摘要:

SEPTEMBER, 1909. Vol. XXXIV., No. 402. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE QUANTITATIVE SEPARATION OF LEAD AND BISMUTH.* BY J. C. GALLETLY AND G, G. HENDERSON, M.A., D.Sc., F.I.C. IT is known that many metals can be estimated with accuracy in the form of their phosphates, and the method appears to be particularly suitable for the estimation of bismuth, which is precipitated quantitatively from solutions of its chloride or nitrate by addition of sodium phosphate (Staehler and Scharfenberg, Ber., 1905, 38, 3862 ; Salkowski, idem., 3943). Moreover, since bismuth phosphate is practically insoluble in dilute phosphoric acid, whilst the phosphates of a number of other metals are dissolved more or less readily by that reagent, the separation of those metals from bismuth can be effected without trouble. Lead phosphate, however, is only sparingly soluble in phosphoric acid, and therefore the attempts which have been made hitherto to separate the phosphates of lead and bismuth have given unsatisfactory results.Staehler and Scharfenberg have suggested that the separation might be effected by precipitating the phosphates together, and then removing the lead phosphate by boiling the precipitate with 1 per cent. nitric acid. Followingup this suggestion, we have made a number of experiments on the separation of the phosphates of lead and bismuth, and have also tested some of the other methods which have been proposed for the estimation of bismuth in presence of lead. Preliminary experiments, of which the details are omitted, confirmed the state- ments that the precipitation of both lead and bismuth phosphates is quantitative, and that bismuth phosphate is insoluble, and lead phosphate only sparingly soluble, in dilute phosphoric acid.I t was also found that lead phosphate dissolves slowly but completely, whilst bismuth phosphate is hardly attacked, when heated with 1 per cent. nitric acid, and that the former salt is readily dissolved by 3.5 per cent. nitric acid in the cold, but the latter only to a small extent. In order to ascertain if a separation of the metals could be effected by precipi- tating bismuth phosphate in presence of sufficient nitric acid to retain lead phosphate i n solution, a series of experiments was carried out with solutions containing from * This work was carried out in accordance with the terms of the “Analytical Investigation Scheme.”390 THE ANALYST.0.5 to 5 per cent. of the acid, It was found that with the weaker solutions the results for bismuth were too high, and with the stronger solutions too low, but on precipitating the bismuth from a solution containing 2-5 per cent. of nitric acid, and subsequently digesting the precipitate with a little more acid of the same concentra- tion, the following figures were obtained : Pb Taken. Bi Taken. Bi Found. Differencc 024549 94163 -24286 -00123 + In view of this result a trial was given to the following method : The solution of the nitrates of the metals was mixed with so much nitric acid that, after addition of the necessary quantity of sodium phosphate, the liquid still contained about 2.5 per cent.of nitric acid. The hot solution of sodium phosphate was added to the boiling solution of the nitrates, and the mixture was boiled for five to ten minutes, allowed to settle on the water-bath, and decanted through a Gooch crucible. The precipitate was digested on the water-bath for about ten minutes with 10 to 15 C.C. of 2.5 per cent. nitric acid, transferred to the crucible, washed with water con- taining a little nitric acid and a trace of ammonium nitrate, ignited, and weighed as BiPO,. The results were disappointing, for whilst in some of the experiments fairly close agreement was reached, there was on the whole considerable variation in the percentage of bismuth found. The following results may be taken as typical of a large number : Pb Taken.-23684 -23684 a23684 *23684 ,23684 *94736 -94736 2.36840 Bi Taken. *25721 -10288 *lo288 *05144 ~05144 -10288 010288 *lo288 Bi Found. -25866 -10187 ~10351 -04819 m04861 -10311 .lo640 *lo901 Difference. ~001.45 + -00101 - -00063 + -00325 - ,00283 - *00023 + -00352 + -00613 + In a number of other experiments we tried the effect of varying the quantity of acid with which the precipitate w a ~ digested, the duration of the process, and, when the proportion of lead was large, the number of digestions ; finally, we came ho the conclusion that, although it is possible to get fairly accurate results, the process is, on the whole, too troublesome for ordinary use on account of the necessity for so care- fully regulating the percentage of nitric acid in the solution.A simpler process was then adopted. A boiling solution of sodium phosphate, in sufficient quantity to precipitate the lead and bismuth completely, was added to the boiling solution of the nitrates, and the mixture was boiled for five to ten minutes and left to settle on the water-bath. The liquid was decanted through a Gooch crucible, and the precipitate w&s washed by decantation. The subsequent treatment of the precipitate was varied in several ways : in some experiments 1 per cent. nitric acid, in others 2.5 per cent. nitric acid was used; in some cases the precipitate was boiled with the acid, in others it was digested on the water-bath with constant stirring ; in some experiments the precipitate was treated once with the acid, in others the boiling or digestion was repeated for a second or a third time, theTHE ANALYST.391 duration of the treatment being also varied in different sets of determinations, The results were again disappointing, for although satisfactory figures were obtained in some cases, the variations in the percentage of bismuth found under similar condir tions of experiment were so great that the process was abandoned. After some trials we also abandoned the following methods : 1. Precipitation of lead by ammonium persulphate, the bismuth being stated to remain in solution (Dittrich and Reise, Ber., 1905, 38, 1829). 2. Electrolytic separation of bismuth and lead according to Balachowsky (Comptes Rendzu, 1900, [3], 131, 179). 3. Electrolytic separation according to Hollard and Bertiaux (Cowqtes Redus, 1904, [S], 139, 366).Finally, a number of estimations of bismuth in presence of lead were carried out by the method proposed by Clark ( J . SOC. Chem. Ind., 1900, 19, 26). A solution of the chlorides of lead and bismuth containing a spiral of steel wire (1 to 2 grms.) was heated until most of the iron was dissolved, and the precipitated bismuth and the remainder of the iron were collected, washed with boiling water until free from lead, and dissolved in hydrochloric acid with the aid of potassium chlorate. After diluting the solution the bismuth was precipitated as sulphide, the precipitate washed with a Bolution of hydrogen sulphide until free from iron, dissolved in nitric acid, and after filtration precipitated with ammonium carbonate.The precipitate was washed, .ignited, and weighed as Bi,O,. The results obained, which are given in the follow- ing table, were much more satisfactory than those given by any other of the processes hried : Pb Taken. Bi Taken. Bi Found. Difference. ,29216 -29216 -29207 *00009 - -29216 -29216 -29316 *00100 + a29216 -11686 -11887 *00201+ -29216 -11686 -11601 .00075 - 1.16860 -11686 011421 a00265 + 1.16860 m11686 .11833 -00147 - 2.92150 -11686 *11744 -00078 + 2.92150 -11686 el1726 -00040 + 5.84300 -11686 -11565 -00121 - 5,84300 -11686 -11780 -00094 + I n conclusion, our attempts to separate lead and bismuth quantitatively by the phosphate method were unmccessful, as was also the case with some of the other methods examined. On the other hand, we consider that Clark's process for the estimation of bismuth in presence of lead is not only easily carried out, but that it is also capable of yielding accurate results. The process, however, can be improved by precipitating the bismuth 8s phosphate-a method which we have found to give excellent results-instead of with ammonium carbonate, as originally described. DEPARTMENT OF CHEMIST~LY, TECHSICAL COLLEGE, GLASGOW.

ISSN:0003-2654    

DOI:10.1039/AN9093400389

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

392 THE ANALYST, THE DETERMINATION OF PHOSPHORIC ACID IN MINERAL PHOSPHATES. BY GUNNER JORGENSEN. IN previous communications (Det Kgl. Dnizske Videnska. Selskabs Slirvter, 7, Rakke ; Naturvidenska. og mathemat. Afdeling, 1905, 2, 4 ; Zeit. fiir And. Chem., 1906, 45, 273; ibid., 1907, 46, 370) I have discussed at some length the molybdic, the magnesia, and the citrate methods for the determination of phosphoric acid, and referred to other methods which from time to time have been proposed. Working with pure sodium ammonium phosphate, I showed (loc. cit.) that the composition of the magnesium ammonium phosphate precipitated at the ordinary temperature varies with the conditions of precipitation. This is the case also with the molybdic and the citrate processes. The composition of the magnesium ammonium phosphate approaches the theoretical with an exactness of about 1 : 1000, provided that the magnesia solution is added slowly, with vigorous agitation, to the nearly boiling solution.The precipitate settles in a compact and crystalline form, but this characteristic appearance cannot be regarded as a proof of its correct composition. Since my method has now become the official one in Denmark for the analysis of fertilisers and mineral phosphates, and as there have been occasional misunderstand- ings concerning the precise procedure to be followed, I believe it will be useful to give a detailed description, as hitherto the method has only been described in general terms. PREPARATION OF THE REAGENTS. (a) Molybdic Solution.-One hundred grms. of pure ammonium molybdate are dissolved in 280 C.C.of ammonia (sp. gr. 0*97), and 300 C.C. of this solution are poured, with vigorous shaking, into 700 C.C. of nitric acid (sp. gr. 1-21>, and the mixture allowed to stand for twenty-four hours. The ammonia solution may be prepared by mixing 84 C.C. of ammonia (sp. gr. 0.91) with 196 C.C. of water, and the nitric acid by mixing the strong acid (sp. gr. 1.4) with about an equal volume of water. ( b ) Acid A?nntonium Nitrate Solution.-This is to contain 40 grms. of ammonium nitrate and 10 grms. of nitric acid per litre. It is prepared by mixing 90 C.C. of nitric acid (sp. gr. 1.4) with about 1,500 C.C. of water, adding 80 c.c, of ammonia (sp. gr. 0*91), and making up to a volume of 2,000 C.C. (c) Mag?zesia Solution.-Fifty grms.of pure magnesium chloride (MgC12 + 6H,O) and 150 grms. of pure ammonium chloride are dissolved in water, and the solution made up to 1,000 C.C. Method.-1. Five grms. of mineral phosphate are placed in a 250-C.C. flask, and dissolved with gentle ebullition in 20 C.C. of nitric acid (sp. gr. 1.21). Solution will be complete in about fifteen minutes. The contents of the flask are cooled, made up to 250 c.c., and filtered, 2. To 50 C.C. of the filtrate contrtined in a beaker flask (250 c.c.) are added 165 C.C. of the molybdic solution, and the flask and its contents placed in a water-bath at a temperature of -50" C. for ten minutes, and occasionally stirred. When quiteTHE ANALYST, 393 cold the contents of the flask are filtered, and the precipitate washed ten times by decantation with acid ammonium nitrate solution, about 20 C.C.being used for each washing. If necessary, the filtrate may be tested for unprecipitated phosphate by adding more molybdic solution, warming up to 50" C., and standing for twelve hours. The estimation of calcium may be proceeded with by adding a little sulphuric acid and twice the volume of the washings of alcohol. 3. The washed molybdic precipitate is dissolved in 100 C.C. of 2.5 per cent. ammonia solution, filtered, if necessary, through the same filter which held the molybdic precipitate, the filter being washed eight times with about 10 C.C. each time of the ammonia solution, so that the final volume is about 180 C.C. 4. The beaker-flask is covered with a clock-glass, the contents brought just to the boiling-point, removed from the burner, and 30 to 35 C.C.of the magnesia solution added drop by drop from a burette, the whole being well stirred. The beaker-flask is recovered, and so long as the liquid remains very warm it is stirred frequently, and if the precipitate is not compact and crystalline the stirring should be con- tinuous. After standing for at least four hours the solution is filtered on to a platinum crucible packed with spongy platinum, the precipitate washed with 2.5 per cent. ammonia solution until free from chlorides, and then once with alcohol. 5. The precipitate is dried and heated gradually over an Argand burner, then ignited strongly, cooled, and weighed. Remarks.-I find that nitric acid is a convenient solvent for ordinary mineral phosphate, as the presence of the small amount of silica does not interfere with the accuracy of the method.If large amounts of organic matter are present, a more energetic aolvent should be used. The elementary precaution that the pipette and 250-C.C. flask should correspond with each other must not be overlooked. The amounts of molybdic and magnesia given alone are suEcient even if the mineral phosphate contained 100 per cent. calcium phosphate. The excess of molybdic solution is smaller than is usually employed in other methods, and the chance of the precipitation of arsenic or silica is thereby diminished. I t should be borne in mind that by a prolonged standing the strength of the molybdic solution may be lessened by the separation of molybdic acid. Too long a boiling before the precipitation with the magnesia solution should be avoided, as the consequent loss of ammonia will result in an incomplete precipitation of magnesium ammonium phosphate. In the analysis of artificial manures the undermentioned quantities of reagents are used : For 50 C.C. of an Aqueous Extract of a n 18 t o 20 per Cent. Superphosphate (1 Grin. of material). For 100 C.C. of a 2 per Cent. Citric Acid Extract of 12 to 15 per Cent. Thomas Phosphate (1 Grm. of ninterkl). Molybdic solution ... 75 C.C. ... ... ... 100 C.C. Ammonia ,, 100 ,) 75 Y , Magnesia ,, ... 15 t o 20 C.C. ... ... ... 12 to 19 C.C. ... ... ... ...

