited without separating it from its filter-paper. The precipitate of silica and insoluble residue is washed back into the original dish and digested with a saturated sodium carbonate solution, when the insoluble residue only is left undissolved. This is filtered off, ignited, and weighed. Its weight, deducted from that of the silica plus insoluble residue found above, gives the weight of available silica in the cement. For loss on ignition-ie., carbonic anhydride and water-0.5 gramme of the cement is ignited for half an hour in a muffle at a temperature not exceeding 800" C. A higher temperature would drive off SO,. Carbonic anhydride is estimated gravimetrically as usual on 2 to 5 grammes.For alkalies, 1 gramme is taken, silica and bases are removed as above, and the alkalies separated with baryta from the magnesia in the residue obtained after destroying ammonium salts. Alumina and ferric oxide may be separated as usual by means of pure caustic soda, and sulphides are determined by decomposing the cement with hydrochloric acid in an atmosphere of coal-gas, the evolved hydrogen sulphide being absorbed in lead acetate solution. The determinations mentioned in this paragraph are usually unnecessary. For the analysis of a mixture ready €or burning to cement 1 gramme is ignited in a platinum crucible at the highest temperature attainable with a blast-lamp, and then analysed as a cement. I n conclusion, the authors call attention to the import- ance of using pure reagents and good filter-papers to insure accurate and quick work, In the discussion of the paper, Dr.W. F. Hillebrand stated that, on trial of the authors' method of separating silica by a single evaporation, he had found that up to 0.66 per cent. silica wars left in the filtrate, which would mean an even larger relative error in the iron and alumina. He believed that double precipitations were necessary to insure the purity of both the iron and alumina and of the lime, and did not agree as to the statement that SO, was volatilized if too high a temperature was employed in the determination of the loss on ignition. The method of estimating insoluble residue was also open to objection. Standard methods of analysis were desirable, in his opinion, since uniformity of results, more than extreme exactness, was necessary in the great manufacturing industries. A.G. L. On the Determination of Sulphur in Coal. Charles W. Stoddart. (Jozmz. Amer. Chem. SOC., xxiv., 852.)-The author has compared the results given by a number of different methods for the estimation of the sulphur in some fifteen different samples of coal with those given by a standard method in which the coal was burnt22 THE ANALYST. under pressure in a calorimeter bomb, suitable precautions against loss of sulphur in the escaping gases and mineral residue being taken, and has come to the conclusion that Eschka’s method is by far the best, both as regards ease of execution and accuracy, provided that the silica obtained on dissolving the mass left after ignition in hydrochloric acid is dehydrated.I n the case of coal containing barium, strontium, or calcium sulphates, practically a11 the sulphur corresponding to these salts is obtained, provided that the heating is finished at a bright red heat, and that this temperature is maintained for some time. A. G. L. Volumetric Method for Determining Selenium. H. Friedrich. (Zeits. f. anyew. Chem., 1902, xxxiv., 852.)-The method depends upon the fact that selenium precipitates silver from an ammoniacal solution of silver nitrate in accordance with the equation : 4AgN0, + 3Se + 3H20 = 2Ag2Se + H2Se0, + 4HN0,. The titration of the unchanged silver nitrate remaining in solution enables one to calculate the quantity of selenium. The selenium is precipitated from dilute solution by means of sulphur dioxide in the usual way.The precipitate is filtered and thoroughly washed, the filter is placed in the precipitation flask, 10 C.C. of ammonia are added, and a considerable excess of ;G silver nitrate solution is run in from a burette. The liquid is boiled for five or ten minutes, a little ammonia being added occasionally, then it is cooled and acidified with dilute nitric acid. The excess of silver is finally titrated with .+; ammo- nium thiocyanate solution, using a ferric salt as indicator. The results are very satisfactory, provided the quantity of selenium does not exceed 0.05 gramme. If there be more, the precipitate of selenium is too coarse, and does not reduce the correct amount of silver.The quantity of silver nitrate added should be at least double that removed from solution. A. M. On the Gravimetric Determination of the Oxides of Tellurium b y means of Hypophosphorous Acid. A. Gutbier. (Zeits. n n o ~ g . Chem., xxxii., 295.)