ISSN:0003-2654    

DOI:10.1039/AN9093400392

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

394 THE ANALYSTo ABS'I'RACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Detection of Benzoic Acid in Flesh and Fats. K, Fischer and 0. Gruenert. (Zeit. Untersuclz. Nahr. Gewussm., 1909, 17, 721-'734.)-The method recommended consists of two essential parts : the first dealing with the extraction of the benzoic acid from the substance under examination, and the second with the identification of the benzoic acid; for the latter purpose, the benzoic acid is con- verted into salicylic acid, and the ferric chloride test then applied. Fifty grms. of the finely-minced meat, or molten fat, are treated with 100 C.C. of 50 per cent. alcohol acidified with sulphuric acid, and frequently stirred for thirty minutes. The alcoholic liquid is then strained off, rendered alkaline, and evaporated to remove all the alcohol.The residue is taken up with water, 5 grms. of sodium chloride are added, the solution is acidified with sulphuric acid, heated just to boiling, cooled, filtered, and the filtrate shaken out with ether. After evaporating the ether, the residue is dissolved in a few drops of sodium hydroxide solution, transferred to a silver crucible, and evaporated to dryness ; 2 grms. of powdered sodium hydroxide are then added, and the mixture is fused over a small flame, being kept in a molten state for about two minutes. When cold, the melt is dissolved in a little water, the solution is acidified, extracted with ether, and the ether evaporated at a low temperature. The residue obtained is then tested with ferric chloride in the usual way.The test as described above will detect the presence of 0.01 per cent. of benzoic acid in fresh meat, 0.02 per cent. in smoked meat, and from 0.005 to 0.01 per cent. in butter, margarine, or lard. The test described by De Brevans (ANALYST, 1902, 27, 56) was found to be useless for detecting benzoic acid in flesh and fats. Rohrig's test, in which the benzoic acid is identified by converting it into ethyl benzoate by heating with alcohol and sulphuric acid, the ethyl benzoate having a characteristic odour, will detect 0.02 per cent. of benzoic acid in fresh meat, but fails in the case of smoked meat. The direct identification of benzoic acid by meaw of ferric chloride can only be applied when not less than 0.02 per cent. of the acid is present, and is reliable only in the case of fresh meat and fata.If the residue of benzoic acid extracted from the meat or fat be converted into benzaldehyde, the odour of the latter will show that the residue actually consisted of benzoic acid, provided that more than 0.04 per cent. of this acid was present in the sample. w. P. s. Estimation of Cantharidin. L. E. Walbum, (Arch. Pharm. u. Kenzi., 1909, 16, 77; through Chem. Zeit. Rep., 1909, 33, 346.)-The author has made a, number of estimations of cantharidin in cantharides by the methods described by Self and Greenish (ANALYST, 1907, 32, 173) and Baudin. He considers that too little carbon disulphide is used in the latter method for the complete extraction of the cantharidin, and that the extraction should be continued until the green coloration disappears.THE ANALYST.395 The author recommends a mixture of 70 C.C. of petroleum spirit and 30 C.C. of absolute alcohol for the extraction ; 15 C.C. of this mixture are added at the commencement, and after the lapse of twenty minutes the solution is removed and a further 30 C.C. of the solvent used for the washing. After applying a correction of 0.025 grm., the results obtained agree with those yielded by Self and Greenish’s method. w. P. s. Constitution of the Carnitine contained in Extract of Meat. R. Engeland. (Ber., 1909, 42, 2457-2462.)-The results of an investigation of the constitution of the base carnitine, which occurs in Liebig’s extract of meat, is given. Carnitine contains a carboxyl group and a hydroxyl group in the a position.A trimethylamine group is also present, being in the y position as regards the carboxyl group. Carnitine is therefore a-hydroxy-y-trimethylamine butyric acid of normal structure. The chloride has the structure- C1( C H) N . CH, . C H1. C H ( 0 H) . C 0 0 H. I t appears probable that the base novaine is identical with carnitine. w. P. s. Factors which Influence the Estimation of Creatine. C. F. Cook. ( J . Amer. Chem. SOC., 1909, 31, 673-693.)-The object of this investigation was to study the factors which have more or less influence on the estimatior, of creatine by Folin’s colorimetric method. These factors are : The amount of picric acid added, the amount of alkali added, the influence of dilution, of standing, of coagulable protein, and, finally, of proteoses and peptones.I t was found that, in using commercial samples of creatine and creatinine, slightly higher results were obtained when 30 C.C. of picric acid solution (1.2 per cent.) were added than when 15 C.C. were added. In the case of meat extracts it appears to have made little difference whether 1.5 or 30 C.C. of picric acid were used. Practically the same results were obtained by using 5 and 10 C.C. portions of 10 per cent. sodium hydroxide solution in the case of both creatine and creatinine. Fifteen C.C. of sodium hydroxide gave lower results; the excess of alkali evidently tended to destroy the creatinine com pound. I n the case of beef extract solution (2.3 per cent.), 10 and 15 C.C. portions of alkali gave practically the same results; but with 5 C.C.the results were lower, The combination of the alkali with the protein of the beef extract may account for this difference. The values for creatine and creatinine, both alone and in meat and meat extracts, were lowered upon dilution. The error due to dilution appeared to be a fairly constant one, and averaged 0*00019 grm. of creatinine per 10 C.C. of dilution. I t was found advisable to allow the solution to stand for five minutes after adding the reagents and before taking the reading. Lower results were obtained if a longer time elapsed before the reading was taken. The presence of coagulable protein, proteoses, and peptones lowered the results, and in exceptional cases it is recom- mended that the proteins be removed from a meat extract before the test is applied; ordinary meat extract does not, however, contain a sufficient quantity of protein bodies to interfere seriously with the estimation.w. P. s,396 THE ANALYST. Presence of Oxalic Acid in Cocoa. C. Girard. (Paper comnzzmicated to the Seventh Internatioizal Coizgress of Applied Chemistry.)-Examination of authentic samples of cocoa showed that they contain as much oxalic acid as is found in sorrel, spinach, and rhubarb, and that the quantity is not diminished by drying. Analyses of the chief brands of cocoa and of their ash are given. Oxalic Acid in Cocoa and Chocolate. J. M. Albahary. (Paper communi- cated to the Seventh Interizational Congress of Applied Chemistry ; through J. SOC. Chenz. Ind., 1909, 28, 738.)-Existing methods having failed to give accurate results in the determination of oxalic acid in cocoa or chocolate, the author devised the following process, which is based on the fact that in an alkaline solution magnesium salts precipitate phosphates and purine bases, whilst oxalic acid remains in solution as magnesium-alkali oxalate ; calcium oxalate is also soluble in an alkaline solution. About 50 grms.of the sample, which has been dried over sulphuric acid until constant in weight, are heated for one hour on the water-bath with 50 C.C. of a 10 per cent. solution of sodium carbonate, fresh water being added to replace that evaporated. The mixture is then treated with 50 C.C. of a solution containing 10 per cent. of magnesium chloride and 20 per cent. of ammonium chloride, a quantity of animal charcoal being also added to retain mucilaginous substances. After concentrating the liquid by heating for another hour, with occasional agitation, the mixture is filtered whilst hot with the aid of the pump, and the insoluble matter is washed with boiling water.The filtrate is concentrated, made strongly ammoniacal, and, after standing for twelve hours, is filtered. The filtrate is treated with a slight excess of calcium chloride, then made faintly acid with acetic acid, and after standing for twelve hours in a warm place, the precipitated calcium oxalate is filtered off, and the oxalic acid determined in the usual way; this gives the total oxalic acid. If the preliminary heating with sodium carbonate be omitted, the oxalic acid present as soluble alkali salts is determined, and the difference between the two results gives the quantity present as calcium oxalate.With this method it was found that a specimen of ‘( alkalinised ” cocoa-powder contained per kilogrm. 3.647 grms. of oxalic acid in the form of soluble salts and 0.188 grm. as calcium oxalate ; in a sample of (‘ non-alkalinised ” cocoa-powder the corresponding figures were 3.763 grrns. and 0.159 grm. In two specimens of chocolate, 0.7238 and 0.385 grm. respectively of oxalic acid per kilogm. were found. Confectionery containing Spirits. Forster. (Zeit. ofentl. Chem., 1909, 15, 243-244.)-The following proportions of absolute alcohol, calculated into grms. per kilogm., were foundindifferent samples of confectionerycontaining spirits and liqueurs : Souverain S.Rrl.N., 52.0; mrac beans, 40.4, 39.6, 28.2; punch beans, 39.3, 2.8; Cognac beans, 37.2, 31.5, 22.5, 17.2 ; melange, 36.0 ; liqueur beans, 31.5, 29.2 ; Bur- gundy punch beans, 22.4 ; Cognac cherries, 17.2 ; and Vanilla liqueur beans, 2.0.C. A . M . Philippine Terpenes and Essential Oils-111. R. F. Bacon. (Philippine J. Scieitce, 1909,4, MANILA ELEMI is always soft when freshly exuded from theTHE ANALYST, 397 tree, the so-called '' hard " elemi (Tschirch) being merely the resin after more or less exposure to weather, when it loses much of its volatile oil. So-called "Tacamahac slemi " (Tschirch) may be either (1) the dark resin obtained from Canayium villosum, which contains cymene as the chief constituent of its volatile oil, and differs markedly from elemi in its odour, or (2) the dipterocarpus resin from balao or apitong, re- sembling elemi in appearance, but differing from it in d o u r , and the volatile oil of which contains much sesquiterpene (see below).The author reiterates the now generally accepted statement of the botanical origin of elemi from Cannrium Luxonicum (Gray). The volatile oil from Manila elemi contains the terpenes dextro-limonene, dipentene (traces), and u- and P-phellandrenes, the phellandrenes being present in 90 per cent. of the samples. The author obtained the phellandrene nitroso-nitrite melting at 121" C., a figure agreeing with that of Schreiner, and at variance with that of Wallach (105" C.). One sample of elemi from one of the Philippine Islands contained pinene as the chief terpene constituent. Elemi contains 12 to 15 per cent.of a higher boiling oil containing elemicin (Semmler), or allyl-1-trimethoxy-3-4-&benzene. From the purified limonene separated from elemi, the author prepared the hydrobromide by Wallach's method, using petroleum ether, however, as the diluent. This new compound had the following characters : Boiling-point, 108" to 112" C. at 12 mm. pressure ; sp. gr. at ~ C., 1.1209 ; and [n]D 300 c., 1.5006. Phellandrene hydrochloride, prepared similarly, had the following characters : Boiling-point, 80" to 83" C. at 1 mm. pressure ; sp. gr. at 30" 4 O 3; c., 0.960 ; [n]D 300 c,, 1-4770 ; chlorine = 20.2 per cent. The oil from Cinnamoinum Mercadoi [Via.] was found to have a sassafras-like d o u r , with the following properties : Sp.gr. at - C., 1.0461 ; [ n ] ~ 300 c., 1.5270 ; [a]D 300 C. + 4". The oil consisted almost entirely of safrol, and was free from cinnamic and other aldehydes. PETROLEUM Num-These are so called because of a fancied resemblance to petro- leum in the odour of the oil, while even the fresh green fruits burn brilliantly. These nuts are the fruit of Pittosporum resiiziferum, a tree found mainly at high altitudes. The nuts yielded by expression 6.8 per cent. of a sticky, resinous oil, having a sp. gr. o€ 0-883 and [iz]D300~., 1.4577. I t distils unchanged up to 165" C., the residue then decomposing and yielding a resinous oil. The chief constituents of the oil are normal heptane and a dihydro-terpene, C,,H,,. VETIVER OIL (Andropogon Muricatus) [Khus-Khus or Khas-Khas].-This oil, normal in character, was found to contain a monobasic fatty acid of the formula C,,H2,02, [%ID 300 c., 1-4850 ; benzoic acid ; a sesquiterpene, probably the '' vetivene " of Genvresse and Langlois ; and sesquiterpene alcohols (?). The oils from various lots of roots differ markedly in odour and composition. BALAO RESIN, panao, or apitong, is a soft resin from Dipterocarpzcs vernicijzcus and D. grandiflorus. I t contains .a sesquiterpene of sp. gr. at 4" C., 0,9104 ; boiling-point, 118" to 119" C. at 8 mm. 30" 4" It is used as a varnish, but dries only slowly. 30"398 THE ANALYST. pressure ; [ n ] ~ 300 c., 1,4956 ; and [ u ] ~ 300 C. + 116-4. Strong sulphuric acid gives a fine red colour, which darkens gradually, when added to a mixture of this sesquiterpene and glacial acetic acid.Three samples of balao resin had the following characters : Very Liquid Specimen. Acid number . . . ... ... 13.0 10.0 20.8 Saponification number.. . ... 18.5 34.2 23.6 BZunzea Balsamifern.-The leaves of this plant yield 0-1 to 0.4 per cent. of a yellow oil having a camphoraceous odour, and consisting almost entirely of laevo- borneol. Laiztavna Camarum-The leaves of this sweet-scented weed yield an oil of sage- - 30" like odour, of sp. gr. 26 c., 0.9132 ; [ n ] ~ 300 c., 1.4913 ; [U]D 300 c., + 11~5". YLANG-YLANG OILS. -The best grades of this oil, besides showing a low refractive index and optical activity, and high ester number, are also characterised by high acetyl numbers (= saponification number of 1 grm. of oil after acetylation), ranging from 147 to 214, while second-grade oils show acetyl numbers varying from 96 to 141 (Zerewitinoffs method, Ber., 1901,40, 2023).Extracted oil of ylang-ylang flowers (the solvent being petroleum ether of high grade, and distilled off under 40° C. in vacuo) has the following characters, and when highly diluted is of fine odour: Sp. gr., -40- c., 0.940; [ % n ] D 3 O O c . , 14920; ester number, 135; acetyl number, 208. The oil is dark coloured. The flowers of Plumeria acutifoZia, yield by enfleurage with parsffin oil a perfume oil which is supposed to be the source of the perfume known as ccfrangipa?ti." An OIL OF ZEDOARY from Curcurnu xedoaria was found to have sp. gr. of 0.933 at 30" - C., a figure much lower than that previously recorded for this oil.4 O 30' A. R. T. Official Method of Testing Formaldehyde in Japan, (Chem. Zeit., 1909, 33, 769.) - According to the Japanese Pharmacopceia, formalin solutions must contain about 35 per cent. by weight of formaldehyde, and only the ammonia method (which is also still retained in the German Pharmacopaia) may be used for the estima- tion. It has been shown that this method gives erroneous results (usually 1.5 per cent. too low) with pure preparations, although in the presence of certain impurities the percentage niay appear to be higher. The use of this method has been the cause of frequent complaints from importers, and it is here advocated that it should be replaced by the process of Blank and Finkenbeiner (ANALYST, 1899, 24, 92). C. A. M. Furfural Reaction for the Deteetion of Sesame Oil.H. Imbert and I,. Dwrand. (Ann. des FaZsi:;fications, 1909, 2,317-319.)-Whilst certain, but not all, Algerian olive oils give a coloration with Villavecchia-Fabris' reagent (hydrochloric acid and furfural), pointing to adulteration with sesame oil, no coloration is obtained when the test is applied to the fatty acids of the oils (Milliau's modification of theTHE ANALYST. 399 test). should, therefore, be applied to the fatty acids and not to the oil itself. To avoid wrong conclusions as to the genuineness of an Algerian oil, the test W. P. S. Copper as an Impurity in Gelatin. W. B. Hart. (Paper communicated to the Seventh International Congress of Applied Chemistry.)-Metallic impurities, when found in cooked and preserved foods, generally originate from the cooking vessel, the packing vessel, the sealing material, such as solder, rubber ring, etc., or from the intentional addition of copper salt for ‘( greening ” purposes. The author has traced a further and hitberto unrecorded source of metallic impurity.Pressed beef, alleged to have caused symptoms of poisoning, when microscopically and bacterio- logically examined, was found to be quite sound; but a small quantity of copper was detected, the origin of which was eventually traced to the gelatin used as a garnish, the results being as follows : Mgms. of Copper per Kilo. Pressed beef 1 ... I .. ... ... 34 Presaed beef 2 ... ... ... ... 0 Gelatin A ... ..- ,.. ... ... 25 Gelatin B ... ... ... ... 104 The examination of a number of samples of gelatin, sold for household use, gave results varying from 0 to 56.3 mgms.of copper per kilogrm., and the figure varied directly with the ash. Jelly preparation ... ... ... ... 60 ... Comparative Estimations of Glycerol in Wine by the Iodide and Lime Methods. J. Schindler and H. Svoboda. (Zeit. Uiztcrsuch. Nuhr. Geizussm., 1909, 17, 735-741.)-The iodide method proposed by Zeisel and Fanto (Zeit. anal. Chem., 1903, 42, 549) for the estimation of glycerol in wine was found by the authors to be quite trustworthy. In this method the wine is prepared for analysis by treating 100 C.C. of it with tannin and barium acetate, distilling off about 70 c.c., and diluting the residue to 100 C.C. Five C.C. of this solution are then distilled in a current of carbon dioxide after the addition of hydriodic acid.The ivopropyl iodide formed by the action of the hydriodic acid on the free and combined glycerol distils over, and, after being passed through a small wash-bottle containing amorphous phosphorus suspended in water, is collected in an alcoholic solution of silver nitrate. The quantity of silver iodide produced corresponds with the amount of glycerol present. The lime method, in the case of wines containing not more than 5 per cent. of sugar, yields results which are somewhat lower than those obtained by the iodide method. With sweet vines much lower results are obtained by the lime method than by the iodide method. w. P. s. Fiehe’s Reaction for the Detection of Artificial Honey. K. Keiser. (Arbeit. Kaiserl. Gesuizdheitsumte, 1909, 30, 637-657.) - The results of an ex- haustive examination of the test proposed by Fiehe (ANALYST, 1908, 33, 397) are given.Whilst pure honey yields only a feeble yellow or red coloration with the test, artificial honey, commercial invert sugar, and starch syrup all give an intense400 THE ANALYST, cherry-red coloration; mixtures of pure honey with either 10 per cent. of invert sugar, 20 per cent. of artificial honey, or 40 per cent. of starch syrup give distinct red colorations. Invert sugar prepared with invertase does not yield a coloration. Pure honey which has been heated to a temperature of 1200 C. gives a red coloration and one hour's heating at 100" C. causes the honey to yield a red-but not cherry-red- colour. A feeble red coloration is obtained if the honey be heated for two hours at 60" C.In the usual course of the preparation of honey a prolonged heating is avoided, as it tends to deteriorate the article; but it is possible, from the difference in tint and intensity of the colorations obtained, to distinguish an over-heated honey from artificial honey. The formation of the red coloration is due to the presence of a-hydroxyl-6-methyl-furfura1, which is formed by the decomposition of the fructose. w. P. s. Use of Lime-Water for the Titration of Acid Solutions. A. de G. Rocasolano. (Rev. Real, Acad. Ciencias Madrid, 1908, 7 , 375-382 ; through Chenz. Zeit. Rep., 1909, 33, 386-387.)-The acidity of beer, wine, etc., may be conveniently titrated by means of saturated calcium hydroxide solution.This solution is con- tained in a storage vessel containing an excess of calcium hydroxide, and the clear solution is drawn off through a siphon, the end of which is covered with filter-paper. The siphon is directly connected to the burette, and a thermometer must be kept in the storage vessel, as the amount of calcium hydroxide dissolved per C.C. varies with the temperature. Tables are given showing the titre of saturated calcium hydroxide solution for different temperatures between 0" and 30" C., and there is consequently no need to standardise the solution in the ordinary way. (CJ G. T. Moody and L. T. Leyson, ANALYST, 1909, 72.) w. P. s. Clarification of Milk for the Estimation of Lactose. C. Carrez. (Rip de Pharm., 1909, 21, 102; through J. Pharm.Chim., 1909, 30, 36-37.)-The use of zinc ferrocyanide, produced in Zoco, is recommended for the clarification of milk previous to the estimation of the lactose in the same by means of Fehling's solution. Ten C.C. of the milk, 50 C.C. of water, 2 C.C. of 15 per cent. potassium ferrocyanide solution, and 2 C.C. of 30 per cent. zinc acetate solution, are placed successively in a 100 C.C. flask, and, after the addition of a little phenolphthalein solution, dilute sodium hydroxide solution is added until a pink coloration is produced. The mixture is then diluted with water to a volume of 100 c.c., mixed, and filtered. A perfectly dear filtrate is obtained both in the case of cow's and human milk. Attention is drawn to the fact that the latter milk contains an optically active, non- reducing substance which is not removed by clarifying agents ; consequently, lactose cannot be estimated in human milk by mems of the polariscope.w. P. s. Microscopical Distinction between Wheat and Rye Starches. W. Lenz. (Zeit. ofentl. Chem., 1909, 15, 224-227.)-A solution of sodium salicylate exerts a swelling effect on starch, and the various kinds of starches are affected by it in different degrees of rapidity ; so that this reagent may, in a measure, serve for the dentification of certain varieties. The most convenient strength of the reagent isTHE ANALYST. 401 obtained by dissolving 1 grm. of crystallised sodium salicylate in 11 C.C. of water. The observations are preferably made in a hanging-drop preparation. The sample of starch is stirred with water, and a trace of the liquid is placed on a square cover- glass and allowed to dry at the ordinary temperature.The quantity of starch thus spread on the glass should be as small as possible, and when dry it should only show as a slight haze on the glass ; the granules should not lie one on the top of another. The prepared side of the glass is then ringed with vaseline, a drop of the salicylate solution is placed on the starch, and the whole is inverted on a hollowed object-glass. I t is important that the hanging drop should be well enclosed, so that the concentra- tion of the reagent does not increase by evaporation. If the slide has been properly prepared, the starch granules should be seen, well separated from one another, adhering to the cover-glass; if a, few of them become detached and sink to the under-surface of the drop, they must be subjected to observation with the others.In the case of rye meal, a visible swelling of the largest granules will be observed after ten to fifteen minutes, The swollen granules have the appearame of flat plates, and no longer show any polarisation crosses. After an hour very few of the large granules will be found to have resisted the swelling action. On the other hand, the small granules will be apparently unaltered. After twenty-four to forty-eight hours only a few of the small granules remain unattacked, and show polarisation crosses. After a week the whole of the granules are attacked, and their contours scarcely recognisable. Wheat-flour or starch, when similarly treated, swells much more slowly.After one hour only a few of the large granules are swollen, and show no polarisation crosses ; the small granules remain unchanged. The contours of the wheat-starch granules stand out clearly and sharply ; no flattening of the granule takes place, as in the case of rye-starch ; the edge remains sharp, and the granule has the appearance of a solid body, especially if the object be shielded from light above the stage-this precaution must always be observed when looking for polarisation crosses. After twenty-four to forty-eight hours most of the granules retain their shape, and the majority their polarisation crosses. After a week many swollen, distorted granules are present, but their contours are mostly clear but faint. The difference between rye and wheat is very distinct with sound meals, but those which have been damaged by damp storage swell rapidly, whether rye or wheat.The author describes the behaviour of a number of other starches with the reagent. The characters are best observed at a magnification of 200 times. The starches apparently fall into two groups : one consisting of those which are readily swollen by the salicylate reagent at the above concentration-e.g., wheat, rye, &.-and the other consisting of starches which resist the action even for eight weeks-e.g., potato, arrowroot, etc. J. F. B. Need for a Definition of Chocolate in England. Norman P. Booth. (Paper communicated to the Seventh International Congress of Applied Chemistry.)- The author refers to the absence of any legal standard for chocolate in England, although in some of the European countries standards are in force, and points out, as the result of this, that articles, of which the sale would be prohibited in some other countries, are permitted to come without restriction on to the English market.402 THE ANALYST, It is suggested that the following definitions for chocolate goods are reasonable, and could be conformed to by makers of the genuine article.These standards are not more stringent than those already enforced in some of the Colonies and European countries : 1. Unsweetened Chocohte must be prepared exclusively from roasted, shelled, finely-ground cocoa-beans, with or without the addition of a small quantity of flavouring matter. It should contain not less than 45 per cent. of cocoa butter. 2. Sweetened Chocolate.-A preparation consisting exclusively of the products of roasted, shelled, finely-ground cocoa-beans, and not more than 65 per cent. of sugar, with or without a small quantity of harmless flavouring matter. 3. Granulated or Ground Chocolate for Drinking Purposes.-The same definition as for sweetened chocolate should apply here, except that the proportion of sugar may be raised to not more than 75 per cent. 4. Chocolate-covered Goods. -Various forms of confectionery covered with chocolate, the composition of the latter agreeing with the definition of sweetened chocolate. 5. Milk Chocolate.-A preparation composed exclusively of roasted, shelled cocoa- beans, sugar, and not less than 15 per cent. of the dry solids of full-cream milk, with or without a small quantity of harmless flavouring matter. The addition of starch other than that naturally present in the cocoa-bean, of fats other than that naturally present in the cocoa-bean, and of cocoa-shell in powder form, should be absolutely excluded from any article which is to be sold under the name of ( ( chocolate.” At the present time a mixture of cocoa with sugar and starch cannot be sold as pure cocoa, but only as “chocolate powder,” and with a definite declaration that the article is a mixture of cocoa with other ingredients. Prosecutions are constantly occurring where mixtures of foreign starch and sugar with cocoa have been sold as (‘ cocoa.” It seems, therefore, a proper step to take to require that a similar declaration shall be made in the case of chocolate ” which contains other constituents than the products of cocoa-nib and sugar.

ISSN:0003-2654    

DOI:10.1039/AN9093400394

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

402 THE ANALYSTo BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Vitality of the Cholera Vibrio in Artificially Infected Samples of Raw Thames, Lea, and New River Water, with Special Reference to the Question of Storage. A. C. Houston. (Metropolitan Water Board: Fowth Report on Research Work, June, 1909.)-The first part of the report deals with the vitality of the cholera organism when added to the ram river water. Four litres of the water were inoculated with 10 C.C. of an emulsion containing known numbers of the cholera vibrio. The sample was stored in the dark at room temperature, and portions of the shaken sample withdrawn each week and examined for the vibrio. The chief tests used were the growth of red colonies on glucose neutral-red bile-salt agar, the cholera- red reaction in peptone water, and acid, but no gas, formation in sugar media.Eighteen experiments were made, and in no case was the vibrio present after three weeks at the longest, 99.9 per cent. of the number perishing in one week. The second part of the research was directed to the important point of theTHE ANALYST. 403 ability to isolate the cholera vibrio from the raw water when present in small number. A litre of the water was inoculated with a known number of the vibrios and incubated with peptone-water; agar plates were then made, and the colonies growing on these subcultured and tested as above. Twenty-three experiments were made, and in sixteen cases the vibrio was successfully isolated, although less than one vibrio per C.C. had in some cases been added. Control samples of the same waters were examined at the same time, and from none of them was any organism resembling the true cholera vibrio isolated.Full details of the methods and media used are given. From these series of experiments the broad conclusions may be drawn that cholera vibrios die very rapidly in raw river water as the result of storage; that the detection of the vibrio in the raw water presents no difficulty even when present in small numbers ; that the advantages of storing the raw water, previously found in the case of typhoid fever, applpalso to the case of cholera ; and that storage previous to filtration would further insure the safety of the Metropolis from an epidemic of water-borne disease. J. EL J. Examination of Milk for Dirt and 66Leucoeytes.” C.Bevis. (J. -Boy. Inst. Public HeaZth, 1908, 16, 734.)-Since sedimentation methods give low results as regards total volume of dirt, the author uses the following centrifugal method. A tube holding about 70 C.C. is used, made of stout glass drawn out at one end, and a small glass cap well ground on. Inside the neck of the tube on which the cap fits a glass rod is ground in, of sufficient length to project beyond the mouth of the tube. The end of the rod is ground flush with the neck, and the cap has such a capacity that, when in place, Q inch in depth is left beyond the end of the tube. The milk is sampled as follows : A cylindrical copper vessel, holding half a pint or less, and fitted with a stout wire handle, is lowered into the milk-churn, in which the milk has been well stirred for about thirty seconds with a (‘ rouser,” and while the milk is still actively in motion.When full, the copper vessel is withdrawn and emptied into a clean, wide-mouthed bottle, care being taken that no dirt is left in the bottom of the vessel. Fifty C.C. of this sample are measured out by means of a pipette having a long indiarubber tube connected to its mouth. The milk is thoroughly agitated with a circular wire-stirrer, and with the jet of the pipette held well into the milk, the latter is slowly sucked up, and when full, clipped by the rubber tube with the fingers. The milk is at once allowed to run out into the rotation tube already described, the cap being put into position and the rod with- drawn. The tube is closed with a rubber stopper, and rotated at 2,000 revolutions per minute for five minutes.The cap should be packed up with cotton-wool to prevent breakage. The rod is carefully inserted in the tube, the cap being removed with a screwing motion. After washing out the tube, the cap is replaced, the deposit stirred up with a platinum needle into 50 C.C. of distilled water, and the tube again rotated. The tube is again emptied, the cap replaced, and 1 C.C. of eau de Javelle run on to the sediment. The tube is next filled again with 50 C.C. of water, and the rotation repeated. I t is afterwards cleaned and reweighed. A blank Eau de Javelle (1 c.o.) + 50 C.C. water experiment is The cap is removed, dried at 100” C., and weighed.404 THE ANALYST. performed, and any residue left in the cap deducted from the previous weight.The treatment with Eau de Javelle completely dissolves ‘( leucocytes,” etc., without having any action on the dirt, which may then be examined microscopically. The ‘‘ leucocytes ” in milk are determined by rotating 5 C.C. of milk, diluted to 20 C.C. with water, for ten minutes at 2,000 revolutions per minute, breaking up the cream, rotating again for five minutes, removing all the milk within $ inch of the deposit, diluting with water to 20 c.c., stirring up, and again rotating. The main quantity of water is removed, 4 to 5 drops of saturated aqueous methylene blue are added, and the whole mixed well. After standing for fifteen minutes it is diluted to 1 C.C. The author is of opinion that the number of (‘ leucocytes ” in milk may be very large without denoting diseased conditions.A. R. T. The cells are counted with a hzmacytometer. New Method for the Destruction of Organic Matters in Toxicological Analysis. J. B. Peset y Aleixandre. (Rev. Real. A d . Cieizcas, Madrid, 1908, 7, 512-518; through Chem. Zeit. Bep., 1909, 33, 387.)-In the method described the organic matter is destroyed by digestion with pure nitric acid and pure sodium nitrite. About 40 grms. of the substance under examination are heated in a porcelain basin on the water-bath with 100 C.C. of water and 40 grms. of concentrated nitric acid. To the thin paste which is formed 3 grms. of sodium nitrite are added, further quantities of about 0.5 grm. of nitrite being added from time to time, and the water which is lost by evaporation is replaced.At the end of three hours the mixture is evaporated to a small volume and diluted. All the organic matters, with the exception of a little fat, will have been destroyed, and the solution, after filtration, may then be tested for metals. Tin, if present, may remain insoluble as metastannic acid, but can be brought into solution by treating the residue with hydrochloric acid. Should silver be present, it would also remain insoluble as silver chloride, most organic substances containing sufficient chloride to convert the silver into this salt. I t is claimed that no poisonous metal is lost by volatilisation during the operation, and that the resulting solution is free from organic substances. w. P. s. Differentiation of Tubercle from Pseudo-tubercle Bacilli.A. Fontes. (Zentralb. Bakteiiol., 1909, 49, 317 ; through Chem. Zed. Rep., 1909, 33, 381.)-The following method ie recommended for the microscopical differentiation of true from pseudo-tubercle bacilli : The bacilli are stained with Ziehl’s solution in the usual way, washed with water, and dyed for two minutes in crystal violet solution; they are next treated with Lugol’s solution until a metallic mirror no longer appears, then with a mixture of equal parts of acetone and alcohol, and, after washing, are stained with methylene blue. True tubercle bacilli then exhibit a dark violet-red appearance, the interstices showing granulations, whilst the pseudo-bacilli are coloured violet without any red border, and the granulations are more dense.w. P. s. Extraction of Acetone from Urine. W. Vaubel. (Zeit. ofeyztl. Chem., 1909, 15, 241-243.)-Experiments to simplify the estimation of acetone in urine by extracting it with solvents, and titrating the extract with standard iodine solution,THE ANALYST. 405 showed that chloroform gave the best results. An addition of sodium chloride (15 grms. to 30 C.C. of water and 348 C.C. of chloroform) greatly reduced the absorptive power of the water for acetone, 92.1 per cent. of which could then be recovered, as gainst 75.1 per cent. when the extraction was made without the addition of the salt. Urea, ammonia, phosphates, sugar, and albumin, were all found to have an effect upon the extractive power of the chloroform, the amounts of acetone extracted when Bhese were present ranging from 50.0 to 85.4 per cent.of the theoretical quantity. C. A. M. Rapid Clinical Method for Determining the Ammonia-Coeffieient of Urine. R. F. Bacon. (Philippine J. Science, 1909, 4, 153-162.)-The ammonia coefficient of a urine is a number corresponding to the percentage of total nitrogen present as ammonia or ammonium salts. Normal adult human urine has an ammonia coefficient of 4.1 to 4.64 per cent., and this amount is markedly increased (to 50 per cent.) in certain pathological conditions. The author proposes to determine the ratio of ammonia to urea + ammonia, .and this is a sufficiently close approximation, for clinical purposes, to the true ammonia coefficient. The urine is treated in a ureometer with acid mercuric nitrate .solution (Millon’s reagent), whereby the urea is decomposed with formation of GO, and nitrogen in equal volumes, so that one-half the gas evolved is nitrogen.This <reagent has no effect upon the ammonia or ammonium salts in the urine, which are determined in a second ureometer (side by side) by means of alkaline hypobromite, the result being the nitrogen from the urea and ammonia of the urine. The reactions are not exactly quantitative, and the author gives tables for calculating the true values according to the formula : (H--) M 100 2.05 A = 9 E .where A = the ammonia coefficient ; M = the number of C.C. gas given off by treat- ment with mercuric nitrate ; H= the number of C.C. gas evolved by hypobromite solution. A specially designed form of ureometer is used by the author, and the reaction with the acid mercuric nitrate solution is carried out over mercury to avoid absorption of the carbon dioxide. The acid reagent is preferably added hot. The two operations are carried out side by side, and no corrections for temperature, etc., are necessary, as the ratio only is required. The results agree fairly well with those obtained from the ratio of the total nitrogen (Kjeldahl) to the amwoniacal nitrogen found by distillation with magnesia. A. R. T.