-The author gives results showing that hypophosphorous acid reduces tellurium quantita- tively to element from hydrochloric acid solutions on heating and, if necessary, con- centrating. The solutions should be as free as possible from nitric or sulphuric acids, and heavy metals reducible by hypophosphorous acid must be absent. A. G. L. On a New Method of Separation of Tellurium and Antimony. A. Gutbier. (Zeits. anoyg. Chem., xxxii., 260.) - The author criticises the older methods of separating tellurium from antimony, and communicates results showing that, from a hydrochloric acid solution of the two elements containing a large excess of tartaric acid, hydrazine hydrate or hydrochloride precipitates tellurium quantitatively as the element, antimony remaining in the solution, from which it can be precipitated as sulphide after boiling with hydrochloric acid.The error of the method is from 0.2 to 1 per cent. calculated on the tellurium.THE ANALYST. 23 By means of hydroxylamine hydrochloride tellurium can also be quantitatively separated from antimony, as stated by P. Jannasch and W. Heimann (Rer., xxxi., 2, 2388), but the author found the method exceedingly tedious. It was carried out by adding a large excess of tartaric acid and 1 or 2 grammes hydroxylamine hydro- chloride to the hydrochloric acid solution of the two elements.After warming slightly, an excess of concentrated ammonia and 6 to 8 grammes hydroxylamine hydrochloride were added, and the whole boiled for several hours, with the constant replacement of the volatilized ammonia, until the precipitate had settled, when the tellurium was rapidly filtered off, dried at 105” C., and weighed. The filtrate was concentrated and treated as before, the operation being repeated until all the tellurium was precipitated. Antimony was estimated in the final filtrate as above. The results obtained were very exact, the error in the determinations being only 0.05 to 0.1 per cent. of the tellurium and up to 0.3 per cent. of the antimony. A. G. L. The Precipitation of Ammonium Vanadate by means of Ammonium Chloride.F. A. Gooch and R. D. Gilbert. (Zeits. uno7*g. Chem., xxxii., 174.)-The authors have examined the question of the reliability of W. Gibbs’s modification (Amer. CZcem. JouT~., v., 371, 378) of Berzelius’s method for the estimation of vanadium, which has been adversely criticised by Rosenheim (Imzuprccl- Diss., Berlin, 1888) and others. As used by them, the method consisted in treating a weighed quantity (about 0.5 gramme) of pure ammonium vanadate, whose content of vanadium had been ascertained by means of Holverscheit’s iodometric method, with 25 C.C. of water and a little ammonia, aud heating on the water-bath till solution was complete. A few drops of ammonia and 25 C.C. of a solution of ammonium chloride saturated in the cold were then added, and the whole concentrated on the water- bath, with occasional addition of a little ammonia, to a volume of 25 C.C.The solution was then cooled, when a little ammonium chloride crystallized out; if its quantity was too considerable, the bulk was dissolved by the cautious addition of ammonia. After allowing the whole to stand for twenty-four hours, the preoipitated ammonium metavanadate was filtered off on to asbestos, placed in a Gooch crucible, washed with a saturated solution of ammonium chloride, and ignited, at first very gently to prevent mechanical loss, which is apt to take place at this stage through decrepitation, and, finally, at a red heat. In soma cases the vanadium was also estimated iodometrically. I n order to prevent crystals of ammonium vanadate from adhering to the sides of the beaker in which the precipitation was carried out, vessels 1:insed out with a solution of 0.5 gramme paraffin-wax in 3GO from which the crystals were easily detached.I n all cases the method gave accurate results, and Rosenheim’s results to his not having adhered with sufficient of the method as given by Gibbs. I n no case could they find from the vanadate, in opposition to Rosenheim’s statement vanadium remain in solution. C.C. naphtha were used, the authors attribute strictness to the details vanadium in the filtrate that small amounts of A. G. L.24 TEB ANALYST. The Determination of Phosphoric Acid by means of Ammonium Phospho- molybdate. Gregory Paul Baxter. (dmer. Chein. Jozmz., xxviii., 298.)