ISSN:0003-2654    

DOI:10.1039/AN9093400402

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 405 ORGANIC ANALYSIS. Use of " Standard Benzine " (Light Petroleum) for the Determination of Asphaltum in Dark Mineral Oils. Holde. (Jfitt. kgl. Materialspriijungsamt Gross-Lichterfelde West, 1909, 27, 143-148 ; through J. SOC. Chem. I d . , 1909, 28, 831.)-Asphaltum in dark mineral lubricating oils is determined by dissolving the406 THE ANALYST. oil in forty times its volume of light petroleum and separating the insoluble residue. The light petroleum to be used for this purpose is supplied by Kahlbaum, of Berlin, t o a specification of a committee of the German Union for Testing Technical Materials. This '' standard benzine " is to be uniform as far as possible, free from unsaturated and aromatic hydrocarbons, with the sp. gr. 0-695 to 0-705 at 15OC. ; at least 95 per cent.must boil between 65" and 95" C. Some analyses of the benzine supplied during the last few years are given in the paper ; unsaturated and aromatic hydrocarbons are' determined by shaking the benzine with fuming sulphuric acid, when the loss should not exceed 2 per cent. I n testing successive batches on the same mineral lubricating oil, it was found that the asphaltum present in the latter increases slightly on keeping. Analysis of Vulcanised Caoutchouc Goods. F. W. Hinrichsen and W. Manasse. (Chem. Zeit., 1909, 33, 735-736.)-1n default of a direct method for the estimation of caoutchouc, the method of precipitation by bromine appears the most promising of the indirect methods. Budde's process, consisting in swelling the rubber with carbon tetrachloride, and brominating with a mixture of bromine and iodine, is probably the best (Gummi Zeit., 1907, 21, 215).With cold-vulcanised goods, the main source of error due to the presence of chlorine in the form of a double compound formed between the rubber and the sulphur chloride, is generally sufficiently small to be neglected. The method is applicable to hot-vulcanised rubber, but the error is greater; it is not applicable in presence of antimony sulphide and lead compounds. Axelrod's process (ibid., 1907, 21, 1779) is not so useful, and the attendant errors are greater. The rubber is dissolved in petroleum of high boiling-point, brominated, and the product is precipitated by alcohol and weighed on a tared filter. In this process the precipitate contains the whole of the combined sulphur, and the factor varies according to the degree of vulcanisation. The drying of the bromide to a constant weight is by no means easy, but the chief error is due to the fact that the loading materials are first weighed as such, together with the bromide, and the weight is then corrected from the ash.I n this way, any loss suffered by the mineral loading during incineration is calculated as caoutchouc, and the error is especially large in the case of red-lead. Hiibener's method (ANALYST, 1909, 365) marks a decided advance in the estimation of caoutchouc. Estimation of Loadings.-The error, mentioned above, involved in correcting the weight of the precipitate by the weight of the ash, induced the authors to endeavour to find a method by which the loading materials may be estimated directly without incineration.This has been effected successfully by dissolving the caoutchouc in a suitable solvent and collecting and weighing the insoluble residue. The petroleum oil (boiling-point up to 300" C.) prescribed by Axelrod (Zoc. cit.) serves this purpose : One grm. of the finely-chopped sample is boiled under a reflux con- denser with 25 C.C. oi petroleum oil distilling between 230" and 260' C. until the caoutchouc is dissolved. After cooling, the solution is diluted with benzene, the residue is allowed to settle, and the liquid is decanted off through a tared Gooch filter. The precipitate is finally washed with hot benzene, petroleum spirit, alcoholTHE ANALYST, 407 a d ether, without removing it from the flask.Flask and filter are dried at 105" C. and weighed. In order to prevent the free sulphur from reacting with the un- vulcanised caoutchouc or the solvent, it is desirable to remove this sulphur by extraction with acetone before treatment with petroleum. A centrifuge is of considerable assistance in separating and purifying the residue, Certain types of rubber goods require a solvent of higher boiling-point than the above, such as paraffin oil. In many cases solvents of lower boiling-points may be used, which is desirable in order to avoid charring. Essential oil of camphor, boiling-point 175" C., is particularly useful for this purpose. The time occupied in dissolving the caoutchouc is from a half to two hours; the results are generally within 2 per cent.of the actual loading added. Estimation of Total Szdphw.-The powerful oxidising action of the NO, ions separated at the anode in the electrolysis of nitric acid may be employed advantageously for the destruction of the organic matter. The procedure is as follows : In a tall beaker of 100 to 150 C.C. capacity, a platinum-wire basket is suspended from a, platinum wire to serve as the anode and to contain the sample to be oxidised. The basket is then covered with the strongest fuming nitric acid, and electrolysed. The oxidation is complete in less than an hour, and the analysis is concluded by ordinary methods after removing the bulk of the nitric acid. A platinum spatula serves as the cathode. J. F. B. New Method of Estimating Combined Sulphur in Vuleanised Caout- chouc.T. Budde. (Gunzmi Zeit., 1909, 23, 1143-1144.)-The author shows, by means of Hiibener's method of estimating caoutchouc in hard vulcanised rubber (ANALYST, 1909, 170), that estimations of sulphur by the acetone method give too high results. Hiibener found that h a d rubber was soluble in bromine, and that on adding water and heating the solution the excess of sulphur was oxidised, whereas that in combination with the caoutchouc was not attaclred. The following modifica- tion, devised by the author, renders this method also applicable to soft rubbers: About 1 grm. of the sample is left in contact with 30 to 40 C.C. of carbon tetrachloride for twenty-four hours, and then mixed with about 250 C.C. of a solution of 6 C.C. of bromine and 1 grm. of iodine in 1,000 C.C.of carbon tetrachloride. After standing for six houm, ths liquid is mixed with half its volume of alcohol, allowed to stand for twelve hours, and then filtered. The filtrate will contain part of the excess of sulphur, resins, etc. The residue of caoutchouc tetrabromide is now treated with 10 to 15 C.C. of bromine, in which it dissolves after twenty-four hours. The solution is mixed with water and heated gently on the water-bath until the caoutchouc tetra- bromide rises to the surface, whilst the aqueous layer will contain the remainder of the excess of sulphur. This liquid is heated and filtered, and the residue heated three times with water to the boiling-point, and finally washed with alcohol and ether, and the sulphur it contains estimated by Henrique's method.Various comparative results by the two methods are given. Thus, a sample of Mexican rubber, which by the acetone method was found to contain 3.36 per cent. of combined sulphur, yielded only 1.52 per cent. by the new method. C. A. M.408 THE ANALYST. Analysis of Coal Gas and Similar Gaseous Mixtures, with Special Reference to the Estimation of Nitrogen in the Same. G. v. Knorre. (Chem. Zeit., 1909, 33, 717-719.)-The method described is a modification of that proposed by Jager (J. Gasbelewht, 1898, 764). The carbon dioxide, carbon monoxide, heavy hydrocarbons, and oxygen, are absorbed in the usual way, and the residue of gas is then passed over copper oxide heated to a temperature of 250" C. in a quartz tube from which the air has been displaced previously by pure nitrogen.The hydrogen is oxidised to water by the copper oxide, and the gas is passed to and fro over the oxide until no further diminution in volume takes place. The diminution in volume is equal to the volume of the hydrogen present. The residue of gas is again passed through the quartz tube after the copper oxide has been heated to bright redness, and the decrease in volume when the gas is brought in contact with potassium hydroxide is equivalent to that of the methane, this having been burned to carbon dioxide and the latter absorbed by the alkali. The final residue of gas represents the nitrogen. The copper oxide must be reoxidised from time to time and renewed when necessary. The total nitrogen may also be estimated by passing the original gas through the copper oxide tube heated to bright redness and filled with nitrogen.The residue of gas left after treatment with potassium hydroxide consists of the nitrogen in the original gas. w. P. s. Estimation of Fatty Acids in Soap. M. Dominiklewicz. (Chem. Zcit., 1909, 33, 728.)-The method proposed is similar in principle to the butyrometric estimation of fat in milk. From 40 to 60 grms. of the soap are dissolved in water and diluted to a volume of 1 litre. Ten C.C. of hydrochloric acid and 10 C.C. of the soap solution are then introduced into a tube having the shape of an ordinary butyrometer tube; the lower and wider part of the tube is closed by means of a rubber stopper, whilst the narrow graduated neck is provided with a metal screw-tap. The soap solution and acid are mixed by gently shaking the tube, and the latter is then placed in boiling water for five minutes, after which it is subjected to centrifugal action for five minutes.Boiling water is then added to the tube so as to bring the fatty acids into the graduated neck, and after being again whirled in the centrifugal machine, the volume of the fatty acids is read off at a temperature of 99" C. Each division of the scale corresponds with 0-1 c.c., and the weight of the acids is then calculated, the sp. gr. of the fatty acids at a temperature of 99O C. being taken into account. The results obtained by the iiiethod are stated to agree well with those yielded by the ordinary gravimetric process. w. P. s. The Alkalimetric Estimation of Hydroxylamine. A.Stahler. (Bey., 1909, 42, 2695-2696.)-Hydroxylamine is reduced by titanium sesquisulphate to ammonia., and may be estimated by titrating back the excess of titanous salt. But the employ- ment of standardised titanium solutions is inconvenient, owing to their extreme liability to oxidation. A better method, therefore, consists in distilling over the ammonia in the usual manner, since elaborate precautions to preserve the titauous reagent are unnecessary, provided an excess be employed. The same principle mayTHE ANALYST. 409 be applied to any substance which yields on reduction a volatile amine which can be titrated with acid--e.g., certain oximes, nitro- and nitroso-compounds. J. F. B. New Colour Reactions of Hydrastine, Hydrastinine and Narcotine.A. Labat. (BzdZ. SOC. Clzinz., 1909, [iv.!, 5, 742-743.)-Hydrastine, hydrastinine, and narcotine give coloured reactions with phenols in the presence of sulphuric acid. Theee colorations may be readily obtained by mixing 2 C.C. of sulphuric acid (sp. gr. 1.84) with 0.1 C.C. of an alcoholic solution of the alkaloid (1 : 300 in the case of hydrastine, and 1 : 100 in the case cf the others), adding 0.1 C.C. of the phenolic solution, and heating the tube in boiling water. With a 5 per cent. alcoholic solution of tannin or gallic acid there is produced an intense emerald-green coloration, which gradually changes to bright blue. On diluting the liquid with sulphuric acid and examining it spectroscopically, a characteristic absorption-band will be observed in the red part of the spectrum. This band can be clearly seen in very dilute solutions --e.g., 1 : 50,000 of hydrastinine, 1 : 40,000 of hydrastine, and 1 : 20,000 of narcotine.If a 5 per cent. alcoholic or aqueous solution of guaiacol or pyrocatechol be used in the test, there is produced a gooseberry-red coloration, which becomes darker, and then changes to a violet tint; whilst the use of an alcoholic solution of morphine hydrochloride (1 : 50) gradually gives a violet coloration. These reactions, however, are not so sensitive, especially as regards narcotine, as the coloration with gallic acid. C. A. IN. New Reactions of Opianic Acid, and their Use in the Detection of Hydrastine and Narcotine. A. Labat. (BUZZ. SOC. Chim., 1909, [iv.], 5, 743- 745.)-On oxidising hydrastine or narcotine by means of perrnanganate there is formed a considerable quantity of opianic acid, which forms characteristic coloured compounds with certsin phenols in the presence of sulphuric acid.A solution of 0.1 grm. of the alkaloid in 0.5 C.C. of 10 per cent, sulphuric acid is gently heated vith 2 C.C. of a 2 per cent. solution of potassium permanganate until the pink colour has disappeared. The liquid (which will be fluorescent in the case of hydrastine) is then mixed with 2-5 C.C. of alcohol, and the solution used for the tests for opianic acid. On mixing 0.1 C.C. of a 1 per cent. alcoholic solution of that acid with 2 C.C. of sulphuric acid (sp. gr. 1.84) and 0.1 C.C. of the phenolic solution, the following reactions are obtained: With a 5 per cent. alcoholic solution of gallic acid a blue coloration rapidly appears, to give place to a leaf-brown.With a 5 per cent. alcoholic solution of guaiacol the coloration is gooseberry-red, changing to an in tense blue when heated on the water-bath. Similar colorations are obtained with pyro- catechol. With a-naphthol there is a gooseberry-red coloration, and with /3-naphthol a wine-red coloration. I n both cases the liquid should be cooled, since the intensity of the colour is diminished on heating. A 5 per cent. alcoholic solution of codeine gives a violet coloration, gradually changing to blue on the water-bath, whilst an alcoholic solution of p-methylnaphthol (1 : 40) gives a bright violet colour, which fades on heating. C. A. M,410 THE ANALYST. Estimation of Indigo in Dyed Cotton.E. Knecht. ( J . SOC. Dyers and Colour., 1909, 25, 135; through Chem. Zeit. Rep., 1909, 33, 347.)-The method proposed is based on the solubility of both cotton and indigotin in 80 per oent. sulphuric acid at a temperature of from 35" to 40" C., and to the fact that the indigotin sulphate formed, when treated with water, dissociates with the separation of the whole of the indigotin. Four grams of the fabric in the form of small pieces are heated with 25 C.C. of 80 per cent. sulphuric acid for about ten minutes at the above-mentioned temperature. The solution is then diluted with water to a volume of 120 c.c., and filtered through a Gooch crucible containing sand and asbestos as a filtering medium. After being dried at 110" to 120" C., the contents of the crucible are heated on the water-bath with a little sulphuric acid for one hour, and the indigo sulphonate is then dissolved in water and titrated with either titanous chloride or permanganate solution.Test analyses showed that the method is accurate, and that the basic colours and sulphide-blues employed with indigo do not interfere with the results obtained; the first mentioned remain in the sulphuric acid solution, and the second are destroyed. Manganese bases must, however, be removed previously by treatment with bisulphite. w. P, s. Colorimetric Method for the Estimation of the Molecular Weights of Carbohydrates - 11. Differentiation of Primary from Secondary and Tertiary Alcohols. L, Wacker. (Ber., 1909, 42, 2675-2680.)-1n a previous paper (ANALYST, 1908, 33, 131) the author described a method for the determination of the molecular complexity of carbohydrates, depending on the fact that solutions of carbohydrates containing an equal number of molecules give colorations of equal intensity with an alkaline solution of phenylhydrazine sulphonic acid.This circum- stance is probably due to the presence of the same number of chromophoric groups in the molecule, and it suggests that only the terminal aldehydic or primary alcoholic group is concerned. Secondary or tertiary alcohols react far less readily, and the reaction may serve for distinguishing the primary alcohols from these others. For the est.imation of the molecular complexity of carbohydrates a colorimetric standard is necessary, which may be either maltose or dextrose; the latter sugar gives some- what bluish shades of red, which causes the results to appear 5 or 10 per cent.stronger than with equivalent solutions of di- or polysaccharides. I n the present communication the author deals more particularly with starch. If starch be boiled with 1,000 times its weight of water, a solution of "readily soluble granulose" is obtained, which remains clear when cold; the product was isolated and tested by this method, and showed a complex of 5 hexose residues. Further €ractions were obtained jn a similar manner by repeated extractions of the residue, and there were thus found : '' Sparingly soluble granulose " composed of 6 hexose groups ; " once- boiled starch cellulose'' with 7 hexose groups; and '' repeatedly boiled starch cellulose " with 8 hexose groups in the molecule. '' Achroodextrin " and " erythrodextrin " were found both to contain 4 hexose groups; glycogen from liver showed 10 hexose groups.For the classification of alcohols centinormal solutions are prepared, and 10 or 20 C.C. are placed in a series of cylinders and diluted to 100 C.C. each. A sufficient quantity of phenylhydrazine sulphonic acid is weighed out to allow 0.4 grm. for each test, andTHE ANALYST+ 411 dissolved in sufficient dilute sodium hydroxide to contain this quantity in 1 C.C. of solution, which should be used quite fresh. Immediately after adding the phenyl- hydrazine compound, 25 C.C. of a 33 per cent. solution of sodium hydroxide are added $0 each cylinder, and these are shaken every fifteen minutes during the first two to three hours to develop the coloration; the colours are best compared after seven to eight hours.If primary, secondary, and tertiary alcohols be compared with each other and with a blank (water), it will be observed that only the primary alcohols show intense colorations, and the other alcohols differ little from the blank. Amines and amino acids also give red colorations with phenylhydrazine sulphonates under the 8ame conditions. J. F. B. Estimation of Molecular Weights by the Boiling-Point Method. R. Meyer and K. Desamari. (Bey., 1909, 42, 2809-2814.)-The authors have investigated a discrepancy which has arisen in the molecular weight of tribromresoquinone. When the boiling-point of the pure solvent (benzene) was redetermined after the estimation of the molecular weight, it was found to have changed: the benzene boiling at 79.400" C. before the experiment, boiled at 79425O C . after the experiment. This difference of 0.025" C. with such dilute solutions (1.5 to 2 per cent.) makes a difference of nearly 300 units in the molecular weight of the quinone, hence the discrepancy. The difference can only be explained by an alteration of the barometric pressure during the period elapsing between the two determinations of the boiling-point, and from existing data, it is calculated that 1 mm. difference in pressure corresponds to 0.0427" C. difference in boiling-point for benzene. Thus, in molecular weight determinations it is of the highest importance to eliminate this error by correcting for any alteration of barometric pressure, For this purpose an ordinary vertical barometer is not sufficiently delicate, and the authors have employed an extremely sensitive aneroid barometer, such as is used for the determination of altitudes, which can be read to tenths and even hundredths of a millimetre. The thermometer employed could be read to of a degree. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9093400405

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST+ 411 INORGANIC ANALYSIS. Estimation of Alkalis in Silicates. G. Starck. (Zeit. aiznl. Chenz., 1909, 48, 415-428.)-This paper deals with the estimation of potassium and sodium in the decomposition products of silicates by means of hydrofluoric and sulphuric acids. The method is based on the solubility of sodium platinic chloride and of barium chloride in methyl alcohol. It has the advantage over the usual method that the excess of barium chloride need not be removed after converting the alkali sulphates to chlorides. The weighed mixture of sodium and potassium sulphates is dissolved in water in a measuring-flask of such capacity that when the flask is filled the concentration of the sulphate is 0.015 to 0.030 normal; hydrochloric acid is then added in such quantity that its concentration is 0.075 to 0.15 normal under the same condition; the flask is then filled as far as possible, the liquid heated to boiling, and precipitated with a, quantity of barium chloride solution calculated on the assumption that the entire mixture is sodium sulpbate, The liquid is cooled, made up to the412 THE ANALYST.mark, and filtered through a dry filter. The first portion being rejected, an aliquot part of the filtrate is measured, concentrated if necessary, and evaporated to dryness in a small dish, after adding one and a half times the calculated quantity of platinu tetrachloride. The residue is moistened with water, which is allowed to evaporate at room temperature. The residue is then stirred with successive small quantities of 80 per cent.methyl alcohol, which are poured through a filter until colourless. The potassium platinic chloride is then transferred to the filter, and dried as usual at 130" C. As it nearly always contains a few tenths of a milligram of barium chloride, the precipitate is finally dissolved in hot water, and a drop of sulphurio acid added, and the barium sulphate weighed. For quantities of up to about 0.2 grm. each of potassium sulphate and sodium sulphate, the method yields results accurate to within 0.5 per cent. on the potassium sulphate. The small error made by neglecting the volume of the barium sulphate precipitated in the measuring-flask is almost exactly balanced by an error due to adsorption of potassium by barium sulphate. A. G. L. Gravimetric Estimation of Boric Acid.K. Arndt. (Chem. Zeit., 1909, 33, 725-726.)-The following method is proposed for the estimation of small quantities of boric acid in such substances as fireproof pottery, ctc., and consists in decomposing the material by fusion with potassium hydroxide, acidifying and distilling the melt in the presence of methyl alcohol, and evaporating the methyl ester with an excess f sodium tungstate: Fifteen grms. of potassium hydroxide are fused in a, nickel crucible; the burner is then removed, and as soon as the alkali has crystallieed a weighed quantity of about 3 grms. of the finely powdered sample are introduced. The crucible is covered, and the contents kept fused at a bright-red heat for three hours. When cold, the melt is dissolved in hot water, the solution is acidified, introduced into a distillation-flask, and the boric acid removed by repeated distilla- tions to dryness with methyl alcohol, The distillate is collected in a vessel contain- ing a known weight of previously fused sodium tungstate ; the solution is evaporated to dryness in a platinum vessel, and the residue is fused, cooled, and weighed.The increase of the weight of the sodium tungstate is equivalent to the amount of boric acid present. The author finds, however, that the results obtained are about 25 per cent. too low ; for instance, if 16 mgm. of boric acid mere really present, only 12 mgm. would be found. The loss appears to be due to the presence of the large excess of aluminium salts, which retain boric acid during the distillation.w. P. s. Some Rapid Electrolytic Precipitations and Separations. H, Alders and A. Stahler. (Bey., 1909, 42, 2685-2695.)-The authors have used a mercury cathode for the electrolytic determination of various metals. The apparatus consists of a, small wide-mouthed flask with a strongly-domed bottom. The mercury cathode then forms a ring around this dome, and electrical contact is established by means of three platinum wires fused into the bottom of the flask, which is then stood on a, copper plate connected with the battery. The anode consists of a flat spiral of platinum wire, situated a short distance from the bottom of the flask and connected with a rotating shaft above, which is rotated at 400 to 600 revolutions per minuteTHE ANALYST. 413 by an electro-motor.The mouth of the flask is closed, to prevent splashing, by a funnel without a stem, through the centre of which passes the wire holding the anode. The mercury employed must be of the purest possible description, carefully washed with pure alcohol and ether ; any impurities left in the mercury will tend to produce a scum. The process is admirably adapted for the electrolytic deter- mination of mercury salts in dilute' nitric acid solutions and for the separation of mercury from arsenic. With a current of 3 to 4 ampires at 6 volts the whole of the mercury is deposited in about fifteen minutes, and the increase in weight of the flask and cathode after washing and drying is ascertained. Satisfactory results have also been obtained in the case of copper and silver salts.In the case of certain other metals-e.g,, zinc, iron, and lead-difficulties were encountered in washing the fluid amalgams produced at the cathode, o.ccing to the formation of films of oxides on the surface. The authors have, however, succeeded in working out a perfectly satisfactory method for the electrolytic deposition of lead and its separa- tion from arsenic, by depositing the metal in the form of a solid amalgam, in presence of nitric and phosphoric acids. The electrolysis is effected in a platinum dish, and the amalgam is produced by adding to the solution of lead nitrate an equal amount of a solution of mercuric chloride or nitrate of known concentration, so that the two metals are deposited together. Since the amalgam is somewhat attacked by acids, it is desirable, when the greater part of the metal has been deposited, to neutralise the acid gradually by the cautious addition of sodium hydroxide, care being taken not to neutralise too soon, otherwise lead phosphate will be precipitated.The course of the exhaustion of the liquid may be followed by testing externally with ammonium sulphide. After all the metal is precipitated, the liquid is nearly neutralised, and the deposit of amalgam is washed. I t is preferable to exclude chlorides, and to work with niercurous nitrate, since in the former case the platinum cathode is slightly attacked. J. F. B. Action of Gaseous Hydrogen Chloride on Aluminium. Estimation of Metallic Aluminium. E. Kohn- Abrest. (Ezdl. SOC. C ~ L . , 1909, 5, 768-775.) - Metallic aluminium is completely volatilised as chloride by heating in a, current of dry hydrogen chloride at 300" C.for twenty-five minutes, after a preliminary heating for ten minutes in dry hydrogen at the same temperature. The aluminium chloride is condensed in dilute sulphuric mid. Any residue left consist8 essentially of the aluminium hydroxide present in the sample, containing a small quantity of chlorine and non-volatile neutral chlorides of other metals such as calcium (cf. ANALYST 1909, 67). A. G. L: Estimation of Iron by Permanganate in the Presence of Hydrogen Chloride. J. A. N. Friend. (J. Chenz. Soc., 1909, 95, 1228-1235.)-The author shows that ferrous iron can be titrnted with potassium permanganate with an error not greater than 0.06 C.C. of the latter solution, in the presence of hydrochloric acid, provided that the concentration of the hydrochloric acid is not greater than :, that about 2 grms. of hydrated manganous sulphate are added, that the total volume does not exceed 200 c.c., and that the titration is performed somewhat slowly,414 THE ANALYST.especially at the end. An increase in dilution diminishes the accuracy of the results, but renders the end-point sharper. The presence of small quantities of sulphuric acid is beneficial. The effect of temperature was not investigated. The quantities of potassium permanganate solution dealt with were about 25 to 28 C.C. of & solution (cf. Jones and Jeffery, ANALYST, 1909, 306). A. G. L. Colorimetric Estimation of Lead in the Presence of Iron, with some Notes on the Preparation of Lead-free Reagents by Coprecipitation with Ferric Hydroxide.J. M. Wilkie. (J. SOC. Chenz. Ind., 1909, 28, 636-6384 --The author shows that small quantities of iron are capable of interfering seriously with the colorimetric estimation of traces of lead as sulphide, unless precautions are taken. Precipitation of iron by ammonia, with subsequent filtration, is not feasible, as lead is completely removed from solution by this operation when only two parts of iron are present for one of lead. If the iron is in the ferrous condition, it may be rendered harmless by adding 1 C.C. of a 10 per cent. solution of potassium cyanide to the neutral or very slightly acid solution, shaking, and adding 0.5 C.C. of strong ammonia solution ; sodium sulphide solution is then added as usud.If the iron is in the ferric condition, it must first be reduced. This is done by adding 1 C.C. of a saturated aqueous solution of sodium sulphite and 4 drops of hydrochloric acid, heating, then adding 1 C.C. of potassium cyanide solution and 2 C.C. of ammonia to the colourless solution, boiling gently, and cooling. This method fails for citric and tartaric acids. If these substances are preseat, any ferric iron must be reduced by boiling the aqueous solution of the acid with 2 C.C. of TT sodium thiosulphate solution for a few minutes; potassium cyanide and excess of ammonia are then added, and the whole gently boiled until colourless. A. G. L. Estimation of Lead and Cadmium in Zinc. E. J. Ericson. (Eyzg. and X ~ L Jozmz., 1909, 87, 1036; Chem.Zeit. Rep., 1909, 33, 368.)-This method for the estimation of lead is claimed to give results accurate to a thousandth of a per cent. The sample may be dissolved in dilute hydrochloric and sulphuric acids. The use of trichloracetic acid, recommended by Fox instead of mineral acids, is advantageous when the cadmium has to be separated. For the estimation of lead, 19.2 grms. of the sample of zinc are placed in a beaker with 50 C.C. of hydrochloric acid (1.1 sp. gr.) and heated; dilute hydrochloric acid is added until the zinc is dissolved, all but 1 to 1.5 grm. The residue is filtered off, washed and dissolved in nitric acid; any traces of tin and antimony which may possibly be present are filtered off, the filtrate is diluted to 100 c.c., 30 C.C. of ammonia and 4 to 5 grms.of solid ammonium persulphate are added; the liquid is boiled for five minutes, allowed to settle, filtered, and the precipitate washed first with 10 per cent. ammonia solution and then with water. The precipitate, still on the filter, is dissolved in 25 to 50 C.C. of hydrogen peroxide, 15 C.C. of nitric acid (1.2 sp. gr.), and 100 C.C. of water are then added ; the excess of peroxide being titrated back with permanganate (0.568 grm. per litre; 1 C.C. = 0.01 per cent. of lead). For the estimation of the cadmium, the ammoniacal filtrate is evaporated uutil it is nearly neutral, 35 C.C. of dilute sulphuric acid (1 : 3) are added, the liquid is boiled down to a volume of 150 c.c., saturated with sulphurettedTHE ANALYST. 415 hydrogen, and warmed after the addition of 25 C.C.of water. The precipitated cadmium sulphide, which is contaminated with zinc sulphide, is filtered off, dissolved in hydrochloric acid (1-1 sp. gr,), and washed; any copper sulphide which may be prasent remains behind. The filtrate is neutralised with ammonia, the precipitate is redissolved in trichloracetic acid, the liquid is diluted to 150 c.c., and again saturated with sulphuretted hydrogen. The cadmium is then estimated as sulphate or phosphate. For the estimation of lead in ores, the author advises that thd permanganate value for lead, which is 1-92 times that of iron, be changed to 1-95 times that of iron, J. F. B. Volumetric Estimation of Lead and Sulphuric Acid. B. Odd0 and A. Beretta. (Gazx. Chiin. ItaZ., 1909, 39, 671-675.)--Lend.-The method proposed is essentially the well-known one of Schwarz, which consists in precipitating the lead by means of a, standard solution of potassium chromate.As it is difficult to determine the end-point of the reaction by the use of silver nitrate as indicator, the author uses test-papers of symetrical diphenyl-semi-carbazide acetate, prepared as described in the abstract on p. 416. A brilliant violet tint is obtained on adding powdered diphenyl carbazide to a solution of a chromate, acidified with acetic or hydrochloric acid, the coloration being still discernible in a solution of 1 part in 1,000,000. Sutphwic Acid in its Salts.-The hot solution of the sulphate is treated with an excess of a standard solution of lead nitrate, bhe precipitate of lead sulphate filtered off and washed with cold water, and the excess of lead in the filtrate estimated by titration with potassium chromate, with diphenyl-carbazide acetate paper as indicator. C.A. M. Electrochemical Behaviou’r of Manganese. C. N. 0 tin. (Zeit. Electro- chem, 1909, 15, 385-385.)-The method of Engels for the electrolytic determination of manganese (Zeit. Electrochem., 1895, 2, 413; 1896, 3, 256, 305) was based on experiments made with manganese ammonium sulphate, and Engels did not recognise that the presence of ammonium sulphate aided the regular deposition of the oxides of manganese on the anode. Applied to solutions of manganese sulphate free from ammonium salts, the method yields low results even when the current density is limited to that suggested by Engels (0% to I ampere per 100 sq.cm.), and with higher current densities the error is greatly increased. The loss is due $0 the deposition of a portion of the manganese as metal on the cathode. Engels’ method gives fair results with solutions of manganese nitrate, but, when manganese is present ag sulphate, 2 grms. of ammonium sulphate should be added in addition to the chrome alum and sodium acetate, With this modification, current densities as high as 5 or 6 amperes per 100 sq. cm. may be employed without ill effect. In absence of ammonium sulphate, the employment of a current density of 4 arnpdres would lead to the deposition of 25 per cent. of the manganese on the cathode. G. Cs. J.416 THE ANALYST, Electrolytic Estimation of Manganese.C. N. Otin. (Zeit. Electrochenz., 1909, 15, 386-389.)-The observation of the influence of ammonium sulphate on the deposition of manganese (see preceding abstract) led the author to try whether the presence of this salt would make it possible to deposit manganese as MnO, instead of as a mixture of oxides. At ordinary temperatures, with a current density of from 0% to 0-9 amperes per 109 sq. cm., deposition as hydrated peroxide is complete iE the experiment be allowed to proceed over-night. At a temperature of 60' to 65" C. 0.5 grm. of MnO, may be deposited in three hours, but the author prefers the slower method. Addition of alcohol (3 to 8 c.c.) to the solution to be electrolysed renders the deposit more closely adherent to the anode and thus facilitates washing.The hydrated peroxide is dried at 200" to 220" C. €or from one and a half to four hours according to its bulk. The dried deposit contains slightly less oxygen than corre- sponds to the formula UnO,, the average composition being represented by the formula Mn0.60;Mn02. The error involved in assuming it to be lllnOa is only 0.3 per cent. G. C . J. Volumetric Method of Estimating Mercury. W. H, Seamon. (Eng. and Mining J o z L ~ . , 1909, 87, 1047-1048.)-Half a grm. of the finely-divided ore (cinnabar) is heated for five to ten minutes at 40" C. with 5 C.C. of strong hydro- chloric acid, after which 3 C.C. of nitric acid are added. If lead is present, 3 C.C. of strong sulphuric acid are also added. The solution is treated drop by drop with 5 C.C. of ammonia solutlion and with 25 C.C.of water and filtered, and the precipitate washed with as little water as possible. The filtrate and washings are acidified with 2 C.C. of nitric acid, containing nitrous compounds and titrated with a solution of 8-3 grms. of potassium iodide in a litre (1 C.C. = 0.005 grm. of mercury), with starch used in a spditing test as indicator. If the volume of the liquid exceeds 50 C.C. a deduction of 0.5 C.C. is made from the reading. Free chlorine interferes with the accuracy of the method, but small quantities of iron, copper, antimony, arsenic, and bismuth do not affect the results. The method is shown to give results agreeing fairly well with those obtained gravimetrically. C. A. M. Volumetric Estimation of Mercury in Mereurous Salts. B. Oddo. (Gaxx.Chim. Itnl., 1909, 39, 666-G69.)-The solution of the mercurous salt is titrated with a solution of sodium chloride until in a, spotting test a drop of the clear liquid (free from mercurous chloride) ceases to give a blue coloration with symmetrical diphenyl-semi-carbazide. This compound reacts with mercurous salts to form a mercurous diphenylcarbazone- n /NHg - NHg.C,H, 'O\N = N.C,H,, which is of an intense blue colour quite distinct from that given by copper salts and certain oxidising salts with diphenylcarbazide. The coloration is also characterised by being fairly stable in the presence of nitric acid, so that it is possible to titrate the mercury in acid solutions of mercurouB nitrate. The indicator may be preparedTHE ANALYST, 417 by the interaction of urea (1 molecule) with phenylhydrazine (2 molecules) at a temperature of about 150" C., until ammonia ceases to be evolved.I t is dissolved in acetic acid, and strips of filter-paper are saturated with the solution and dried. For the estimation of mercury in mercurous salts in the presence of mercuric salts, the mercurous mercury is first precipitated by means of a known excess of sodium chloride and filtered off. The mercuric mercury in the filtrate is then precipitated by means of hydrogen sulphide, and the filtrate from this precipitate boiled (to expel hydrogen sulphide), and the excess of sodium chloride present titrated with a standard solution of mercurous nitrate. Mercurous nitrate containing 2.17 per cent. of mercury was found by this method to contain from 2.01 to 2-13 per cent.C. A. M. Eleetrolytie Estimation of Nickel in Ores, Steel, ete. C. S. Tatlock. (Zeits. anaZ. Chein., 1909, 48, 433-437.)-Five grms. of the ore are dissolved in aqua regia, and the solution is evaporated to dryness. The residue is dissolved in hydro- chloric acid and hot water; the total volume should be less than 200 C.C. The cooled liquid is then treated with bromine water, followed after a few minutes by ammonia. The precipitate is dissolved in hydrochloric acid, and reprecipitated as before. The mixed filtrates are then electrolysed with a current density of 2 LO 4 ampdres. Electrolysis is continued until the cathode shows no further gain in weight. If the deposit is large, it is advisable to dissolve it, and to redeposit it on a clean electrode.The nickel and cobalt so obtained are separated by a modification of Clark's process: The deposit is dissolved in hydrochloric, nitric, or sulphuric acid. Ammonium phosphate (about five times the total weight of nickel and cobalt) is added, followed by hydrochloric acid (about twenty-five times the same weight) ; the liquid is boiled for a few minutes, and ammonia added in small quantities at a time, until the precipitate formed just redissolves. The liquid is well stirred for one minute, when the cobalt is precipitated as crystalline cobalt ammonium phosphate ; 10 drops of ammonia are added, and the whole heated for one or two minutes on a water-bath. The precipitate is allowed to settle, filtered, washed, ignited, and weighed as Co,P,07. The filtrate, ehich is blue if nickel is present, is boiled until nickel begins to separate.If this precipitate shows a red tint, it contains cobalt ; in this case it is dissolved in hydrochloric acid, and cobalt separated as above. Manganese must be absent in this separation. The same method is used for the analysis of steels, but the original solution need not be evaporated to dryness. Up to the end of the electrolysis the analysis requires only three hours. The test results agree to within 0.2 per cent. with those given by purely chemical methods, the electrolytic values being generally higher. A. G. L. Estimation of Total Nitrogen. V. Schenke. (Chem. Zeit., 1909, 33, 712-713.)-1n the presence of large quantities of nitrites the results obtained by the usual methods of estimating nitrogen are too low.To obviate this it is necessary first to oxidise and then to reduce the nitrous compounds, and afterwards to destroy the organic matter by Kjeldahl's method. This can be done in the following418 THE ANALYST. manner : From 0.5 to 2 grms. of the substance containing the nitrite, is mixed in 8, Iijeldahl flask with about 50 C.C. of water and about 1 grm, of potassium chlorate (at least one part of chlorate for each three parts of nitrous acid), and about 3 C.C. of dilute sulphuric acid (1 : 2) introduced, drop by drop, so as to prevent the escape of nitrous vapours. The flask is then left for at least 15 minutes in the cold, after which its contents are reduced by Ulsch's method by the addition of 2 to 4 grms. of ferrum redactunz, and about 15 C.C. of the dilute sulphuric acid.Finally, 30 C.C. of concentrated sulphuric acid and a drop of mercury are added, and the nitrogen estimated by Kjeldahl's method. In the case of a crude calcium nitrite the oxidation of the nitrous nitrogen was also effected by means of an excess of potassium permauganate, with the addition, drop by drop, of a few C.C. of dilute (1 : 2) sulphuric acid. The product contained 17.8 per cent. of nitrogen, of which 16-7 per cent. was nitrous nitrogen. The accuracy of the method of oxidation with potassium chlorate and sulphuric acid was tested upon a sample of pure silver aitrite. The nitrogen found in four estirnaticns varied from 8.99 to 9.03 per cent., as against the theoretical 9.09 per cent. C. A. M. Some Modifications in the Estimation of Nitrogen by Kj eldahl's Method.J. Sebelien, A. Brynildsen, and 0. Haavardsholm. (Chenz. Zeit., 1909, 33, 785; 795-'796.)--The digestion part of the Kjeldahl process may be carried out in an electrical heater. I t is constructed of fire-resisting material enclosed in a metal jacket, the interior being of mfficient size to hold the digestion flask which rests on a resistance gauze fitted at the bottom of the heater. By using a current of 110 volts and 1.7 ampAres the contents of the flask may be heated to a temperature of 200' C. within 15 minutes, and to 360" C., or more, in a short time. Instead of distilling the ammonia in the usual way, the authors place the diluted acid liquid in a flask, which is closed by a stopper carrying two tubes; one reaches below the surface of the liquid in the flask, and the outer end of this tube is connected with a flask containing the necessary quantity of sodium hydroxide solution, to which a little sodium sulphide has been added.The other tube is connected with a flask containing a definite volume of standard acid. Air is then aspirated through the three flasks, drawing the sodium hydroxide over into the acid solution. On continuing the current of air all the ammonia is carried over into and absorbed by the standard acid. I t is necessary to draw 100 litres of air per hour for about two hours to insure all the ammonia being removed from the digestion solution to the standard acid. A series of the apparatus (three flasks) may be connected together, and one current of air used for the whole, so that a number of estimations may be carried out together.w. P. s. Detection of Nitrates in the Presence of Bromides. Villedieu. ( J . Plznin~ Chim., 190'3, 30, 66-67.)-The coloration given by nitrates with sulphuric acid and ferrous sulphate is masked by the colour of the iron bromide formed when a bromide is present. In such cases the following method of applying the test gives good results with solutions containing only a minute quantity of nitrate and a large amount of bromide: The liquid, after neutralisation, if required, isTHE ANALYST. 419 shaken with an excess of basic lead acetate solution, and allowed to stand. The supernatant liquid is decanted from :he lead bromide on to a filter, and the filtrate heated to the boiling-point, treated with sufficient powdered sodium sulphate to precipitate the lead, and again filtered. One C.C. of the filtrate is mixed with 1 c.c, of sulphuric acid, and one drop of the cooled mixture added to a few drops of a reagent prepared by mixing sulphuric acid with a very small quantity of powdered ferrous sulphate. I n the presence of nitric acid the characteristic reddish-vjolet coloration is obtained. C. A. M. Estimation of Small Quantities of Nitric Acid. L. Farcy. (BzLZZ. Xoc. Chim., 1909, 5, 775-779.)-The author shows that, in the estimation of nitric acid, the presence of ammonium chloride causes large errors, both when MacGowan’s method (distillation with hydrochloric acid and titration of iodino liberated from potassium iodide) and Frerich’s method (conversion into chloride by evaporation with hydrochloric acid) are used. When ammonium chloride is present, the method of Granval and Lajoux is recommended. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9093400411