-From his experiments the author concludes that the composition of the precipitate obtained by adding a solution of a phosphate to an excess of molybdic acid solution, washing with a 10 per cent.ammonium nitrate solution, and subsequent drying of the precipitate at 300" C., is represented by the formula (NH4),PO;12MoO,, but that the dried precipitate not only contains a small quantity of water (0.079 per cent.), but also occludes additional ammonium molybdate both at the moment of precipitation and later on standing. The ammonia corresponding to this occluded ammonium molybdate is volatilized at 300°, so that it is only represented in the dried precipitate by an excess of molybdic anhydride, which, however, has very littIe effect in lowering the percentage of P,Os in the phosphomolybdate.The author shows how to calculate the quantity of occluded molybdate in each case when working under given conditions. He found that an excess of ammonium nitrate in the solution not only hastens the precipitation , but increases the amount of molybdate occluded, whilst nitric acid exerts a solvent action on the precipitate, but diminishes the occlusion. A. G. L. A New Acidimetric Indicator. L. J. Simon. (Conzptes R m d w , cxxxv., No. 10 ; through Ch&?n. AT~zcs, lxxxvi., 174.)-The new indicator consists of the ferric salt-(C,H,O,),Fe + 2H2O-of a new isopyrotri-tartaric acid, which is formed on heating tartaric acid in the presence of potassium bisulphate. The salt dissolves easily in water with a brownish-red colour, which is nearly black in concentrated solutions, and becomes orange-red and finally reddish yellow on dilution.Acids change this colour to violet in concentrated, and rose-red in dilute, solutions, whilst alkalies occasion a pale yellow tint. A. G. L. On the Accuracy of Certain Iodometric Determinations. J. Pinnow. ( h i t . anal. Chenz., 1902, xli., 485-488.)-When a solution of iodine in potassium iodide is titrated with thiosulphate and starch a point is reached at which no coloration is given, although free iodine is present, equivalent, in those cases where no other substance is present other than the I, KI, and starch, to a 0*0000181 to 0.000019 normal iodine solution. The addition of more starch or of non-electrolytes does not appreciably increase the sensitiveness of the reaction, but electrolytes considerably increase it, in some cases as much 8s tenfold.The effect of various bodies is shown in the following table. I n the test experiments 1 C.C. starch solution was added to 50 C.C. of a solution made by diluting 1 volume of 0.009733 N. iodine solution with 99 volumes of H,O. The thiosulphate solution, of which 20.84 C.C. = 20 C.C. of the undiluted I solution, was diluted tenfold. Theoretically, 5-21 C.C. of the diluted thiosulphate were equivalent to 50 C.C. of the diluted iodine solution.THE ANALYST. 25 Substance added. Blank determination . . . More starch . . . ... Sulphuric acid ... ... Nit& acid ... ... Phosphoric acid ... ... 7 , * * . Acetic acid ... ... Potassium sulphate . . . Sodium sulphate ... Potassium chloride . . . Sodium chloride .. . Tartaric acid ... ... Citric acid ... ... Alcohol ... ... ... Acetone ... ... ... Cane-sugar , . , ... Equi valeiit added per Litre. - - 0.066 0-018 0.069 0.191 0.31 0,044 0.221 0.042 0.042 0.239 0.261 0.533 (mol.) 0.25 ,, 0.053 ,, Forni of the Addition. - 4 C.C. starch solution 1 C.C. !$! N. acid 1 C.C. N. acid 2 C.C. 2 N. acid 3 C.C. IF- N . acid 1 C.C. glacial acid 0.2 grainme in 3 C.C. 2 grammes salt 2 C.C. of 89.9 grammes in a litre 2 C.C. of 70.4 grainrnes in a litre 1 gramnie 1 9 , 2 C.C. 1 C.C. 1 grainme water Thiosulphate. C.C. 4.09-4.14 4.17 4.86 4.7 4.97 4.73 4.43 4.99 5.11 5.01 4.88 4.8 4.74 4.24 4.29 4.16 C. A. I T . The Standardization of Permanganate by means of Salts of Oxalic Acid. C. Rust. (Zeit. a d . Clzem., 1902, xli., 606-608.)-Manganese oxalate has been found by the author to be the most suitable salt for this purpose, since it is readily obtained in a pure state, of constant composition, and is not hygroscopic.I t is best prepared from ordinary pure manganese carbonate, which is suspended in boiling water, and treated with a solution of pure oxalic acid until the reaction is unmistakably acid. The precipitate is washed until free from acid, the water with- drawn by means of suction, and the oxalate spread in thin layers and dried in the air, and finally over sulphuric acid in a desiccator. As thus prepared, its composition invariably corresponds with the formula MnC,O, + 2H,O. If dried at 100" to 120" C. it loses nearly the whole of its water of crystallization. c. A. XI. On Boedeker's Reaction for Sulphites.J. Fages. (A?zn. de C h k . anal., 1902, vii., 333-335.)