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 419 APPARATUS, ETC. (Pharm. Zeiztmlb., 1909, 50, 506 ; Chm. h i t . Rep., 1909, 33, 369.)-The Allihn’s sugar-tube is constructed with a platinum wire-gauze support for the asbestos, which is suitably kept in position by means of a moderately thick wire bent at right angles. Improved Allihn’s Tube. W. Friese. C. A. M. Apparatus for the Automatic Regulation of the Pneumatic Agitation of Liquids. H. Deneve. (BUZZ. SOC. Clzinz. Bely., 1909, 23, 315-318.)-Muller’s method of agitating, by means of a single water-pump, the liquids contained in any number of vessels consists in alternately raising and lowering part of these liquids. I I For this purpose a horizontal tube attached to the pump is connected by means of side tubulures with a number of glass cylinders of varying, diameter and length, perforated at their lower ends with a certain-number of openings.These tubes are420 THE ANALYST. placed vertically in the liquids to be agitated, and when the connection with the pump is opened, the liquid rises in each of them, to fall again and produce an agitation as soon as the vacuum disappears. The interrupter intended to create and suppress the vacuum in Muller’s apparatus is on the principle of a mercury valve; but as this has not proved satisfactory in the author’s hands he has constructed the electrical device shown in the diagram. It consists of a brass rod moving vertically on a pivot at 0, so that it can close at a, a tube, t, connected with the vacuum tube: Below the other arm of the rod is fixed an iron plate, a’ (which will be attracted by the electro-magnet below), and a screw, v, the point of which can dip into the mercury in 9.The tube, Z’, in which a double contact can be made, is also connected with the horizontal vacuum tube. Two electric circuits can thus be formed with the aid of an accumulator. The tube, t, being closed, the aspiration is started. The mercury rises in T, touches b without result, and then reaches a, and closes the circuit which works the electro-magnet. The rod turns on o and opens the tube, t, with the result that air is admitted and the mercury falls again in T. But the point of the screw, v, is now immersed in the mercury in 9, and thus closes a new circuit, which lasts until the fall of the mercury in T breaks the current at b. The rod then falls back at a and closes the tube, t, again, and the suction begins anew.With the aid of this apparatus it is possible to eEect from 1,200 to 1,800 consecutive ‘‘ stirrings ” of aqueous solutions per hour. C. A. M. New Laboratory Apparatus. J. Wiese. (Chenz. Zeit., 1909, 33, 738.)- I . Water Suction-pipe with enclosed Check-valve. - A new form of water-pump containing a check-valve for preventing the sucking back of the water into the flask is described; it also possesses the advantage of closing up the orifice so that the vacuum is maintained for several hours. The arrangement (see Fig. 1) con- sists of a flat rubber-washer resting on the lower stem of the pump. When the water tends to rise in the jet-chamber, this washer rises with it and is pressed against an annular constriction made in the jet- chamber to act as a seating.II. Vacuum Desiccator with Safety Air-cock. - A vacuum desiccator is de- scribed which is provided with an air inlet which avoids the disturbance of any powdered substance which may be inside the desiccator when the air-cock is opened. FIG. 2. When the air-cock, a (Fig. 2), is opened, the air first enters the tube, b, which is widened out at the bottom in the shape of an inverted mushroom, aud has several small holes, c, in the upper surface of the widened portion, through which the air enters the desiccator in an upward direction, The tube, b, is surrounded by a, glass dome, d, which constitutes the ground-glass .&opper of the desiccator. The air impinges against the dome, and is thence deflected FIG.1. UTHE ANALYST 421 uniformly downwards through the annular orifice between the widened inlet tube and the edge of the stopper into the body of the desiccator. J. F. B. New Apparatus for Purification of and Extraction by Ether. R. Fritsch. (Chem. Zeit., 1909, 33, 759-760.)-For syntheses according to Grignard’s method a copious supply of ether, carefully purified from water and alcohol, is necessary. Kopp’s method, depending on the oxidation of the alcohol by chromic acid and the destruction of the aldehyde produced, by means of potassium hydroxide, is economical, but very tedious for large quantities. The usual method, consisting in shaking the ether twenty to twenty-five times with successive quantities of water, involves a great waste of ether and,is very laborious.The waste may be avoided to a large extent by using calcium chloride solution instead of water. The author has devised an apparatus for effecting this extraction automatically, thus saving the labour of shaking. The calcium chloride solution, C, is contained in the inverted Woulff’s bottle, W (see Fig.), which is filled up to a point 3 or 4 mm. below the mouth of the siphon arrangement, H. The ether is placed in the spherical flask, A, and boiled in the water-bath, B. The vapours rise through the tube u, and enter the calcium chloride solution at the point b. Passing thus in the form of vapour through the washing liquid, the ether is brought into the most intimate contact with the latter. The vapours ascend through Vinto the condenser K, and the ether collects in the form of a layer, A, on the surface of the calcium chloride until it reaches a level at which the siphon comes into action and returns it to the distillation flask. The same arrangement may also be used instead of a separatiug B funnel for the extraction of liquids by means of ether, the liquid to be exhausted being substituted for the calcium chloride solution, and the extracted substance being accumulated in the distillation flask.When the operation is finished, the pinch- cock, Q, must be opened to prevent the calcium chloride from being sucked back into the flask, and the latter is cooled with water. Owing to the fact that the calcium chloride solution, or the liquid under extraction, is maintained at a temperature about the boiling-point of the ether, the purification of the ether, or the extraction of the liquid, is very rapidly effected.Other solvents than ether may be used, provided their sp. gr. is less than that of the liquid in the Woulff’s bottle. J. F. B. Use of the Centrifuge in Assay of Volatile Oils. F. X. Moerk. (Amer. J. Phurrn., 1909, 81, 326-328.)-The author has applied the centrifugal method to the assay of the oils of cloves, pimenta, thyme, and cassia. The Babcock milk- and cream-bottles were employed in connection with a Bausch and Lomb centrifuge, The milk-bottles held 48.8 C.C. up to the graduated neck, and the latter 2.32 C.C. from 0-10 divisions in fifths, and thus one division = 0,046 C.C. ; the cream-bottles held 46.4 c.c., the graduated neck 7.82 C.C. from 0-40 with divisions into halves, thus422 THE ANALYST. =0*09775 C.C.per division. These bottles, when corked, were found to answer the purpose, and the necessary calculation can be easily made. All bottles should be verified as to the graduations. Assay of Oils of Cloves, Pimenta, and Thyme.-Mix about 5 C.C. or 10 C.C. of carefully-measured oil with 30 to 35 C.C. of 10 per cent. caustic potash or soda solution ; cork the ,bottle and shake thoroughly for several minutes, add alkali to bring the mixture well into the graduated neck, cork, and whirl in the centrifuge for three to ten minutes at 1,000 revolutions per minute. The results are 1 to 2 per cent. in excess of the amount of phenols obtained by the U.S. pharmacopaial process, and are constant, Assay of Oil of Cassia.-Mix 2 or 3 C.C.of the carefully-measured oil with an equal volume of turpentine oil, then add 30 C.C. of saturated sodium sulphite solution and a few drops of phenolphthalein solution, cork the bottle and warm in the water- bath for ten to fifteen minutes, repeatedly agitate, acidify with 36 per cent. acetic acid, make up with sulphite solution into the graduated neck, recork the bottle, and whirl until the insoluble oil separates. Perform a blank test with the turpentine oil, and make the necessary deduction. The results are 5 per cent. by rolume of aldehyde in excess of those given by the pharmacopoeia1 method. A. R. T. Cool, and read off the volume. Mercury Joint for connecting a Combustion-Tube with the Calcium Chloride Tube. J. Marek. ( J .pmkt. Chem., 1909, 79, 510-512.)-The mercury joint, devised by the author (ANALYST, 1907, 32, 398), has been further simplified as shown in the figure. The end of the combustionis drawn out to a point about 2 to 5 rnm. in diameter and bent at right angles. Over this part is fitted, by msans of a, cork, a glass tube about 2.5 to 3 c.m. in length and about 3 c.m. in diameter, and beneath the cork is fixed an asbestos disc. In the well thus formed is poured the necessary amount of pure dry mercury. The calcium chloride tube has an attach- ment which ends in a wide-mouthed tube directed downwards. This tube passes over the upward point of the combustion-tube and rests on the cork forming the bottom of the mercury-well, the mercury thus forming an air-tight joint. C.A. N. Constant Level Reservoir. W. P. Fitzgerald. ( J . Amer. Chem. SOC., 1909, 31, 839-840.)-The author has devised an apparatus similar in action to the inverted flask over a funnel containing its filter-paper. It consists of a cylindrical reservoir having a perforated stopper at the top carrying a glass rod, a d a stoppered side-tube at the top. The lower portion of the vessel is drawn out to a small opening, about one-third of the bore of the cylindrical reservoir, The glass rod passing through the perforated stopper at the top terminates in a glass stopper at its lower extremity, and, to use the apparatus, is pushed down until it closes the apparatus. The solid rubber stopper is then removed from the side-tube, and the liquid to be filteredTHE ANALYST, 423 poured in.The rod is slightly raised until enough liquid has entered the funnel to close the lower opening. The stopper is then replaced in the side opening, and the glass rod raised one or two inches. The level of liquid in the funnel recedes, air enters the reservoir from the bottom, and more liquid passes into the funnel. The precipitate may be washed by filling the apparatus with distilled water. I t is possible to filter and wash a precipitate by the use of two reservoirs placed side by side, the second one filled with distilled water and its lower opening a little below that containing the precipitate, thus ensuring that this reservoir containing the washing liquid will remain inactive until the other is empty. A. R. T. New Steam-Meter. E. A. J. Kuhnke.( J . Soc. Che?72. I~zd., 1909, 28, 633- 636.)-The action of the meter is based on the formula W= SyV, in which W is the total steam passing through the meter, expressed in kilograms per second, S the sectional area in sq. metres, V the velocity of steam in metres per second, and y the weight of 1 cbm. of steam of the average pressure expressed in kilogrms. I n the meter described, the steam is passed downwards through a vertical truncated cone (or rather paraboloid), in which is placed a horizontal disc, suspended by a freely moving wire, and counterpoised by an external weight. As the pressure of the steam on the disc increases or diminishes, owing to a change of velocity in the supply pipes, the disc moves down or up, so that V in the above formula is always constant, as long as y is constant, and only S varies, The vertical section of the truncated cone being a parabola, the horizontal section through which the steam passes varies directly as the linear displacement of the disc from the top of the cone, and is read off by a pointer attached to the wire outside the meter.This pointer moves on a rotating cylinder of squared paper, and makes a continuous record, which can be afterwards integrated by a plani- meter if desired. The consumption of steam at any point is also given by tables supplied with the instru- ment, the values of y being calculated for both dry and wet steam at different pressures. By means of a trap in the casing of the cone, any condensed water can be removed from time to time. The apparatus is claimed to be accurate to about 3 per cent.It is made by the Farbenwerke vorm. Friedr. Bayer and GO. A. G. L.424 THE ANALYST. Pressure-Regulator for Vacuum Distillation. H. J. Reiff. (Zeit. angew' Chew., 1909, 22,1360-1361.)-Bertrand devised an automatic arrangement for main- taining a constant reduced pressure during distillation, consisting of a long barometer tube connected with an adjustable mercury reservoir and branching out at the upper end, one branch being connected with the pump and the other with the distillation vessel. The mercury trap at the fork of the branch then acted in such a way as to throw the pump in or out of connection with the flask, according to the pressure existing in the apparatus. This arrange- ment, however, is cumbersome? owing to its length, and the internal pressure corresponding to any given setting of the mercury reservoir has different values according to variations of the external atmospheric pressure. The author% apparatus surmounts both these objections by having the adjustable mercury reservoir closed from the atmosphere, and possesses the additional advantage that no rubber joints are necessary.The forked tube, GRG (see Fig.), terminates at the lower end of R in a hollow cone, into which a bent, closed tube, V, is ground to fit ; this tube can be rotated in the cone. The tube, V , and a, portion of the tube, R, contain mercury. If now the branch, G, be connected with the pump, and G with the distillation apparatus, the tube, V, being vertical, mercury will pass from V to R until it closes the fork GG. The pressure at which this cutting-off takes place may be varied by inclining the tube, V, by rotating it in the axis of the cone, and the instrument may be calibrated by means of a scale and pointer. The two arms, G and G , are provided with bulbs, KK', containing splash-traps, PF, to prevent particles of mercury from being splashed up into the connecting-tubes. J. F. B. New Back-Pressure Valve for Water-Suction Pumps. C. Gerhardt. (Zeit. anal. Chem., 1909, 48, 460-462.)-The valve consists of a vertical glass cylinder terminating at each end in two short glass tubes. The upper tube projects inside the cylinder to a point near the bottom of the latter. Inside the cylinder, and with its point in the upper tube, is placed a small rubber cone, resting on the lower shoulder of the cylinder. The whole valve is joined to the water-suction pump, either by a rubber connection, or else by sealing the lower tube to the side-tube of the pump, the upper tube communicating with the apparatus to be exhausted. If back-pressure occurs, the rubber cone is forced tightly into the upper tube, thereby closing the latter and preventing entry of water into the apparatus. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9093400419

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 425 GOVERNMENT REPORTS, ETC. Commercial Feeding-Stuffs and Agricultural Fertilisers Acts, Canada. (Edward VII., 8-9, Chaps. 15 and 16,1909. Assented to, May 19,1909.)-Under these Acts, which come into force on January 1, 1910, feeding-stuffs and fertilisers shall be considered as of distinct brands when differing either in guaranteed composition, trade- mark, name, or in any other characteristic method of marking. Each brand must bear a registration number, which must be attached to every package sold or offered for sale, and in addition the package must bear the name of the brand, the name and address of the manufacturer, and the analysis as guaranteed by the manufacturer ; in the case of feeding-stuffs, this analysis shall show the percentage content of protein, fat, and fibra.If the composition of a feeding-stuff or fertiliser be changed, a new registration number must be obtained, the former number being cancelled and not reissued. All manufacturers must obtain yearly licences. Any purchaser may have an analysis made on payment of a certain fee, provided that application be made to the Minister, and that the application be accompanied by a sample of at least one pound weight of the registered feeding-stuff or fertiliser in question. The sample must be enclosed in a sealed glass jar or bottle, and be taken in the presence of the vendor or his representative. In lots of five tons, or less, portions must be taken from each separate package, and from at least ten packages; or if less than ten packages be present, all shall be sampled.I n lots of over five tons, at least 10 per cent. of the packages shall be sampled. The portions so drawn are to be mixed, and from the mixture two samples are taken, one to be sent for analysis, and the other handed to the vendor. Inspectors appointed under the Acts shall, whenever instructed by the Minister, take samples and have them analysed by the chief analyst, whose reports shall be published annually. The Acts do not apply to feeding-stuffs and fertilisers which are manufactured to the order of the purchaser, but the latter may have analyses made of such feeding-stuffs and fertilisers on payment of a stated fee. Penalties are prescribed for non-compliance with the requirements of the Acts, for unlawful use of registration numbers, false certificates, etc.In the case of feeding-stuffs, a deficiency of 1 per cent. of the protein or fat, or an excess of 2 per cent. of fibre claimed to be present, shall not be considered as evidence of fraudulent intent if the total value of the feeding-stuff in nutrient materials is substantially equivalent to the guaranteed statement. With a similar proviso, a deficiency of 0.5 per cent. of ammonia, phosphoric acid, or potash, is allowed in the case of a fertiliser. w. P. s. FINAL REPORT OF THE ROYAL COMMISSION ON WHISKY AND OTHER POTABLE SPIRITS, 1909. The fica.1 Report of the Royal Commission on Whisky and Other Potable Spirits is issued in the form of a Blue Book (Cd. 4796). The Commissioners were Lord James of Hereford, Mr. L. N. Guillemard (Deputy Chairman of the Board of Inland Revenue), Dr.W. E. Adeney, Dr. J. R. Bradford, Dr. H. T. Brown, Dr. G. S.426 THE ANALYST. Buchanan (Inspector of Foods to the Local Government Board), Mr. J. Y. Buchanan, and Dr. A. R. Cushny, and they were directed to inquire and report : 1. Whether, in the general interest of the consumer, or in the interest of public health, or otherwise, it is desirable- (a) To place restrictions upon the materials or the processes which may be used in the manufacture or preparation in the United Kingdom of Scotch whisky, Irish whisky, or any spirit to which the term (( whisky ” may be applied as a trade description ; ( b ) To require declarations to be made as to the materials, processes of . manufacture or preparation, or age of any such spirit ; ( c ) To require a minimum period during which any such matured in bond ; and (d) To extend any requirements of the kind mentioned in the immediately preceding to any such spirit imported Kingdom.spirit should be two sub-divisions into the United 2. By what means, if it be found desirable that any such restrictions or period should be prescribed, a uniform practice in this respect may be satisfactorily secured ; and to make the like inquiry and report as regards other kinds of potable spirits which are manufactured in, or imported into, the United Kingdom. Certain legal proceedings which were taken in November, 1905, at the North London Police Court, compelled whisky traders to take united action with the common object of obtaining some final and authoritative settlement of the questions raised. The Royal Commission was appointed, and, in an interim Report issued in June, 1908, it was stated that (1) no restrictions should be placed upon the processes of, or apparatus used in, the distillation of any spirit to which the term (‘ whisky ” might be applied as a trade description ; and (2) that the term ‘‘ whisky,” having been recognised in the past as applicable to a potable spirit manufactured from malt, or malt and unmalted barley, or other cereals, the application of the term ( 6 whisky ” should not be denied to the product manufactured from such materials, Certain reservations were made in this interim Report, including the advisability or otherwise of attaching special significance to particular designations, such as ( ( Scotch whisky,” ( 6 Irish whisky,” ‘‘ grain whisky,” and “ malt whisky ”; of placing restrictions upon the use of such designations as trade descriptions, or of requiring such designations to be used in connection with the sale of whisky.The present Report deals with the matters thus reserved, states the grounds upon which the Commissioners arrived at the conclusions set out in their interim Report, and also deals with subjects which they have inquired into other than whisky. I n a short history of the term ‘‘ whisky,” the Commissioners state that it was, at the end of the eighteenth century, undoubtedly synonymous in Scotland with ‘( aqua vita:”; Robert Burns applied to the same subject the three terms “aqua vite,” 6‘ usquebae,” and ‘‘ whisky.” They say that the last eight years,practically no materials other than malt and unmalted grain have been used in either pot or patent stills in Scotland, and that no other materials have been used to any great extent in pot or patent stills in Ireland during the last fifty years, further that the Commissioners seeTHE ANALYST.427 no reason for excluding the use of maize, which is now very estensively used in the patent still process. The arguments of those who would limit the use of the term 6‘ whisky ” to the product of the pot still are classified under three heads-Historical, Chemical or Technological, and Medical. Analyses of a large number of whiskies are given in Appendices 14, F, and G to Volume I., and in Appendix Q, Volume II., of the Minutes of Evidence ; the maturity and flavour of the spirit were insisted upon by the medical witnesses.After dealing at some length with the question of processes, the conclusions to which the Commissioners have come to in that part of their inquiry are summarised as follows : The spirit which is produced and sold to the public in the United Kingdom a t the present time under the na:ne of whisky, is distilled in various kinds of apparatus which may be broadly classified as pot and patent stills. The former are used in the manufacture of whiskies with special and pronounced characteristics in the matter of flavour and taste. They vary inter se, those used in Ireland for the distillation of a fermented wort, derived from malt and unmalted barley, rye, and oats, differing, for example, in some respects, from those used in Scotland for the distillation of worts obtained solely from malt.The patent still, as applied to the production of whisky in this country, is used for the distillation of fermented worts derived from various cereals, principally maize, with the addition of a, proportion of malt. I t is adapted for the economical production from such materials of whiskies which in general have less of the pronounced characteristics above referred to. In the distilling season 1906-7 there were in England 8, in Scotland 150, and in Ireland 27 distilleries actually working. I n England 3 of these distilleries were using both pot and patent stills, and 5 patent stills only. I n Scotland 137 were using pot stills only, 10 were using patent stills only, and 3 were using both pot and patent stills.In Ireland 18 were using pot stills only, 2 were using patent stills only, and 7 were using both pot and patent stills. But the patent-still distilleries are of so much greater productive capacity than those using the pot still, that in the year 1907, 22,000,000 proof gallons of spirits were produced from patent still distilleries in Scotland and Ireland against 14,000,OO~ proof gallons produced from pot stills. Thus, nearly two-thirds of the potable spirits produced at the present time in Scotland and Ireland are distilled in patent stills. The evidence shows that such spirits have been frequently described as ‘6 whisky ” by distillers and traders since the patent still came into use ; and that for many years a section of the public, particularly in parts of Scotland and Ireland, has recognised patent-still spirit, without admixture, under the name of whisky,” and has purchased it as whisky, no attempt being made by distillers or vendors to conceal the method of distillation.Moreover, spirit produced in the patent still has long been employed for blending with or diluting whiskies of different character and distilled in different forms of still. This has been by far its largest use, and most of the whisky now sold in the United Kingdom contains in greater or less degree spirit which has been obtained by patent-still distillation. Again, apart from the fact that pot stills differ so much that a comprehensive legal definition would be diflicult to frame without either excluding certain types of still which are now commonly recognised as pot stills, or including other types which428 THE ANALYST, are not now looked upon as legitimate variations of the pot still, there are strong objections to hampering the development of an industry by stereotyping particular forms of apparatus. Finally, no evidence has been brought forward to show that the form of still has any necessary relation to the wholesomeness of the spirit produced.For these reasons the Commissioners are unable to reccmmend that the use of the word ‘( whisky ” should be restricted to spirit manufactured by the pot-still process. Their general conclusion, therefore, on this part of the inquiry is that ‘‘ whisky ” is a spirit obtained by distillation from a mash of cereal grains saccharified by the diastase of malt ; that ci Scotch whisky” is whisky as above defined, distilled in Scotland ; and that As regards the demand for a minimum quantity of malt in the mash, the Report shows the difficulty of making any such minimum as 30 per cent., and it is pointed out that the proportion of the different whiskies employed in preparing blends is controlled by an influence stronger than that of the law.The taste of the consumer creates the demand which ultimately controls the trade. The public purchases the whisky that meets its taste, and the blender must satisfy that taste or lose his trade. I t is not for the State to say what that taste ought to be. After full consideration, the Commissioners do not think it is desirable to require declarations to be made as to the materials, processes of manufacture, of preparation, or age of Scotch whisky, Irish whisky, or any spirit to which the term l C whisky ” may be applied as a trade description.The distilleries in the United Kingdom seem t o be honestly conducted, and compulsory labelling cannot be recommended as a means of protecting the consumer of whisky. What is to be labelled? For the purposes of trade the glass cannot be labelled, and the licensed victualler cannot be called upon always to show a label which the customer does not want to see. At the same time, the manufacturer or vendor of a superior article has a right to derive what benefits he can from a mark or label, and a competitor selling an inferior article should be prevented, if possible, from employing any description calculated to deceive the purchaser who wishes to buy the superior article.Irish whisky ” is whisky as above defined, distilled in Ireland. BRANDY. The Commissioners are of the opinion that the term “brandy” is applicable only to a potable spirit manufactured from fermented grape juice, and from no other materials. The compounded spirit known by the name of British brandy is entitled still to be so named and sold as “British brandy”; it is defined as “ a spirit prepared by a rectifier or compounder by redistilling duty-paid spirits, made from grain, with flavouring ingredients, or by adding flavouring materials to such spirits. The nature of these flavouring materials is regarded as a trade secret, which is not disclosed to the Excise officers, and was not disclosed to us.” Whilst certain benefits have been obtained from the adoption of an ‘<ether standard” of 80 parts of ethers per 100,000 parts of absolute alcohol (a standard largely adopted by public analysts), the Commissioners report that a standard based on a minimum quantity of ethers alone is quite incapable of affording generalTHE ANALYST* 429 protection against fraud.For instance, genuine brandies are frequently found to contain upwards of 100 parts of ethers ” per 100,000 parts of alcohol ; admixtures of such with 20 per cent. of neutral spirit would be passed as genuine brandies by the standard. Bgain, the requisite proportion of “ethers” in any spirit can be insured by the addition of suitable ‘( ethers.” The standard can, therefore, no longer be regarded as useful, and may even be mischievous.All the usual analytical data, and, in addition, the flavour, and any information obtainable from the Excise records as to the origin of the sample, should be taken into account in order to form a reliable opinion as to the genuineness or otherwise of a sample of reputed brandy. OTHER SPIRITS. Rums, gin, Geneva, liqueurs, etc., are included under this heading. Rum is defined as a spirit distilled direct from sugar-cane products in sugar-cane growing countries,” and the Commissioners insist that the Customs differentiation between “ rum,” ‘‘ rum from Jamaica,” and “ imitation- rum ” (a spirit made in countries where the sugar-cane is not grown), should be continued. Geneva, also called Hollands, is a foreign spirit imported into this country ; it resembles gin, inasmuch &S in both cases the genuine article is made from grain only, and flavoured with juniper.Gin may be defined as a spirit distilled from grain doubly rectified, and then flavoured by distillation with juniper berries and other herbs. Liqueurs are described in the Warehouse Regulations issued for the guidance of Revenue officers as “ compounded spirits, the ingredients in which interfere with the correct action of the hydrometer.” Brandy, rum, imitation rum, and Geneva are classified by the Customs as enumerated spirits; all other imported spirits come under the class ‘ I unenumerated,” and may be either sweetened or unsweetened. The sweetened varieties include vodka, arrack, kirschwasser, rye whisky, and Canadian Club whisky.The Commissioners are unable to recommend any restrictions upon the numerous materials used in the preparation of gin, Geneva, and other compounded spirits, or on the processes employed in their manufacture. They received no evidence that any spirits of this nature, with the exception of absinthe, have an especially toxic action. COMPULSORY BONDING. The Commissioners consider that they would not be justified in holding that it was necessary for the protection of the public health that any spirits should remain in bond for a minimum period. Whatever period might be fixed would inevitably be open to one of two objections; it would either impose an unnecessary burden on particular classes of spirits, or it would be too short for the maturing of other classes. With regard to the question of labelling in bond, they hope that their definitions of whisky will lead to many labels, which have hitherto only been regarded as mis- leading and of doubtful accuracy, being classed as definite misdescriptions. APPLICATION OF THE MERCHANDISE MAR.I~S ACTS AND THE SALE OF FOOD AND DRUGS ACTS TO OFFENCES CONNECTED WITH POTABLE SPIRITS.Proprietary spirits, such as well-known brands of bottled brandies and whiskies, are, as a rule, of very constant composition, and there would be little difficulty in430 THE ANALYST. distinguishing between such spirits and other spirits sold in bottles bearing false labels. But, while the makers of proprietary spirits are frequently prejudiced by the sale of these false-labelled spirits, there appears to be considerable reluctance on the part of the firms who are damaged by the malpractice to utilise the Merchandise Marks Acts for their protection.This has probably resulted from the uncertainty 8s to trade descriptions of whisky which has prevailed hitherto. In considering the application of the Sale of Food and Drugs Acts to offences connected with yotable spirits, the Commissioners state that, although it is impossible, with the present limited knowledge of the composition and properties of the secondary con- stituents of spirits, to establish trustworthy standards for controlling the description of potable spirits, they are satisfied that chemical analysis is capable of affording very important assistance in many, if not in all, cases of suspected misdescription, when the results of the analysis are taken in conjunction with other evidence, such as that of the expert taster, and Excise records when obtainable, and when a common practice as regards methods is employed.They also express themselves favourably towards a suggestion that magistrates should have the power, in certain cases, to engage the assistance of expert assessors. They also think it desirable to consider whether a committee of skilled persons may be formed under Government authority, who might assist in mitigating some of the difficulties mentioned by advising on technical questions which affect the administration of the Acts by local authorities and the practice of public analysts. w. P.s. On the “Facing” and other Methods of Preparing Rice for Sale. J. M. Hamill. (Reports of Inspectors of Foods, 1909, No. 8, 1-2l.)-The question whether the ‘‘ facing ” of rice with mineral substances constitutes a falsification being open to some doubt, the Local Government Board instructed the author to make inquiries into the conditions under which rice is prepared and sold, with a view to ascertaining how far such practices obtained, and to what extent and in what circumstances, if any, they are justified. The results of the investigation are embodied in this Report. The amount of rice milled in England is relatively small, the greater bulk of the rice consumed in this country being milled abroad, chiefly in Holland. The operation of milling includes the polishing of the grains, which is carried out in revolving cylinders lined with sheepskins ; but millers are generally not content with the appearance given to rice by this mechanical treatment, and modify it by the addition of talc to increase the polish of the grain.Pigments (ultramarine or aniline blues) are also added to improve the colour, and oil to increase the translucency. A glazing mixture-usually consisting of talc, glucose, glycerol, and starch paste-is sometimes used after the polishing process. From the results of analyses given in the Report it is seen that the talc added during the milling was without appreciable effect upon the mineral content of the rice ; glazing, however, added approximately 0.2 per cent. of mineral matter to the finished rice.Fourteen samples of rice milled in Holland yielded from 0.16 to 1-25 per cent. of extraneous mineral matter. The results obtained by Hefelmsnn (Zeit. ofentl. Chem., 1905, 2, 309) in the examination of 509 samples of rice are given in the Report.THE ANALYST, 431 These results also show that rice frequently contains from 1 to 2 per cent. of extraneous mineral matter (talc). Whilst the purchaser generally prefers highly polished to unpolished rice, and there Seems to be no reason to anticipate that injurious results are likely to follow the consumption of polished rice when the polishing materials have been used in such a way that only comparatively small amounts remain in the rice, it is quite possible that the presence of large quantities (such as 1 or 2 per cent.) of irritating mineral matter may in some cases be definitely prejudicial to health, especially as this food is given in considerable quantities to children and invalids. I t is not considered desirable that the consumer should have to rely on washing the grains to reduce the quantity of mineral matter which has been added. The small quantity of oil used in dressing rice does not appear to retard tho digestion of the rice, but on general principles the use of mineral oil should be avoided.On the whole, it seems regrettable that the practice of polishing rice with mineral matter has been allowed to grow up and reach its present proportions, but, as the process has become practically a trade custom, it is suggested that an outside limit of not more than 0.5 per cent.of mineral matter might be fixed; this would amply meet the requirements of traders who represent this practice as necessary. Authorities under the Food Acts might usefully coneider cases where the Public Analyst reports a sample of rice as containing more than 0-5 per cent. of mineral matter. Administration in this matter would probably be facilitated by taking samples, in the first instance, informally, and giving suitable notice to vendors in the locality that the subject is engaging the attention of the authority, in order that any necessary precautions may be taken in obtaining future stocks. The method proposed by Krxizan (ANALYST, 1906, 31, 263) was employed in analysing the samples of rice dealt with in this Report. w. P. s. On the Work of Inspectors of Foods, 1906-08.G. S. Buchanan. The Report deals with the work of the separate sub-division of the Medical Department of the Board which has been established to advise the Board as to the Administra- tion of the Sale of Food and Drugs Acts and other Acts relating to food questions; to deal with matters relating to the purity and adulteration of food which are brought to the Board's notice by public analysts, medical officers of health, and others; to obtain information upon special questions relating to the purity and adulteration of food, and the use of deleterious substances therein; and to make suitable inquiries and investigations for the purpose. Five reports have been issued by the sub-depart- ment during the period reported upon (see ANALYST, 1908,33,382 ; 1909,121).Local inquiries were made in certain cases, and better arrangements were made with the local authorities for taking samples under the Act ; consideration has also been given to proposals of local authorities for the modification of agreements under which the Public Analyst has been appointed. Certain authorities have shown a desire to engage local analysts who shall give their whole time to the work of their office, and it is thought that the advantages of such appointments are worthy of consideration. As the result of the investigation on the impurities of tartaric acid, citric acid, and cream of tartar, a limit of + grain per pound of lead and TaG grain per pound of432 THE ANALYST. arsenic (as arsenious oxide) was recommended in the report as guides for trade guarantees and analytical practice in dealing with these substances. The report on the misdescription of vinegar drew special attention to the varieties of vinegar which are prepared in this country, and to the definitions of vinegar which are officially prescribed by the food laws of the United States and other countries ; like definitions, if supported by administrative control, might operate to the benefit of consumer and trader in this country. Reasons are stated for considering that the powers conferred by the Sale of Food and Drugs Acts should be more strictly applied to prevent the sale as vinegar of coloured and flavoured solutions of acetic acid, and to check the sale of any vinegar containing less than 4 per cent. of acetic acid. I t was found that in one instance the practice of adulterating vinegar with sulphuric acid, which is sometimes stated to be obsolete, was still being practised. The questions of imported meat foods, home-prepared foods and wholesomeness of foods, food inspection at English ports, the Public Health 9ct, 1907, and foreign and colonial food legislation, are also discussed, mainly from a public health point of view. w. P. s. ?I.+*+++