-Sulphites can be detected by the red coloration which they give with a solution of zinc sulphate containing a trace of sodium nitroprusside, the sensitiveness of the reaction being increased by the addition of a little potassium ferrocyanide. The solution of the sulphite must first be neutralized, preferably by means of sodium bicarbonate. From a study of this reaction the author has arrived at the following con- clusions: (1) The red compound formed is due to double decomposition between the sulphite and the nitroprusside. The solution of the sulphite must not be too26 THE ANALYST. dilute, for the reaction, though the most characteristic of sulphites, is not the most sensitive. (2) The reaction is given by other nitroprussides, and most readily by insoluble nitroprussides, such as those of nickel, cobalt, zinc, manganese, copper, cadmium, palladium, etc.In each case the compound formed is an amorphous, unstable red substance. (3) The red substance is probably an addition compound of the nitroprusside with the sulphite. (4) The action of potassium ferrocyanide in rendering the reaction more sensitive is very irregular. I t does not take any direct part in the formation of the red compound, and its influence is less marked when a large excess of sodium nitroprusside is employed. I t can be replaced by sodium carbonate or by any other salt that precipitates zinc, without changing the neutrality of the solution or reacting with the sulphite or nitroprusside.c. A. B!. The Differentiation of Chlorides from Bromides. G. Viard. (Bzdl. soc. Clzim., 1902, xxvii., 1022-1026.)-This qualitative test is based on the fact, recorded by Gmelin, that on adding sulphuric acid to a solution of copper chloride a yellow precipitate of the anhydrous chloride is obtained, whilst in like manner copper bromide yields a black precipitate of the anhydrous bromide. According to the author’s experiments, if the sulphuric acid is not in excess, the green hydrated chloride, CuC1, + 2H,O, is precipitated ; and it is essential for the precipitation of the anhydrous chloride that the liquid should contain more than 68.4 per cent. by weight of sulphuric acid at 1 5 O C. The dehydration varies with the temperature, and when the chloride is precipitated by acid of slightly lower strength than 68.4 per cent.the anhydrous yellow chloride precipitate is slowly transformed into the green hydrated chloride on cooling the liquid, and vice versci. In the case of copper bromide, the precipitate formed by sulphuric acid in excess invariably consists of the black anhydrous salt, and never of the green hydrated bromide, which is a very unstable salt. By adding 2 parts of sulphuric acid to 1 part of a 10 per cent. solution of copper bromide (CuBr,) the pracipitation is nearly complete, the supernatant liquid being free from copper and containing only an inappreciable quantity of hydro- bromic acid. To distinguish chlorides from bromides by these reactions the author uses a reagent consisting of 1 part of 10 per cent.copper sulphate solution and 10 parts of sulphuric acid, a few drops of the solution under examination being added to this mixture. The test is stated to be capable of identifying 1 part of potassium chloride in 100, or 1 of potassium bromide in 200 of water. Nitrates in sufficient excess either prevent the appearance of the precipitates or cause them to disappear as soon as formed. When chlorides or bromides of cadmium, mercury, or tin are prasent, white precipitates are produced instead of a yellow or black precipitate. C. A. M. Analysis of Carborundum. A. Goetzl. (Chem. Zeit., 1902, xxvi., 967.)- Crystalline silicon carbide is so hard that it cannot be ground in porcelain or steel without risk of contamination. I t s igneous decomposition with mixed alkali car- bonates is tedious, and does not permit the determination of its carbon. TreatmentTHE ANALYST. 27 with nitric and hydrofluoric acids drives off any admixed silica (sand), but the carbo- rundum itself is attacked to some extent: Large quantities of graphite may be detected by the appearance, greater softness, and lowered specific gravity of the material ; but its amount can only be determined by difference, which is not altogether satisfactory. Goetzl therefore proposes to analyse the substance by igniting it in a suitable crucible with lead oxide of known purity, covering the mixture with a layer of lead carbonate or borax in order to exclude air. The oxide is reduced to the metallic state by the carborundum, so that if more than the theoretical weight of lead is obtained as a button, graphite must have been present in the sample, while less than the theoretical yield points to the presence of sand. An arrangement for the simultaneous estimation of the carbon dioxide liberated makes the process more exact and convenient. F. H. L. APPARATUS. Corks versus Rubber. T. H. Page. (Chew. News, lxxxvi., 162).-In working with the terpenes and other essential oils the author recommends the use of corks coated with gun1 instead of rubber stoppers, which are attacked very quickly. A perfectly tight joint can be easily obtained by fitting the apparatus together, exhausting, and repeatedly brushing the corks over with ordinary thick mucilage. Any large holes occurring in the corks may be easily stopped with gum or shellac softened in water. The corks can be used repeatedly, are not affected by the oils, and do not contaminate the latter. They are also much less expensive than rubber stoppers. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9032800014