ISSN:0003-2654    

DOI:10.1039/AN9093400425

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

432 THE ANALYST. REVIEW. A MANUAL OF VOLUMETRIC ANALYSI~. By HENRY W. SCHINPF, Ph.G., M.D. Fifth New York : John Wiley and Sons. London : Chapman and Hall, The book before us is an octavo volume of 725 pages, the present edition, we are told, being much enlarged and almost entirely rewritten. Dealing chiefly with pharmaceutical and food analysis, its avowed object is for the use of practising chemists as well as for teachers and students; and without committing ourselves to the view that there is any very pressing need at the present time for a volume of the kind, we believe that a book setting forth clearly the principles of volumetric analysis, and giving a description of the most important methods in sufficient detail, together with their limits of accuracy, would be acceptable to both students and practitioners.Too often works on analytical chemistry, whilst they may be descriptive, are empirical, and hence defective from the didactic standpoint. Any such need is, however, scarcely supplied by the appearance of Dr. Schirnpf’s book, for although freely admitting that it contains some useful matter, and is free from any glaring errors, we must confess ourselves disappointed with it. One of the defects of the book, in our opinion, is undue prolixity and, frequently, repetition. The most elementary student into whose hands it may come should be assumed to possess a knowledge of ordinary arithmetical methods of calculating an analysis, yet these calculations are set out at length, even to the extent of showing the whole of the working. Much space is also wasted by giving useless chemical equations, simple double decompositions being thus illustrated in numerous cases, whilst many reactions are equated in such detail as to have their meaning obscured.A case in point is the three equations showing oxidation by potassium bichromate. Dr. Schimpf tells us that an effort has been made to bring the work up to date, Edition. Limited. 1909. Price $5.THE ANALYST. 433 and that the processes described are mostly such as have been tried and found of value. We can, however, point out many portions of the book which are decidedly behind the times ; and with regard to the processes described, these are given one after another without any remarks as to their relative accuracy. With one general remark we cannot help disagreeing--e.g., that the results obtained by volumetric methods are, as a rule, more accurate than those obtained by gravimetric; scarcely inferior in accuracy in .the case of the best volumetric methods would have been a statement more in accordance with facts.The general principles of volumetric analysis are clearly stated, but the definition of a normal solution is, we think, cumbersome. The ionisation and tautomeric theories of indicators are given, and there is a reference to a paper on the latter by J. Steiglitz, in 1903, but no mention is made of the subsequent paper by this author (1908), in which he expressed himself in agreement with S. F. Acree, whose work, as well as that of J. T. Hewitt on the subject, is ignored. However, the chapter on indicators is a useful one.For the standardisation of hydrochloric acid, the author describes the usual methods, but he also mentions Catford’s suggestion to employ marble, although he points out the obvious sources of error likely to accrue from such a procedure. After recommending for the reduction of ferric salts the addition of small pieces of zinc, or of coarsely-powdered magnesium, the author attributes to D. J. Carnegie the statement that reduction takes place more rapidly in neutral than in acid solutions. Carnegie’s observation (J. Chenz. Soc. Trans., 1888, 53, 468) was, however, that zinc dust rapidly reduces ferric salts in neutral solution. Under water analysis, the only method given for the estimation of nitrates is the nitrophenol colorimetric method, but there is no mention of the well-known fact that the presence of chlorides impairs the accuracy of the results.For the determination of hardness the soap method only is given. The methods recommended for the determination of starch are antiquated, and some of them, notably the diastase method, are lengthy and inaccurate. No mention is made of the recent modifications of the Dubrunfaut-Effront method by Lintner, Wenglein, and Ewers. The determination of reducing sugars is dealt with in a very perfunctory manner, recent literature on the subject being entirely ignored. The estimation of alkaloids and the assay of drugs is a useful feature of the work, and covers 144 pages. The book is remarkably free from typographical errors, but we have to complain of several cases of inconsistencies and loose expressions in the text. Thus we find the words ( ( sulphocyanate ” and thiocyanate ” in different parts of the book. 6 L Nitromuriatic ” acid, which the author employs in one place, is surely an obsolete expression. We read: “If a, nitrate is heated in an alkaline solution in which nascent hydrogen i s being evolved.” Nitric acid, we are told, (‘ gives of oxygen ” to a ferrous salt, oxidising it to the ferric state. It is stated that cow’s milk is generally neutral in reaction, but no mention is made of the indicator employed ; it is needless to point out that milk is amphoteric. The book is not without its good points; but, considered as a whole, we cannot recommend it, as there are other treatises in which the subject is dealt with in a much more comprehensive and useful manner. The italics are ours. ARTHUR R. LING.

ISSN:0003-2654    

DOI:10.1039/AN9093400432

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

434 THE ANALYST. NEW BOOKS. COLLOIDS AND THE ULTRA-MICROSCOPE. A Manual of Colloid Chemistry and Ultra- microscopy. By R. ZSIGMONDY. Translated by J. ALEXANDER. New York : J. Wiley and Sons. London: Chapman and Hall. 1909. Small Svo., xiii + 245 pages, Illustrated. Cloth, 12s. 6d. net. After discussing the principles governing the colloidal condition, and the classification of colloids, the author describes the development’of the ultra-microscope, by which the range of vision is carried in the direction of molecular dimensions. The contents comprise : Limitation of the field ; classification of hydrosols according to two different points of view ; history of the irreversible colloids ; facts pointing to the homogeneity of gold hydrosols ; development of ultra-microscopy ; description of the apparatus for making visible ultra-microscopic particles ; certain terms often used herein ; principles of the ultra-microscopic investigation of fluids ; preparation of colloidal gold solutions ; ultra-microscopic examination of the solutions of gold ; motion of the gold particles; size and colour of the particles ; the colour change of the colloidal gold ; the precipitation and protection of colloidal gold ; filtration experiments ; the size of the gold particles compared with the size of other bodies; superior and inferior limits of the size of the particles; a microscopic nuclei in colourless ruby glass ; general remarks concerning metal hydrosols ; ultra-microscopic examination of certain solutions and suspensions ; ultra-microscopic investigations from the publications of other scientists ; on the formation of hydrosol and hydrogel ; recapitulation.THE MANUFACTURE OF RUBBER GOODS. A Practical Handbook for the Use of Manufacturers, Chemists, and others. English edition by E. W. LEWIS. London : C. Griffin and Go. 1909. Svo., 231 pp., with 100 Illustrations. Indexes. Cloth. Price 10s. 6d. net. The subject-matter of this book is classified as follows : Plan and arrangement of a rubber-goods factory; the raw material; the vulcanisation of rubber; the mixings ; the manufacture of soft-rubber articles ; manufacture of ebonite ; and an appendix dealing with the regeneration or reclaiming of rubber waste as carried off in rubber factories. By A. HEIL and W. ESCH. THE POISONS AND PHARMACY ACT, 1908. With Notes by H. W. GADD. London: BailliAre, Tindall, and Cox. 1909. Crown Svo., 53 pp., and Index. Price Is. net. The contents are divided into Poisons and Pharmacy Act, 1908; Poisons Schedule ; 1868 and 1908 Poisons Schedules compared ; detailed list of poisons commonly sold, showing in which part of the Schedule they are contained; Arsenic Act, 1851 ; regulations under Section 2 ; Schedule F, 1868 ; wholesale sales ; aispensing scheduled poisons ; regulations as to keeping, dispensing, and selling poisons.

ISSN:0003-2654    

DOI:10.1039/AN9093400434

出版商:RSC    

年代:1909

数据来源: RSC