出版商:RSC    

年代:1903

数据来源: RSC

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THE ANALYST. 27 THE GORDON MEMORIAL COLLEGE AT KHARTOUM. THIS College, which Lord Kitchener recently opened, is now ready for the chemical and bacteriological research laboratories, presented by Mr. Henry S. Wellcome during his recent visit to the Soudan. The equipment for scientific work is most complete in every detail, and will be equal to any similar laboratories in Europe. The Sirdar has appointed as Director of these research laboratories Andrew Balfour, M.D., B.Sc., D.P.H., of Edinburgh. The Soudan presents exceptional opportunities for the study of tropical diseases, and Dr. Balfour will also assist the authorities in the investigation of criminal poisoning cases. The character of the poisons used by the native8 is at present often obscure, and it is possible that the work in these laboratories may con- siderably increase the knowledge of our toxic agents. Apart from the original researches and general sanitary work, Dr. Balfour and his staff will devote their attention to the study of the cereals, textile fibres, and various matters affecting the development of the agricultural and mineral resources of the country.

ISSN:0003-2654    

DOI:10.1039/AN9032800027

出版商:RSC    

年代:1903

数据来源: RSC

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28 THE ANALYST. REVIEWS. INORGANIC CHEMISTRY, WITH THE ELEMENTS OF PHYSICAL AND THEORETICAL By J. I. D. HINDS, Ph.D., Professor of Chemistry in the Univer- (New York : John Wiley and Sons. London : Chapman According to the preface, this volume is intended to serve ‘( both as a rather complete text-book of inorganic chemistry and as a handy reference book for students and teachers.” Considered as a text-book, however, it supplies a, rather good example of how chemistry should not be taught a t the present time, and this in spite of the undeniable fact that the main portion of the book, devoted to descriptive chemistry, is well written, and may meet with some success as a work of reference. The author has employed the very latest American designations and spelling; there is a good account of the rare gases, and even an appendix relating to radium ; but in the arrangement of his subject he has gone back to the bad old- fashioned plan of completely separating the theoretical from the descriptive part, and has, moreover, made the theoretical portion appear more as a set of definitions to be learnt by heart than as theories and facts to be understood.The definitions given are often curiously arbitrary and sometimes mutually contradictory, certain of the statements made being unduly sweeping. As a minor fault, it may be pointed out that the periodic system is followed too slavishly, with the result, i72ter alia, that nitrogen is only discussed after the halogens and the elements of the sulphur, chromium, and argon groups. The manner in which ionic equations are occasionally introduced is also open to great objection. The book is well printed on good paper, and is almost free from errors, typo- graphical and ot’herwise.On p. 53, however, a mistake has evidently been made, both in the substitution of GO for GO, and in the critical constants assigned to steam; while the statement, on p. 411, that Welsbach mantles are composed of lanthanum and related oxides, no mention being made of the use of ceria and thoria in this connection, shows a strange ignorance on the author’s part of all the later history of incandescent lighting. CHEMISTRY. sity of Nashville. and Hall, Ltd. 1902. Price $3.) A. G. L. A TEXT-BOOK OF PHYSICS. By J. H. POYNTING, I).Sc., F.R.S., and J. J. THOMSON, The authors state in their preface that this is the first volume of a series which is chiefly intended for students who lay most stress on the experimental part of physics, and who have not reached the stage at which the reading of advanced treatises on special subjects is desirable. An account only of phenomena of special importance is given, and the mathematical methods adopted are very elementary. The present volume deals with weight, mass, gravitation, elasticity, fluid viscosity, surface tension, diffusion, and solution. The work well bears out the claims of its authors ; it is couched in clear and lucid language, and the large amount of experi- mental work described renders the book exceedingly interesting reading, The last five chapters are of special interest to chemists. The printing, paper, and general get-up of the book are all that could be desired. M.A., F.R.S., etc. (London : Charles Griffin and Go. Price 10s. 6d.) W. J. S.

ISSN:0003-2654    

DOI:10.1039/AN9032800028

出版商:RSC    

年代:1903

数据来源: RSC